WO2025045612A1

WO2025045612A1 - Accessing a heterogeneous network through a transmission and reception point or through a uplink only reception point

Info

Publication number: WO2025045612A1
Application number: PCT/EP2024/073147
Authority: WO
Inventors: Shin Horng Wong; Yassin Aden Awad; Naoki Kusashima; Vivek Sharma
Original assignee: Sony Group Corporation; Sony Europe B.V.
Priority date: 2023-08-25
Filing date: 2024-08-16
Publication date: 2025-03-06

Abstract

A method of operating a communications device is provided. The method comprises receiving, from a transmission and reception point, TRP, of a heterogeneous communications network, an indicator that provides an indication of whether the communications device is to perform a first initial access procedure for connecting to the heterogeneous communications network via the TRP or a second initial access procedure for connecting to the heterogeneous communications network via an uplink-only reception point, URP, of the heterogeneous communications network, wherein the TRP provides both uplink connectivity and downlink connectivity for the communications device, and wherein the URP provides only uplink connectivity for the communications device, determining, based on the received indicator, whether to perform the first initial access procedure or the second initial access procedure, wherein the first initial access procedure comprises selecting one of a plurality of synchronisation signal blocks, SSBs, transmitted by the TRP to the communications device and performing a first random access procedure together with the TRP on the basis of the selected SSB, and wherein the second initial access procedure comprises selecting one of the plurality of SSBs and performing a second random access procedure together with the TRP and the URP on the basis of the selected SSB, and performing the determined one of the first initial access procedure and the second initial access procedure to connect to the heterogeneous communications network.

Description

ACCESSING A HETEROGENEOUS NETWORK THROUGH A TRANSMISSION AND RECEPTION POINT OR THROUGH A UPLINK ONLY RECEPTION POINT

BACKGROUND Field of Disclosure

The present disclosure relates to communications devices and infrastructure equipment (such as transmission and reception points (TRPs)) of wireless communications networks and methods of operating such communications devices and infrastructure equipment (e.g., TRPs) for the more efficient performance of network access procedures by such communications devices.

The present application claims the Paris Convention priority from European patent application number EP23193603.0, filed on 25 August 2023, the contents of which are hereby incorporated by reference.

Description of Related Art

The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.

Previous generation mobile telecommunication systems, such as those based on the 3GPP defined UMTS and Long Term Evolution (LTE) architecture, are able to support a wider range of services than simple voice and messaging services offered by previous generations of mobile telecommunication systems. For example, with the improved radio interface and enhanced data rates provided by LTE systems, a user is able to enjoy high data rate applications such as mobile video streaming and mobile video conferencing that would previously only have been available via a fixed line data connection. The demand to deploy such networks is therefore strong and the coverage area of these networks, i.e. geographic locations where access to the networks is possible, is expected to continue to increase rapidly.

Current and future wireless communications networks are expected to routinely and efficiently support communications with an ever-increasing range of devices associated with a wider range of data traffic profiles and types than existing systems are optimised to support. For example, it is expected future wireless communications networks will be expected to efficiently support communications with devices including reduced complexity devices, machine type communication (MTC) devices, high resolution video displays, virtual reality headsets, extended Reality (XR) and so on. Some of these different types of devices may be deployed in very large numbers, for example low complexity devices for supporting the “The Internet of Things”, and may typically be associated with the transmissions of relatively small amounts of data with relatively high latency tolerance. Other types of device, for example supporting high-definition video streaming, may be associated with transmissions of relatively large amounts of data with relatively low latency tolerance. Other types of device, for example used for autonomous vehicle communications and for other critical applications, may be characterised by data that should be transmitted through the network with low latency and high reliability. A single device type might also be associated with different traffic profiles / characteristics depending on the application(s) it is running. For example, different consideration may apply for efficiently supporting data exchange with a smartphone when it is running a video streaming application (high downlink data) as compared to when it is running an Internet browsing application (sporadic uplink and downlink data) or being used for voice communications by an emergency responder in an emergency scenario (data subject to stringent reliability and latency requirements).

In view of this there is expected to be a desire for current wireless communications networks, for example those which may be referred to as 5G or new radio (NR) systems / new radio access technology (RAT) systems, or indeed future 6G wireless communications, as well as future iterations / releases of existing systems, to efficiently support connectivity for a wide range of devices associated with different applications and different characteristic data traffic profiles and requirements. The desire to support these new use-cases and scenarios gives rise to new challenges for efficiently handling communications in wireless communications systems that need to be addressed.

SUMMARY OF THE DISCLOSURE

The present disclosure can help address or mitigate at least some of the issues discussed above.

Some embodiments of the present technique can provide a method of operating a communications device. The method comprises receiving, from a transmission and reception point, TRP, of a heterogeneous communications network, an indicator that provides an indication of whether the communications device is to perform a first initial access procedure for connecting to the heterogeneous communications network via the TRP or a second initial access procedure for connecting to the heterogeneous communications network via an uplink-only reception point, URP, of the heterogeneous communications network, wherein the TRP provides both uplink connectivity and downlink connectivity for the communications device, and wherein the URP provides only uplink connectivity for the communications device, determining, based on the received indicator, whether to perform the first initial access procedure or the second initial access procedure, wherein the first initial access procedure comprises selecting one of a plurality of synchronisation signal blocks, SSBs, transmitted by the TRP to the communications device and performing a first random access procedure together with the TRP on the basis of the selected SSB, and wherein the second initial access procedure comprises selecting one of the plurality of SSBs and performing a second random access procedure together with the TRP and the URP on the basis of the selected SSB, and performing the determined one of the first initial access procedure and the second initial access procedure to connect to the heterogeneous communications network.

Such embodiments of the present technique, which, in addition to methods of operating communications devices, relate to methods of operating infrastructure equipment (e.g. TRPs), to communications devices and infrastructure equipment (e.g. TRPs), to circuitry for communications devices and infrastructure equipment (e.g. TRPs), to wireless communications systems, to computer programs, and to computer- readable storage mediums, can allow for the more efficient performance of network access procedures by such communications devices.

Respective aspects and features of the present disclosure are defined in the appended claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the present technology. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein like reference numerals designate identical or corresponding parts throughout the several views, and wherein:

Figure 1 schematically represents some aspects of an LTE-type wireless telecommunication system which may be configured to operate in accordance with certain embodiments of the present disclosure; Figure 2 schematically represents some aspects of an NR-type wireless telecommunications system which may be configured to operate in accordance with certain embodiments of the present disclosure;

Figure 3 is a schematic block diagram of an example infrastructure equipment and communications device which may be configured to operate in accordance with certain embodiments of the present disclosure;

Figure 4 schematically represents an example of a Heterogeneous Network (HetNet);

Figure 5 schematically represents an example of a HetNet including a plurality of uplink-only reception points (URPs);

Figure 6 illustrates an example of the selection of a Synchronisation Signal Block (SSB) from a set of eight SSBs using an SSB beam sweeping technique;

Figure 7 is a message flow diagram showing a typical four-step random access (RACH) procedure;

Figure 8 is a message flow diagram showing a typical two-step RACH procedure;

Figure 9 shows a part schematic, part message flow diagram representation of a heterogeneous communications system comprising a communications device and an infrastructure equipment in accordance with embodiments of the present technique;

Figures 10A and 10B illustrate scenarios in which there may, respectively, a sparse deployment of URPs and a dense deployment of URPs in accordance with embodiments of the present technique;

Figure 11 shows an example of two different sets of received signal reference power (RSRP) thresholds used to define locations of URPs in accordance with embodiments of the present technique;

Figure 12 illustrates an example scenario in which multiple URPs are deployed at the cell edges in accordance with embodiments of the present technique;

Figure 13 shows an example of SSB-to-URP association in accordance with embodiments of the present technique;

Figure 14 shows an example of a combined SSB and URP-RSRP indicator in accordance with embodiments of the present technique;

Figure 15A and 15B shows an example of SSB-to-uplink beam association in which each SSB may be associated with two sets of corresponding uplink beams in accordance with embodiments of the present technique;

Figure 16 illustrates an example of SSB-to-uplink beam association in which corresponding uplink beams for SSBs associated with URPs may be omnidirectional uplink beams in accordance with embodiments of the present technique;

Figure 17 illustrates an example of the use of beam weeping at a UE in order to determine an appropriate beam to use for transmissions to a URP in accordance with embodiments of the present technique; and Figure 18 shows a flow diagram illustrating an example process of communications in a heterogeneous communications system in accordance with embodiments of the present technique.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Long Term Evolution Advanced Radio Access Technology (4G)

Figure 1 provides a schematic diagram illustrating some basic functionality of a mobile telecommunications network / system 6 operating generally in accordance with LTE principles, but which may also support other radio access technologies, and which may be adapted to implement embodiments of the disclosure as described herein. Various elements of Figure 1 and certain aspects of their respective modes of operation are well-known and defined in the relevant standards administered by the 3GPP (RTM) body, and also described in many books on the subject, for example, Holma H. and Toskala A [1], It will be appreciated that operational aspects of the telecommunications networks discussed herein which are not specifically described (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be implemented in accordance with any known techniques, for example according to the relevant standards and known proposed modifications and additions to the relevant standards. The network 6 includes a plurality of base stations 1 connected to a core network 2, which may be for example an Evolved Packet Core (EPC). Each base station provides a coverage area 3 (i.e., a cell) within which data can be communicated to and from communications devices 4. Although each base station 1 is shown in Figure 1 as a single entity, the skilled person will appreciate that some of the functions of the base station may be carried out by disparate, inter-connected elements, such as antennas (or antennae), remote radio heads, amplifiers, etc. Collectively, one or more base stations may form a radio access network.

Data is transmitted from base stations 1 to communications devices 4 within their respective coverage areas 3 via a radio downlink (DL). Data is transmitted from communications devices 4 to the base stations 1 via a radio uplink (UL). The core network 2 routes data to and from the communications devices 4 via the respective base stations 1 and provides functions such as authentication, mobility management, charging and so on. Terminal devices may also be referred to as mobile stations, user equipment (UE), user terminal, mobile radio, communications device, and so forth. Services provided by the core network 2 may include connectivity to the internet or to external telephony services. The core network 2 may further track the location of the communications devices 4 so that it can efficiently contact (i.e., page) the communications devices 4 for transmitting downlink data towards the communications devices 4.

Base stations, which are an example of network infrastructure equipment, may also be referred to as transceiver stations, nodeBs, eNodeBs, eNB, gNodeBs, gNB and so forth. In this regard different terminology is often associated with different generations of wireless telecommunications systems for elements providing broadly comparable functionality. However, certain embodiments of the disclosure may be equally implemented in different generations of wireless telecommunications systems, and for simplicity certain terminology may be used regardless of the underlying network architecture. That is to say, the use of a specific term in relation to certain example implementations is not intended to indicate these implementations are limited to a certain generation of network that may be most associated with that particular terminology.

New Radio Access Technology (5G)

An example configuration of a wireless communications network which uses some of the terminology proposed for and used in NR and 5G is shown in Figure 2. In Figure 2 a plurality of transmission and reception points (TRPs) 10 are connected to distributed control units (DUs) 41, 42 by a connection interface represented as a line 16. Each of the TRPs 10 is arranged to transmit and receive signals via a wireless access interface within a radio frequency bandwidth available to the wireless communications network. Thus, within a range for performing radio communications via the wireless access interface, each of the TRPs 10, forms a cell of the wireless communications network as represented by a circle 12. As such, wireless communications devices 14 which are within a radio communications range provided by the cells 12 can transmit and receive signals to and from the TRPs 10 via the wireless access interface. Each of the distributed units 41, 42 are connected to a central unit (CU) 40 (which may be referred to as a controlling node) via an interface 46. The central unit 40 is then connected to the core network 20 (which may be for example referred to as 5GC) which may contain all other functions required to transmit data for communicating to and from the wireless communications devices and the core network 20 may be connected to other networks 30.

The elements of the wireless access network shown in Figure 2 may operate in a similar way to corresponding elements of an LTE network as described with regard to the example of Figure 1. It will be appreciated that operational aspects of the telecommunications network represented in Figure 2, and of other networks discussed herein in accordance with embodiments of the disclosure, which are not specifically described (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be implemented in accordance with any known techniques, for example according to currently used approaches for implementing such operational aspects of wireless telecommunications systems, e.g. in accordance with the relevant standards.

The TRPs 10 of Figure 2 may in part have a corresponding functionality to a base station or eNodeB of an LTE network. Similarly, the communications devices 14 may have a functionality corresponding to the UE devices 4 known for operation with an LTE network. It will be appreciated therefore that operational aspects of a new RAT network (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be different to those known from LTE or other known mobile telecommunications standards. However, it will also be appreciated that each of the core network component, base stations and communications devices of a new RAT network will be functionally similar to, respectively, the core network component, base stations and communications devices of an LTE wireless communications network.

In terms of broad top-level functionality, the core network 20 connected to the new RAT telecommunications system represented in Figure 2 may be broadly considered to correspond with the core network 2 represented in Figure 1, and the respective central units 40 and their associated distributed units / TRPs 10 may be broadly considered to provide functionality corresponding to the base stations 1 of Figure 1. The term network infrastructure equipment / access node may be used to encompass these elements and more conventional base station type elements of wireless telecommunications systems. Depending on the application at hand the responsibility for scheduling transmissions which are scheduled on the radio interface between the respective distributed units and the communications devices may lie with the controlling node / central unit and / or the distributed units / TRPs. A communications device 14 is represented in Figure 2 within the coverage area of the first communication cell 12. This communications device 14 may thus exchange signalling with the first central unit 40 in the first communication cell 12 via one of the distributed units / TRPs 10 associated with the first communication cell 12.

It will further be appreciated that Figure 2 represents merely one example of a proposed architecture for a new RAT based telecommunications system in which approaches in accordance with the principles described herein may be adopted, and the functionality disclosed herein may also be applied in respect of wireless telecommunications systems having different architectures.

Thus, certain embodiments of the disclosure as discussed herein may be implemented in wireless telecommunication systems / networks according to various different architectures, such as the example architectures shown in Figures 1 and 2. It will thus be appreciated the specific wireless telecommunications architecture in any given implementation is not of primary significance to the principles described herein. In this regard, certain embodiments of the disclosure may be described generally in the context of communications between network infrastructure equipment / access nodes and a communications device, wherein the specific nature of the network infrastructure equipment / access node and the communications device will depend on the network infrastructure for the implementation at hand. For example, in some scenarios the network infrastructure equipment / access node may comprise a base station, such as an LTE-type base station 1 as shown in Figure 1 which is adapted to provide functionality in accordance with the principles described herein, and in other examples the network infrastructure equipment may comprise a control unit / controlling node 40 and / or a TRP 10 of the kind shown in Figure 2 which is adapted to provide functionality in accordance with the principles described herein. A more detailed diagram of some of the components of the network shown in Figure 2 is provided by Figure 3. In Figure 3, a TRP 10 as shown in Figure 2 comprises, as a simplified representation, a wireless transmitter 30, a wireless receiver 32 and a controller or controlling processor 34 which may operate to control the transmitter 30 and the wireless receiver 32 to transmit and receive radio signals to one or more UEs 14 within a cell 12 formed by the TRP 10. As shown in Figure 3, an example UE 14 is shown to include a corresponding transmitter 49, a receiver 48 and a controller 44 which is configured to control the transmitter 49 and the receiver 48 to transmit signals representing uplink data to the wireless communications network via the wireless access interface formed by the TRP 10 and to receive downlink data as signals transmitted by the transmitter 30 and received by the receiver 48 in accordance with the conventional operation.

