GB2592569A

GB2592569A - Apparatus, method and computer program

Info

Publication number: GB2592569A
Application number: GB2000933.8A
Authority: GB
Inventors: Lauridsen Mads; Laselva Daniela; Koskinen Jussi-Pekka; Kaasalainen Janne
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2020-01-22
Filing date: 2020-01-22
Publication date: 2021-09-08
Also published as: GB202000933D0; WO2021148193A1

Abstract

There is provided an apparatus, said apparatus comprising means for receiving, at a network node, an indication of a radio access network notification area update, RNAU, performed by a user equipment (UE) operating in a first mode and acquiring a count of a number of RNAUs performed by the user equipment in a given time period. The count of the number of RNAUs performed by the UE in a given time period is used to determine whether the UE should operate in a first mode or a second mode. The first mode is RRC inactive mode and the second mode is RRC idle mode or RRC connected mode.

Description

APPARATUS, METHOD AND COMPUTER PROGRAM

Field

The present application relates to a method, apparatus, system and computer program and in particular but not exclusively to a method and assistance information for the release of RRC Inactive user equipment (UE).

Background

A communication system can be seen as a facility that enables communication sessions between two or more entities such as user terminals, base stations and/or other nodes by providing carriers between the various entities involved in the communications path. A communication system can be provided for example by means of a communication network and one or more compatible communication devices. The communication sessions may comprise, for example, communication of data for carrying communications such as voice, video, electronic mail (email), text message, multimedia and/or content data and so on. Non-limiting examples of services provided comprise two-way or multi-way calls, data communication or multimedia services and access to a data network system, such as the Internet.

In a wireless communication system at least a part of a communication session between at least two stations occurs over a wireless link. Examples of wireless systems comprise public land mobile networks (PLMN), satellite based communication systems and different wireless local networks, for example wireless local area networks (WLAN). Some wireless systems can be divided into cells, and are therefore often referred to as cellular systems.

A user can access the communication system by means of an appropriate communication device or terminal. A communication device of a user may be referred to as user equipment (UE) or user device. A communication device is provided with an appropriate signal receiving and transmitting apparatus for enabling communications, for example enabling access to a communication network or communications directly with other users. The communication device may access a carrier provided by a station, for example a base station of a cell, and transmit and/or receive communications on the carrier.

The communication system and associated devices typically operate in accordance with a given standard or specification which sets out what the various entities associated with the system are permitted to do and how that should be achieved. Communication protocols and/or parameters which shall be used for the connection are also typically defined. One example of a communications system is UTRAN (3G radio). Other examples of communication systems are the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology and so-called 5G or New Radio (NR) networks. NR is being standardized by the 3rd Generation Partnership Project (3GPP).

Summary

In a first aspect there is provided an apparatus comprising means for receiving, at a network node, an indication of a radio access network notification area update, RNAU, performed by a user equipment operating in a first mod; and acquiring a count of a number of RNAUs performed by the user equipment in a given time period.

The apparatus may comprise means for receiving the indication of the RNAU from a target node.

The apparatus may comprise means for providing an indication of the count to the target node.

The indication of the count may comprise an indication of at least one of the given time period and a time stamp.

The apparatus may comprise means for providing the indication of the count to the target node in response to a request from the target node.

The request may include the indication of the RNAU.

The apparatus may comprise means for providing an indication to the target node that the count is greater than or equal to a threshold or less than the threshold in the given time period.

The apparatus may comprise means for providing an indication of the count to the target node if the count is greater than or equal to the threshold.

Means for receiving the indication of the RNAU may comprise means for receiving the RNAU from the user equipment.

The apparatus may comprise means for receiving an indication of the count from a last serving node or the user equipment.

The indication of the count from the last serving node may comprise an indication of at least one of the given time period and a time stamp.

The apparatus may comprise means for providing a request to the last serving node for the indication of the count.

The request may include the indication of the RNAU.

The apparatus may comprise means for receiving an indication from the last serving node or the user equipment that the count is greater than or equal to a threshold or less than the threshold in the given time period.

The number of RNAUs in the given time period may be the number of consecutive RNAUs without at least one of data transmission and data reception at the user equipment in the given time period.

The count of the number of RNAUs performed by the user equipment in a given time period may be for use in determining whether the user equipment should operate in the first mode or 25 a second mode.

The first mode may be RRC inactive mode. The second mode may be RRC Idle mode or RRC Connected mode.

In a second aspect there is provided an apparatus comprising means for providing a radio access network notification area update, RNAU, to a network from a user equipment operating in a first mode and acquiring a count of a number of RNAUs performed by the user equipment in a given time period.

The apparatus may comprise means for receiving at least one an indication of the count, the given time period, a time stamp and a threshold from the network.

The apparatus may comprise means for providing an indication of the count in the given time period to a target node of the network.

The apparatus may comprise means for providing an indication of the count to the target node if the count is greater than or equal to the threshold The apparatus may comprise means for providing an indication to the target node that the count is greater than or equal to a threshold or less than the threshold in the given time period.

The count of the number of RNAUs performed by the user equipment in a given time period may be for use in determining whether the user equipment should operate in the first mode or a second mode.

The apparatus may comprise means for determining at the apparatus to move the user 15 equipment to the second mode based on the count of the number of RNAUs performed by the user equipment in the given time period.

