GB2562109A

GB2562109A - Methods, radio network node and user equipment for managing control information

Info

Publication number: GB2562109A
Application number: GB1707229.9A
Authority: GB
Inventors: Xirouchakis Ioannis; Marco Olivier; Vivier Guillaume; Palgy Michal
Original assignee: TCL Communication Ltd
Current assignee: TCL Communication Ltd
Priority date: 2017-05-05
Filing date: 2017-05-05
Publication date: 2018-11-07
Also published as: GB201707229D0

Abstract

A radio network node (120) assigns a respective multi-user radio network temporary identifier (MU-RNTI) to each user equipment (UE) (110-112) in a set of UE. Each MU-RNTI comprises a common multi-user radio network temporary identifier (CMU-RNTI) and a respective multi-user group index (MUGI). The node (120) encodes downlink control information (DCI) messages for the set of UE (110-112) by use of the CMU-RNTI. The DCI messages comprise control information, including common information for the set of UE (110-112) and respective specific information for each respective UE. The DCI messages may be one message comprising each respective specific information in order according to the respective MUGI (fig. 5), or a first message comprising the common information and a second message comprising the specific information in order as above (fig. 6). The set of UE may operate in multi-user multiple-input and multiple-output (MU-MIMO) transmission.

Description

(71) Applicant(s):

TCL Communication Limited

1910-12A, Tower 3, 33 Canton Road, Tsim Sha Tsui,

Kowloon, Hong Kong, China (72) Inventor(s):

loannis Xirouchakis Olivier Marco Guillaume Vivier Michal Palgy (56) Documents Cited:

EP 2775640 A1 US 20160088594 A1

WO 2013/068834 A1 US 20160066345 A1 (58) Field of Search:

INT CL H04B, H04J, H04L, H04W Other: WPI, EPODOC, Patent Full-text (74) Agent and/or Address for Service:

Simmons & Simmons LLP

CityPoint, One Ropemaker Street, London, EC2Y 9SS, United Kingdom (54) Title of the Invention: Methods, radio network node and user equipment for managing control information Abstract Title: Method, Radio Network Node and User Equipment for Managing Control Information (57) A radio network node (120) assigns a respective multi-user radio network temporary identifier (MU-RNTI) to each user equipment (UE) (110-112) in a set of UE. Each MU-RNTI comprises a common multi-user radio network temporary identifier (CMU-RNTI) and a respective multi-user group index (MUGI). The node (120) encodes downlink control information (DCI) messages for the set of UE (110-112) by use of the CMU-RNTI. The DCI messages comprise control information, including common information for the set of UE (110-112) and respective specific information for each respective UE. The DCI messages may be one message comprising each respective specific information in order according to the respective MUGI (fig. 5), or a first message comprising the common information and a second message comprising the specific information in order as above (fig. 6). The set of UE may operate in multi-user multiple-input and multiple-output (MU-MIMO) transmission.

UE 110 Radio network node^120 ! S005 Select UE(s) ί S 015 Receive MU-R NTI k—| S 010 Assign MU-RNTI~ ! S030 Configure UE(s) in MU! ΜΙΜΟ

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: S120 Use MUGI to shift DM-RS ;
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S015 Receive MU-RNTI

S070 Receive DCI message(s)

S080 Generate CMU-RNTI

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Fig. 12b

METHODS, RADIO NETWORK NODE AND USER EQUIPMENT FOR MANAGING CONTROL INFORMATION

Technical Field

Embodiments of the present disclosure generally relate to control information, such as downlink control information (DCI), used in a wireless communication system. Specifically, a method and a radio network node for managing control information as well as a method and a user equipment for managing the control information are disclosed.

Background

Multi-User Multiple-Input Multiple-Output (MU-MIMO) is a multi-antenna element transmission technique where data streams of selected users are spatially multiplexed in the same time/frequency resources. The multiplexing shall occur in a way that, from each user’s point of view, the received interference caused by data of other users is suppressed in order to allow successful decoding. This is achieved by an evolved Node B (eNB aka base station) thanks to adequately precoding the transmitted data using the users’ channel state information (CSI).

In addition, quality of service (QoS) management in MU-MIMO is performed by managing the transmitted power of each data stream since users share the same resources and there is no option of frequency dependent scheduling. The power management can be performed under different QoS criteria like for example sum user throughput maximization, user fairness, etc.

MU-MIMO may be applied to the downlink (DL) or the uplink (UL) referred to as DL MU-MIMO and UL MU-MIMO, respectively.

Mathematically, a DL MU-MIMO system of K selected users with single receive antennas and an eNB with A/transmit antennas is expressed as:

y = Hx + n (1) where:

i (?} x - F Q s — F diag(qz} s ^v ' and y is a Kx1 column vector where the Mh element corresponds to the received signal from the Mh single antenna user, x is a NxK transmitter matrix, F is a NxK linear precoder matrix, diagfaT) is a KxK diagonal matrix where its diagonal elements are given by the elements of the length K power allocation vector q, where q > 0, s is a Kx1 column vector containing the data symbols of the K users (e.g QAM symbols of a specific resource element), and finally n is a Kx1 column vector where its elements simulate the additive noise in every user antenna. It may be noted that focus is directed towards single antenna receivers since e.g. Internet of Things (loT) devices, including Machine Type Communication (MTC) device, are assumed to operate with a single antenna for both uplink and downlink.

The system is under a transmitter power constraint which corresponds to the maximum allowed transmit power P of the eNB:

Tr(x-x^H)<P (3) where Tr(-) is the trace of a diagonal matrix.

The received signal at the kth user is then:

Vk h-kf k'/fk^k + hk f jy/j · s, + n_k /-i

7*k (4) where: h_k is the kth row of H and f_k is the kth column of F. The first part of the summation expresses the wanted signal, the second part expresses the interference signal from the other user data and the final part expresses the additive noise. Thus, the resulting SNR of the kth user y_/{ is:

QdWkl²

Y_k =-= ^+ς?₌ι</,·ιμ

Hk (5) given that E{\n_k|} = (noise power) and £{|s^|} = 1 for every k.

F and q _are computed by the eNB based on the desired interference management and QoS design criteria. Generally, MU-MIMO can be as efficient as its CSI feedback mechanism.

In Long Term Evolution (LTE) downlink, there are three transmission modes supporting MU-MIMO; TM5 (two layers, very limited CSI feedback), TM8 (four layers, limited CSI feedback), and TM9 (8 layers, advanced CSI feedback), where TM stands for transmission mode. Each technique has a different number of supported codewords/layers and CSI efficiency. TM9 is the most efficient MU-MIMO scheme in LTE as it supports up to 8 layers and has an advanced CSI mechanism. MTC devices configured with CEmodeB are not required to perform CSI reporting.

Now turning to UL MU-MIMO, which is designed similarly or derivable from the corresponding downlink MU-MIMO described above.

A difference is that a transmitter is a “virtual” transmitter, composed of the uplink transmit antennas of the K users, and the receiver is the N receive antennas of an eNB. Obviously, the eNB is not applying a precoder matrix in the transmitted signal, but rather a detector matrix in the uplink received signals. Also, the uplink power constraint is not given from (3) as each user equipment (UE) has its own power restriction and the power management is performed at the UEs and not the eNB. Finally, H^h,which is the corresponding uplink channel, is not obtained from CSI reporting but from the uplink demodulation reference signals (DMRS) which are Orthogonal Cover Codes (OCC) multiplexed which the eNB processes to obtain the uplink channel estimates.