The transmitters 30, 49 and the receivers 32, 48 (as well as other transmitters, receivers and transceivers described in relation to examples and embodiments of the present disclosure) may include radio frequency filters and amplifiers as well as signal processing components and devices in order to transmit and receive radio signals in accordance for example with the 5G/NR standard. The controllers 34, 44 (as well as other controllers described in relation to examples and embodiments of the present disclosure) may be, for example, a microprocessor, a CPU, or a dedicated chipset, etc., configured to carry out instructions which are stored on a computer readable medium, such as a non-volatile memory. The processing steps described herein may be carried out by, for example, a microprocessor in conjunction with a random access memory, operating according to instructions stored on a computer readable medium. The transmitters, the receivers and the controllers are schematically shown in Figure 3 as separate elements for ease of representation. However, it will be appreciated that the functionality of these elements can be provided in various different ways, for example using one or more suitably programmed programmable computer(s), or one or more suitably configured application-specific integrated circuit(s) / circuitry / chip(s) / chipset(s). As will be appreciated the infrastructure equipment / TRP / base station as well as the UE / communications device will in general comprise various other elements associated with its operating functionality.

As shown in Figure 3, the TRP 10 also includes a network interface 50 which connects to the DU 42 via a physical interface 16. The network interface 50 therefore provides a communication link for data and signalling traffic from the TRP 10 via the DU 42 and the CU 40 to the core network 20.

The interface 46 between the DU 42 and the CU 40 is known as the F 1 interface which can be a physical or a logical interface. The Fl interface 46 between CU and DU may operate in accordance with 3GPP technical specifications [2] and [3], and may be formed from a fibre optic or other wired or wireless high bandwidth connection. In one example the connection 16 from the TRP 10 to the DU 42 is via fibre optic. The connection between a TRP 10 and the core network 20 can be generally referred to as a backhaul, which comprises the interface 16 from the network interface 50 of the TRP 10 to the DU 42 and the Fl interface 46 from the DU 42 to the CU 40. Although Figures 2 and 3 illustrate the TRP 10 as a separate object to the DU 42 and the CU 40, the TRP may alternatively comprise the DU 42 and/or CU 40. The term “TRP” may be used interchangeably with “gNB”.

As will be appreciated by those acquainted with 5G architecture, the CU 40 may be a logical node which hosts Radio Resource Control (RRC) protocols, Service Data Adaptation Protocols (SDAP), and Packet Data Convergence Protocols (PDCP) of a gNB. Alternatively, the CU 40 may be a logical node which hosts RRC and PDCP protocols of an en-gNB (which is a gNB that is able to connect with both EPC and eNBs and can be understood as being, for example, a secondary node (SgNB) used in dual connectivity scenarios). The CU 40 partly controls the operation of one or more DUs 40 and terminates the Fl interface 46 for the DUs that it controls. The DU 42 may be a logical node which hosts Radio Link Control (RLC), Medium Access Control (MAC), and Physical (PHY) layers of a gNB or en-gNB. The operation of the DU 42 is partly controlled by the CU 40 for which the DU 42 terminates the F 1 interface 46.

Although not shown in Figures 2 or 3, it will be familiar to those acquainted with 5G architecture that the CU 40 may be further split into a CU-CP which performs the control plane functions of the CU 40 and a CU-UP which performs the user plane functions of the CU 40 (see for example, [4]). In more detail, the CU-CP may be a logical node hosting an RRC protocol and a control plane part of a PDCP protocol of the CU 40 for the gNB or en-gNB. The CU-CP terminates an El interface connected with the CU-UP and an Fl-C interface connected with the DU 42. As will be appreciated, the Fl-C interface carries control plane signalling of the Fl interface 46. The CU-UP may be a logical node which hosts a user plane part of a PDCP protocol of the CU 40 for an en-gNB. Alternatively, the CU-UP may be a logical node which hosts a user plane part of the PDCP protocol and an SDAP protocol of the CU 40 for a gNB. The CU-UP terminates an El interface connected with the CU-CP and an Fl-U interface connected with the DU 42. As will be appreciated, the Fl-U interface carries user plane signalling of the Fl interface 46.

Heterogeneous Network (HetNet)

In a 5G operation, a Heterogeneous Network (HetNet) may be deployed. A HetNet is a network comprising a plurality of TRPs including a TRP which provides a macro cell and one or more TRPs which provide a respective one or more small cells. A TRP which provides a macro cell may alternatively be referred to as a “macro gNB”. The macro TRP may be connected to a core network via a DU and a CU (as shown in Figures 2 and 3). In some cases, the TRP may comprise the DU and CU. As will be known to one skilled in the art, a TRP providing a macro cell transmits with a higher power than a TRP providing a small cell. Therefore, a macro cell provides a larger coverage area for UEs than a small cell. As will be understood by a person skilled in the art, small cells are typically provided to alleviate a load on the TRP which provides the macro cell caused by uplink and downlink traffic. This is particularly advantageous when there is a large number of UEs present in the macro cell (referred to as “dense macro cell deployment”). Furthermore, TRPs providing small cells may be deployed near the edge of the macro cell to enhance coverage near the cell edge. An example of a HetNet is schematically illustrated in Figure 4.

As shown in Figure 4, a first TRP 402 provides a macro cell 404 for a first UE 424, a second UE 426, a third UE 428 and a fourth UE 430 located within the macro cell 404. Also shown is a second TRP 406 providing a small cell 408 for the first UE 424 which is located within the small cell 408 provided by the second TRP 406. Also shown is a third TRP 414 providing a small cell 416 for the third UE 428 which is located within the small cell 416 provided by the third TRP 414. The second UE 426 and the fourth UE 430 are located within the macro cell 404 but are not located within the small cell 408 provided by the second TRP 406 or the small cell 416 provided by the third TRP 414.

Although not shown in Figure 4, the second TRP 406 and the third TRP 414 may be connected to the first TRP 402 via wired backhaul connections such as fibre optic cables or wireless backhaul connections, thereby allowing communication between the first TRP 402 and the second TRP 406 and between the first TRP 402 and the third TRP 414. When the second TRP 406 and the third TRP 414 are connected to the first TRP 402, scheduling may be coordinated and multi-TRP MIMO may be provided.

A technical problem associated with HetNets is that UEs, particularly those near the edge of a small cell, may experience significant downlink interference from the TRP which provides the macro cell. For example, as shown in Figure 4, the first UE 424 is located near the edge of the small cell 408 provided by the second TRP 406. The first UE 424 is receiving a downlink transmission 420 from the second TRP 406. At the same time, the second UE 418 is receiving a downlink transmission 418 from the first TRP 402. Since the first UE 424 is near the edge of the small cell 408 provided by the second TRP 406, a power of the downlink transmission 420 from the second TRP 406 is likely to be lower than a power of the downlink transmission 418 from the first TRP 402 at the location of the first UE 424. Therefore, the downlink transmission 418 from the first TRP 402 causes significant interference 418a to the downlink transmission from the second TRP 406.

Similarly, UEs being served by the TRP providing the macro cell may experience significant downlink interference from UEs being served by a TRP providing a small cell. For example, as shown in Figure 4, the fourth UE 430 is located near the edge of the macro cell 404 provided by the first TRP 402. The fourth UE 430 is receiving a downlink transmission 432 from the first TRP 402. At the same time, the third UE 428 is receiving a downlink transmission 422 from the third TRP 414. Since the fourth UE 430 is near the edge of the macro cell 404 provided by the first TRP 402, a power of the downlink transmission 432 from the first TRP 402 is likely to be lower than a power of the downlink transmission 422 from the third TRP 414 at the location of the fourth UE 430. Therefore, the downlink transmission 422 from the third TRP 414 causes significant interference 422a to the downlink transmission 432 from the first TRP 402.

On the other hand, uplink interference may also be experienced in HetNet deployments. For example, interference may occur between an uplink transmission from a UE to a TRP providing a small cell and an uplink transmission from another UE to a TRP providing a macro cell, or another small cell. However, uplink interference can typically be reduced by one of the UEs reducing a transmission power of its uplink transmission.

Uplink-only Reception Point (URP)

It has been observed that there is often a bottleneck of uplink traffic in dense macro cell deployments. The load caused by the uplink traffic on the TRP providing the macro cell can be alleviated by providing a HetNet deployment such as that described with reference to Figure 4. However, as described above, such networks can present significant problems due to downlink interference. Recognising this, it has been proposed to introduce uplink-only reception points (URP) in HetNets (see [5] for example). URPs are configured to receive uplink transmissions from UEs but cannot transmit downlink transmissions to UEs. A URP may be connected to a TRP providing a macro cell via a wired backhaul connection, such as a fibre optic cable, thereby allowing communication between the URP and the TRP providing the macro cell. By deploying URPs in a HetNet, the load on the TRP providing the macro cell can be alleviated and the downlink interference which would otherwise be experienced, or caused, by TRPs providing small cells can be prevented. However, URPs are not able to alleviate the load on the TRP providing the macro cell caused by downlink transmissions. URPs deployed near the macro cell edge may increase the throughput of a UE being served by that URP because the UE may be close to the URP and therefore likely have better radio conditions with the URP compared to the TRP providing the macro cell. Furthermore, UEs near the macro cell edge may transmit uplink transmissions to the URP with a lower transmission power than a transmission power with which the UE transmits uplink transmissions to the TRP providing the macro cell, which results in reduced uplink interference. Furthermore, URPs can be low cost because they do not require a wireless transmitter for communicating downlink transmissions to UEs. URPs may also help replace dual connectivity (DC) and solve uplink problems such as traffic split ratio and power sharing in DC scenarios. Traffic split ratios and power sharing are typically semi statically configured in DC but they may be dynamically configured if URPs are used. An example of a HetNet which includes URPs is shown in Figure 5. As shown in Figure 5, a first TRP 502 provides a macro cell 504 for a first UE 534, a second UE 536, a third UE 538 and a fourth UE 540 located within the macro cell 504. Also shown is a first URP 506 providing a small cell 508 for the first UE 534 which is located within the small cell 508 provided by the first URP 506. Also shown is a second URP 510 providing a small cell 512 for the third UE 538 which is located within the small cell 512 provided by the second URP 510. Also shown is a second TRP 514 providing a small cell 516 for the fourth UE 540 which is located within the small cell 516 provided by the second TRP 514. The second UE 536 is located within the macro cell 504 but is not located within the small cell 508 provided by the first URP, the small cell 512 provided by the second URP 510 or the small cell 516 provided by the second TRP 514.

Since the first UE 534 is located within the macro cell 504 provided by the first TRP 502 and the small cell 508 provided by the first URP 506, then the first UE 534 is served by the first URP 506 for uplink transmissions 520 and is served by the first TRP 502 for downlink transmissions 518. In other words, the first UE 534 is able to transmit uplink transmissions 520 to the first URP 506 and receive downlink transmissions 518 from the first TRP 502.

Since the second UE 536 is within the macro cell 504 provided by the first TRP 502 but is not located within the small cell 508 provided by the first URP, the small cell 512 provided by the second URP 510 or the small cell 516 provided by the second TRP 514, then the second UE 536 is served by the first TRP 502 for uplink transmissions 522 and downlink transmissions 524. In other words, the second UE 536 is able to transmit uplink transmissions 522 to the first TRP 502 and receive downlink transmissions 524 from the first TRP 502.

Since the third UE 538 is located within the macro cell 504 provided by the first TRP 502 and the small cell 512 provided by the second URP 510, then the third UE 538 is served by the second URP 510 for uplink transmissions 528 and is served by the first TRP 502 for downlink transmissions 526. In other words, the third UE 538 is able to transmit uplink transmissions 528 to the second URP 510 and receive downlink transmissions 526 from the first TRP 502.

Since the fourth UE 540 is located within the small cell 516 provided by the second TRP 514, then the fourth UE 540 is served by the second TRP 514 for uplink transmissions 532 and for downlink transmissions 530. In other words, the fourth UE 540 is able to transmit uplink transmissions 532 and receive downlink transmissions 530 from the second TRP 514.

Although not shown in Figure 5, the first URP 506, second URP 510 and second TRP 514 may be connected to the first TRP 502 via a wired backhaul connections, such as fibre optic cables, thereby allowing communication between the first URP 506, second URP 510, second TRP 514 and the first TRP 502.

Initial Access

The Synchronisation Signal Block (SSB) is used for initial access and cell reselection, which consists of a Primary Synchronisation Signal (PSS), a Secondary Synchronisation Signal (SSS) and the Physical Broadcast Channel (PBCH). The PSS and SSS are used for detection and synchronisation with the gNB and the PBCH carries the Master Information Block which contains broadcast information regarding the cell and the location of System Information Blocks (SIBs) for further access information, such as RACH configurations. The SSB is transmitted periodically with a configurable periodicity from 5 ms to 160 ms. An SSB burst set contains a set of one or more time-multiplexed SSBs, where each SSB is associated and transmitted using a beam, which enables beam sweeping to be implemented for SSB. The SSB burst set is confined within a 5 ms and can contain up to 4, 8 and 64 SSBs for frequency bands below 3 GHz, between 3 GHz - 6 GHz and for Frequency Range 2 (FR2) which is defined as frequency between 24.25 GHz and 71 GHz, respectively.

An example of SSB beam sweeping is shown in Figure 6, where a gNB 601 configures a SSB burst set consisting of eight SSBs (labelled SSB1 to SSB8), where each of these eight SSBs have a different beam direction covering the cell controlled by the gNB 601. A UE 602 measures the RSRP of the SSBs in an SSB burst set, and selects an SSB that has an RSRP above a predefined threshold rsrp-ThresholdSSB . In the example of Figure 6, this selected SSB is SSB4. Each SSB can be associated with up to eight RACH Occasions (ROs). An RO can also be configured to be associated with more than one SSB. The RO and SSB association are indicated in the SIBs.

Each SSB may have a corresponding UL beam, which may be used by the UE 602 for the transmission of an initial message such as a Physical Random Access Channel (PRACH) preamble or a Message A to the network. The SSB-corresponding UL beam has a beam direction which is reciprocal to the direction of the SSB beam, so that any UL transmissions from the UE 602 using that beam are directed towards the gNB 601. For example, in Figure 6, UE 602 selects SSB4, which has a corresponding UL beam 603 directed towards the gNB 601.

After the selection of the SSB, the UE 602 can access the network using 4 step RACH or 2 step RACH, which are described in more detail below.

Random Access (RACH) Procedures

In wireless telecommunications networks, such as LTE and NR type networks, there are different Radio Resource Control (RRC) modes for terminal devices. For example, it is common to support an RRC idle mode (RRC IDLE), an RRC inactive mode (RRC INACTIVE), and an RRC connected mode (RRC CONNECTED). A terminal device in the idle mode may transition to connected mode, for example because it needs to transmit uplink data or respond to a paging request, by undertaking a random access procedure. The random access procedure involves the terminal device transmitting a preamble on a physical random access channel, and so the procedure is commonly referred to as a RACH or PRACH procedure / process.

In addition to a terminal device deciding itself to initiate a random access procedure to connect to the network, it is also possible for the network, e.g. a base station, to instruct a terminal device in connected mode to initiate a random access procedure by transmitting to the terminal device an instruction to do so. Such an instruction is sometimes referred to as a PDCCH order (Physical Downlink Control Channel order). There are various scenarios in which a network triggered RACH procedure (PDCCH order) may arise.

Figure 7 shows atypical four-step RACH procedure used in LTE systems such as that described by reference to Figure 1 which could also be applied to an NR wireless communications system such as that described by reference to Figure 2. A communications device (or UE), which could be in an inactive or idle mode, may have some data which it needs to send to the network (e.g. to a gNB). To do so, the UE first selects an RO associated with its selected SSB for PRACH transmission, where the PRACH is transmitted using a UL-corresponding beam of the selected SSB. Using the example of Figure 6, the UE measures each SSB and here the UE selects SSB4 which has the highest RSRP (or, alternatively, has an RSRP above a predefined threshold). The UE then transmits a random access preamble 701 (message 1), which is also referred to as a PRACH, to the gNB. This random access preamble 701 indicates the identity of the communications device to the gNB, such that the gNB can address the communications device during later stages of the RACH procedure.