The apparatus may comprise means for providing an indication to the network that the user equipment is moving to the second mode.

In a third aspect there is provided a method comprising receiving, at a network node, an indication of a radio access network notification area update, RNAU, performed by a user equipment operating in a first mod; and acquiring a count of a number of RNAUs performed by the user equipment in a given time period.

The method may comprise receiving the indication of the RNAU from a target node.

The method may comprise providing an indication of the count to the target node.

The method may comprise for providing the indication of the count to the target node in response to a request from the target node.

The request may include the indication of the RNAU.

The method may comprise providing an indication to the target node that the count is greater than or equal to a threshold or less than the threshold in the given time period.

The method may comprise providing an indication of the count to the target node if the count is greater than or equal to the threshold.

Receiving the indication of the RNAU may comprise receiving the RNAU from the user equipment.

The method may comprise receiving an indication of the count from a last serving node or the user equipment.

The method may comprise providing a request to the last serving node for the indication of the count.

The request may include the indication of the RNAU.

The method may comprise receiving an indication from the last serving node or the user equipment that the count is greater than or equal to a threshold or less than the threshold in the given time period.

In a fourth aspect there is provided a method comprising providing a radio access network notification area update, RNAU, to a network from a user equipment operating in a first mode and acquiring a count of a number of RNAUs performed by the user equipment in a given time period.

The method may comprise receiving at least one an indication of the count, the given time period, a time stamp and a threshold from the network.

The method may comprise providing an indication of the count in the given time period to a target node of the network.

The method may comprise providing an indication of the count to the target node if the count is greater than or equal to the threshold The method may comprise providing an indication to the target node that the count is greater than or equal to a threshold or less than the threshold in the given time period.

The method may comprise determining at the apparatus to move the user equipment to the 30 second mode based on the count of the number of RNAUs performed by the user equipment in the given time period.

The method may comprise providing an indication to the network that the user equipment is moving to the second mode.

In a fifth aspect there is provided an apparatus comprising: at least one processor and at least one memory including a computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus at least to receive, at a network node, an indication of a radio access network notification area update, RNAU, performed by a user equipment operating in a first mode and acquire a count of a number of RNAUs performed by the user equipment in a given time period.

The apparatus may be configured to receive the indication of the RNAU from a target node.

The apparatus may be configured to provide an indication of the count to the target node.

The apparatus may be configured to provide the indication of the count to the target node in response to a request from the target node.

The request may include the indication of the RNAU.

The apparatus may be configured to provide an indication to the target node that the count is greater than or equal to a threshold or less than the threshold in the given time period.

The apparatus may be configured to provide an indication of the count to the target node if the count is greater than or equal to the threshold.

The apparatus may be configured to receive the RNAU from the user equipment.

The apparatus may be configured to receive an indication of the count from a last serving node or the user equipment.

The apparatus may be configured to provide a request to the last serving node for the indication of the count.

The request may include the indication of the RNAU.

The apparatus may be configured to receive an indication from the last serving node or the user equipment that the count is greater than or equal to a threshold or less than the threshold in the given time period.

The first mode may be RRC inactive mode. The second mode may be RRC Idle mode or RRC 20 Connected mode.

In a sixth aspect there is provided an apparatus comprising: at least one processor and at least one memory including a computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus at least to provide a radio access network notification area update, RNAU, to a network from a user equipment operating in a first mode and acquire a count of a number of RNAUs performed by the user equipment in a given time period.

The apparatus may be configured to receive at least one an indication of the count, the given time period, a time stamp and a threshold from the network.

The apparatus may be configured to provide an indication of the count in the given time period to a target node of the network.

The apparatus may be configured to provide an indication of the count to the target node if the count is greater than or equal to the threshold The apparatus may be configured to provide an indication to the target node that the count is greater than or equal to a threshold or less than the threshold in the given time period.

The apparatus may be configured to determine at the apparatus to move the user equipment to the second mode based on the count of the number of RNAUs performed by the user equipment in the given time period.

The apparatus may be configured to provide an indication to the network that the user equipment is moving to the second mode.

In a seventh aspect there is provided a computer readable medium comprising program instructions for causing an apparatus to perform at least the following receiving, at a network node, an indication of a radio access network notification area update, RNAU, performed by a user equipment operating in a first mode and acquiring a count of a number of RNAUs performed by the user equipment in a given time period.

The apparatus may be caused to perform receiving the indication of the RNAU from a target node.

The apparatus may be caused to perform providing an indication of the count to the target node The indication of the count may comprise an indication of at least one of the given time period and a time stamp.

The apparatus may be caused to perform providing the indication of the count to the target node in response to a request from the target node.

The request may include the indication of the RNAU.

The apparatus may be caused to perform providing an indication to the target node that the count is greater than or equal to a threshold or less than the threshold in the given time period.

The apparatus may be caused to perform providing an indication of the count to the target node if the count is greater than or equal to the threshold.

The apparatus may be caused to perform receiving an indication of the count from a last serving node or the user equipment.

The apparatus may be caused to perform providing a request to the last serving node for the indication of the count.

The request may include the indication of the RNAU.

The apparatus may be caused to perform receiving an indication from the last serving node or the user equipment that the count is greater than or equal to a threshold or less than the threshold in the given time period.