The K detected symbols are gathered inside the 1xK vector s:

s = Fy = FH^HQs + n (6)

In LTE uplink for UEs with one transmit antenna, the MU-MIMO scheme is practically transparent to the UEs. The eNB can schedule users to transmit in the same uplink resources and attempts to spatially de-multiplex them. To do this it retrieves their uplink CSI from the demodulation reference signals (DMRS) which are multiplexed in the code domain using OCC. In LTE, the UEs’ uplink transmit power allocations can be signaled from the eNB using transmit power control (TPC) commands to each of the grouped UEs.

Further details of LTE uplink and downlink MU-MIMO schemes are not covered in this document.

Uplink and downlink MU-MIMO SINR is a well-studied max-min problem max min v_k ( 7 ) {F,q) kEK which in the downlink is additionally subject to the power constraint (3), and aims to find a combination of precoder matrix and power allocation vector which maximize the minimum user SINR. This is translated to balancing the SINR of the grouped UEs as a user fairness QoS method. The derivation of the precoder, detector and power allocation matrices previously discussed is left to eNB implementation.

Semi persistent scheduling (SPS) was introduced to LTE to serve applications which require persistent allocations of small packets, e.g. Voice over Internet Protocol (VoIP). With SPS, there is no need to signal a different DCI for each uplink or downlink allocation in a subframe basis. Instead, an SPS DCI is signaled to a UE once, and the UE can use the same configuration to receive transmissions which are transmitted with a specific periodicity. This way the signaling overhead is significantly reduced.

A UE configured with a SPS is required to monitor for a release of this configuration which practically is an indication to the UE when to stop receiving transmissions with the previously configured SPS periodicity. Finally, when configured with SPS any occurring HARQ re-transmissions are required to be sent with dynamic DCIs. Thus, UEs need to be able to monitor both SRS and dynamic DCIs.

MTC devices which are limited to operate within the narrow band of 1.4MHz cannot monitor the entire bandwidth of a LTE cell higher than 6 Resource Blocks (RB). Thus, they are unable to scan the entire legacy control region to detect any potential uplink or downlink related DCIs. For this reason, control information for MTC is sent within the legacy LTE data channel, such as physical downlink shared channel (PDSCH), and not within the legacy physical downlink control channel (PDCCH) and it is defined as machine type communication PDCCH (MPDCCH). Clearly, increased number of MPDCCH transmissions reduces the available resources for PDSCH transmissions which otherwise could be used by e.g. highend devices. Figure 1 illustrates that MPDCCH occupy legacy PDSCH resources.

Some more characteristics of MTC control channel is that it can be sent in either localized or distributed manner, depending if reliable channel state information is available at the eNB. Additionally, MPDCCH channel can use repetitions to increase its robustness to penetration losses, resulting to further occupation of PDSCH resources. Finally, its length can be up to 6 RBs.

A MPDCCH resource contains a DCI message intended for a specific MTC UE, and the following MTC DCIs were defined:

• DCI 6-OA and 6-OB, CEmodeA and CEmodeB DCIs for uplink assignments, respectively.

• DCI 6-1A and 6-1B, CEmodeA and CEmodeB DCIs for downlink assignments, respectively. These two formats can also be used for PRACH.

• DCI 6-2, paging.

• DCI 3/3A, power control.

Notice that the DCIs relative to uplink and downlink assignments have two types, depending on the Coverage Enhancement (CE) capabilities of the device, one corresponding to MTC CEmodeA devices (type A) and one corresponding to MTC CEmodeB devices (type B). DCIs of type B have limited length compared to type A.

A concept of search spaces goes back to Release 8 of LTE where UEs are required to monitor through ‘blind decoding’ only a subset of the available control region to extract different types of control information. A purpose of limiting the number of decoding attempts is to save UE power/cycles.

Generally, there are two types of search spaces, common and UE-specific. Common search spaces can be decoded by several UEs, and UE-specific can by decoded by an individual UE, depending on the content of the control information. For example, paging information is nested inside common search spaces where several UEs can receive information about potential incoming data information. On the other hand, DCIs use UE-specific search spaces where each UE can receive the control information for either downlink or uplink packets. The blind decoding of search spaces is performed using different RNTI types. E.g. paging uses P-RNTIs, which can be common to several UEs. DCIs use C-RNTI which are unique per UE. Different types of RNTIs are assigned to each UE during RRC configuration. SPS, mentioned above, also uses search-spaces using a SPS-RNTI.

MTC devices, as discussed above, cannot access the entire legacy LTE control region and use part of the data region. Thus, control search spaces are carried inside the PDSCH but use the same concept of common and UE-specific information. A MTC device is required to monitor different MPDCCH using different types of RNTIs to retrieve common and/or UE-specific control information.

Both legacy and MTC search spaces support multiple aggregation levels or Control Channel Elements (CCEs). Higher aggregation levels, or equivalently more CCEs, result to more available PDCCH/MPDCCH resources for mapping a DCI message. The choice of aggregation level depends on the length of the original uncoded DCI message and the channel conditions which dictate the coding rate (hence the number of coded DCI bits) to be used for coding the DCI message.

Summary

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

According to an aspect, there is provided a method for managing control information to be transmitted to a set of user equipments. The radio network node assigns a respective multi-user radio network temporary identifier to each user equipment of the set of user equipments. Each respective multi-user radio network temporary identifier comprises a common multi-user radio network temporary identifier and a respective multi-user group index. The radio network node encodes one or more downlink control information messages for the set of user equipments by use of the common multi-user radio network temporary identifier. Said one or more downlink control information messages comprise the control information. The control information comprises common information for the set of user equipments and respective specific information for each respective user equipment of the set of user equipments. Furthermore, the radio network node transmits said one or more downlink control information messages to the set of user equipments.

According to another aspect, there is provided a method for managing control information for a set of user equipments. A respective multi-user radio network temporary identifier is assigned to each user equipment of the set of user equipments. Each respective multi-user radio network temporary identifier comprises a common multi-user radio network temporary identifier and a respective multi-user group index. The user equipment receives, from a radio network node, one or more downlink control information messages comprising the control information. The user equipment decodes said one or more downlink control information messages for the user equipment by use of the common multi-user radio network temporary identifier. The control information comprises common information for the set of user equipments and respective specific information for each respective user equipment of the set of user equipments.

With at least some embodiments herein, the spectral efficiency of a wireless communications system, which supports the set of user equipments, such as a number of ΙοΤ-like devices, Machine Type Communications (MTC), Narrow Band loT (NB-loT) or the like, is improved. The embodiments herein introduce methods which reduce required control information for serving these devices, such as the set of user equipments, which results in an increase of available resources for data transmission and thus use available resources efficiently.

An expected continuous increase of the number of ΙοΤ-like devices, such as the set of user equipments, using a specific cell, results in a shortage of spectral resources. A considerable portion of the spectral resources is used to support control and data transmissions of these devices. There may be scenarios where the resource requirements to support these devices does not leave sufficient resources to support other services, e.g. high throughputs for broadband devices using the same cell.

In fact, loT-like devices have relatively low requirements on throughput in the level that the required control information volume in some cases becomes comparable to the corresponding data volume for these devices. This is because each data transmission (either uplink or downlink) requires a corresponding control message to enable that transmission.

In view of the above, the embodiments herein may be particularly applicable within LTE MTC architecture. However, the embodiments herein may be used in other systems or architectures, such as NB-loT, capable of multi-antenna processing.