After the PRACH transmission, the UE expects to receive a Random-Access Response (RAR) from the gNB. Assuming the random access preamble 701 is successfully received by the gNB, the gNB will transmit a random access response (RAR) 702 message (message 2) to the communications device(s) based on the identity indicated in the received random access preamble 701. The random access response 702 message carries a further identity which is assigned by the gNB to identify the communications device, as well as a timing advance value such that the communications device can change its timing to compensate for the round trip delay caused by its distance from the gNB and grant uplink resources for the communications device to transmit the data in. The RAR is carried by a PDSCH and that PDSCH is scheduled by a DL Grant carried by a PDCCH with CRC masked with RA-RNTI. The UE monitors for this PDCCH in the earliest PDCCH Type 1 Common Search Space (CSS) within a RAR Window. The RAR Window starts at the first occurrence of PDCCH Type 1 CSS after the RO and has a duration configured by the parameter ra-ResponseWindow that can have values { 1, 2, 4, 8, 10, 20, 40, 80} slots. If the UE fails to detect a RAR from the gNB, the UE will attempt to transmit another PRACH until a maximum number of attempts is reached. The RAR is transmitted using the same beam as the selected SSB and indicates the preamble that it responds to. As noted above, the RAR contains an UL Grant for Message 3.

Following the reception of the random access response message 702, the communications device transmits the scheduled transmission of data 703 to the gNB (message 3), using the identity assigned to it in the random access response message 702, and in the Physical Uplink Shared Channel (PUSCH) as scheduled by the UL grant in the RAR. Assuming there are no collisions with other UEs, which may occur if another UE and the communications device send the same random access preamble 701 to the gNB at the same time and using the same frequency resources, the scheduled transmission of data 703 is successfully received by the gNB. The UE also transmits an ID, e.g., TC-RNTI (Temporary C-RNTI), in message 3 for contention resolution purposes. The gNB will respond to the scheduled transmission 703 with a contention resolution message 704 (message 4) , which for initial access, contains an RRC Connection Setup message for the UE. The gNB will also indicate the UE ID that the message 4 is intended for. This allows for contention resolution since there may be more than one UE using the same preamble (and SSB) in its PRACH transmission. The UE is then connected to the network and the RACH process ends.

In addition to the four-step RACH procedure described above with respect to Figure 7, a UE may connect to the network through performance of a two-step RACH procedure. As will be appreciated, compared with the four-step RACH process, the two-step RACH process can provide a facility for transmitting data more quickly. Accordingly, it has been proposed to develop general MAC procedures covering both physical layer and higher layer aspects for the two-step RACH process. In general, the benefit of the two- step RACH procedure compared with the four-step PRACH procedure is to reduce the time it takes for connection setup/resume procedure. For example, in an ideal situation, the two-step RACH will reduce the latency by halving the number of steps from four to two for initial access UEs.

Broadly, the two-step RACH allows the combination of the transmission of the random access preamble 701 with the transmission of data 703 of Figure 7 as an initial transmission (“Message A” or “MsgA”), and similarly the combination of the transmission of the random access response 702 and contention resolution message 704 as a response (“Message B”, or “MsgB”). A fallback procedure may be provided to allow a RACH procedure which is started according to the specifications for a two-step RACH to instead proceed according to the four-step RACH procedure. Two-step RACH may be applicable for communications devices in the RRC INACTIVE, RRC CONNECTED and RRC IDLE states.

A message flow diagram illustrating the two-step RACH process is shown in Figure 8. As its name suggests, in the two-step RACH process, there are only two-steps as noted above. In the first step, the UE transmits a Message A 801, using the S SB-corresponding UL beam, where this Message A 801 comprises a RACH preamble (i.e. PRACH) 802 and data 803. The data 803 is transmitted on a shared uplink channel, such as a PUSCH that in a four-step RACH procedure would be transmitted in Message 3. More specifically, the choice of a particular preamble 802 may pre-configure the communications device to transmit the data 803 in pre-configured resources of the uplink shared channel. In the second step, the network, having successfully received the Message A 801, responds with a Message B 804 which incorporates both a RAR, as would be carried by message 2 of the four-step RACH procedure described above, and the corresponding contention resolution and/or data (PDSCH) that in a four-step RACH procedure would be transmitted in Message 4. The RAR contains the RRC Connection Setup message, which enables the UE to establish an RRC connection with the network.

Technical Issue with Initial Access in Deployments Utilising URPs

Since a URP does not transmit in the DL, and therefore does not transmit any SSBs, the UE cannot detect its presence. That is, the UE would not be aware whether or not it is within the UL coverage of a URP. For initial access, it is therefore challenging for the UE to direct its PRACH preamble towards an appropriate URP. Hence, an initial access procedure that utilises the benefit of URP is required. Arrangements of embodiments of the present technique propose solutions to such a problem.

Initial Access Procedure for UL-only Reception Points (URPs)

Figure 9 shows a part schematic, part message flow diagram representation of a first heterogeneous communications system comprising a first infrastructure equipment (e.g. TRP such as a gNB) 901, a second infrastructure equipment (e.g. a URP) 902, and a communications device 903 (e.g. a UE 14) in accordance with at least some embodiments of the present technique. Here, the TRP 901 provides both uplink connectivity and downlink connectivity for the communications device 903, while the URP 902 provides only uplink connectivity for the communications device 903; that is, the URP 902 is unable to transmit downlink signals to the communications device 903. The TRP 901 is configured to transmit signals to and receive signals from the URP 902 via a backhaul communications link. The TRP 901, URP 902, and communications device 903 each comprise a transceiver (or transceiver circuitry) 901.1,

902.1, 903.1, and a controller (or controller circuitry) 901.2, 902.2, 903.2. Each of the controllers 901.2,

902.2, 903.2 may be, for example, a microprocessor, a CPU, or a dedicated chipset, etc.

As shown in the example of Figure 9, the transceiver circuitry 903.1 and the controller circuitry 903.2 of the communications device 903 are configured in combination to receive 904, from the TRP 901, an indicator that provides an indication of whether the communications device 903 is to perform a first initial access procedure 910 for connecting to the heterogeneous communications network via the TRP 901 or a second initial access procedure 920 for connecting to the heterogeneous communications network via the URP 902, to determine 906, based on the received indicator 904, whether to perform the first initial access procedure 910 or the second initial access procedure 920, wherein the first initial access procedure 910 comprises the communications device 903 being configured to select 911 one of a plurality of synchronisation signal blocks, SSBs, transmitted by the TRP 901 to the communications device 903 and to perform 912 a first random access procedure together with the TRP 901 on the basis of the selected SSB 911, and wherein the second initial access procedure 920 comprises the communications device 903 being configured to select 921 one of the plurality of SSBs and to perform 922 a second random access procedure together with the TRP 901 and the URP 902 on the basis of the selected SSB 921, and to perform 908 the determined 906 one of the first initial access procedure 910 and the second initial access procedure 920 to connect to the heterogeneous communications network. Here, each of the first random access procedure 912 or the second random access procedure 922 may either be a four-step RACH procedure such as that described above with respect to Figure 7 or a two-step RACH procedure such as that described above with respect to Figure 8.

Essentially, such embodiments of the present technique as exemplified by Figure 9 propose that the network (e.g. the TRP within the cell of which the UE is currently located, which may be a macro gNB) indicates to the UE whether the UE should perform a first initial access procedure or a second initial access procedure. Here, specifically, the first initial access procedure is the legacy initial access procedure for access to the (macro) TRP, while the second initial access procedure is targeted at a URP. In accordance with such embodiments of the present technique, of which further specific arrangements are described in the paragraphs below, and throughout the present disclosure, reference to the terms TRP and macro gNB (or indeed just gNB) is made interchangeably, where such terms are considered to refer to the same thing.

In some arrangements of embodiments of the present technique, the gNB indicates for the entire cell whether the UE performs the first initial access procedure or the second initial access procedure. In other words, the indicator may explicitly indicate that the communications device is to perform the first initial access procedure or the second initial access procedure. That is, regardless of whether the UE is near to a URP or not, the UE will perform the indicated initial access procedure. This can be implemented with a single bit in the SIBs (transmitted to the UE by the gNB/TRP) that indicates whether or not the UE is to use the first or second initial access procedure. That is, the network can enable the second initial access procedure or disable it, and when it is disabled, the UE uses the first initial access procedure.

Figures 10A and 10B show an example application of such arrangements. As can be seen in the first scenario as shown in Figure 10A, there is a single URP 1001 located in a cell controlled by a TRP/macro gNB 1000. Here, the operator can indicate to the cell to use the first initial access procedure if the URP deployment is sparse, as is the case in Figure 10A, and the gNB 1000 can therefore transmit an indication to any UEs in the cell to do so as described above. This recognises that the probability of a UE being near to a URP 1001 is low and so it is more sensible to use the first initial access procedure targeting the macro-gNB 1000. On the other hand, if the URP deployment is dense like in Figure 10B, where there are eight URPs 1011, 1012, 1013, 1014, 1015, 1016, 1017, 1018 located within the cell controlled by a TRP/macro gNB 1010, then the probability of a UE being near to a URP 1011 to 1018 is much higher than in the case of Figure 10A. Therefore, it is sensible for such a UE to use the second initial access procedure to target a URP and benefit from the advantages offered by the URP as discussed above with respect to the example of Figure 5.

In some arrangements of embodiments of the present technique, when the network indicates that the UE uses the second initial access procedure, the network also indicates a probability PURP that the UE should use the second initial access procedure. In other words, the indicator may comprise an indication of a probability with which the communications device is to perform the second initial access procedure. That is, if the network enables second initial access procedure for the cell, a UE has a probability of PURP of using the second initial access procedure. This enables the network to avoid congesting any URP, especially if the URP density is sparse. This also enables the network to adapt the network in cases where the deployment of URPs is gradual, for example, if the deployment starts off with sparse density of URP and slowly add more URPs to increase their density. Here, the network may only indicate one probability (i.e. the probability PURP that the UE should use the second initial access procedure), where the probability that the UE would use the other (i.e. first) initial access procedure is therefore implicit. However, in some implementations, the network may indicate both the probability PURP that the UE should use the second initial access procedure and a probability PTRP that the UE should use the first initial access procedure. In some implementations, the probability PTRP = 1 - PURP.

For example, the network may enable the second initial access procedure and set PURP = 0.1 for the sparse URP deployment shown in Figure 10A. When the UE wants to access the network, it may generate a random number between 0 to 1 from a uniform distribution. If the generated random number is smaller than PURP, then the UE uses the second initial access procedure to access the network via the URP 1001, or otherwise it uses the first initial access procedure to access the network via the TRP 1000. Hence, a UE has a probably of 10% of using the URP 1000 or only 10% of the UEs within the cell would use the URP 1001 in a sparse URP deployment such as that illustrated by Figure 10A. On the other hand, for denser URP deployments such as that shown in Figure 10B, the network may set PURP = 0.8 SO that a UE has a probability of 80% of using one of the large number of URPs 1011 to 1018 or 80% of the UEs located in the cell will use the second initial access procedure to access the network via one of the one of the larger number of URPs 1011 to 1018.

In some arrangements of embodiments of the present technique, the gNB configures one or more sets of RSRP thresholds { URP-RSRPMIN , URP-RSRPMAX} . Here, a UE performs the second initial access procedure if its measured RSRP (of reference signals received from the TRP, since the UE cannot receive any reference signals from the URP which has no downlink transmitter) is between URP-RSRPMIN and URP-RSRPMAX, i.e., URP-RSRPMIN < Measured RSRP < URP-RSRPMAX, and otherwise the UE uses the first initial access procedure. In other words, the indicator comprises an indication of at least a first set of upper and lower threshold signal strengths (where, for example, the first set may be associated with the URP) and wherein the communications device determines that it is to perform the second initial access procedure if a measured strength of a signal received by the communications device from the TRP is between the upper threshold signal strength and the lower threshold signal strength (and therefore the communications device determines that it is to perform the first initial access procedure if the measured strength of the signal is outside of the range defined by the upper threshold signal strength and the lower threshold signal strength). This allows the operator to deploy URPs within a certain range from the macro-gNB, and the thresholds URP-RSRPMIN and URP-RSRPMAX can be determined a-priori, e.g., during setup of the URP, to provide an estimation of where the deployed URPs are; if a UE has an RSRP measurement from signals received from the TRP within a range defined by such thresholds, then it is likely to be located close to the URP, or at least, a similar distance from the TRP as the URP. Therefore, it is sensible for the UE to - at least at first - try to connect to the network by performing the second initial access procedure with the URP.

Such arrangements are not restricted to only one set of URP-RSRPMIN and URP-RSRPMAX thresholds, but they can be multiple sets of thresholds to locate the URP. In other words, the indicator comprises an indication of one or more further sets of upper and lower threshold signal strengths different to the first set (where, for example, each of the further sets may be associated with one of one or more further URPs of the heterogeneous communications network).

An example is shown in Figure 11, where a macro-gNB 1100 coverage has two URPs 1101, 1102 at different range from the macro-gNB 1100. Using such arrangements, the gNB 1100 can indicate two sets of RSRP thresholds, {URP-RSRP#1MIN, URP-RSRP#1MAX} and {URP-RSRP#2MIN, URP -RSRP# 2MAX} for URP 1101 and URP 1102 respectively. A UE falling within either one of these sets of RSRP thresholds would use the second initial access procedure to connect to the network via one of the URPs 1101, 1102, and a UE falling outside all of these sets of RSRP thresholds would use the first initial access procedure to connect to the network via the TRP 1100. In some arrangements of embodiments of the present technique, the gNB indicates a single RSRP threshold URP-RSRP. Here, the UE uses the first initial access procedure if its measured RSRP is above URP-RSRP, i.e., measured RSRP > URP-RSRP, while otherwise, if it is below URP-RSRP, i.e., measured RSRP < URP-RSRP, the UE uses the second initial access procedure. In other words, the indicator comprises an indication of a threshold signal strength, and wherein the communications device determines that it is to perform the second initial access procedure if a measured strength of a signal received by the communications device from the TRP is below the threshold signal strength (and therefore the communications device determines that it is to perform the first initial access procedure if the measured strength of the signal is above the threshold signal strength). The URP-RSRP can be set for URPs at the cell edge. Such arrangements recognise that URPs are most beneficial when deployed at the cell edge further away from the macro-gNB/TRP. UEs which are located at the cell edge can therefore avoid transmitting at high transmission powers to reach the macro-gNB and can instead use a lower transmission power to reach one of the URPs and, being closer to the URP, the UE can also support a higher UL throughput with the URP compared to the macro-gNB.

An example is in Figure 12 showing a macro-gNB 1200 with four URPs 1201, 1202, 1203, 1204 located at various places close to the cell edge of the macro-gNB ’s 1200 coverage. A URP-RSRP is indicated, where such a threshold is illustrated by the dotted circle in Figure 12. A first UE 1211 located within the cell of the macro-gNB 1200 has an RSRP that is poorer, i.e., lower than URP-RSRP (as the UE 1211 is located outside of the dotted circle shown) and hence this UE 1211 uses the second initial access procedure and target its PRACH 1220 to URP 1201. Meanwhile, a second UE 1212 has an RSRP greater than URP-RSRP (as the UE 1212 is located within the dotted circle shown) and so it uses the first initial access procedure where it transmits its PRACH 1230 targeting the macro-gNB 1200.

In some arrangements of embodiments of the present technique, the network indicates the set of SSBs that uses the first initial access procedure and another set of SSBs that uses the second initial access procedure. In other words, the indicator comprises an indication of whether each of the plurality of SSBs forms part of a first set of SSBs associated with the first initial access procedure or a second set of SSBs associated with the second initial access procedure. Each SSB is associated with a beam direction which provides an estimation of the UE’s location in the macro cell coverage and thereby the network can determine whether that UE is close to a URP or not. That is, the network indicates a SSB to URP association to the UE.