In an eighth aspect there is provided a computer readable medium comprising program instructions for causing an apparatus to perform at least the following providing a radio access network notification area update, RNAU, to a network from a user equipment operating in a first mode and acquiring a count of a number of RNAUs performed by the user equipment in a given time period.

The apparatus may be caused to perform receiving at least one an indication of the count, the given time period, a time stamp and a threshold from the network.

The apparatus may be caused to perform providing an indication of the count in the given time period to a target node of the network.

The apparatus may be caused to perform providing an indication of the count to the target node if the count is greater than or equal to the threshold The apparatus may be caused to perform providing an indication to the target node that the count is greater than or equal to a threshold or less than the threshold in the given time period.

The apparatus may be caused to perform determining at the apparatus to move the user equipment to the second mode based on the count of the number of RNAUs performed by the user equipment in the given time period.

The apparatus may be caused to perform providing an indication to the network that the user equipment is moving to the second mode.

In a ninth aspect there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method according to the third or fourth aspect.

In the above, many different embodiments have been described. It should be appreciated that 10 further embodiments may be provided by the combination of any two or more of the embodiments described above.

Description of Figures

Embodiments will now be described, by way of example only, with reference to the accompanying Figures in which: Figure 1 shows a schematic diagram of an example communication system comprising a base station and a plurality of communication devices; Figure 2 shows a schematic diagram of an example mobile communication device; Figure 3 shows a schematic diagram of an example control apparatus; Figure 4 shows a block diagram of the relationship between NR RRC states; Figure 5 shows an example signalling flow for a UE moving from RRC_Idle to RRC_Connected; Figure 6 shows an example signalling flow for a UE moving from RRC_Inactive to RRC_Connected; Figure 7 shows a flowchart of a method according to an example embodiment; Figure 8 shows a flowchart of a method according to an example embodiment; Figure 9 shows a signalling flow according to an example embodiment; Figure 10 shows a flowchart of a method performed at a target gNB; Figure 11 shows a flowchart of a method performed at a last serving gNB.

Detailed description

Before explaining in detail the examples, certain general principles of a wireless communication system and mobile communication devices are briefly explained with reference to Figures 1 to 3 to assist in understanding the technology underlying the described

examples.

In a wireless communication system 100, such as that shown in figure 1, communication devices (e.g., user equipment (UE)) 102, 104, 105 are provided wireless access via at least one base station or similar wireless transmitting and/or receiving node or point. Base stations are typically controlled by at least one appropriate controller apparatus, so as to enable operation thereof and management of mobile communication devices in communication with the base stations. The controller apparatus may be located in a Radio Access Network (RAN) (e.g. wireless communication system 100) or in a core network (CN) (not shown) and may be implemented as one central apparatus or its functionality may be distributed over several apparatuses. The controller apparatus may be part of the base station and/or provided by a separate entity such as a radio network controller. In Figure 1 control apparatus 108 and 109 are shown to control the respective macro level base stations 106 and 107. The control apparatus of a base station can be interconnected with other control entities. The control apparatus is typically provided with memory capacity and at least one data processor. The control apparatus and functions may be distributed between a plurality of control units. In some systems, the control apparatus may additionally or alternatively be provided in a radio network controller.

In Figure 1 base stations 106 and 107 are shown as connected to a wider communications network 113 via gateway 112. A further gateway function may be provided to connect to another network The smaller base stations 116, 118 and 120 may also be connected to the network 113, for example by a separate gateway function and/or via the controllers of the macro level stations.

The base stations 116, 118 and 120 may be pico or femto level base stations or the like. In the example, base stations 116 and 118 are connected via a gateway 111 whilst base station connects via the controller apparatus 108. In some embodiments, the smaller base stations may not be provided. Smaller base stations 116, 118 and 120 may be part of a second network, for example WLAN and may be WLAN Access Points (APs).

The communication devices 102, 104, 105 may access the communication system based on various access techniques, such as code division multiple access (CDMA), or wideband CDMA (WCDMA). Other non-limiting examples comprise time division multiple access (TDMA), frequency division multiple access (FDMA) and various schemes thereof such as the interleaved frequency division multiple access (IFDMA), single carrier frequency division multiple access (SC-FDMA) and orthogonal frequency division multiple access (OFDMA), space division multiple access (SDMA) and so on.

An example of wireless communication systems are architectures standardized by the 3rd Generation Partnership Project (3GPP). A latest 3GPP based development is often referred to as the long term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology. The various development stages of the 3GPP specifications are referred to as releases. More recent developments of the LTE are often referred to as LTE Advanced (LTE-A). The LTE (LTE-A) employs a radio mobile architecture known as the Evolved Universal Terrestrial Radio Access Network (E-UTRAN) and a core network known as the Evolved Packet Core (EPC). Base stations of such systems are known as evolved or enhanced Node Bs (eNBs) and provide E-UTRAN features such as user plane Packet Data Convergence/Radio Link Control/Medium Access Control/Physical layer protocol (PDCP/RLC/MAC/PHY) and control plane Radio Resource Control (RRC) protocol terminations towards the communication devices. Other examples of radio access system comprise those provided by base stations of systems that are based on technologies such as wireless local area network (WLAN). A base station can provide coverage for an entire cell or similar radio service area. Core network elements include Mobility Management Entity (MME), Serving Gateway (S-GVV) and Packet Gateway (P-GW).