According to at least some embodiments herein, a selected set of loT-type devices, e.g. the set of user equipment mentioned above, are grouped together by the radio network node, such as an LTE base station, eNB or the like, and members of the group may be configured to, at least one of:

• Use the same resources to receive (downlink) and/or transmit (uplink) data by being configured in a multi-user Multiple Input - Multiple Output (MU-MIMO) transmission scheme.

• Have common uplink and/or downlink transmission characteristics, i.e. at least resource allocation (RA), modulation and coding scheme (MCS), physical channel repetition. Physical channel repetition is a method where data packet transmissions to a MTC UE within HARQ transmissions are repeated several times. The UE combines these repetitions in order to increase the probability of decoding the corresponding packet. With every repetition, the effective Signal-to-Noise Ratio (SNR) of the received packet is improved.

• Use common control resources to signal these common transmission characteristics. To enable this, new control search-spaces and DCI types need to be defined.

MU-MIMO is an established transmission scheme in LTE. However, according to existing 3GPP standards, each spatially multiplexed UE still requires an individual Downlink Control Information (DCI) message. Embodiments herein propose that UE data streams selected for MU-MIMO are processed in a manner, which results in common transmission characteristics. This may be achieved by performing Signal-to-Noise-plus-lnterference (SINR) balancing of the data streams through power allocation management at the radio network node prior to the MUMIMO transmission. By doing this, the radio network node ensures that the resulting SINRs of the transmitted codewords are identical, thus common transmission characteristics can be selected for these codewords.

By performing the above, a large portion of the control information is common for the set of user equipments. Thus, there is no need to transmit the entire DCI message to each UE separately. Instead, the grouped UEs can retrieve this common control information from the same DCI and, consequently, the same resources. Any remaining non-common control information can remain UE-specific, either in the same (extended) DCI (one-step DCI), or in a complimentary DCI to the common DCI (two-step DCI). Each UE group member can extract its UE-specific control information by using a multi user group index assigned by the eNB. In other words, the invention proposes a novel hybrid DCI, either one or two step, containing both group and UE-specific control information.

When applying the embodiments herein the control resources reserved for serving MTC devices (MPDCCH) can be significantly reduced. The spectral efficiency improvement depends on the number of K grouped UEs. Currently LTE Release 14 supports MU-MIMO with up to 8 layers (Transmission Mode 9), however, future releases which would potentially support more eNB antenna ports (e.g. massive ΜΙΜΟ) could further increase the number of grouped UE and further improve the spectral efficiency.

As a result, the embodiments herein increase spectral efficiency of a wireless communications system through use of:

• MU-MIMO, where UEs share data resources, i.e. reduced size of retransmissions is achieved, and • a particular downlink control information message that comprises the control information, wherein the control information comprises common control information and specific control information pieces. In this manner, required control information is reduced thanks to that common control information need not be duplicated for each user equipment of the set of user equipments.

The spectral efficiency gain is dependent on various parameters such as the number of MU-MIMO grouped users K, the transport block size, the users’ channel conditions, etc.

According to further aspects, there is provided computing device, such as the radio network node and/or the user equipment above, including a processor unit, a storage unit and a communications interface, where the processor unit, storage unit, and communications interface are configured to perform the method(s) herein.

The methods described herein may be performed by software in machine readable form on a tangible storage medium or computer readable medium e.g. in the form of a computer program comprising computer program code means adapted to perform all the steps of any of the methods described herein when the program is run on the computing device, and where the computer program may be embodied on a computer readable medium. Examples of tangible, or non-transitory, storage media include disks, thumb drives, memory cards etc. and do not include propagated signals. The software can be suitable for execution on a parallel processor or a serial processor such that the method steps may be carried out in any suitable order, or simultaneously.

According to a further aspect, there is provided a computer readable medium comprising a computer program, program code or instructions stored thereon, which when executed on a processor, causes the processor to perform the methods herein.

This acknowledges that firmware and software can be valuable, separately tradable commodities. It is intended to encompass software, which runs on or controls “dumb” or standard hardware, to carry out the desired functions. It is also intended to encompass software which “describes” or defines the configuration of hardware, such as hardware description language (HDL) software, as is used for designing silicon chips, or for configuring universal programmable chips, to carryout desired functions.

The preferred features may be combined as appropriate, as would be apparent to a skilled person, and may be combined with any of the aspects of the invention.

Brief Description of the Drawings

Further details, aspects and embodiments will be described, by way of example only, with reference to the drawings. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. Like reference numerals have been included in the respective drawings to ease understanding.

Figure 1 is a block diagram illustrating that MPDCCH is located in a legacy shared data region.

Figure 2 is a schematic overview of a wireless communication system.

Figure 3 is an illustration describing common multi-user radio network temporary identifier, multi-user radio network temporary identifier and multi-user group index.

Figure 4 is a simplified combined signalling and flow chart illustrating exemplary methods when implemented in the wireless communication system of Figure 2.

Figure 5 is a simplified block diagram illustrating one-step embodiments.

Figure 6 is a simplified block diagram illustrating two-step embodiments.

Figure 7 is a diagram illustrating MTC MCS index as a function of SNR.

Figure 8 is a further diagram illustrating spectral efficiency as a function of

SNR.

Figure 9 is a flowchart illustrating a simplified method performed by the radio network node.

Figures 10a and 10b are simplified block diagrams illustrating embodiments of the radio network node.

Figure 11 is a flowchart illustrating a simplified method performed by the user equipment.

Figures 12a and 12b are simplified block diagrams illustrating embodiments of the user equipment.

Detailed Description

Those skilled in the art will recognise and appreciate that the specifics of the examples described are merely illustrative of some embodiments and that the teachings set forth herein are applicable in a variety of alternative settings.

Referring now to Figure 2, an exemplifying wireless communication system 100 is shown.

The wireless communication system 100 comprises a set of user equipments 110-112 and a radio network node 120, The set of user equipments 110-112 comprises a user equipment 110.

The wireless communication system 100 may be any cellular or non-cellular 3GPP based wireless communication system, such as a 3th generation system (3G), a 4^th generation system (4G), a 5^th generation system (5G), a NR system, a Long-Term Evolution (LTE), e.g. LTE Frequency Division Duplex (FDD), LTE Time Division Duplex (TDD), |_TE Half-Duplex Frequency Division Duplex (HD-FDD), LTE operating in an unlicensed band, or a Wideband Code Division Multiple Access (WCDMA), Universal Terrestrial Radio Access (UTRA) TDD, Ultra-Mobile Broadband (UMB), Global System for Mobile communications (GSM) network, GSM/Enhanced Data Rate for GSM Evolution (EDGE) Radio Access Network (GERAN) network, EDGE network, a network comprising of any combination of Radio Access Technologies (RATs) such as e.g. Multi-Standard Radio (MSR) base stations, multi-RAT base stations etc., any 3rd Generation Partnership Project (3GPP) cellular network, WiFi networks, Worldwide Interoperability for Microwave Access (WiMax), or any other cellular network or system or an evolution of any one of the aforementioned networks or systems.

As used herein, the term “radio network node” may refer to an evolved Node B, a Node B, a radio base station, a radio network controller, a relay node, a base station, a macro base station, a micro base station or the like.

As used herein, the term “user equipment” may refer to a wireless communication device, a machine-to-machine (M2M) device, a mobile phone, a cellular phone, a smartphone, a laptop or personal computer (PC) equipped with an internal or external mobile broadband modem, a tablet PC with radio communication capabilities, a portable electronic radio communication device, a sensor device equipped with radio communication capabilities or the like. The term “user” may indirectly refer to the wireless device. Sometimes, the term “user” may be used to refer to the user equipment or the like as above. It shall be understood that the user may not necessarily involve a human user. The term “user” may also refer to a machine, a software component or the like using certain functions, methods and similar.