The UE may select the appropriate SSB to use in accordance with the legacy manner as described above with respect to Figure 6 (e.g. the UE selects an SSB that has an RSRP above a predefined threshold rsrp- ThresholdSSB), though the UE may select an SSB to use in accordance with any appropriate method. After selecting the SSB, the UE then determines from the indicator which set of SSBs the selected SSB belongs to, and performs the appropriate initial access procedure on this basis. In other words, when performing the step of determining whether to perform the first initial access procedure or the second initial access procedure, the communications device may be configured to select one of the plurality of SSBs, to determine whether the selected SSB forms part of the first set of SSBs or the second set of SSBs, and to determine either that the communications device is to perform the first initial access procedure if the selected SSB forms part of the first set of SSBs or that the communications device is to perform the second initial access procedure if the selected SSB forms part of the second set of SSBs. Here, when performing the step of selecting the one of the plurality of SSBs, the communications device may be configured to measure a strength of each of the plurality of SSBs, and to select the selected SSB on the basis of the selected SSB having either a highest measured strength from among the plurality of SSBs or having a measured strength above a predefined threshold strength. An example is shown in Figure 13, where a macro-gNB 1300 uses eight SSB covering the macro cell. Two URPs 1301, 1302, are deployed within the macro coverage. The gNB 1300 indicates (for example, in the SIB) that one SSB set {SSB1, SSB6, SSB8} uses the second initial access procedure and the remaining SSBs, i.e. another SSB set {SSB2, SSB3, SSB4, SSB5, SSB7} uses the first initial access procedure. As part of the initial access, a first UE 1311 selects SSB4 and, since SSB4 is associated with the first initial access procedure, the first UE 1311 transmits its PRACH 1320 targeting the macro-gNB 1300 by using the UL-corresponding beam of SSB4. A second UE 1312 selects SSB 1, which is associated with the second initial access procedure and so this second UE 1312 transmits its PRACH 1330 targeting URP 1302.

The above-described arrangements of embodiments of the present technique can be implemented individually or combined in any logical manner, such that multiple indicators may be used to more efficiently and effectively inform UEs which initial access procedure to perform. For example, the indicator described above with respect to Figure 13 defining the SSB and URP association can be combined one of the indicators relating to RSRP thresholds as described above with respect to Figures 11 and 12. That is, in one example, the UE may be provided by the TRP with a set of SSBs for which the UE will use the second initial access procedure, but only if its RSRP measurement of reference signals received from the TRP is below URP-RSRP.

An example implementation of a combined indicators is shown in Figure 14, where here the macro-gNB 1400 uses eight SSBs and configures in the SIBs that for UEs that select SSBs from the set {SSB1, SSB6} and where their RSRP measurements are also below URP-RSRP, then they will use the second initial access procedure to connect to the network. Otherwise, such UEs will use the first initial access procedure to connect to the network. The URP-RSRP threshold is also configured in the SIBs, and it is represented by the dotted circle shown in Figure 14. A first UE 1411 selects SSB6, which is associated with a URP (i.e. URP 1401) but since its RSRP is greater than URP-RSRP - i.e. the first UE 1411 is inside of the dotted circle shown in Figure 14, the first UE 1411 uses the first initial access procedure, i.e., it follows the legacy procedure and transmits its PRACH 1420 using the UL-corresponding beam for SSB6, targeting the macro-gNB 1400. A second UE 1412 selects SSB1 which is also associated with a URP (i.e. URP 1402) and the second UE’s 1412 RSRP measurement is below URP-RSRP, thereby meeting the two conditions to use the second initial access procedure. Accordingly, here, the second UE 1412 transmits its PRACH 1430 targeting URP 1402.

It should be appreciated by those skilled in the art that the example of combined indicators illustrated Figure 14 is not the only combination that can be implemented, and other combinations can be used in accordance with the arrangements of embodiments of the present technique as described above.

The first initial access procedure targets the PRACH to a TRP such as the macro-gNB, and here the legacy initial access procedure can be used. The below paragraphs describe some arrangements of embodiments of the present technique detailing how the second initial access procedure is performed by UEs. As described above, in the second initial access procedure, the UE firstly selects a SSB from a TRP such as, but not limited, to the macro-gNB, as per the legacy procedure. The SSB selection is required since the gNB needs to transmit the RAR or Message B using the same beam as the selected SSB to reach the UE, because the URP has no downlink transmitter and cannot transmit these messages itself.

In some arrangements of embodiments of the present technique, if the UE fails to access the network using the second initial access procedure, the UE will switch and use the first initial access procedure. In other words, the communications device may be configured to determine that the communications device has been unable to connect to the heterogeneous communications network by performing the second initial access procedure, and to perform, in response to determining that the communications device has been unable to connect to the heterogeneous communications network by performing the second initial access procedure, the first initial access procedure to connect to the heterogeneous communications network. For example, the UE may attempt the second initial access procedure for a predetermined number of attempts, and it fails, it will switch to the first initial access procedure. That is, this acts as a fallback mechanism for the UE. Here, the operation in terms of how the fallback is performed by UEs may be indicated (e.g. dynamically or semi-statically) to such UEs by the network (e.g. by the TRP/macro-gNB), or this may be something known to the UE (and TRP) in advance and defined in the specifications.

In some arrangements of embodiments of the present technique, the gNB configures a separate set of RACH Occasions (ROs) for the second initial access procedure as compared to those used for the first initial access procedure. In other words, the second random access procedure may be initiated by the communications device by transmitting a first message to the URP in a second set of uplink resources, wherein the second set of uplink resources is different to a first set of uplink resources configured for the transmission of a first message of the first random access procedure to the TRP. Here, such first and second sets of uplink resources may be configured by the network, and may therefore be indicated (e.g. dynamically or semi-statically) to such UEs by the network (e.g. by the TRP/macro-gNB). Alternatively, this may be something known to the UE (and TRP) in advance and defined in the specifications. That is, the second initial access procedure has a different SSB-to-RO association to that of the first initial access procedure, which enables the network to know that the UE is targeting a URP. Here, these different ROs/sets of resources may be completely different sets of resources in time and frequency, but also may be resources which overlap (e.g. in frequency) but which have time resources by having different periodicities for the first random access procedure and the second random access procedure. The ROs/sets of resources may also have overlapping time resources but separate frequency resources for the first random access procedure and the second random access procedure.

In some arrangements of embodiments of the present technique, the gNB configures separate preambles for the second initial access procedure. In other words, the second random access procedure may be initiated by the communications device by transmitting a first message to the URP, the first message comprising one of a second set of preamble signals, wherein the second set of preamble signals is different to a first set of preamble signals configured for the transmission of a first message of the first random access procedure to the TRP. Here, such first and second sets of preambles may be configured by the network, and may therefore be indicated (e.g. dynamically or semi-statically) to such UEs by the network (e.g. by the TRP/macro-gNB). Alternatively, this may be something known to the UE (and TRP) in advance and defined in the specifications. This enables the gNB to distinguish between a PRACH transmission targeting a URP as compared to a PRACH transmission targeting a TRP such as the macro- gNB. Using different preambles enables the gNB to share the RO resources for UEs targeting URPs and TRPs; that is, the same RO resources can be used by both URPs and TRPs, but where they use different sets of preambles to enable the gNB to distinguish among them.

It should be noted that the use of different ROs and/or preambles, as would be well understood by those skilled in the art, is up to gNB configurations/implementations. The gNB can configure both separate ROs and separate preambles; e.g., it can share some ROs with UEs accessing URPs and TRPs but using different preambles, and another set of ROs exclusively for UEs accessing the URP. It should also be noted that the need for different ROs and/or preambles is an optional configuration which not needed to be implemented by the network (or defined in the specifications) in order to implement the embodiments of the present disclosure, which will be explain in subsequent arrangements of embodiments of the present technique below.

After the UE selects an SSB, the UE will transmit either a PRACH (if it is performing a four-step RACH procedure) or a Message A (if it is performing a two-step RACH procedure). The following paragraphs detail arrangements of embodiments of the present technique in respect of the UL beam used for the transmission of such a PRACH/Message A.

In some arrangements of embodiments of the present technique, the gNB configures a separate SSB- corresponding UL beam. In other words, the plurality of SSBs each have an associated uplink beam of a first set of uplink beams directed from the communications device towards the TRP and an associated uplink beam of a second set of uplink beams directed from the communications device towards one of the URP and the TRP. Such arrangements recognise that the URP is likely to be in a different location and a different relative direction to the UE as compared to the TRP, and so it is beneficial that the UE directs its UL beam towards the URP rather than towards the TRP. That is, the UE is provided, e.g., via the SIBs received from the TRP, two sets of S SB-corresponding UL beams, where a first set of uplink beams are used for the first initial access procedure that uses the legacy UL beam correspondence targeting a legacy TRP such as the macro-gNB, and a second set of uplink beams are used for the second initial access procedure that targets the nearest URP (where different ones of the second set of uplink beams may therefore target different URPs if there are multiple URPs in the deployment).

An example is shown in Figure 15, where the network indicates two sets of S SB-corresponding UL beams to the UEs. The first set of S SB-corresponding UL beams 1501, 1502, 1503, 1504, 1505, 1506, 1507, 1508 contains beams that targets the macro-gNB 1500 as shown in Figure 15A, which are used for the first initial access procedure. For the second initial access procedure, the second set of SSB- corresponding UL beams 1511, 1512, 1513, 1514, 1515, 1516, 1517, 1518 is shown in Figure 15B. For SSB2 and SSB3, their corresponding UL beams 1512, 1513 are directed towards a first URP 1521. Similarly, UL beams 1516, 1517 corresponding to SSB6 and SSB7 respectively, are directed towards a second URP 1522, which is the nearest URP to such beams. The remaining S SB-corresponding UL beams 1511, 1514, 1515, 1518 are directed towards the macro-gNB 1510 in the same manner as their corresponding UL beams 1501, 1504, 1505, 1508 in the first set of uplink beams, since there are no nearby URPs forthose corresponding SSBs (i.e. SSB1, SSB4, SSB5, SSB8).

In some arrangements of embodiments of the present technique, the SSB-corresponding UL beams used for the second initial access procedure are wide beams. In other words, one or more of the second set of uplink beams are each wider than the a corresponding one of the first set of uplink beams (e.g. the SSB2- corresponding UL beam in the second set is wider than the SSB2-corresponding UL beam in the first set, and the SSB6-corresponding UL beam in the second set is wider than the SSB6-corresponding UL beam in the first set). Such arrangements recognise that accurate direction of the URP is not known to the UE and hence a wide beam has a greater chance of reaching the URP. For those beams which are not targeting the URP, i.e. those which correspond to SSB1, SSB4, SSB5, and SSB8 in the example of Figure 15, these beams may be of equal width in both the first and second sets. In an implementation, an omnidirectional beam is used. In other words, specifically, the second set of (wider) uplink beams are omnidirectional uplink beams.

An example is shown in Figure 16, where the macro-gNB 1600 uses eight SSBs and the macro coverage consists of two URPs 1601, 1602. The network (e.g. the macro-gNB 1600) indicates in the SIBs that the first set of SSB-corresponding UL beams follow the legacy SSB UL-corresponding beam. The network (e.g., the macro-gNB 1600 also indicates in the SIBs) that the second set of SSB-corresponding UL beams for {SSB2, SSB3, SSB6, SSB7} are omnidirectional and the remaining SSB, i.e., {SSB1, SSB4, SSB5, SSB8} uses the legacy SSB UL-corresponding beam. A first UE 1611 selects SSB4 and, regardless of whether it uses the first initial access procedure or the second initial access procedure, it uses the SSB4 UL-corresponding beam 1620 since in both cases the UL beam used are the same. A second UE 1612 however selects SSB2, and here it is indicated (e.g., using one of the previous arrangement) that the second UE 1612 is to use the second initial access procedure. Following the gNB’s 1600 configuration, the second UE 1612 uses an omnidirectional beam 1630 for its PRACH/Message A transmission targeting the URP 1602. As those skilled in the art would understand, such an omnidirectional beam 1630 has a greater chance of being successfully received by the URP 1602, but may necessitate the use of more power by the second UE 1612 in transmitting it.

In some arrangements of embodiments of the present technique, beam sweeping at UE is performed in the second initial access procedure. In other words, when performing the second access procedure, the communications device may be configured to perform, after selecting the selected SSB, a beam sweeping procedure using a plurality of uplink beams configured for the communications device, wherein the step of performing the second random access procedure together with the TRP and the URP on the basis of the selected SSB comprises the communications device being configured to transmit at least one message to the URP using the plurality of uplink beams. Similar to the previous arrangement, the accurate direction of the URP is not known to the UE and using wide beam is difficult to reach to the URP especially in high frequency such as FR2 due to high pathloss.

An example is shown in Figure 17, where two UEs 1711 and 1712 are located within a cell controlled by a macro-gNB 1700 and containing two URPs 1701, 1702. The first UE 1711 is not located near to a UE, and so in accordance with any appropriate one of the above described arrangements of embodiments of the present technique, transmits its PRACH/Message A using an S SB-corresponding uplink beam 1720 to the macro-gNB 1700. The second UE 1712 is configured with four UL beams 1731, 1732, 1733, 1734. The second UE 1712 is indicated by the network to use the second initial access procedure attempts to perform beam sweeping 1730 by using UL beams 1731, 1732, 1733, 1734 in turn for its PRACH/Message A transmission to the URP 1702. In such arrangements, it is desirable (though not essential) that power ramping for PRACH/Message A transmission is applied after the second UE 1712 uses all UL beams 1731, 1732, 1733, 1734 in order to avoid unnecessary strong UL interference caused by beam sweeping. In such arrangements, in other words, for the second initial access procedure, the second UE 1712 is indicated not to use the UL beam correspondence derived from the DL beam of SSB2.

In some arrangements of embodiments of the present technique, the second S SB-corresponding UL beams are the same as the first SSB-corresponding UL beams. In other words, each of the plurality of SSBs may have an associated uplink beam directed from the communications device towards the TRP, and wherein either the first random access procedure is initiated by the communications device by transmitting a first message to the TRP using the uplink beam associated with the selected SSB or the second random access procedure is initiated by the communications device by transmitting the first message to the TRP using the uplink beam associated with the selected SSB. That is, the UE uses the legacy SSB-corresponding UL beams for its PRACH/Message A transmission in the second initial access procedure as well as in the first initial access procedure. Such arrangements may be beneficial for implementation where the network uses separate ROs and/or preambles to distinguish between UE using the first initial access procedure and the second initial access procedure. Since the gNB is aware that the UE is using the second initial access procedure, the UE may not need to target the URP but it may target the TRP such as the macro-gNB. The TRP (e.g., macro-gNB) is aware that the UE is near to a URP, and so would direct the UE to transmit its Message 3 to a nearby URP (in accordance with the techniques described in respect of subsequent arrangements of embodiments of the present technique). In some arrangements of embodiments of the present technique, in the second initial access procedure, the UE transmits two PRACHs or two Message As; one using the first S SB-corresponding UL beam and another using the second S SB-corresponding UL beam, if both beams are different. In other words, the step of performing the second random access procedure together with the TRP and the URP on the basis of the selected SSB, the communications device may be configured to transmit, to the TRP, a first message using the uplink beam of the first set of uplink beams associated with the selected SSB, and to transmit, to the URP, the first message using the uplink beam of the second set of uplink beams associated with the selected SSB. The network may configure two ROs for the UE to transmits these two PRACHs or Message As. Effectively, the UE therefore performs PRACH repetitions with different beams. In addition to providing diversity gain and combining gain for the PRACH or Message A, such arrangements enable the network to determine the timing of the PRACH or Message A from the UE to the URP compared to the PRACH from the UE to the TRP, such as the macro-gNB. This timing information may be used to determine the Timing Advance (TA) for the UE to the URP.

In some arrangements of embodiments of the present technique, the Message A indicates whether the UE is targeting a URP or a TRP. That is, the Message A indicates whether the UE is using the first initial access procedure or the second initial access procedure. In other words, the first random access procedure or the second random access procedure is initiated by the communications device by transmitting a first message comprising an indication of whether the communications device intends to connect to the heterogeneous communications network via the TRP or the URP. Here, the first message (which might be a PRACH instead of a Message A) may be transmitted to the URP or to the TRP (if the same set of corresponding UL beams for SSBs is used for both the first and second initial access procedures for example) or indeed to both the TRP and URP as described in the paragraph above.