An example of a suitable communications system is the 5G or NR concept. Network architecture in NR may be similar to that of LTE-advanced. Base stations of NR systems may be known as next generation Node Bs (gNBs). Changes to the network architecture may depend on the need to support various radio technologies and finer QoS support, and some on-demand requirements for e.g. Quality of Service (QoS) levels to support Quality of Experience (QoE) for a user. Also network aware services and applications, and service and application aware networks may bring changes to the architecture. Those are related to Information Centric Network (ICN) and User-Centric Content Delivery Network (UC-CDN) approaches. NR may use multiple input -multiple output (M IMO) antennas, many more base stations or nodes than the LIE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and perhaps also employing a variety of radio technologies for better coverage and enhanced data rates.

Future networks may utilise network functions virtualization (NFV) which is a network architecture concept that proposes virtualizing network node functions into "building blocks" or entities that may be operationally connected or linked together to provide services. A virtualized network function (VNF) may comprise one or more virtual machines running computer program codes using standard or general type servers instead of customized hardware. Cloud computing or data storage may also be utilized. In radio communications this may mean node operations to be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head. It is also possible that node operations will be distributed among a plurality of servers, nodes or hosts. It should also be understood that the distribution of labour between core network operations and base station operations may differ from that of the LTE or even be non-existent.

An example 50 core network (CN) comprises functional entities. The CN is connected to a UE via the radio access network (RAN). A User Plane Function (UPF) whose role is called PDU Session Anchor (PSA) may be responsible for forwarding frames back and forth between the data network (DN) and the tunnels established over the 50 towards the UE(s) exchanging traffic with the DN.

The UPF is controlled by a Session Management Function (SMF) that receives policies from a Policy Control Function (PCF). The CN may also include an Access & Mobility Function (AMF).

A possible mobile communication device will now be described in more detail with reference to Figure 2 showing a schematic, partially sectioned view of a communication device 200.

Such a communication device is often referred to as user equipment (UE) or terminal. An appropriate mobile communication device may be provided by any device capable of sending and receiving radio signals. Non-limiting examples comprise a mobile station (MS) or mobile device such as a mobile phone or what is known as a 'smart phone', a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), personal data assistant (PDA) or a tablet provided with wireless communication capabilities, voice over IP (VolP) phones, portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), smart devices, wireless customer-premises equipment (CPE), or any combinations of these or the like. A mobile communication device may provide, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and so on. Users may thus be offered and provided numerous services via their communication devices. Non-limiting examples of these services comprise two-way or multi-way calls, data communication or multimedia services or simply an access to a data communications network system, such as the Internet. Users may also be provided broadcast or multicast data. Non-limiting examples of the content comprise downloads, television and radio programs, videos, advertisements, various alerts and other information.

A mobile device is typically provided with at least one data processing entity 201, at least one memory 202 and other possible components 203 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The data processing, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 204. The user may control the operation of the mobile device by means of a suitable user interface such as key pad 205, voice commands, touch sensitive screen or pad, combinations thereof or the like. A display 208, a speaker and a microphone can be also provided. Furthermore, a mobile communication device may comprise appropriate connectors (either wired or wireless) to other devices and/or for connecting external accessories, for example hands-free equipment, thereto.

The mobile device 200 may receive signals over an air or radio interface 207 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Figure 2 transceiver apparatus is designated schematically by block 206. The transceiver apparatus 206 may be provided for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device.

Figure 3 shows an example of a control apparatus 300 for a communication system, for example to be coupled to and/or for controlling a station of an access system, such as a RAN node, e.g. a base station, eNB or gNB, a relay node or a core network node such as an MME or S-GW or P-GW, or a core network function such as AMF/SMF, or a server or host. The method may be implemented in a single control apparatus or across more than one control apparatus. The control apparatus may be integrated with or external to a node or module of a core network or RAN. In some embodiments, base stations comprise a separate control apparatus unit or module. In other embodiments, the control apparatus can be another network element such as a radio network controller or a spectrum controller. In some embodiments, each base station may have such a control apparatus as well as a control apparatus being provided in a radio network controller. The control apparatus 300 can be arranged to provide control on communications in the service area of the system. The control apparatus 300 comprises at least one memory 301, at least one data processing unit 302, 303 and an input/output interface 304. Via the interface the control apparatus can be coupled to a receiver and a transmitter of the base station. The receiver and/or the transmitter may be implemented as a radio front end or a remote radio head.

5G New Radio communication standards, specifically around the use of and enhancements to Radio Resource Control (RRC) Idle and Inactive modes (defined in TS 38.304). In 5G NR communication standards, Radio Resource Control (RRC) Idle and Inactive modes are defined, as well as RRC Connected mode. RRC Idle and RRC Inactive modes allow a UE to discontinuously monitor for paging messages and reduce RRM measurement activity, thus reducing the UE's power consumption compared to RRC Connected mode.

Figure 4 illustrates the three RRC modes of 3GPP 5G NR. If a UE in RRC inactive or RRC Idle mode has data to transfer it may initiate RRC connection resume or establishment, respectively, to move to RRC Connected mode. The move from RRC Connected or RRC Inactive to RRC Idle is network initiated (besides the failure scenario, where the RRC Inactive UE cannot find a suitable cell, where the move is UE initiated).