The embodiments herein provide method(s) of reducing the amount of resources used by the set of user equipments 110-112, such as aforementioned expected large amount of ΙοΤ-like devices.

The proposed spectral efficiency improvement may be achieved by the radio network node 120 by selecting K user equipments, i.e. the set of user equipments, and configuring them in a MU-MIMO scheme using one or more control information messages, e.g. one or more at least partially common DCI message, for K parallel transmissions. In order to be able to apply common transmission characteristics for each of codeword, i.e. one or more codewords of the transmission(s) to be transmitted, the radio network node 120 may balance channel quality experienced by the set of user equipments. By doing so, the radio network node 120 may configure the corresponding codewords with a common resource allocation, MCS, repetition level and other common control parameters. These parameters are referred to as common control information herein and these parameters also compose a largest portion of one or more control information messages. The radio network node 120 does not have to repeat the common control information K times since the set of user equipments may retrieve it from said one or more control information messages, e.g. at the same control resources (MPDCCH).

As mentioned in the background section, there are common and UE-specific search spaces. The embodiments herein introduces of a particular type of search space which is a hybrid type between common and UE-specific. The particular type of search space is herein referred to as a multi-user (MU) search space. The MU search space is a common search space, but only to the set of user equipments 110-112, e.g. operating in MU-MIMO. An aggregation level of the MU search space may be chosen according to a target coding rate of for UE with the worst channel conditions amongst the set of UEs 110-112 to ensure that a nested DCI will be successfully decoded by all user equipments 110-112 in the set.

To achieve this, while referring to Figure 3, a particular RNTI type may be assigned to each user equipment of the set, e.g. MU grouped UEs. The particular RNTI is herein referred to as MU-RNTI. The MU-RNTI may comprise two parts, a common part, referred to as common multi-user (CMU)-RNTI, and a specific part, referred to as a UE-specific multi user group index (MUGI). Each UE 110-112 can derive the CMU-RNTI part by subtracting the MUGI from the assigned MU-RNTI. CMU-RNTI is preferably used to monitor the MU search space. The MUGI is sent to notify each UE of its identity/index within the MU-MIMO group.

In the Figure, the MUGI is located at the three least significant bits of the MU-RNTI, but other possibilities exist. For example, if K = 8 is the maximum supported UEs per group, then the 3 LSB of the assigned MU-RNTI is the UE’s MUGI. By subtracting MUGI from MU-RNTI each UE can derive the common CMURNTI which can be used to monitor the MU search spaces.

The proposed relation between MU-RNTI, CMU-RNTI and MUGI is CMURNTI = (MU-RNTI) - (MUGI).

Figure 4 illustrates embodiments of the method when implemented in the wireless communication system 100 of Figure 2. The radio network node 120 performs a method for managing control information to be transmitted to the set of user equipments 110-112. The user equipment 110 performs a method for managing control information for the set of user equipments 110-112.

A respective multi-user radio network temporary identifier is assigned to each user equipment 110-112 of the set of user equipments 110-112. Each respective multi-user radio network temporary identifier comprises a common multi-user radio network temporary identifier and a respective multi-user group index.

The control information may relate to one or more transmissions between the user equipments 110-112 and the radio network node 120.

According to the various embodiments herein, one or more of the following steps may be performed as applicable.

In a step S005, the radio network node 120 may select the set of user equipments 110-112 based on one or more criteria, e.g. level of grouping, relating to said one or more transmissions.

Said one or more criteria may comprise one or more of:

• Semi Persistent Scheduling opportunities, • DRX synchronization opportunities, • CSI reporting requirements, and • MU-MIMO transmission and re-transmission requirements.

E.g. some users may be grouped for a single transmission once. However, there could be cases that a group of users are grouped for a longer period of time,

i.e. their DRX cycles are synchronized, and/or they are using the same SPS configuration, CSI reporting, etc. These embodiments are described in more detail in section “multi-user grouping” below.

In a step S010, the radio network node 120 assigns a respective multi-user radio network temporary identifier to each user equipment 110-112 of the set of user equipments 110-112. Each respective multi-user radio network temporary identifier comprises a common multi-user radio network temporary identifier and a respective multi-user group index.

In a step S030, the radio network node 120 may configure the set of user equipments 110-112 to operate in MU-MIMO transmission.

In a step S040, the radio network node 120 may generate the common multiuser radio network temporary identifier, e.g. by subtracting the respective multi-user group index from the multi-user radio network temporary identifier. E.g. in step S010, the radio network node 120 may assig the MU-RNTI to each UE of the group and then the radio network node 120 adds the MUGI to the CMU-RNTI to derive each user equipments 110-112 MU-RNTI.

In a step S050, the radio network node 120 encodes one or more downlink control information messages for the set of user equipments 110-112 by use of the common multi-user radio network temporary identifier. Said one or more downlink control information messages comprise the control information. The control information comprises common information for the set of user equipments 110-112 and respective specific information for each respective user equipment 110-112 of the set of user equipments 110-112.

According the one-step-embodiments, said one or more downlink control information messages may be only one downlink control information message. Said only one downlink control information message includes the common information. A set of specific information pieces may comprise each of the respective specific information, i.e. the set of specific information pieces comprises the respective specific information for each individual user equipment in the set of user equipments.

The control information may comprise the set of specific information pieces in order according to the respective multi-user group index, e.g. following after the common information. The expression “in order” may herein refer to increasing order or decreasing order according to the respective multi-user group index while starting from either the most significant bits or the least significant bits of the control information.

According the two-step-embodiments, said one or more downlink control information messages may comprise a first downlink control information message and a second downlink control information message. The first downlink control information message may comprise the common information, and the second downlink control information message may comprise a set of specific information pieces comprising each of the respective specific information. The second downlink control information message may comprise the set of specific information pieces in order according to the respective multi-user group index. The expression “in order” may herein refer to increasing order or decreasing order according to the respective multi-user group index while starting from either the most significant bits or the least significant bits of the control information.

In a step S060, the radio network node 120 transmits said one or more downlink control information messages to the set of user equipments 110-112.

In a step S070, the user equipment 110 receives, from a radio network node 120, one or more downlink control information messages comprising the control information.

In a step S080, the user equipment 110 may generate the common multi-user radio network temporary identifier by subtracting the respective multi-user group index from the multi-user radio network temporary identifier.

In a step S090, the user equipment 110 decodes said one or more downlink control information messages for the user equipment 110 by use of the common multi-user radio network temporary identifier. The control information comprises common information for the set of user equipments 110-112 and respective specific information for each respective user equipment 110-112 of the set of user equipments 110-112.

In a step S095, the user equipment 110 may find, or retrieve, the common information. Subsequently, e.g. after step S110, the user equipment 110 may combine the common information and the respective specific information to obtain the control information, i.e. the complete control information.

According the one-step-embodiments, the common information may e.g. be found as the most significant bits of the payload of said only one downlink control information message.

According to the two-step-embodiments, the common information may be found in the first downlink control information message.

According the one-step-embodiments, in a step S100, the user equipment 110 may find the respective specific information for the user equipment 110 after the common information by taking into account the respective multi-user group index of the user equipment 110 and a number of bits of the respective specific information.

According the two-step-embodiments, in a step S110, the user equipment 110 may find the respective specific information for the user equipment 110 in the second downlink control information message by taking into account the respective multi-user group index of the user equipment 110 and a number of bits of the respective specific information.