It should be appreciated by those skilled in the art that the above-described arrangements of embodiments of the present technique can be implemented individually or combined in any appropriate manner. For example, the network, for the second set of S SB-corresponding UL beams, may configured that only some of the beams may use wideband (e.g. omnidirectional), while others may instead employ beam sweeping and others may simply use a specific beam direction. Those skilled in the art would of course appreciate that such a combination is simply an example, and that any other appropriate combinations are possible.

In some arrangements of embodiments of the present technique, the gNB configures a separate power control for the first initial access procedure and the second initial access procedure. In other words, the communications device uses a first power control function for performing the first random access procedure and a second power control function for performing the second random access procedure, wherein the first power control function is different to the second power control function. Here, such first and second power control functions may be configured by the network, and may therefore be indicated (e.g. dynamically or semi-statically) to such UEs by the network (e.g. by the TRP/macro-gNB). Alternatively, this may be something known to the UE (and TRP) in advance and defined in the specifications.

The first initial access procedure may use the legacy power control, where the UE calculates the path loss PL, between the UE and the TRP and applies a power offset called the Preamble Received Target Power, P PRACH, target, to determine the PRACH/Message A transmit power. That is, the PRACH power P PRACH in dBm is calculated as defined by Equation [1] below:

P PRACH = Ulin { P CMAX, P PRACH, target + PL} dBm [1] PCMAX is the configured maximum transmit power for the UE. The path loss PL in dB is calculated by the UE using a Reference Signal Power P_ref and its measured RSRP PRSRP at the UE in accordance with Equation [2] below:

The parameters PCMAX, PPRACH,

and P_ref are indicated in the SIBs by the network.

In some arrangements of embodiments of the present technique, the said different separate power control is to configure separate Preamble Received Target Power, PPRACH, for the first initial access procedure and the second initial access procedure. In other words, the first power control function comprises a first power offset value and the second power control function comprises a second power offset value, wherein the first power offset value is different to the second power offset value. That is, the network provides two PPRACH, parameters, e.g.,

first initial access procedure and the second initial access procedure respectively. The network may set PPRACH,

for implementations where the second S SB-corresponding UL beam is a wideband or omnidirectional beam, which may not provide sufficient gain for the transmission to reach the TRP such as the macro-gNB; albeit the transmission will reach the URP. It should be noted here that it may be beneficial for the PRACH/Message A transmission to reach both the TRP and the URP. On the other hand, the gNB may wish to set PPRACH,

thereby reducing the UE PRACH/Message A transmit power, since the path loss between the URP and the UE may be less than the path loss between the TRP and the UE. Hence, by allowing a separate PPRACH, the network has the flexibility to manage the UE’s transmission power in the first initial access procedure and the second initial access procedure.

In some arrangements of embodiments of the present technique, the said different separate power control is to configure separate power ramping step for the first initial access procedure and the second initial access procedure. In other words, the first power control function comprises a first power ramping step amount and the second power control function comprises a second power ramping step amount, wherein the first power ramping step amount is different to the second power ramping step amount. That is, the network may configure two parameters of PREAMBLE POWER RAMPING STEP for the first initial access procedure and the second initial access procedure respectively. For example, PREAMBLE POWER RAMPING STEP for the second initial access procedure may be configured to be smaller than PREAMBLE POWER RAMPING STEP for the first initial access procedure because the URP is closer to the UE than the macro-TRP.

In some arrangements of embodiments of the present technique, the said different separate power control is that the UE has separate power ramping counter for the first initial access procedure and the second initial access procedure. In other words, the first power control function comprises the communications device using a first power ramping counter and the second power control function comprises the communications device using a second power ramping counter, wherein the first power ramping counter is different to the second power ramping counter. For example, PREAMBLE POWER RAMPING COUNTER may be used for the first initial access procedure while PREAMBLE POWER RAMPING COUNTER URP may be used for the second initial access procedure. That is, the UE increments a first counter, i.e. PREAMBLE POWER RAMPING COUNTER, by 1 when the UE retransmits PRACH/Message A for the first initial access procedure and increments a second counter, i.e. PREAMBLE POWER RAMPING COUNTER URP, by 1 when the UE retransmits PRACH/Message A for the second initial access procedure respectively. In some arrangements of embodiments of the present technique, the said different separate power control is to configure separate maximum number of preamble transmissions, e.g., preambleTransMax and preambleTransMaxURP for the first initial access procedure and the second initial access procedure respectively. In other words, the first power control function comprises a first maximum number of transmissions of a first message of the first random access procedure (e.g. a PRACH or Message A) and the second power control function comprises a second maximum number of transmissions of a first message of the second random access procedure (e.g. a PRACH or Message A), wherein the first maximum number of transmissions of the preamble signal is different to the second maximum number of transmissions of the preamble signal. That is, the network may configure different maximum number of retransmission for PRACH/Message A for the first initial access procedure and the second initial access procedure respectively. Here, preambleTransMaxURP may be configured with a smaller value than preambleTransMax, and if the UE fails to successfully transmit its PRACH/Message A within the specified number of times, the UE may fall back to using the first initial access procedure.

In some arrangements of embodiments of the present technique, the said different separate power control is to configure separate maximum transmit power for the UE PCMAX, for the first initial access procedure and the second initial access procedure. In other words, the first power control function comprises a first maximum transmission power value and the second power control function comprises a second maximum transmission power value, wherein the first maximum transmission power value is different to the second maximum transmission power value. That is, the network may configure the UE with two PCMAX, namely PCMAXI and PCMAX2 for the first initial access procedure and the second initial access procedure respectively.

In some arrangements of embodiments of the present technique, the said different separate power control is to configure separate Reference Signal Power P_ref for the first initial access procedure and the second initial access procedure. In other words, the first power control function comprises a first reference signal power value and the second power control function comprises a second reference signal power value, wherein the first reference signal power value is different to the second reference signal power value. That is the network configures two P_ref, Prep and P_rep for the first initial access procedure and the second initial access procedure respectively. Although the URP does not transmit in the DL, the Prep can be configured based on the UL coverage of the URP.

In some arrangements of embodiments of the present technique, the UE may start with the PRACH transmission of the second initial access procedure (URP) with a separate power control, and if it does not receive response from the network, the UE switches to the PRACH transmission of the first initial access procedure (macro-TRP) with a separate power control - that is, fallback from the second initial access procedure to the first initial access procedure as described above also involves the changing of power control function. In some implementations however, fallback may only involve the changing of power control function, while the UE is otherwise still performing the second initial access procedure. In other words, when performing the step of performing the second random access procedure together with the TRP and the URP on the basis of the selected SSB, the communications device may be configured to transmit, to the URP or the TRP, a first message of the second random access procedure using the second power control function, to determine that the communications device has received no response to the first message, and to retransmit, to the URP or the TRP, the first message of the second random access procedure using the first power control function. Here, operation of the fallback procedure may be configured by the network, and may therefore be indicated (e.g. dynamically or semi-statically) to such UEs by the network (e.g. by the TRP/macro-gNB). Alternatively, this may be something known to the UE (and TRP) in advance and defined in the specifications. It would be appreciated by those skilled in the art that the above-described arrangements of embodiments of the present technique relating to power control can be implemented individually or combined in any appropriate manner. For example, the network may have separate configurations for PPRACH, and but not for PCMAX. It should also be noted that using separate power control is optional, and that embodiments of the present disclosure may be implemented without using separate power control for the first initial access procedure and the second initial access procedure.

The RAR is typically transmitted using the beam direction of the SSB selected by the UE for its PRACH/Message A transmission. In some arrangements of embodiments of the present technique, the RAR contains information of transmission to the URP, if the network decides that the UE should use the URP. In other words, when performing the step of performing the determined one of the first initial access procedure and the second initial access procedure, the communications device may be configured to receive, from the TRP, a second message of either the first random access procedure or the second random access procedure, wherein the second message comprises information to be used by the communications device to transmit signals to the URP.

This information may also tell the UE to use the second initial access procedure. In other words, the second message may comprise an indication that the communications device is to perform the second initial access procedure. This may be beneficial for UE that started its PRACH transmission using the first initial access procedure and the network may decide that the UE is better served by a URP. In some cases, the UE might have already initiated the second initial access procedure, in which case the UE continues to perform the second initial access procedure. However, if the UE had started its PRACH transmission using the first initial access procedure, the communications device would therefore switch to using the second initial access procedure on the basis of receipt of such information.

In some arrangements of embodiments of the present technique, the RAR alternatively indicates to the UE to use the first initial access procedure. In other words, the second message may comprise an indication that the communications device is to perform the first initial access procedure. Such arrangements recognise that the network may decide that the UE should not use a URP even though the UE started its PRACH using the second initial access procedure. This may be due to the URP being congested or the network decides that the UE is better served by a TRP. In some cases, the UE might have already initiated the first initial access procedure, in which case the UE continues to perform the first initial access procedure. However, if the UE had started its PRACH transmission using the second initial access procedure, the communications device would therefore switch to using the first initial access procedure on the basis of receipt of such information.

The said information for transmission to a URP may be the UL beam for Message 3 (i.e. specifically of a four-step RACH procedure). In other words, the information to be used by the communications device to transmit signals to the URP may comprise an indication of an uplink beam that is to be used by the communications device for transmitting a third message of the second random access procedure to the URP. Even if the UE used a second S SB-corresponding UL beam directed toward the URP in transmitting its PRACH, that beam may not be fine enough as the location of the URP is unknown to the UE at the point where the UE transmits the PRACH. Hence, a more refined beam may instead be used where this beam may be determined by the URP after detecting the UE’s PRACH.

The said information for transmission to a URP may be a Timing Advance for the URP. In other words, the information to be used by the communications device to transmit signals to the URP may comprise a timing advance value associated with the URP to be applied by the communications device when transmitting signals to the URP. Additionally, in some implementations, the RAR may also contain Timing Advance for the TRP such as the macro-gNB. In other words, the second message may also comprise a timing advance value associated with the TRP be applied by the communications device when transmitting signals to the TRP, wherein the timing advance value associated with the TRP is different to the timing advance value associated with the URP. Such implementations recognise that the URP and TRP may be in different location and therefore they have different propagation delay to the UE, which requires different Timing Advance.

The said information for transmission to a URP may be an UL pathloss estimated based on PRACH/Message A received power. In other words, the information to be used by the communications device to transmit signals to the URP may comprise an estimated uplink pathloss value between the communications device and the URP. The network can measure the UE pathloss between the URP and the UE if the network knows the transmission power of PRACH/Message A for the URP. The network may indicate the UL pathloss to the UE using the RAR/Message B, and then the UE is able to update the UL pathloss value. The indicated UL pathloss is used for determining UL transmission power for Message 3 and subsequent UL transmission.

In some arrangements of embodiments of the present technique, the Message B (i.e. specifically of a two- step RACH procedure) may also contains information of transmission to the URP, if the network decides that the UE should use the URP. In other words, when performing the step of performing the determined one of the first initial access procedure and the second initial access procedure, the communications device may be configured to receive, from the TRP, a second message of either the first random access procedure or the second random access procedure, wherein the second message comprises information to be used by the communications device to transmit signals to the URP.

This information may also tell the UE to use the second initial access procedure. In other words, the second message may comprise an indication that the communications device is to perform the second initial access procedure. This may be beneficial for UE that started its Message A transmission using the first initial access and the network may decide that the UE is better served by a URP. In some cases, the UE might have already initiated the second initial access procedure, in which case the UE continues to perform the second initial access procedure. However, if the UE had started its Message A transmission using the first initial access procedure, the communications device would therefore switch to using the second initial access procedure on the basis of receipt of such information.

In some arrangements of embodiments of the present technique, the Message B may indicate to the UE to use the first initial access procedure. In other words, the second message may comprise an indication that the communications device is to perform the first initial access procedure. Such arrangements recognise that the network may decide that the UE should not use a URP even though the UE starter its Message A using the second initial access procedure. This may be due to the URP being congested or the network decides that the UE is better served by a TRP. In some cases, the UE might have already initiated the first initial access procedure, in which case the UE continues to perform the first initial access procedure. However, if the UE had started its Message A transmission using the second initial access procedure, the communications device would therefore switch to using the first initial access procedure on the basis of receipt of such information.

The said information for transmission to a URP may also be the UL beam for the UE’s RRC Connection Setup Complete message (e.g. when the UE is performing a two-step RACH procedure as part of the initial access procedure). In other words, the information to be used by the communications device to transmit signals to the URP may comprise an indication of an uplink beam that is to be used by the communications device for transmitting an uplink signal to the URP indicating that the communications device has successfully connected to the heterogeneous communications network via the URP. Even if the UE used a second SSB-corresponding UL beam directed toward the URP in transmitting its Message A, that beam may not be fine enough as the location of the URP is unknown to the UE at the point where the UE transmits the Message A. Hence, a more refined beam may instead be used where this beam may be determined by the URP after detecting the UE’s Message A.

The said information for transmission to a URP may be Timing Advance for the URP. In other words, the information to be used by the communications device to transmit signals to the URP may comprise a timing advance value associated with the URP to be applied by the communications device when transmitting signals to the URP. Additionally, in some implementations, the Message B may also contain Timing Advance for the TRP such as the macro-gNB. In other words, the second message may also comprise a timing advance value associated with the TRP be applied by the communications device when transmitting signals to the TRP, wherein the timing advance value associated with the TRP is different to the timing advance value associated with the URP. Such implementations recognise that the URP and TRP may be in different location and therefore they have different propagation delay to the UE, which requires different Timing Advance.

In some arrangements of embodiments of the present technique, the Message 4 in a 4 step RACH can indicate whether the UE uses the first initial access procedure or the second initial access procedure. In other words, when performing the step of performing the determined one of the first initial access procedure and the second initial access procedure, the communications device may be configured to receive, from the TRP, a fourth message of either the first random access procedure or the second random access procedure, wherein the fourth message comprises an indication that the communications device is to perform the first/second initial access procedure. As described previously, the network may change its mind whether the UE should continue using a URP or a TRP after it has established RRC Connection with the network.

Figure 18 shows a flow diagram illustrating a first example process of communications in a heterogeneous communications system in accordance with embodiments of the present technique. The process shown by Figure 18 is specifically a method of operating a communications device (e.g., UE).

The method begins in step S 1. The method comprises, in step S2, receiving, from a transmission and reception point, TRP, of a heterogeneous communications network (such as a gNB), an indicator that provides an indication of whether the communications device is to perform a first initial access procedure for connecting to the heterogeneous communications network via the TRP or a second initial access procedure for connecting to the heterogeneous communications network via an uplink-only reception point, URP, of the heterogeneous communications network, wherein the TRP provides both uplink connectivity and downlink connectivity for the communications device, and wherein the URP provides only uplink connectivity for the communications device. In step S3, the process comprises determining, based on the received indicator, whether to perform the first initial access procedure or the second initial access procedure, wherein the first initial access procedure comprises selecting one of a plurality of synchronisation signal blocks, SSBs, transmitted by the TRP to the communications device and performing a first random access procedure together with the TRP on the basis of the selected SSB, and wherein the second initial access procedure comprises selecting one of the plurality of SSBs and performing a second random access procedure together with the TRP and the URP on the basis of the selected SSB. Then, in step S4, the method comprises performing the determined one of the first initial access procedure and the second initial access procedure to connect to the heterogeneous communications network. The process ends in step S5. Those skilled in the art would appreciate that the method shown by Figure 18 may be adapted in accordance with embodiments of the present technique. For example, other intermediate steps may be included in such a method, or the steps may be performed in any logical order. Though embodiments of the present technique have been described largely by way of the example heterogeneous communications system shown in Figure 9, and further described by way of the examples illustrated by Figures 10 to 17, it would be clear to those skilled in the art that they could be equally applied to other systems and procedures to those described herein.

Those skilled in the art would further appreciate that such infrastructure equipment (e.g. TRPs and URPs) and/or communications devices as herein defined may be further defined in accordance with the various arrangements and embodiments discussed in the preceding paragraphs. It would be further appreciated by those skilled in the art that such infrastructure equipment (e.g. TRPs and URPs) and communications devices as herein defined and described may form part of communications systems other than those defined by the present disclosure.