Figure 5 illustrates signalling flows for the transition from RRC Idle to RRC Connected and Figure 6 shows signalling flows for the transition from RRC Inactive to RRC Connected from TS 38.300.

In RRC Idle and RRC Inactive modes the UE performs cell (re-) selection autonomously based on RRM measurements. In RRC Idle the UE moves autonomously in a Tracking Area (TA), composed of one or more cells, and sends TA Updates (TAU). TAU may be periodic or event driven, the latter being triggered when the UE moves to a new TA. Additionally, and in a similar fashion, in RRC Inactive the UE can move within a pre-defined RAN Notification Area (RNA), composed of one or more cells, without notifying the network. If the UE enters a cell not included in the RNA it sends an RNA update (RNAU).

However, the RNA size is usually much smaller than the TA size, which may result in more RNAU updates for mobile UEs. In addition, the RRC Inactive UE is also required to send periodic RNAUs (similarly to the periodic TAU). Thus, from a power saving perspective it may be preferable for a mobile UE to be in RRC Idle. However, RRC Idle prolongs the communication latency compared to being in RRC Inactive, because the procedures related to becoming RRC Connected include increased signalling.

One of the reasons why the RRC Inactive to RRC Connected transition is faster is that the network maintains some information related to the UE connection with the Access Stratum (AS), known as the UE Inactive AS Context (referred to as UE Context) when the UE is in RRC Inactive mode. The contents of the UE Context include information on the used RRC and security configuration. As a result, for example, the UP/CF connectivity of the anchor node with UPF and AM F for the UE in RRC Inactive is maintained (i.e., a UE in RRC Inactive is CM Connected, see Figure 6), while the RRC Idle UE needs to establish the connection with the AMF.

The UE context is stored in the last serving gNB, i.e., anchor gNB. Thus, if the UE attempts resuming RRC Connected mode in a different node than the anchor node, the target gNB needs to obtain the context from the last serving gNB by identifying the gNB identity through the I-RNTI (if possible) and then initiating the "XnAP Retrieve UE Context" procedure (TS 38.300).

Note that a RRC Inactive UE will initiate the RRC Connection Resume procedure of Figure 6 if it has to perform an RNA Update with resumeCause set to ma-Update (TS 38.331).

As mentioned above, when a UE is in RRC Connected state, the network controls whether the UE is to be kept in RRC Connected (e.g. if data is expected) or moved to either RRC Inactive or RRC Idle. As outlined previously, the two states, RRC Inactive and RRC Idle, result in different UE power consumption and application layer latency, but they also impose different requirements on the network. On one side, the UE context needs to be stored for all RRC Inactive UEs, increasing storage requirements. On the other side, paging of RRC Inactive mobile UEs may require an increased Xn-capacity demand, if Xn-based RAN paging via nodes in the RNA is considered.

The following addresses the case where RRC Inactive mobile UEs are performing several RNA updates (without data activity between RNA updates) over time. If the UE has moved to a node in the RNA and/or to a node in a different RNA (a "new RNA"), the gNB needs to fetch the UE context from the last serving gNB and consider whether the UE shall remain RRC Inactive or move to RRC Idle due to the number of RNA updates.

It has been proposed in 3GPP that an RRC Inactive UE moves autonomously to RRC Idle upon the expiration of a timer. However, autonomous RRC state transition may create challenges for the network, because the network may not know whether the UE is still in RRC Inactive or it has moved autonomously to RRC Idle. In case of RRC state mismatch (UE is in different RRC state than the network assumes) between network and UE, the network may use the "wrong" UE identity for paging, which may lead to a paging failure.

The RRC state switch from RRC Connected to RRC Idle may be based on data inactivity timers (at the network side). In Rel-16 WID on UE power saving in NR, UE assistance information is being defined for moving a UE out of the RRC Connected mode, based on the UE capability to estimate (lack of) upcoming traffic. Using this capability, the UE can then suggest RRC state transition (Connected to Idle) to the network (TR 38.840).

Figure 7 shows a flowchart of a method according to an example embodiment. The method may be performed at a target network node or a last serving network node.

In a first step, Si, the method comprises receiving, at a network node, an indication of a radio access network notification area update, RNAU, performed by a user equipment operating in a first mode.

In a second step, 32, the method comprises acquiring a count of a number of RNAUs performed by the user equipment in a given time period.

Figure 8 shows a flow chart of a method according to an example embodiment. The method may be performed at the user equipment.

In a first step, Ti, the method comprises providing a radio access network notification area update, RNAU, to a network from a user equipment operating in a first mode.

In a second step, T2, the method comprises acquiring a count of a number of RNAUs performed by the user equipment in a given time period.

The count of the number of RNAUs performed by the user equipment in a given time period may be for use in determining whether the user equipment should operate in the first mode, a second mode, or a third mode. The first mode may be the RRC Inactive mode. The second mode may be the RRC Idle mode. The third mode may be the RRC Connected mode.