In a step S120, the user equipment 110 may use the multi-user group index to cyclically shift a respective demodulation reference signal for the user equipment 110.

In a step S130, the user equipment 110 may transmit the respective demodulation reference signal.

In a step S140, the radio network node 120 may receive demodulation reference signals from the set of user equipments 110-112 while assuming a respective demodulation reference signal for each user equipment 110-112 to be cyclically shifted by use of the respective multi-user group index for said user equipment 110-112.

Multi User DCI

The embodiments herein propose to introduce a multi-user DCI (MU DCI) which is sent within the MU search space described above. MU DCI may comprise, e.g. shall contain, both common and UE-specific control information for the MUMIMO grouped UEs. Thus, when a UE successfully decodes a MU DCI within a MU search space it can retrieve both the common MU group information and the UEspecific group information to complete the necessary control information.

Obviously, since the UE-specific part of the MU DCI is required to provide UEspecific information to K grouped UEs, this part of the DCI will be K times longer compared to the legacy MTC DCI.

It is herein proposed that MU DCI may modify/extend the existing MTC DCIs to include both common and UE-specific configuration. To manage the increased MU DCI length the invention proposes two different options:

1. Single-step MU DCI, i.e. the one-step-embodiments:

a. Extend the DCI to contain both common and UE-specific information (see Figure 5).

b. Increase the aggregation level/number of CCEs until the desired coding rate is reached which matches the common channel conditions/MCS.

2. Two-step MU DCI, i.e. the two-step embodiments:

a. Create two MU DCI messages, MU DCI-A and MU DCI-B, one with the common and one with the UE-specific control information, respectively (see Figure 6).

b. For each of the MU DCI-A and MU DCI-B select an aggregation level/number of CCEs until the desired coding rate is reached which matches the common channel conditions/MCS.

c. These two different DCI messages shall be transmitted in different subframes.

The selection between single-step and two-step MU-DCI may for example be based on the number K of grouped UEs. E.g. for K = 2 and 4 a single-step DCI can be sufficient. As an example, for K > 4 a two-step MU DCI may be used.

Notice that generally a 16 bit CRC is added in legacy LTE DCIs. However, for the case of the proposed MU DCI-B of the two-step MU DCI, a smaller CRC can be potentially used.

Multi User Group Index

Each UE can use their individual assigned MUGI to extract their UE-specific information, for both single and two step MU DCI options. Each UE knows the length of the common information L_COmmon and the length of the UE-specific information of the MU DCI LuE-specific- For single-step MU DCI, each UE can extract the first L_common bits and then extract LuE-specific bits starting from the bit L_common + K-Imugi + 1, see example depicted in Figure 5.

For two-step MU DCI, a UE decodes the length Lcommon MU DCI-A for the common control information, and the length K-Imugi MU DCI-B for the UE-specific information, using again the MUGI to extract the control bits related that UE, see

TIT-DL

Figure 6. The two-step MU DCI 6-1B has rr = 6, Lcommon = 15, LuE-specific = 2, and K = 8.

Finally, to facilitate UL MU-MIMO, the MUGI can replace the cyclic shift for DMRS/OCC index as defined in section 5.5.2.1.1 of 3GPP TS 36.211 Physical channels and modulation, V14.1.0 (2016-12) which is necessary for codemultiplexing of the DM RS of the grouped MU-MIMO UEs. Instead of the eNB signaling a different OCC index, the UE can use the MUGI to create the cyclically shifted DM RS. In other words, MUGI can replace the cyclic shift field in Table 5.5.2.1.1-1 of 3GPP TS 36.211 Physical channels and modulation, V14.1.0 (201612).

Multi User grouping

Embodiments relating to multi-user grouping, or MU-MIMO grouping, are described in the following. MU-MIMO grouping applies to the set of user equipments, referred to as MTC device in the following.

A considerable amount of MTC devices most likely require seldom transmissions/receptions of relatively small IP packets. In addition, several of these devices require a similar amount of information with the same frequency during a longer period of time. It is also quite possible that several identical devices are camped inside the same cell. Finally, some MTC devices are stationary or near stationary, and for those a valid assumption is that their channel quality, e.g. reference signal received power/reference signal received quality (RSRP/RSRQ) remains the same for a long period of time, even near permanently.

Given the above, the radio network node 120, such as an eNB, may create MU-MIMO groups of these devices which have similar or even the same transmission and/or reception IP packet and transport block requirements and follow the MU-MIMO grouping discussed in the previous sections. In addition, the signaling of the control information for the MTC MU groups can be done in a dynamically or in a semi-persistent way, and both options should be considered.

The following sections discuss different levels of MU-MIMO grouping, e.g. said one or more criteria, such as the aforementioned:

• Semi Persistent Scheduling opportunities, and/or • DRX synchronization opportunities, and/or • CSI reporting requirements, and/or • MU-MIMO transmission and re-transmission requirements.

MU-MIMO SPS grouping or Semi Persistent Scheduling opportunities

Since a large portion of MTC devices have low packet requirements and need to report or receive transmissions periodically (similarly to VoIP), SPS is a fitting scheduling mechanism for reducing the signaling volume of these devices. SPS for MTC devices can be defined to include different values of periodicity to serve different kind of MTC devices. In contrast to the VoIP SPS periodicity (~20msec), SPS for MTC can define configurations with a much longer periodicity to match the corresponding latency MTC requirements. Practically, this means that the MU DCI discussed above would act as a SPS setup for the grouped MTCs.

MU-MIMO DRX grouping or DRX synchronization opportunities

Once the eNB has categorized several MTC devices according to their uplink/downlink data requirements, it can group them also in Discontinuous Reception (DRX) level. This means that grouped MTC devices can be configured with the same DRX at the same time, i.e. synchronize their DRX on and off periods, both for short and long DRX. By doing this, the eNB makes sure that all group members are awake for simultaneous packet transmission and/or reception

MU-MIMO CSI reporting or CSI reporting requirements

During a DRX on period and in case of downlink transmissions, the grouped MTC devices are required to do CSI reporting to allow accurate CSI at the eNB. The eNB needs to make sure that all grouped MTCs have reported their CSI prior to any downlink MU-MIMO transmissions. In fact, MTCs grouped with MU-MIMO should not attempt to receive any MPDCCH before they report their CSI.

MU-MIMO transmissions and re-transmissions or MU-MIMO transmission and retransmission requirements

During a DRX on period the grouped MTC devices are expected to monitor the MPDCCH for possible downlink or uplink related DCIs as presented above. This will allow simultaneous uplink and/or downlink transmissions to grouped MTCs with reduced control information.

If HARQ NACKs occur for some transport blocks of a subset of the grouped MTCs, then the retransmission and the corresponding DCI can be sent in a nongrouped manner, i.e. not using the MU search space or MU-MIMO transmission scheme. Instead, any retransmission DCI shall be sent within UE-specific search spaces, and retransmission of the data part can use SU-MIMO or another transmission scheme. This is similar to SPS where first transmissions use the SPS configuration, while re-transmissions use the dynamic UE-specific DCIs.

Figures 7 and 8 illustrate results of simulations implementing the embodiments herein. Potential spectral efficiency improvement is shown for the embodiments herein. The simulations compare the amount of total PDSCH resources (control and data) required to support a number of MTC devices between (legacy) SU-MIMO and new proposed MU-MIMO with reduced control information.