The following numbered paragraphs provide further example aspects and features of the present technique:

Paragraph 1. A method of operating a communications device, the method comprising receiving, from a transmission and reception point, TRP, of a heterogeneous communications network, an indicator that provides an indication of whether the communications device is to perform a first initial access procedure for connecting to the heterogeneous communications network via the TRP or a second initial access procedure for connecting to the heterogeneous communications network via an uplink-only reception point, URP, of the heterogeneous communications network, wherein the TRP provides both uplink connectivity and downlink connectivity for the communications device, and wherein the URP provides only uplink connectivity for the communications device, determining, based on the received indicator, whether to perform the first initial access procedure or the second initial access procedure, wherein the first initial access procedure comprises selecting one of a plurality of synchronisation signal blocks, SSBs, transmitted by the TRP to the communications device and performing a first random access procedure together with the TRP on the basis of the selected SSB, and wherein the second initial access procedure comprises selecting one of the plurality of SSBs and performing a second random access procedure together with the TRP and the URP on the basis of the selected SSB, and performing the determined one of the first initial access procedure and the second initial access procedure to connect to the heterogeneous communications network.

Paragraph 2. A method according to Paragraph 1, wherein the indicator explicitly indicates that the communications device is to perform the first initial access procedure or the second initial access procedure.

Paragraph 3. A method according to Paragraph lor Paragraph 2, wherein the indicator comprises an indication of a probability with which the communications device is to perform the second initial access procedure.

Paragraph 4. A method according to any one of Paragraphs 1 to 3, wherein the indicator comprises an indication of at least a first set of upper and lower threshold signal strengths, and wherein the communications device determines that it is to perform the second initial access procedure if a measured strength of a signal received by the communications device from the TRP is between the upper threshold signal strength and the lower threshold signal strength.

Paragraph 5. A method according to Paragraph 4, wherein the indicator comprises an indication of one or more further sets of upper and lower threshold signal strengths different to the first set.

Paragraph 6. A method according to any one of Paragraphs 1 to 5, wherein the indicator comprises an indication of a threshold signal strength, and wherein the communications device determines that it is to perform the second initial access procedure if a measured strength of a signal received by the communications device from the TRP is below the threshold signal strength.

Paragraph 7. A method according to any one of Paragraphs 1 to 6, wherein the indicator comprises an indication of whether each of the plurality of SSBs forms part of a first set of SSBs associated with the first initial access procedure or a second set of SSBs associated with the second initial access procedure. Paragraph 8. A method according to Paragraph 7, wherein the step of determining whether to perform the first initial access procedure or the second initial access procedure comprises selecting one of the plurality of SSBs, determining whether the selected SSB forms part of the first set of SSBs or the second set of SSBs, and determining either that the communications device is to perform the first initial access procedure if the selected SSB forms part of the first set of SSBs or that the communications device is to perform the second initial access procedure if the selected SSB forms part of the second set of SSBs.

Paragraph 9. A method according to Paragraph 8, wherein the step of selecting the one of the plurality of SSBs comprises measuring a strength of each of the plurality of SSBs, and selecting the selected SSB on the basis of the selected SSB having a measured strength that is higher than a predefined threshold strength.

Paragraph 10. A method according to any one of Paragraphs 1 to 9, comprising determining that the communications device has been unable to connect to the heterogeneous communications network by performing the second initial access procedure, and performing, in response to determining that the communications device has been unable to connect to the heterogeneous communications network by performing the second initial access procedure, the first initial access procedure to connect to the heterogeneous communications network.

Paragraph 11. A method according to any one of Paragraphs 1 to 10, wherein the second random access procedure is initiated by the communications device by transmitting a first message to the URP in a second set of uplink resources, wherein the second set of uplink resources is different to a first set of uplink resources configured for the transmission of a first message of the first random access procedure to the TRP.

Paragraph 12. A method according to any one of Paragraphs 1 to 11, wherein the second random access procedure is initiated by the communications device by transmitting a first message to the URP, the first message comprising one of a second set of preamble signals, wherein the second set of preamble signals is different to a first set of preamble signals configured for the transmission of a first message of the first random access procedure to the TRP.

Paragraph 13. A method according to any one of Paragraphs 1 to 12, wherein each of the plurality of SSBs has an associated uplink beam directed from the communications device towards the TRP, and wherein either the first random access procedure is initiated by the communications device by transmitting a first message to the TRP using the uplink beam associated with the selected SSB or the second random access procedure is initiated by the communications device by transmitting the first message to the TRP using the uplink beam associated with the selected SSB.

Paragraph 14. A method according to any one of Paragraphs 1 to 13, wherein the plurality of SSBs each have an associated uplink beam of a first set of uplink beams directed from the communications device towards the TRP and an associated uplink beam of a second set of uplink beams directed from the communications device towards one of the URP and the TRP.

Paragraph 15. A method according to Paragraph 14, wherein one or more of the second set of uplink beams are each wider than a corresponding one of the first set of uplink beams.

Paragraph 16. A method according to Paragraph 15, wherein one or more of the second set of uplink beams are omnidirectional uplink beams.

Paragraph 17. A method according to any one of Paragraphs 14 to 16, wherein the step of performing the second random access procedure together with the TRP and the URP on the basis of the selected SSB comprises transmitting, to the TRP, a first message using the uplink beam of the first set of uplink beams associated with the selected SSB, and transmitting, to the URP, the first message using the uplink beam of the second set of uplink beams associated with the selected SSB.

Paragraph 18. A method according to any one of Paragraphs 1 to 17, wherein the second access procedure comprises performing, after selecting the selected SSB, a beam sweeping procedure using a plurality of uplink beams configured for the communications device, wherein the step of performing the second random access procedure together with the TRP and the URP on the basis of the selected SSB comprises transmitting at least one message to the URP using the plurality of uplink beams.

Paragraph 19. A method according to any one of Paragraphs 1 to 18, wherein the first random access procedure or the second random access procedure is initiated by the communications device by transmiting a first message comprising an indication of whether the communications device intends to connect to the heterogeneous communications network via the TRP or the URP.

Paragraph 20. A method according to any one of Paragraphs 1 to 19, wherein the communications device uses a first power control function for performing the first random access procedure and a second power control function for performing the second random access procedure, wherein the first power control function is different to the second power control function.

Paragraph 21. A method according to Paragraph 20, wherein the first power control function comprises a first power offset value and the second power control function comprises a second power offset value, wherein the first power offset value is different to the second power offset value.

Paragraph 22. A method according to Paragraph 20 or Paragraph 21, wherein the first power control function comprises a first power ramping step amount and the second power control function comprises a second power ramping step amount, wherein the first power ramping step amount is different to the second power ramping step amount.

Paragraph 23. A method according to any one of Paragraphs 20 to 22, wherein the first power control function comprises the communications device using a first power ramping counter and the second power control function comprises the communications device using a second power ramping counter, wherein the first power ramping counter is different to the second power ramping counter.

Paragraph 24. A method according to any one of Paragraphs 20 to 23, wherein the first power control function comprises a first maximum number of transmissions of a first message of the first random access procedure and the second power control function comprises a second maximum number of transmissions of a first message of the second random access procedure, wherein the first maximum number of transmissions of the preamble signal is different to the second maximum number of transmissions of the preamble signal.

Paragraph 25. A method according to any one of Paragraphs 20 to 24, wherein the first power control function comprises a first maximum transmission power value and the second power control function comprises a second maximum transmission power value, wherein the first maximum transmission power value is different to the second maximum transmission power value.

Paragraph 26. A method according to any one of Paragraphs 20 to 25, wherein the first power control function comprises a first reference signal power value and the second power control function comprises a second reference signal power value, wherein the first reference signal power value is different to the second reference signal power value.

Paragraph 27. A method according to any one of Paragraphs 20 to 26, wherein the step of performing the second random access procedure together with the TRP and the URP on the basis of the selected SSB comprises transmiting, to the URP or the TRP, a first message of the second random access procedure using the second power control function, determining that the communications device has received no response to the first message, and retransmiting, to the URP or the TRP, the first message of the second random access procedure using the first power control function.

Paragraph 28. A method according to any one of Paragraphs 1 to 27, wherein the step of performing the determined one of the first initial access procedure and the second initial access procedure comprises receiving, from the TRP, a second message of either the first random access procedure or the second random access procedure, wherein the second message comprises information to be used by the communications device to transmit signals to the URP.

Paragraph 29. A method according to Paragraph 28, wherein the second message comprises an indication that the communications device is to perform the first initial access procedure.

Paragraph 30. A method according to Paragraph 28 or Paragraph 29, wherein the second message comprises an indication that the communications device is to perform the second initial access procedure. Paragraph 31. A method according to any one of Paragraphs 28 to 30, wherein the information to be used by the communications device to transmit signals to the URP comprises an indication of an uplink beam that is to be used by the communications device for transmitting a third message of the second random access procedure to the URP.

Paragraph 32. A method according to any one of Paragraphs 28 to 31, wherein the information to be used by the communications device to transmit signals to the URP comprises an indication of an uplink beam that is to be used by the communications device for transmitting an uplink signal to the URP indicating that the communications device has successfully connected to the heterogeneous communications network via the URP.

Paragraph 33. A method according to any one of Paragraphs 28 to 32, wherein the information to be used by the communications device to transmit signals to the URP comprises a timing advance value associated with the URP to be applied by the communications device when transmitting signals to the URP.

Paragraph 34. A method according to Paragraph 33, wherein the second message comprises a timing advance value associated with the TRP be applied by the communications device when transmitting signals to the TRP, wherein the timing advance value associated with the TRP is different to the timing advance value associated with the URP.

Paragraph 35. A method according to any one of Paragraphs 28 to 34, wherein the information to be used by the communications device to transmit signals to the URP comprises an estimated uplink pathloss value between the communications device and the URP.

Paragraph 36. A method according to any one of Paragraphs 1 to 35, wherein the step of performing the determined one of the first initial access procedure and the second initial access procedure comprises receiving, from the TRP, a fourth message of either the first random access procedure or the second random access procedure, wherein the fourth message comprises an indication that the communications device is to perform the first initial access procedure.

Paragraph 37. A method according to any one of Paragraphs 1 to 36, wherein the step of performing the determined one of the first initial access procedure and the second initial access procedure comprises receiving, from the TRP, a fourth message of either the first random access procedure or the second random access procedure, wherein the fourth message comprises an indication that the communications device is to perform the second initial access procedure.

Paragraph 38. A communications device comprising transceiver circuitry configured to transmit signals to and/or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to receive, from a transmission and reception point, TRP, of a heterogeneous communications network, an indicator that provides an indication of whether the communications device is to perform a first initial access procedure for connecting to the heterogeneous communications network via the TRP or a second initial access procedure for connecting to the heterogeneous communications network via an uplink-only reception point, URP, of the heterogeneous communications network, wherein the TRP provides both uplink connectivity and downlink connectivity for the communications device, and wherein the URP provides only uplink connectivity for the communications device, to determine, based on the received indicator, whether to perform the first initial access procedure or the second initial access procedure, wherein the first initial access procedure comprises the communications device being configured to select one of a plurality of synchronisation signal blocks, SSBs, transmitted by the TRP to the communications device and to perform a first random access procedure together with the TRP on the basis of the selected SSB, and wherein the second initial access procedure comprises the communications device being configured to select one of the plurality of SSBs and to perform a second random access procedure together with the TRP and the URP on the basis of the selected SSB, and to perform the determined one of the first initial access procedure and the second initial access procedure to connect to the heterogeneous communications network.

Paragraph 39. Circuitry for a communications device, the circuitry comprising transceiver circuitry configured to transmit signals to and/or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to receive, from a transmission and reception point, TRP, of a heterogeneous communications network, an indicator that provides an indication of whether the circuitry is to perform a first initial access procedure for connecting to the heterogeneous communications network via the TRP or a second initial access procedure for connecting to the heterogeneous communications network via an uplink-only reception point, URP, of the heterogeneous communications network, wherein the TRP provides both uplink connectivity and downlink connectivity for the communications device, and wherein the URP provides only uplink connectivity for the communications device, to determine, based on the received indicator, whether to perform the first initial access procedure or the second initial access procedure, wherein the first initial access procedure comprises the circuitry being configured to select one of a plurality of synchronisation signal blocks, SSBs, transmitted by the TRP to the communications device and to perform a first random access procedure together with the TRP on the basis of the selected SSB, and wherein the second initial access procedure comprises the circuitry being configured to select one of the plurality of SSBs and to perform a second random access procedure together with the TRP and the URP on the basis of the selected SSB, and to perform the determined one of the first initial access procedure and the second initial access procedure to connect to the heterogeneous communications network.

Paragraph 40. A method of operating a transmission and reception point, TRP, of a heterogeneous communications network, the TRP providing both uplink connectivity and downlink connectivity for communications devices, wherein the TRP is configured to transmit signals to and receive signals from an uplink-only reception point, URP, of the heterogeneous communications network via a backhaul communications link, the URP providing only uplink connectivity for communications devices, the method comprising transmitting, to a communications device, an indicator that provides an indication of whether the communications device is to perform a first initial access procedure for connecting to the heterogeneous communications network via the TRP or a second initial access procedure for connecting to the heterogeneous communications network via the URP, and performing either a first random access procedure together with the communications device as part of the first initial access procedure or a second random access procedure together with the communications device and the URP as part of the second initial access procedure.

Paragraph 41. A method according to Paragraph 40, wherein the indicator explicitly indicates that the communications device is to perform the first initial access procedure or the second initial access procedure.

Paragraph 42. A method according to Paragraph 40 or Paragraph 41, wherein the indicator comprises an indication of a probability with which the communications device is to perform the second initial access procedure.

Paragraph 43. A method according to any one of Paragraphs 40 to 42, wherein the indicator comprises an indication of at least a first set of upper and lower threshold signal strengths.

Paragraph 44. A method according to Paragraph 43, wherein the indicator comprises an indication of one or more further sets of upper and lower threshold signal strengths different to the first set.

Paragraph 45. A method according to any one of Paragraphs 40 to 44, wherein the indicator comprises an indication of a threshold signal strength.

Paragraph 46. A method according to any one of Paragraphs 40 to 45, wherein the indicator comprises an indication of whether each of a plurality of synchronisation signal blocks, SSBs, transmitting to the communications device by the TRP forms part of a first set of SSBs associated with the first initial access procedure or a second set of SSBs associated with the second initial access procedure.

Paragraph 47. A method according to any one of Paragraphs 40 to 46, the method comprising configuring a first set of uplink resources configured for the transmission of a first message of the first random access procedure to the TRP, and configuring a second set of uplink resources configured for the transmission of a first message of the second random access procedure to the URP, wherein the second set of uplink resources is different to the first set of uplink resources.

Paragraph 48. A method according to any one of Paragraphs 40 to 47, the method comprising configuring a first set of preamble signals configured for the transmission of a first message of the first random access procedure to the TRP, and configuring a second set of preamble signals configured for the transmission of a first message of the second random access procedure to the URP, wherein the second set of preamble signals is different to the first set of preamble signals.

Paragraph 49. A method according to any one of Paragraphs 40 to 48, the method comprising transmitting, to the communications device, an indication of a plurality of SSBs, configuring each of the plurality of SSBs with an associated uplink beam directed from the communications device towards the TRP, wherein either the first random access procedure is initiated by the communications device by transmitting a first message to the TRP using the uplink beam associated with the selected SSB or the second random access procedure is initiated by the communications device by transmitting the first message to the TRP using the uplink beam associated with the selected SSB.

Paragraph 50. A method according to any one of Paragraphs 40 to 49, the method comprising transmitting, to the communications device, an indication of a plurality of SSBs, configuring each of the plurality of SSBs with an associated uplink beam of a first set of uplink beams directed from the communications device towards the TRP and an associated uplink beam of a second set of uplink beams directed from the communications device towards one of the URP and the TRP.

Paragraph 51. A method according to Paragraph 50, wherein one or more of the second set of uplink beams are each wider than a corresponding one of the first set of uplink beams.