Determining whether the user equipment should operate in the first mode or a second mode may comprise determining whether the count of the number of RNAUs, A, in a given time period, B, is higher than a threshold, C. The target node may set this threshold based on its own RRC load to avoid too many UEs in RRC Inactive using RRC resources. Alternatively, or in addition, the last serving node may set the threshold. The last serving node may set the threshold based, e.g., on the number of UE contexts stored and/or how long the UE has been in Inactive mode without data activity (i.e., data transmission and/or reception).

In an example embodiment, the network acquires the number of RNAUs A, which a UE has performed during a time window B, and if A C, the network moves the UE to RRC Idle, upon receiving the Ath RRC Resume Request.

A may be referred to as the RNAU count. The indication of the count may be an explicit indication of the RNAU count. The RNAU count may comprise a count of occurred RNAUs or 20 consecutive RNAUs without DL/UL data activity between RNAUs The target node may receive an indication of the count from the last serving node or from the user equipment.

The last serving node may be the node where the UE was last RRC Connected.

In one example embodiment, receiving the indication of the RNAU comprises receiving an RNAU at a target node from a user equipment. The RNAU may be included in a request to resume connection from the UE. Alternatively, or in addition, the RNAU may be sent as part of a "small data transmission", which is currently under discussion in 3GPP. The RNAU may be sent in RRC Inactive in msgA (message A) of 2-step Random Access procedure or msg3 of the 4-step Random Access procedure or in a configured grant-like transmission, The target node may provide a request to the last serving node for the indication of the count.

The indication of the count may be provided by the last serving node in response to the request from the target network node. The request may be a UE Context Retrieval Request. The request may include the indication of the RNAU, i.e., that the target node has received an RNAU, e.g., a request to resume connection including an RNAU, from a UE.

The indication of the count may comprise an indication of at least one of the given time period and a time stamp so that, e.g., the target node can determine if A a. C in the given time period.

The time stamp may be defined as the timing of the e.g. each RNAU and/or the timing of the first and last RNAU within the time period.

In one example embodiment, the last serving gNB monitors the number of RNAUs for all UEs in RRC Inactive for which it acts as anchor cell. In this example, the target gNB obtains the RNAU count from the last serving gNB, over Xn, in response to the UE Context Retrieval request as a supplement to the UE context.

In an alternative example embodiment, the UE indicates to the network node, e.g., the network node of the resuming cell (the target node), or the last serving node, information related to the number of observed RNAUs encountered earlier. The indication may be provided from the UE to the network node using e.g., RRC (e.g. RRC Resume Request), MAC (e.g. MAC CE) or PHY layer signaling In one example embodiment, the network may configure the time window B to the UE in advance. The UE may report the RNAU count within B at each Connection Resume procedure or only at RNAU events. The network may provide an indication of at least one of A, B, C and a time stamp to the user equipment. The time window, B, or threshold, C, may be configured at the UE with dedicated (e.g. RRC Release message) and/or broadcast signaling (system information).

The method may comprise determining at the user equipment to move the user equipment to the second mode based on the count of the number of RNAUs performed by the user equipment in the given time period. The user equipment may use the values of A, B and C as indicated to determine autonomously to move to the second mode, e.g., if A is greater than or equal to the threshold C the UE determines to move to Inactive mode. The UE may provide an indication to the network that it is moving to the second mode. The indication may be sent e.g., along with an RNAU when the RNAU count equals the threshold.

The network may indicate to the UE the count of RNAUs, and how many RNAUs will cause the network to move the UE to RRC idle if the UE does not have DL/UL activity (i.e., the network threshold C). For example, if an application needs to have RRC Inactive connection it knows to trigger data before a certain number of RNAUs are sent. This may also be used to avoid the move from first to second mode upon the next RNAU.

The last serving network node (anchor gNB) may add the RNAU count to the UE identity Information Element (1E) when it moves the UE to the RRC inactive. In this way the anchor gNB can deliver the RNAU count to the target gNB.

The RNAU count may be part of the UE identity IL (i.e. one or more bits from I-RNTI) and when the UE knows the coding rule then it knows when a RNAU count may result in a move to RRC Idle (provided that the UE also knows the network threshold C) if it does not trigger DLJUL data in the period. Furthermore, when the target gNB knows the coding rule it knows the UE has been in RRC Inactive in the anchor gNB without DLJUL data activity.

The method may comprise providing an indication of the count from the UE or the last serving node to the target node if the count is greater than or equal to the threshold or less than the threshold. That is, the indication of the count to the target node may be requested/transferred only if certain conditions are met, e.g., if the count exceeds the network threshold or is lower than the threshold.

The indication of the count from the UE or the last serving node may comprise an indication that A is greater than or equal to the threshold in the given time period. The indication may be a one-bit indication.

In one example embodiment, the network configures C at the UE. If RNAU count A within time window B equals or is greater than C, the UE sets a (e.g. one-bit) flag during the RNAU event to indicate that the RNAU count C is reached.

In the example embodiment where the last serving network node provides the RNAU count to the target node, the signalling between the network node may be on the Xn interface which connects two gNBs.

Figure 9 illustrates a signalling flow for an example embodiment. A gNB receives a RRC Connection Resume message from a UE with the resumeCause set to ma-Update.

The gNB retrieves UE context from the last serving gNB. The gNB may determine the anchor gNB ID based on the I-RNTI. The last serving gNB keeps track of the "context requests" for RNAU purposes (without data activity being involved) of that specific UE and of the number of RNA updates since the last data connection. According to current NR specification, as shown in Table 1 (part of the table 9.1.1.8 in IS 38.423), the last serving gNB will receive the RRC resume cause information, which enables the serving gNB to track the number of RNA updates.