The spectral efficiency improvement percentage is calculated as:

/ N SU-MIMO

Spectral Efficiency Improvement (%) = 100 mu-mimo ~ \NpRB

where Nf_RB ^MIM0 and NpR^uB~^MI are the number of control (MPDCCH) and information (PDSCH) PRBs used for the transmission of the K UEs IP packets/transport blocks for SU and MU ΜΙΜΟ, respectively.

Additional simulation parameters are shown in Table 6.

Table 6 Simulation Parameters.

Parameter	Value	Parameter	Value
Number of UEs	{2,4,8}	DCI	Format 6-IB
Number of eNB antennas	{2,4,8}	Bandwidth	10 MHz
Number of UE antennas	1	Channel estimation	Ideal
SU-MIMO beamformer	Zero Forcing	Channel	AWGN

MU-MIMO beamforraer	Zero Forcing	IP packet size/TBS	504
Maximum RSRP separation between MU-MIMO UEs	8dBs

The system level simulations are performed using the following procedure:

1. A set of K UEs are configured with either a SU or MU ΜΙΜΟ transmission scheme.

2. For each UE the receiver SNR is calculated and then translated to a MCS index according to Figure 7.

3. The MCS index is translated into a TBS index according to Section 7.1.7.1 of

3GPP TS 36.213, Physical layer procedures, V14.1.0 (2016-12).

4. For the given TBS index, a number of PRBs is selected which fit the packet size. If the channel conditions do not allow a TBS selection which fits the entire packet, several transmissions are performed until the whole packet is transmitted. The total number of data PRBs is calculated.

5. For a given SNR, the coding rate c is calculated. It is used to calculate the number of PRBs for transmitting the DCI by deriving the number of required DCI resources. The total number of control PRBs is calculated.

6. The total number of control and data PRBs is calculated.

7. Finally, the SU and MU number of PRBs are compared to derive the spectral efficiency improvement % according to equation (8).

Figure 7 illustrates SNR received at e.g. the user equipment 110 as a function of MCS. The spectral efficiency improvement for different number of K users is shown in Figure 8. Thus, Figure 8 illustrates spectral efficiency gain for said different number of K users.

Figure 9 illustrates exemplifying methods, performed by the radio network node 120, for managing control information to be transmitted to a set of user equipments 110-112.. According to the various embodiments herein, one or more of the following steps may be performed as applicable. The same or similar reference numerals as above have been used to denote the same or similar steps, or actions.

As mentioned, the control information may relate to one or more transmissions between the user equipments 110-112 and the radio network node 120.

In a step S005, the radio network node 120 may select the set of user equipments 110-112 based on one or more criteria, or level of grouping, relating to said one or more transmissions.

Said one or more criteria may comprise one or more of:

In a step S040, the radio network node 120 may generate the common multiuser radio network temporary identifier by subtracting the respective multi-user group index from the multi-user radio network temporary identifier.

According the one-step-embodiments, said one or more downlink control information messages may be only one downlink control information message. Said only one downlink control information comprises the common information for the set of user equipments 110-112. A set of specific information pieces may comprise each of the respective specific information. The control information may comprise the set of specific information pieces in order according to the respective multi-user group index, e.g. following after the common information.

According the two-step-embodiments, said one or more downlink control information messages may comprise a first downlink control information message and a second downlink control information message. The first downlink control information message may comprise the common information, and the second downlink control information message may comprise a set of specific information pieces comprising each of the respective specific information. The second downlink control information message may comprise the set of specific information pieces in order according to the respective multi-user group index.

In a step S060, the radio network node 120 transmits S060 said one or more downlink control information messages to the set of user equipments 110-112.

Figures 10a and 10b illustrate embodiments of the radio network node 120.

Figure 10a illustrates various components of an exemplary computing-based device 1000 which may be implemented to include the functionality of the radio network node 120 as disclosed herein.

The computing-based device 1000 comprises one or more processors 1002 which may be microprocessors, controllers or any other suitable type of processors for processing computer executable instructions to control the operation of the device in order to perform measurements, receive measurement reports, schedule and/or allocate communication resources as described in the process(es) and method(s) as described herein.

In some examples, for example where a system on a chip architecture is used, the processors 1002, or processor units, may include one or more fixed function blocks which implement the methods and/or processes as described herein in hardware (rather than software or firmware).

Platform software and/or computer executable instructions comprising an operating system 1004a or any other suitable platform software may be provided at the computing-based device to enable application software to be executed on the device. Depending on the functionality and capabilities of the computing device 1000 and application of the computing device, software and/or computer executable instructions may include the functionality for performing methods of the radio network node 120.

For example, the computing device 1000 may be used to implement the radio network node 120 and may include software and/or computer executable instructions that may include functionality of perform measurements, receive measurement reports, schedule and/or allocate communication resources and/or the functionality of the radio network node 1210 according to the embodiments herein.

The software and/or computer executable instructions may be provided using any computer-readable media that is accessible by computing based device 1000. Computer-readable media may include, for example, computer storage media such as memory 1004 and communications media. Computer storage media, such as memory 1004, includes volatile and non-volatile, removable and non-removable media implemented in any method or technology. A data store 1004A of the memory 1004 is configured for storage of information such as computer readable instructions, data structures, program modules or other data.

Computer storage media may include, but is not limited to, RAM, ROM, EPROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other nontransmission medium that can be used to store information for access by a computing device. In contrast, communication media may embody computer readable instructions, data structures, program modules, or other data in a modulated data signal, such as a carrier wave, or other transport mechanism. As defined herein, computer storage media does not include communication media. Although the computer storage media, such as the memory 1004, is shown within the computing-based device 1000 it will be appreciated that the storage may be distributed or located remotely and accessed via a network or other communication link, e.g. using communication interface 1006.

The computing-based device 1000 may also optionally or if desired comprises an input/output controller 1015 arranged to output display information to a display device 1012 which may be separate from or integral to the computing-based device 1000. The display information may provide a graphical user interface. The input/output controller 1015 is also arranged to receive and process input from one or more devices, such as a user input device 1014, e.g. a mouse or a keyboard.

This user input may be used to set scheduling for measurement reports, or for allocating communication resources, or to set which communications resources are of a first type and/or of a second type etc. In an embodiment the display device 1012 may also act as the user input device 1014 if it is a touch sensitive display device. The input/output controller 1015 may also output data to devices other than the display device, e.g. other computing devices via communication interface 1006, any other communication interface, or a locally connected printing device/computing devices etc.

Figure 10b illustrates a schematic block diagram of the radio network node 120 according to another embodiment. The radio network node 120 comprises an assigning module 1010, an encoding module 1020, a transmitting module 1030, a generating module 1040, a configuring module 1050, a selecting module 1060, and a receiving module 1070, which are configured to perform one or more of the steps performed by the radio network node 120 according to Figure 9.

In view of the above, the radio network node 120 provides the following embodiments. The radio network node 120 is configured for managing control information to be transmitted to a set of user equipments 110-112.

The radio network node 120 and/or the processor 1002 and/or the assigning module 1010 is configured to assign a respective multi-user radio network temporary identifier to each user equipment 110-112 of the set of user equipments 110-112. Each respective multi-user radio network temporary identifier comprises a common multi-user radio network temporary identifier and a respective multi-user group index.

The radio network node 120 and/or the processor 1002 and/or the selecting module 1060 may be configured to select the set of user equipments 110-112 based on one or more criteria, or level of grouping, relating to said one or more transmissions.

Said one or more criteria may comprise one or more of:

The radio network node 120 and/or the processor 1002 and/or the configuring module 1050 may be configured to configure the set of user equipments 110-112 to operate in MU-MIMO transmission.