Paragraph 52. A method according to Paragraph 50 or Paragraph 51, wherein one or more the second set of uplink beams are omnidirectional uplink beams.

Paragraph 53. A method according to any one of Paragraphs 40 to 52, the method comprising receiving, from the communications device, a first message of either the first random access procedure or the second random access procedure, the first message comprising an indication of whether the communications device intends to connect to the heterogeneous communications network via the TRP or the URP.

Paragraph 54. A method according to any one of Paragraphs 40 to 53, the method comprising configuring a first power control function for the communications device to perform the first random access procedure, and configuring a second power control function for the communications device to perform the second random access procedure, wherein the first power control function is different to the second power control function.

Paragraph 55. A method according to Paragraph 54, wherein the first power control function comprises a first power offset value and the second power control function comprises a second power offset value, wherein the first power offset value is different to the second power offset value.

Paragraph 56. A method according to Paragraph 54 or Paragraph 55, wherein the first power control function comprises a first power ramping step amount and the second power control function comprises a second power ramping step amount, wherein the first power ramping step amount is different to the second power ramping step amount.

Paragraph 57. A method according to any one of Paragraphs 54 to 56, wherein the first power control function comprises the communications device using a first power ramping counter and the second power control function comprises the communications device using a second power ramping counter, wherein the first power ramping counter is different to the second power ramping counter.

Paragraph 58. A method according to any one of Paragraphs 54 to 57, wherein the first power control function comprises a first maximum number of transmissions of a first message of the first random access procedure and the second power control function comprises a second maximum number of transmissions of a first message of the second random access procedure, wherein the first maximum number of transmissions of the preamble signal is different to the second maximum number of transmissions of the preamble signal.

Paragraph 59. A method according to any one of Paragraphs 54 to 58, wherein the first power control function comprises a first maximum transmission power value and the second power control function comprises a second maximum transmission power value, wherein the first maximum transmission power value is different to the second maximum transmission power value.

Paragraph 60. A method according to any one of Paragraphs 54 to 60, wherein the first power control function comprises a first reference signal power value and the second power control function comprises a second reference signal power value, wherein the first reference signal power value is different to the second reference signal power value.

Paragraph 61. A method according to any one of Paragraphs 40 to 60, wherein the step of performing either the first initial access procedure or the second initial access procedure comprises transmitting, to the communications device, a second message of either the first random access procedure or the second random access procedure, wherein the second message comprises information to be used by the communications device to transmit signals to the URP.

Paragraph 62. A method according to Paragraph 61, wherein the second message comprises an indication that the communications device is to perform the first initial access procedure.

Paragraph 63. A method according to Paragraph 61 or Paragraph 62, wherein the second message comprises an indication that the communications device is to perform the second initial access procedure. Paragraph 64. A method according to any one of Paragraphs 61 to 63, wherein the information to be used by the communications device to transmit signals to the URP comprises an indication of an uplink beam that is to be used by the communications device for transmitting a third message of the second random access procedure to the URP.

Paragraph 65. A method according to any one of Paragraphs 61 to 64, wherein the information to be used by the communications device to transmit signals to the URP comprises an indication of an uplink beam that is to be used by the communications device for transmitting an uplink signal to the URP indicating that the communications device has successfully connected to the heterogeneous communications network via the URP.

Paragraph 66. A method according to any one of Paragraphs 61 to 65, wherein the information to be used by the communications device to transmit signals to the URP comprises a timing advance value associated with the URP to be applied by the communications device when transmitting signals to the URP.

Paragraph 67. A method according to Paragraph 66, wherein the second message comprises a timing advance value associated with the TRP be applied by the communications device when transmitting signals to the TRP, wherein the timing advance value associated with the TRP is different to the timing advance value associated with the URP.

Paragraph 68. A method according to any one of Paragraphs 61 to 67, wherein the information to be used by the communications device to transmit signals to the URP comprises an estimated uplink pathloss value between the communications device and the URP. Paragraph 69. A method according to any one of Paragraphs 40 to 68, wherein the step of performing either the first initial access procedure or the second initial access procedure comprises transmitting, to the communications device, a fourth message of either the first random access procedure or the second random access procedure, wherein the fourth message comprises an indication that the communications device is to perform the first initial access procedure.

Paragraph 70. A method according to any one of Paragraphs 40 to 69, wherein the step of performing either the first initial access procedure or the second initial access procedure comprises transmitting, to the communications device, a fourth message of either the first random access procedure or the second random access procedure, wherein the fourth message comprises an indication that the communications device is to perform the second initial access procedure.

Paragraph 71. A transmission and reception point, TRP, of a heterogeneous communications network, the TRP providing both uplink connectivity and downlink connectivity for communications devices, wherein the TRP is configured to transmit signals to and receive signals from an uplink-only reception point, URP, of the heterogeneous communications network via a backhaul communications link, the URP providing only uplink connectivity for communications devices, the TRP comprising transceiver circuitry configured to transmit signals to and/or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to transmit, to a communications device, an indicator that provides an indication of whether the communications device is to perform a first initial access procedure for connecting to the heterogeneous communications network via the TRP or a second initial access procedure for connecting to the heterogeneous communications network via the URP, and to perform either a first random access procedure together with the communications device as part of the first initial access procedure or a second random access procedure together with the communications device and the URP as part of the second initial access procedure.

Paragraph 72. Circuitry for a transmission and reception point, TRP, of a heterogeneous communications network, the circuitry providing both uplink connectivity and downlink connectivity for communications devices, wherein the circuitry is configured to transmit signals to and receive signals from an uplink-only reception point, URP, of the heterogeneous communications network via a backhaul communications link, the URP providing only uplink connectivity for communications devices, the circuitry comprising transceiver circuitry configured to transmit signals to and/or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to transmit, to a communications device, an indicator that provides an indication of whether the communications device is to perform a first initial access procedure for connecting to the heterogeneous communications network via the TRP or a second initial access procedure for connecting to the heterogeneous communications network via the URP, and to perform either a first random access procedure together with the communications device as part of the first initial access procedure or a second random access procedure together with the communications device and the URP as part of the second initial access procedure.

Paragraph 73. A method of operating an uplink-only reception point, URP, of a heterogeneous communications network, the URP providing only uplink connectivity for communications devices, wherein the URP is configured to transmit signals to and receive signals from a transmission and reception point, TRP, of the heterogeneous communications network via a backhaul communications link, the TRP providing both uplink connectivity and downlink connectivity for communications devices, the method comprising receiving, from a communications device, a first message of a random access procedure, and transmitting, to the TRP in response to receiving the first message, an indication that the URP received the first message from the communications device.

Paragraph 74. A method according to Paragraph 73, comprising receiving, from the communications device in response to transmitting the indication that the URP received the first message from the communications device, a third message of the random access procedure, and transmitting, to the TRP in response to receiving the third message, an indication that the URP received the third message from the communications device.

Paragraph 75. An uplink-only reception point, URP, of a heterogeneous communications network, the URP providing only uplink connectivity for communications devices, wherein the URP is configured to transmit signals to and receive signals from a transmission and reception point, TRP, of the heterogeneous communications network via a backhaul communications link, the TRP providing both uplink connectivity and downlink connectivity for communications devices, the URP comprising transceiver circuitry configured to transmit signals to and/or to receive signals, and controller circuitry configured in combination with the transceiver circuitry controller circuitry configured in combination with the transceiver circuitry to receive, from a communications device, a first message of a random access procedure, and to transmit, to the TRP in response to receiving the first message, an indication that the URP received the first message from the communications device.

Paragraph 76. Circuitry for an uplink-only reception point, URP, of a heterogeneous communications network, the circuitry providing only uplink connectivity for communications devices, wherein the circuitry is configured to transmit signals to and receive signals from a transmission and reception point, TRP, of the heterogeneous communications network via a backhaul communications link, the TRP providing both uplink connectivity and downlink connectivity for communications devices, the circuitry comprising transceiver circuitry configured to transmit signals to and/or to receive signals, and controller circuitry configured in combination with the transceiver circuitry controller circuitry configured in combination with the transceiver circuitry to receive, from a communications device, a first message of a random access procedure, and to transmit, to the TRP in response to receiving the first message, an indication that the circuitry received the first message from the communications device.

Paragraph 77. A communications system comprising a communications device according to Paragraph 38, a transmission and reception point, TRP, according to Paragraph 71, and an uplink-only reception point, URP, according to Paragraph 75.

Paragraph 78. A computer program comprising instructions which, when loaded onto a computer, cause the computer to perform a method according to any one of Paragraphs 1 to 37, Paragraphs 40 to 70, or Paragraphs 73 to 74.

Paragraph 79. A non-transitory computer-readable storage medium storing a computer program according to Paragraph 78.

It will be appreciated that the above description for clarity has described embodiments with reference to different functional units, circuitry and/or processors. However, it will be apparent that any suitable distribution of functionality between different functional units, circuitry and/or processors may be used without detracting from the embodiments.

Described embodiments may be implemented in any suitable form including hardware, software, firmware or any combination of these. Described embodiments may optionally be implemented at least partly as computer software running on one or more data processors and/or digital signal processors. The elements and components of any embodiment may be physically, functionally and logically implemented in any suitable way. Indeed, the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. As such, the disclosed embodiments may be implemented in a single unit or may be physically and functionally distributed between different units, circuitry and/or processors. Although the present disclosure has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognise that various features of the described embodiments may be combined in any manner suitable to implement the technique.

References

[1] Holma H. and Toskala A, “LTE for UMTS OFDMA and SC-FDMA based radio access”, John Wiley and Sons, 2009.

[2] TS 38.470, “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NG-RAN; Fl general aspects and principles (Release 17)”, 3GPP, V17.4.0, March

2023.

[3] TS 38.473, “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NG-RAN; Fl application protocol (F1AP) (Release 17)”, 3GPP, V17.4.1, April 2023.

[4] TS 38.401, “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NG-RAN; Architecture description (Release 17)”, 3GPP, V17.4.0, March 2023.

[5] RWS-230248, “Views on Rel-19 MIMO/UL enhancements,” NTT DOCOMO, 3GPP TSG RAN Rel-19 workshop, June 2023.

Claims

CLAIMS What is claimed is:

1. A method of operating a communications device, the method comprising receiving, from a transmission and reception point, TRP, of a heterogeneous communications network, an indicator that provides an indication of whether the communications device is to perform a first initial access procedure for connecting to the heterogeneous communications network via the TRP or a second initial access procedure for connecting to the heterogeneous communications network via an uplink-only reception point, URP, of the heterogeneous communications network, wherein the TRP provides both uplink connectivity and downlink connectivity for the communications device, and wherein the URP provides only uplink connectivity for the communications device, determining, based on the received indicator, whether to perform the first initial access procedure or the second initial access procedure, wherein the first initial access procedure comprises selecting one of a plurality of synchronisation signal blocks, SSBs, transmitted by the TRP to the communications device and performing a first random access procedure together with the TRP on the basis of the selected SSB, and wherein the second initial access procedure comprises selecting one of the plurality of SSBs and performing a second random access procedure together with the TRP and the URP on the basis of the selected SSB, and performing the determined one of the first initial access procedure and the second initial access procedure to connect to the heterogeneous communications network.

2. A method according to Claim 1, wherein the indicator explicitly indicates that the communications device is to perform the first initial access procedure or the second initial access procedure.

3. A method according to Claim 1, wherein the indicator comprises an indication of a probability with which the communications device is to perform the second initial access procedure.

4. A method according to Claim 1, wherein the indicator comprises an indication of at least a first set of upper and lower threshold signal strengths, and wherein the communications device determines that it is to perform the second initial access procedure if a measured strength of a signal received by the communications device from the TRP is between the upper threshold signal strength and the lower threshold signal strength.

5. A method according to Claim 4, wherein the indicator comprises an indication of one or more further sets of upper and lower threshold signal strengths different to the first set.

6. A method according to Claim 1, wherein the indicator comprises an indication of a threshold signal strength, and wherein the communications device determines that it is to perform the second initial access procedure if a measured strength of a signal received by the communications device from the TRP is below the threshold signal strength.

7. A method according to Claim 1, wherein the indicator comprises an indication of whether each of the plurality of SSBs forms part of a first set of SSBs associated with the first initial access procedure or a second set of SSBs associated with the second initial access procedure.

8. A method according to Claim 7, wherein the step of determining whether to perform the first initial access procedure or the second initial access procedure comprises selecting one of the plurality of SSBs, determining whether the selected SSB forms part of the first set of SSBs or the second set of SSBs, and determining either that the communications device is to perform the first initial access procedure if the selected SSB forms part of the first set of SSBs or that the communications device is to perform the second initial access procedure if the selected SSB forms part of the second set of SSBs.

9. A method according to Claim 8, wherein the step of selecting the one of the plurality of SSBs comprises measuring a strength of each of the plurality of SSBs, and selecting the selected SSB on the basis of the selected SSB having a measured strength that is higher than a predefined threshold strength.

10. A method according to Claim 1, comprising determining that the communications device has been unable to connect to the heterogeneous communications network by performing the second initial access procedure, and performing, in response to determining that the communications device has been unable to connect to the heterogeneous communications network by performing the second initial access procedure, the first initial access procedure to connect to the heterogeneous communications network.

11. A method according to Claim 1, wherein the second random access procedure is initiated by the communications device by transmitting a first message to the URP in a second set of uplink resources, wherein the second set of uplink resources is different to a first set of uplink resources configured for the transmission of a first message of the first random access procedure to the TRP.

12. A method according to Claim 1, wherein the second random access procedure is initiated by the communications device by transmitting a first message to the URP, the first message comprising one of a second set of preamble signals, wherein the second set of preamble signals is different to a first set of preamble signals configured for the transmission of a first message of the first random access procedure to the TRP.

13. A method according to Claim 1, wherein each of the plurality of SSBs has an associated uplink beam directed from the communications device towards the TRP, and wherein either the first random access procedure is initiated by the communications device by transmitting a first message to the TRP using the uplink beam associated with the selected SSB or the second random access procedure is initiated by the communications device by transmitting the first message to the TRP using the uplink beam associated with the selected SSB.

14. A method according to Claim 1, wherein the plurality of SSBs each have an associated uplink beam of a first set of uplink beams directed from the communications device towards the TRP and an associated uplink beam of a second set of uplink beams directed from the communications device towards one of the URP and the TRP.

15. A method according to Claim 14, wherein one or more of the second set of uplink beams are each wider than a corresponding one of the first set of uplink beams.

16. A method according to Claim 15, wherein one or more of the second set of uplink beams are omnidirectional uplink beams.

17. A method according to Claim 14, wherein the step of performing the second random access procedure together with the TRP and the URP on the basis of the selected SSB comprises transmitting, to the TRP, a first message using the uplink beam of the first set of uplink beams associated with the selected SSB, and transmitting, to the URP, the first message using the uplink beam of the second set of uplink beams associated with the selected SSB.

18. A method according to Claim 1, wherein the second access procedure comprises performing, after selecting the selected SSB, a beam sweeping procedure using a plurality of uplink beams configured for the communications device, wherein the step of performing the second random access procedure together with the TRP and the URP on the basis of the selected SSB comprises transmitting at least one message to the URP using the plurality of uplink beams.

19. A method according to Claim 1, wherein the first random access procedure or the second random access procedure is initiated by the communications device by transmitting a first message comprising an indication of whether the communications device intends to connect to the heterogeneous communications network via the TRP or the URP.

20. A method according to Claim 1, wherein the communications device uses a first power control function for performing the first random access procedure and a second power control function for performing the second random access procedure, wherein the first power control function is different to the second power control function.

21. A method according to Claim 20, wherein the first power control function comprises a first power offset value and the second power control function comprises a second power offset value, wherein the first power offset value is different to the second power offset value.

22. A method according to Claim 20, wherein the first power control function comprises a first power ramping step amount and the second power control function comprises a second power ramping step amount, wherein the first power ramping step amount is different to the second power ramping step amount.

23. A method according to Claim 20, wherein the first power control function comprises the communications device using a first power ramping counter and the second power control function comprises the communications device using a second power ramping counter, wherein the first power ramping counter is different to the second power ramping counter.