IE/Group Name Presence Range IE type and Semantics description Criticality Assigned reference Criticality RRC Resume Cause 0 9.2.3.61 In case of RNA Update, contains the cause value provided by the UE in the RRC ResumeRe quest or the RRCResumeRe quest message, as defined in IS 38.331 [10], YES ignore or in the RRCConnection ResumeRe quest message, as defined in TS 36.331 [14].

Table 1

When the last serving gNB provides the UE context, via the Xn interface, to the gNB using the "RETRIEVE UE CONTEXT RESPONSE" (TS 38.423), it includes the RNAU counter A (i.e. an IE to be added to the RETRIEVE UE CONTEXT RESPONSE message defined in 9.1.1.9 of TS 38.423). Using this additional information the gNB then decides whether or not to move the UE to RRC Idle and provides feedback to the UE dependent on the RRC state decision.

Flow charts for the gNB receiving the RNA update and the last serving gNB in the example embodiment of Figure 10 are shown in Figure 11 and Figure 12, respectively.

In Figure 10, the gNB receives the RRC Resume Request (including the RNA update) from the UE. The gNB then requests context from the last serving gNB and receives the UE context including an indication of A. If A is greater than or equal to C the network moves the UE to RRC Idle. If A is less than C, the network moves the UE back to RRC Inactive.

In Figure 11, the last serving gNB determines to move a UE to RRC Inactive and stores the UE context. When a UE context request is received at the gNB with the cause: RAN update, the gNB increments the RNAU count A by 1 and sends the context, including an indication of A to the requesting gNB.

Depending on e.g. implementation, the last serving gNB may assume that the target gNB will release the UE to RRC Idle upon receiving the RNAU Counter A = network threshold C, and thus discard the UE context and release the N2 path to the UPF.

Figure 11 demonstrates one embodiment (marked with the shaded box), where the RNA update counter A is reset to 0 if the RRC Resume message cause is not RNA update. This could e.g. be the case in case of the cause being a new user plane data transfer. In a similar embodiment, if the anchor gNB is changed, e.g. due to the new gNB having user plane data exchange with the UE, the RNA update counter A may also be reset to 0.

In one embodiment, the anchor gNB that is experiencing bottlenecks related to the use of RRC Inactive mode (e.g. in terms of context storage or available I-RNTI values) will release a RRC Inactive UE to RRC Idle, upon receiving a RNAU message if the count of that UE is large (according to network thresholds).

An apparatus may comprise means for receiving, at a network node, an indication of a radio access network notification area update, RNAU, performed by a user equipment operating in a first mode and acquiring a count of a number of RNAUs performed by the user equipment in a given time period.

Alternatively, or in addition, an apparatus may comprise means for providing a radio access network notification area update, RNAU, to a network from a user equipment operating in a first mode and acquiring a count of a number of RNAUs performed by the user equipment in a given time period.

It should be understood that the apparatuses may comprise or be coupled to other units or modules etc., such as radio parts or radio heads, used in or for transmission and/or reception.

Although the apparatuses have been described as one entity, different modules and memory may be implemented in one or more physical or logical entities.

It is noted that whilst some embodiments have been described in relation to 5G networks, similar principles can be applied in relation to other networks and communication systems.

Therefore, although certain embodiments were described above by way of example with reference to certain example architectures for wireless networks, technologies and standards, embodiments may be applied to any other suitable forms of communication systems than those illustrated and described herein.

It is also noted herein that while the above describes example embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

In general, the various embodiments may be implemented in hardware or special purpose circuitry, software, logic or any combination thereof. Some aspects of the disclosure may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the disclosure is not limited thereto. While various aspects of the disclosure may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and (b) combinations of hardware circuits and software, such as (as applicable): (i) a combination of analog and/or digital hardware circuit(s) with software/firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation." This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

The embodiments of this disclosure may be implemented by computer software executable by a data processor of the mobile device, such as in the processor entity, or by hardware, or by a combination of software and hardware. Computer software or program, also called program product, including software routines, applets and/or macros, may be stored in any apparatus-readable data storage medium and they comprise program instructions to perform particular tasks. A computer program product may comprise one or more computer-executable components which, when the program is run, are configured to carry out embodiments. The one or more computer-executable components may be at least one software code or portions of it.

Further in this regard it should be noted that any blocks of the logic flow as in the Figures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD. The physical media is a non-transitory media.

The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may comprise one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), FPGA, gate level circuits and processors based on multi core processor architecture, as non-limiting examples.

Embodiments of the disclosure may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

The scope of protection sought for various embodiments of the disclosure is set out by the independent claims. The embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the disclosure.

The foregoing description has provided by way of non-limiting examples a full and informative description of the exemplary embodiment of this disclosure. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings of this disclosure will still fall within the scope of this invention as defined in the appended claims.

Indeed, there is a further embodiment comprising a combination of one or more embodiments with any of the other embodiments previously discussed.