The radio network node 120 and/or the processor 1002 and/or the generating module 1040 may be configured to generate the common multi-user radio network temporary identifier by subtracting the respective multi-user group index from the multi-user radio network temporary identifier.

The radio network node 120 and/or the processor 1002 and/or the encoding module 1020 is configured to encode one or more downlink control information messages for the set of user equipments 110-112 by use of the common multi-user radio network temporary identifier. Said one or more downlink control information messages comprise the control information. The control information comprises common information for the set of user equipments 110-112 and respective specific information for each respective user equipment 110-112 of the set of user equipments 110-112.

According the one-step-embodiments, said one or more downlink control information messages may be only one downlink control information message. A set of specific information pieces may comprise each of the respective specific information. The control information may comprise the set of specific information pieces in order according to the respective multi-user group index.

The radio network node 120 and/or the processor 1002 and/or the transmitting module 1030 is configured to transmit said one or more downlink control information messages to the set of user equipments 110-112.

The radio network node 120 and/or the processor 1002 and/or the receiving module 1070 may be configured to receive demodulation reference signals from the set of user equipments 110-112 while assuming a respective demodulation reference signal for each user equipment 110-112 to be cyclically shifted by use of the respective multi-user group index for said user equipment 110-112.

Figure 11 illustrates exemplifying methods, performed by the user equipment 110, for managing control information for a set of user equipments 110-112.

According to the various embodiments herein, one or more of the following steps may be performed as applicable. The same or similar reference numerals as above have been used to denote the same or similar steps, or actions.

As mentioned, a respective multi-user radio network temporary identifier is assigned to each user equipment 110-112 of the set of user equipments 110-112. Each respective multi-user radio network temporary identifier comprises a common multi-user radio network temporary identifier and a respective multi-user group index.

According the one-step-embodiments, said one or more downlink control information messages may be only one downlink control information message. Said only one downlink control information comprises the common information for the set of user equipments 110-112. A set of specific information pieces may comprise each of the respective specific information. The control information may comprise the set of specific information pieces in order according to the respective multi-user group index.

Hence, in a step S100, the user equipment 110 may find the respective specific information for the user equipment 110 after the common information by taking into account the respective multi-user group index of the user equipment 110 and a number of bits of the respective specific information.

According the two-step-embodiments, said one or more downlink control information messages comprises a first downlink control information message and a second downlink control information message. The first downlink control information message may comprise the common information, and the second downlink control information message may comprise a set of specific information pieces comprising each of the respective specific information. The second downlink control information message may comprise the set of specific information pieces in order according to the respective multi-user group index.

Hence, in a step S110, the user equipment 110 may find the respective specific information for the user equipment 110 in the second downlink control information message by taking into account the respective multi-user group index of the user equipment 110 and a number of bits of the respective specific information.

Figures 12a and 12b illustrate embodiments of the user equipment 110.

Figure 12a illustrates various components of an exemplary computing-based device 1200 which may be implemented to include the functionality of the user equipment 110 disclosed herein.

The computing-based device 1200 comprises one or more processors 1202 which may be microprocessors, controllers or any other suitable type of processors for processing computer executable instructions to control the operation of the device in order to perform measurements, receive measurement reports, schedule and/or allocate communication resources as described in the process(es) and method(s) as described herein.

In some examples, for example where a system on a chip architecture is used, the processors 1202, or processor unit, may include one or more fixed function blocks which implement the methods and/or processes as described herein in hardware (rather than software or firmware).

Platform software and/or computer executable instructions comprising an operating system 1204a or any other suitable platform software may be provided at the computing-based device to enable application software to be executed on the device. Depending on the functionality and capabilities of the computing device 1200 and application of the computing device, software and/or computer executable instructions may include functionality to perform one or more of the steps according to Figure 11.

For example, the computing device 1200 may be used to implement the user equipment 110 and may include software and/or computer executable instructions that may include functionality to perform one or more of the steps according to Figure 11.

The software and/or computer executable instructions may be provided using any computer-readable media that is accessible by computing based device 1200. Computer-readable media may include, for example, computer storage media such as memory 1204 and communications media. Computer storage media, such as memory 1204, includes volatile and non-volatile, removable and non-removable media implemented in any method or technology. A data store 1204A of the memory 1204 is configured for storage of information such as computer readable instructions, data structures, program modules or other data.

Computer storage media may include, but is not limited to, RAM, ROM, EPROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other nontransmission medium that can be used to store information for access by a computing device. In contrast, communication media may embody computer readable instructions, data structures, program modules, or other data in a modulated data signal, such as a carrier wave, or other transport mechanism. As defined herein, computer storage media does not include communication media. Although the computer storage media, such as the memory 1204, is shown within the computing-based device 1200 it will be appreciated that the storage may be distributed or located remotely and accessed via a network or other communication link, e.g. using communication interface 1206.

The computing-based device 1200 may also optionally or if desired comprises an input/output controller 1215 arranged to output display information to a display device 1212 which may be separate from or integral to the computing-based device 1200. The display information may provide a graphical user interface. The input/output controller 1215 is also arranged to receive and process input from one or more devices, such as a user input device 1214, e.g. a mouse or a keyboard.

This user input may be used to set scheduling for measurement reports, or for allocating communication resources, or to set which communications resources are of a first type and/or of a second type etc. In an embodiment the display device 1212 may also act as the user input device 1214 if it is a touch sensitive display device. The input/output controller 1215 may also output data to devices other than the display device, e.g. other computing devices via communication interface 1206, any other communication interface, or a locally connected printing device/computing devices etc.

Figure 12b illustrates a schematic block diagram of the user equipment 110 according to another embodiment. The user equipment 110 comprises a receiving module 1210, a decoding module 1220, a generating module 1230, a finding module 1240, a using module 1250 and a transmitting module 1260, which are configured to perform one or more of the steps performed by the user equipment

110 according to Figure 11.

In view of the above, the user equipment 110 provides the following embodiments. The user equipment 110 is configured for managing control information for a set of user equipments 110-112.

As mentioned, a respective multi-user radio network temporary identifier is assigned to each user equipment 110-112 of the set of user equipments 110-112. Each respective multi-user radio network temporary identifier comprises a common multi-user radio network temporary identifier and a respective multi-user group index. The control information may relate to one or more transmissions between the user equipments 110-112 and the radio network node 120.

The user equipment 110 and/or the processor 1202 and/or the receiving module 1210 is configured to receives, from a radio network node 120, one or more downlink control information messages comprising the control information.

The user equipment 110 and/or the processor 1202 and/or the generating module 1230 may be configured to generate the common multi-user radio network temporary identifier by subtracting the respective multi-user group index from the multi-user radio network temporary identifier.

The user equipment 110 and/or the processor 1202 and/or the decoding module 1220 is configured to decode said one or more downlink control information messages for the user equipment 110 by use of the common multi-user radio network temporary identifier. The control information comprises common information for the set of user equipments 110-112 and respective specific information for each respective user equipment 110-112 of the set of user equipments 110-112.

Hence, the user equipment 110 and/or the processor 1202 and/or the finding module 1240 may be configured to find the respective specific information for the user equipment 110 after the common information by taking into account the respective multi-user group index of the user equipment 110 and a number of bits of the respective specific information.

As an example, the user equipment 110 and/or the processor 1202 and/or the finding module 1240, or another finding module (not shown) may be configured to find the common information.

The user equipment 110 and/or the processor 1202 and/or the finding module 1240, or a further finding module (not shown), may be configured to find the respective specific information for the user equipment 110 in the second downlink control information message by taking into account the respective multi-user group index of the user equipment 110 and a number of bits of the respective specific information.