24. A method according to Claim 20, wherein the first power control function comprises a first maximum number of transmissions of a first message of the first random access procedure and the second power control function comprises a second maximum number of transmissions of a first message of the second random access procedure, wherein the first maximum number of transmissions of the preamble signal is different to the second maximum number of transmissions of the preamble signal.

25. A method according to Claim 20, wherein the first power control function comprises a first maximum transmission power value and the second power control function comprises a second maximum transmission power value, wherein the first maximum transmission power value is different to the second maximum transmission power value.

26. A method according to Claim 20, wherein the first power control function comprises a first reference signal power value and the second power control function comprises a second reference signal power value, wherein the first reference signal power value is different to the second reference signal power value.

27. A method according to Claim 20, wherein the step of performing the second random access procedure together with the TRP and the URP on the basis of the selected SSB comprises transmitting, to the URP or the TRP, a first message of the second random access procedure using the second power control function, determining that the communications device has received no response to the first message, and retransmitting, to the URP or the TRP, the first message of the second random access procedure using the first power control function.

28. A method according to Claim 1, wherein the step of performing the determined one of the first initial access procedure and the second initial access procedure comprises receiving, from the TRP, a second message of either the first random access procedure or the second random access procedure, wherein the second message comprises information to be used by the communications device to transmit signals to the URP.

29. A method according to Claim 28, wherein the second message comprises an indication that the communications device is to perform the first initial access procedure.

30. A method according to Claim 28, wherein the second message comprises an indication that the communications device is to perform the second initial access procedure.

31. A method according to Claim 28, wherein the information to be used by the communications device to transmit signals to the URP comprises an indication of an uplink beam that is to be used by the communications device for transmitting a third message of the second random access procedure to the URP.

32. A method according to Claim 28, wherein the information to be used by the communications device to transmit signals to the URP comprises an indication of an uplink beam that is to be used by the communications device for transmitting an uplink signal to the URP indicating that the communications device has successfully connected to the heterogeneous communications network via the URP.

33. A method according to Claim 28, wherein the information to be used by the communications device to transmit signals to the URP comprises a timing advance value associated with the URP to be applied by the communications device when transmitting signals to the URP.

34. A method according to Claim 33, wherein the second message comprises a timing advance value associated with the TRP be applied by the communications device when transmitting signals to the TRP, wherein the timing advance value associated with the TRP is different to the timing advance value associated with the URP.

35. A method according to Claim 28, wherein the information to be used by the communications device to transmit signals to the URP comprises an estimated uplink pathloss value between the communications device and the URP.

36. A method according to Claim 1, wherein the step of performing the determined one of the first initial access procedure and the second initial access procedure comprises receiving, from the TRP, a fourth message of either the first random access procedure or the second random access procedure, wherein the fourth message comprises an indication that the communications device is to perform the first initial access procedure.

37. A method according to Claim 1, wherein the step of performing the determined one of the first initial access procedure and the second initial access procedure comprises receiving, from the TRP, a fourth message of either the first random access procedure or the second random access procedure, wherein the fourth message comprises an indication that the communications device is to perform the second initial access procedure.

38. A communications device comprising transceiver circuitry configured to transmit signals to and/or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to receive, from a transmission and reception point, TRP, of a heterogeneous communications network, an indicator that provides an indication of whether the communications device is to perform a first initial access procedure for connecting to the heterogeneous communications network via the TRP or a second initial access procedure for connecting to the heterogeneous communications network via an uplink-only reception point, URP, of the heterogeneous communications network, wherein the TRP provides both uplink connectivity and downlink connectivity for the communications device, and wherein the URP provides only uplink connectivity for the communications device, to determine, based on the received indicator, whether to perform the first initial access procedure or the second initial access procedure, wherein the first initial access procedure comprises the communications device being configured to select one of a plurality of synchronisation signal blocks, SSBs, transmitted by the TRP to the communications device and to perform a first random access procedure together with the TRP on the basis of the selected SSB, and wherein the second initial access procedure comprises the communications device being configured to select one of the plurality of SSBs and to perform a second random access procedure together with the TRP and the URP on the basis of the selected SSB, and to perform the determined one of the first initial access procedure and the second initial access procedure to connect to the heterogeneous communications network.

39. Circuitry for a communications device, the circuitry comprising transceiver circuitry configured to transmit signals to and/or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to receive, from a transmission and reception point, TRP, of a heterogeneous communications network, an indicator that provides an indication of whether the circuitry is to perform a first initial access procedure for connecting to the heterogeneous communications network via the TRP or a second initial access procedure for connecting to the heterogeneous communications network via an uplink-only reception point, URP, of the heterogeneous communications network, wherein the TRP provides both uplink connectivity and downlink connectivity for the communications device, and wherein the URP provides only uplink connectivity for the communications device, to determine, based on the received indicator, whether to perform the first initial access procedure or the second initial access procedure, wherein the first initial access procedure comprises the circuitry being configured to select one of a plurality of synchronisation signal blocks, SSBs, transmitted by the TRP to the communications device and to perform a first random access procedure together with the TRP on the basis of the selected SSB, and wherein the second initial access procedure comprises the circuitry being configured to select one of the plurality of SSBs and to perform a second random access procedure together with the TRP and the URP on the basis of the selected SSB, and to perform the determined one of the first initial access procedure and the second initial access procedure to connect to the heterogeneous communications network.

40. A method of operating a transmission and reception point, TRP, of a heterogeneous communications network, the TRP providing both uplink connectivity and downlink connectivity for communications devices, wherein the TRP is configured to transmit signals to and receive signals from an uplink-only reception point, URP, of the heterogeneous communications network via a backhaul communications link, the URP providing only uplink connectivity for communications devices, the method comprising transmitting, to a communications device, an indicator that provides an indication of whether the communications device is to perform a first initial access procedure for connecting to the heterogeneous communications network via the TRP or a second initial access procedure for connecting to the heterogeneous communications network via the URP, and performing either a first random access procedure together with the communications device as part of the first initial access procedure or a second random access procedure together with the communications device and the URP as part of the second initial access procedure.

41. A method according to Claim 40, wherein the indicator explicitly indicates that the communications device is to perform the first initial access procedure or the second initial access procedure.

42. A method according to Claim 40, wherein the indicator comprises an indication of a probability with which the communications device is to perform the second initial access procedure.

43. A method according to Claim 40, wherein the indicator comprises an indication of at least a first set of upper and lower threshold signal strengths.

44. A method according to Claim 43, wherein the indicator comprises an indication of one or more further sets of upper and lower threshold signal strengths different to the first set.

45. A method according to Claim 40, wherein the indicator comprises an indication of a threshold signal strength.

46. A method according to Claim 40, wherein the indicator comprises an indication of whether each of a plurality of synchronisation signal blocks, SSBs, transmitting to the communications device by the TRP forms part of a first set of SSBs associated with the first initial access procedure or a second set of SSBs associated with the second initial access procedure.

47. A method according to Claim 40, the method comprising configuring a first set of uplink resources configured for the transmission of a first message of the first random access procedure to the TRP, and configuring a second set of uplink resources configured for the transmission of a first message of the second random access procedure to the URP, wherein the second set of uplink resources is different to the first set of uplink resources.

48. A method according to Claim 40, the method comprising configuring a first set of preamble signals configured for the transmission of a first message of the first random access procedure to the TRP, and configuring a second set of preamble signals configured for the transmission of a first message of the second random access procedure to the URP, wherein the second set of preamble signals is different to the first set of preamble signals.

49. A method according to Claim 40, the method comprising transmitting, to the communications device, an indication of a plurality of SSBs, configuring each of the plurality of SSBs with an associated uplink beam directed from the communications device towards the TRP, wherein either the first random access procedure is initiated by the communications device by transmitting a first message to the TRP using the uplink beam associated with the selected SSB or the second random access procedure is initiated by the communications device by transmitting the first message to the TRP using the uplink beam associated with the selected SSB.

50. A method according to Claim 40, the method comprising transmitting, to the communications device, an indication of a plurality of SSBs, configuring each of the plurality of SSBs with an associated uplink beam of a first set of uplink beams directed from the communications device towards the TRP and an associated uplink beam of a second set of uplink beams directed from the communications device towards one of the URP and the TRP.

51. A method according to Claim 50, wherein one or more of the second set of uplink beams are each wider than a corresponding one of the first set of uplink beams.

52. A method according to Claim 50, wherein one or more the second set of uplink beams are omnidirectional uplink beams.

53. A method according to Claim 40, the method comprising receiving, from the communications device, a first message of either the first random access procedure or the second random access procedure, the first message comprising an indication of whether the communications device intends to connect to the heterogeneous communications network via the TRP or the URP.

54. A method according to Claim 40, the method comprising configuring a first power control function for the communications device to perform the first random access procedure, and configuring a second power control function for the communications device to perform the second random access procedure, wherein the first power control function is different to the second power control function.

55. A method according to Claim 54, wherein the first power control function comprises a first power offset value and the second power control function comprises a second power offset value, wherein the first power offset value is different to the second power offset value.

56. A method according to Claim 54, wherein the first power control function comprises a first power ramping step amount and the second power control function comprises a second power ramping step amount, wherein the first power ramping step amount is different to the second power ramping step amount.

57. A method according to Claim 54, wherein the first power control function comprises the communications device using a first power ramping counter and the second power control function comprises the communications device using a second power ramping counter, wherein the first power ramping counter is different to the second power ramping counter.

58. A method according to Claim 54, wherein the first power control function comprises a first maximum number of transmissions of a first message of the first random access procedure and the second power control function comprises a second maximum number of transmissions of a first message of the second random access procedure, wherein the first maximum number of transmissions of the preamble signal is different to the second maximum number of transmissions of the preamble signal.

59. A method according to Claim 54, wherein the first power control function comprises a first maximum transmission power value and the second power control function comprises a second maximum transmission power value, wherein the first maximum transmission power value is different to the second maximum transmission power value.

60. A method according to Claim 54, wherein the first power control function comprises a first reference signal power value and the second power control function comprises a second reference signal power value, wherein the first reference signal power value is different to the second reference signal power value.

61. A method according to Claim 40, wherein the step of performing either the first initial access procedure or the second initial access procedure comprises transmitting, to the communications device, a second message of either the first random access procedure or the second random access procedure, wherein the second message comprises information to be used by the communications device to transmit signals to the URP.

62. A method according to Claim 61, wherein the second message comprises an indication that the communications device is to perform the first initial access procedure.

63. A method according to Claim 61, wherein the second message comprises an indication that the communications device is to perform the second initial access procedure.

64. A method according to Claim 61, wherein the information to be used by the communications device to transmit signals to the URP comprises an indication of an uplink beam that is to be used by the communications device for transmitting a third message of the second random access procedure to the URP.

65. A method according to Claim 61, wherein the information to be used by the communications device to transmit signals to the URP comprises an indication of an uplink beam that is to be used by the communications device for transmitting an uplink signal to the URP indicating that the communications device has successfully connected to the heterogeneous communications network via the URP.

66. A method according to Claim 61, wherein the information to be used by the communications device to transmit signals to the URP comprises a timing advance value associated with the URP to be applied by the communications device when transmitting signals to the URP.

67. A method according to Claim 66, wherein the second message comprises a timing advance value associated with the TRP be applied by the communications device when transmitting signals to the TRP, wherein the timing advance value associated with the TRP is different to the timing advance value associated with the URP.

68. A method according to Claim 61, wherein the information to be used by the communications device to transmit signals to the URP comprises an estimated uplink pathloss value between the communications device and the URP.

69. A method according to Claim 40, wherein the step of performing either the first initial access procedure or the second initial access procedure comprises transmitting, to the communications device, a fourth message of either the first random access procedure or the second random access procedure, wherein the fourth message comprises an indication that the communications device is to perform the first initial access procedure.

70. A method according to Claim 40, wherein the step of performing either the first initial access procedure or the second initial access procedure comprises transmitting, to the communications device, a fourth message of either the first random access procedure or the second random access procedure, wherein the fourth message comprises an indication that the communications device is to perform the second initial access procedure.

71. A transmission and reception point, TRP, of a heterogeneous communications network, the TRP providing both uplink connectivity and downlink connectivity for communications devices, wherein the TRP is configured to transmit signals to and receive signals from an uplink-only reception point, URP, of the heterogeneous communications network via a backhaul communications link, the URP providing only uplink connectivity for communications devices, the TRP comprising transceiver circuitry configured to transmit signals to and/or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to transmit, to a communications device, an indicator that provides an indication of whether the communications device is to perform a first initial access procedure for connecting to the heterogeneous communications network via the TRP or a second initial access procedure for connecting to the heterogeneous communications network via the URP, and to perform either a first random access procedure together with the communications device as part of the first initial access procedure or a second random access procedure together with the communications device and the URP as part of the second initial access procedure.

72. Circuitry for a transmission and reception point, TRP, of a heterogeneous communications network, the circuitry providing both uplink connectivity and downlink connectivity for communications devices, wherein the circuitry is configured to transmit signals to and receive signals from an uplink-only reception point, URP, of the heterogeneous communications network via a backhaul communications link, the URP providing only uplink connectivity for communications devices, the circuitry comprising transceiver circuitry configured to transmit signals to and/or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to transmit, to a communications device, an indicator that provides an indication of whether the communications device is to perform a first initial access procedure for connecting to the heterogeneous communications network via the TRP or a second initial access procedure for connecting to the heterogeneous communications network via the URP, and to perform either a first random access procedure together with the communications device as part of the first initial access procedure or a second random access procedure together with the communications device and the URP as part of the second initial access procedure.

73. A method of operating an uplink-only reception point, URP, of a heterogeneous communications network, the URP providing only uplink connectivity for communications devices, wherein the URP is configured to transmit signals to and receive signals from a transmission and reception point, TRP, of the heterogeneous communications network via a backhaul communications link, the TRP providing both uplink connectivity and downlink connectivity for communications devices, the method comprising receiving, from a communications device, a first message of a random access procedure, and transmitting, to the TRP in response to receiving the first message, an indication that the URP received the first message from the communications device.

74. A method according to Claim 73, comprising receiving, from the communications device in response to transmitting the indication that the URP received the first message from the communications device, a third message of the random access procedure, and transmitting, to the TRP in response to receiving the third message, an indication that the URP received the third message from the communications device.

75. An uplink-only reception point, URP, of a heterogeneous communications network, the URP providing only uplink connectivity for communications devices, wherein the URP is configured to transmit signals to and receive signals from a transmission and reception point, TRP, of the heterogeneous communications network via a backhaul communications link, the TRP providing both uplink connectivity and downlink connectivity for communications devices, the URP comprising transceiver circuitry configured to transmit signals to and/or to receive signals, and controller circuitry configured in combination with the transceiver circuitry controller circuitry configured in combination with the transceiver circuitry to receive, from a communications device, a first message of a random access procedure, and to transmit, to the TRP in response to receiving the first message, an indication that the URP received the first message from the communications device.

76. Circuitry for an uplink-only reception point, URP, of a heterogeneous communications network, the circuitry providing only uplink connectivity for communications devices, wherein the circuitry is configured to transmit signals to and receive signals from a transmission and reception point, TRP, of the heterogeneous communications network via a backhaul communications link, the TRP providing both uplink connectivity and downlink connectivity for communications devices, the circuitry comprising transceiver circuitry configured to transmit signals to and/or to receive signals, and controller circuitry configured in combination with the transceiver circuitry controller circuitry configured in combination with the transceiver circuitry to receive, from a communications device, a first message of a random access procedure, and to transmit, to the TRP in response to receiving the first message, an indication that the circuitry received the first message from the communications device.

77. A communications system comprising a communications device according to Claim 38, a transmission and reception point, TRP, according to Claim 71, and an uplink-only reception point, URP, according to Claim 75.

78. A computer program comprising instructions which, when loaded onto a computer, cause the computer to perform a method according to Claim 1, Claim 40, or Claim 73.

79. A non-transitory computer-readable storage medium storing a computer program according to Claim 78.