Claims

Claims 1. An apparatus comprising means for: receiving, at a network node, an indication of a radio access network notification area update, RNAU, performed by a user equipment operating in a first mode; and acquiring a count of a number of RNAUs performed by the user equipment in a given time period.
2. An apparatus according to claim 1, comprising means for receiving the indication of the RNAU from a target node.
3. An apparatus according to claim 2 comprising means for providing an indication of the count to the target node. 15
4. An apparatus according to claim 3 wherein the indication of the count comprises an indication of at least one of the given time period and a time stamp.
5. An apparatus according to a claim 3 or claim 4, comprising means for providing the indication of the count to the target node in response to a request from the target node.
6. An apparatus according to claim 5, wherein the request includes the indication of the RNAU. 25
7. An apparatus according to any of claims 3 to 6, comprising means for providing an indication to the target node that the count is greater than or equal to a threshold or less than the threshold in the given time period.
8. An apparatus according to claim 7, comprising means for providing an indication of the count to the target node if the count is greater than or equal to the threshold or less than the threshold.
9. An apparatus according to claim 1, wherein means for receiving the indication of the RNAU comprises means for receiving the RNAU from the user equipment.
10. An apparatus according to claim 9 comprising means for receiving an indication of the count from a last serving node or the user equipment.
11. An apparatus according to claim 10 wherein the indication of the count from the last serving node comprises an indication of at least one of the given time period and a time stamp.
12. An apparatus according to any of claims 9 to 11, comprising means for providing a request to the last serving node for the indication of the count. 10
13. An apparatus according to claim 12, wherein the request includes the indication of the RNAU.
14. An apparatus according to any of claims 9 to 13, comprising means for receiving an indication from the last serving node or the user equipment that the count is greater than or equal to a threshold or less than the threshold in the given time period.
15. An apparatus according to any of claims 1 to 14, wherein the number of RNAUs in the given time period is the number of consecutive RNAUs without at least one of data transmission and data reception at the user equipment in the given time period.
16. An apparatus according to any of claims 1 to 15, wherein the count of the number of RNAUs performed by the user equipment in a given time period is for use in determining whether the user equipment should operate in the first mode or a second mode.
17. An apparatus according to claim 16, wherein the first mode is RRC inactive mode and the second mode is RRC Idle mode.
18. An apparatus according to claim 16, wherein the first mode is RRC inactive mode and the second mode is RRC Connected mode.
19. An apparatus comprising means for: providing a radio access network notification area update, RNAU, to a network from a user equipment operating in a first mode; and acquiring a count of a number of RNAUs performed by the user equipment in a given time period.
20. An apparatus according to claim 19, comprising means for receiving at least one an indication of the count, the given time period, a time stamp and a threshold from the network.
21. An apparatus according to claim 20, comprising means for providing an indication of the count in the given time period to a target node of the network. 10
22. An apparatus according to claim 21, comprising means for providing an indication of the count to the target node if the count is greater than or equal to a threshold or less than the threshold.
23. An apparatus according to claim 22, comprising means for providing an indication to the target node that the count is greater than or equal to the threshold or less than the threshold in the given time period.
24. An apparatus according to any of claims 19 to 23, wherein the count of the number of RNAUs performed by the user equipment in a given time period is for use in determining whether the user equipment should operate in the first mode or a second mode.
25. An apparatus according to claim 24, comprising means for determining at the apparatus to move the user equipment to the second mode based on the count of the number of RNAUs performed by the user equipment in the given time period.
26. An apparatus according to claim 25, comprising means for providing an indication to the network that the user equipment is moving to the second mode.
27. An apparatus according to any of claims 24 to 26, wherein the first mode is RRC inactive mode and the second mode is RRC Idle mode.
28. An apparatus according to claim 24 to 26, wherein the first mode is RRC inactive mode and the second mode is RRC Connected mode.
29. An apparatus according to any of claims 19 to 28, wherein the number of RNAUs in the given time period is the number of consecutive RNAUs without at least one of data transmission and data reception at the user equipment in the given time period.
30. A method comprising: receiving, at a network node, an indication of a radio access network notification area update, RNAU, performed by a user equipment operating in a first mode; and acquiring a count of a number of RNAUs performed by the user equipment in a given time period.
31 A method comprising providing a radio access network notification area update, RNAU, to a network from a user equipment operating in a first mode; and acquiring a count of a number of RNAUs performed by the user equipment in a given time period.
32. An apparatus comprising: at least one processor and at least one memory including a computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus at least to: receive, at a network node, an indication of a radio access network notification area update, RNAU, performed by a user equipment operating in a first mode; and acquire a count of a number of RNAUs performed by the user equipment in a given time period.
33. An apparatus comprising: at least one processor and at least one memory including a computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus at least to: provide a radio access network notification area update, RNAU, to a network from a user equipment operating in a first mode; and acquire a count of a number of RNAUs performed by the user equipment in a given time period.
34. A computer readable medium comprising program instructions for causing an apparatus to perform at least the following: receiving, at a network node, an indication of a radio access network notification area update, RNAU, performed by a user equipment operating in a first mode; and acquiring a count of a number of RNAUs performed by the user equipment in a given time period.
35. A computer readable medium comprising program instructions for causing an apparatus to perform at least the following: providing a radio access network notification area update, RNAU, to a network from a user equipment operating in a first mode; and acquiring a count of a number of RNAUs performed by the user equipment in a given time period.