The user equipment 110 and/or the processor 1202 and/or the using module 1250 may be configured to use the multi-user group index to cyclically shift a respective demodulation reference signal for the user equipment 110.

The user equipment 110 and/or the processor 1202 and/or the transmitting module 1260 may be configured to transmit the respective demodulation reference signal.

The term 'computer' is used herein to refer to any device with processing capability such that it can execute instructions. Those skilled in the art will realise that such processing capabilities are incorporated into many different devices and therefore the term 'computer' or 'computing device' includes PCs, servers, base stations, eNBs, network nodes and other network elements, mobile telephones, UEs, personal digital assistants, other portable wireless communications devices and many other devices.

Those skilled in the art will realise that storage devices utilised to store program instructions can be distributed across a network. For example, a remote computer may store an example of the process described as software. A local or terminal computer may access the remote computer and download a part or all of the software to run the program.

Alternatively, the local computer may download pieces of the software as needed, or execute some software instructions at the local terminal and some at the remote computer (or computer network). Those skilled in the art will also realise that by utilising conventional techniques known to those skilled in the art that all, or a portion of the software instructions may be carried out by a dedicated circuit, such as a DSP, programmable logic array, or the like.

Any range or device value given herein may be extended or altered without losing the effect sought, as will be apparent to the skilled person.

It will be understood that the benefits and advantages described above may relate to one example or embodiment or may relate to several examples or embodiments. The examples or embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages.

Any reference to 'an' item refers to one or more of those items. The term 'comprising' is used herein to mean including the method blocks, features or elements identified, but that such blocks, features or elements do not comprise an exclusive list and a method or apparatus may contain additional blocks, features or elements.

The steps of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate. Additionally, individual blocks may be deleted from any of the methods without departing from the spirit and scope of the subject matter described herein. Aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples without losing the effect sought.

It will be understood that the above description of a preferred embodiment is given by way of example only and that various modifications may be made by those skilled in the art. Although various embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this disclosure.

Claims

1. A method for managing control information to be transmitted to a set of user equipments (110-112), wherein the method, performed by the radio network node (120), comprises:

assigning (S010) a respective multi-user radio network temporary identifier to each user equipment (110-112) of the set of user equipments (110-112), wherein each respective multi-user radio network temporary identifier comprises a common multi-user radio network temporary identifier and a respective multiuser group index, encoding (S050) one or more downlink control information messages for the set of user equipments (110-112) by use of the common multi-user radio network temporary identifier, wherein said one or more downlink control information messages comprise the control information, wherein the control information comprises common information for the set of user equipments (110-112) and respective specific information for each respective user equipment (110-112) of the set of user equipments (110-112), and transmitting (S060) said one or more downlink control information messages to the set of user equipments (110-112).

2. The method of claim 1, wherein said one or more downlink control information messages is only one downlink control information message, wherein a set of specific information pieces comprises each of the respective specific information, wherein the control information comprises the set of specific information pieces in order according to the respective multi-user group index.

3. The method of claim 1, wherein said one or more downlink control information messages comprises a first downlink control information message and a second downlink control information message, wherein the first downlink control information message comprises the common information, and wherein the second downlink control information message comprises a set of specific information pieces comprising each of the respective specific information, wherein the second downlink control information message comprises the set of specific information pieces in order according to the respective multi-user group index.

4. The method of claim 1, further comprising:

generating (S040) the common multi-user radio network temporary identifier by subtracting the respective multi-user group index from the multi-user radio network temporary identifier.

5. The method of claim 1 or 2, further comprising:

configuring (S030) the set of user equipments () to operate in MU-MIMO transmission.

6. The method according to any one of claims 1-5, wherein the control information relates to one or more transmissions between the user equipments (110-112) and the radio network node (120).

7. The method of claim 6, further comprising:

selecting (S020) the set of user equipments (110-112) based on one or more criteria relating to said one or more transmissions.

8. The method of claim 7, wherein said one or more criteria comprise one or more of:

- Semi Persistent Scheduling opportunities,

- DRX synchronization opportunities,

- CSI reporting requirements, and

- MU-MIMO transmission and re-transmission requirements.

9. The method of any one of claims 1-8, further comprising:

receiving (S140) demodulation reference signals from the set of user equipments (110-112) while assuming a respective demodulation reference signal for each user equipment (110-112) to be cyclically shifted by use of the respective multi-user group index for said user equipment (110-112).

10. A method for managing control information for a set of user equipments (1 ΙΟ112), wherein a respective multi-user radio network temporary identifier is assigned to each user equipment (110-112) of the set of user equipments (110112), wherein each respective multi-user radio network temporary identifier comprises a common multi-user radio network temporary identifier and a respective multi-user group index, wherein the method, performed by a user equipment (110) of the set of user equipments (110-112), comprises:

receiving (S070), from a radio network node (120), one or more downlink control information messages comprising the control information, and decoding (S090) said one or more downlink control information messages for the user equipment (110) by use of the common multi-user radio network temporary identifier, wherein the control information comprises common information for the set of user equipments (110-112) and respective specific information for each respective user equipment (110-112) of the set of user equipments (110-112).

11. The method of claim 10, wherein said one or more downlink control information messages is only one downlink control information message, wherein a set of specific information pieces comprises each of the respective specific information, wherein the control information comprises the set of specific information pieces in order according to the respective multi-user group index, wherein the method comprises:

finding (S100) the respective specific information for the user equipment (110) after the common information by taking into account the respective multiuser group index of the user equipment (110) and a number of bits of the respective specific information.

12. The method of claim 10, wherein said one or more downlink control information messages comprises a first downlink control information message and a second downlink control information message, wherein the first downlink control information message comprises the common information, and wherein the second downlink control information message comprises a set of specific information pieces comprising each of the respective specific information, wherein the second downlink control information message comprises the set of specific information pieces in order according to the respective multi-user group index, wherein the method comprises:

finding (S110) the respective specific information for the user equipment (110) in the second downlink control information message by taking into account the respective multi-user group index of the user equipment (110) and a number of bits of the respective specific information.

13. The method of any one of claims 10-12, further comprising:

generating (S080) the common multi-user radio network temporary identifier by subtracting the respective multi-user group index from the multi-user radio network temporary identifier.

14. The method of any one of claim 10-13, further comprising:

using (S120) the multi-user group index to cyclically shift a respective demodulation reference signal for the user equipment (110), and transmitting (S130) the respective demodulation reference signal.

15. A computer readable medium comprising program code stored thereon, which when executed on a processor, causes the processor to perform a method according to any one of claims 1 -9 or any one of claims 10-14.

16. A non-transitory computer readable medium having computer readable instructions stored thereon for execution by a processor to perform the method according to any one of claims 1 -9 or any one of claims 10-14.

17. The non-transitory computer readable medium of claim 16 comprising at least one of: a hard disk, a Compact Disc, an optical storage device, a magnetic storage device, a Read Only Memory, a Programmable Read Only Memory, an Erasable Programmable Read Only Memory, an Electrically Erasable Programmable Read Only Memory and a Flash memory and a Solid State Drive.

18. A radio network node (120) comprising a processor unit, a storage unit and a communications interface, wherein the processor unit, the storage unit, and the communications interface are configured to perform a method as claimed in any one of claims 1-9.

19. A user equipment (110) comprising a processor unit, a storage unit and a communications interface, wherein the processor unit, the storage unit, and the communications interface are configured to perform a method as claimed in any one of claims 10-14.

GB1707229.9

1-19