Bearer mapping configuration for UE-to-UE sidelink relaying

Abstract

The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. There is disclosed a method of a first Remote UE in a sidelink relay network, the sidelink relay network comprising the first Remote UE, a Relay UE, and a second Remote UE, wherein the method comprises: determining a pair identifier (ID) identifying the first remote UE and a second remote UE at a sidelink relay adaptation protocol (SRAP) layer; and transmitting, to at least one of the second remote UE and a relay UE, the pair ID identifying the first remote UE and the second remote UE.

Description

BEARER MAPPING CONFIGURATION FOR UE-TO-UE SIDELINK RELAYING

[0001] Certain examples of the present disclosure provide various techniques relating to UE-to-UE sidelink relaying, for example within 3rdGeneration Partnership Project (3GPP) 5th Generation (5G) New Radio (NR) and NR-based relay networks.

[0002] 5G mobile communication technologies define broad frequency bands such that high transmission rates and new services are possible, and can be implemented not only in "Sub 6GHz" bands such as 3.5GHz, but also in "Above 6GHz" bands referred to as mmWave including 28GHz and 39GHz. In addition, it has been considered to implement 6G mobile communication technologies (referred to as Beyond 5G systems) in terahertz bands (for example, 95GHz to 3THz bands) in order to accomplish transmission rates fifty times faster than 5G mobile communication technologies and ultra-low latencies one-tenth of 5G mobile communication technologies.

[0003] At the beginning of the development of 5G mobile communication technologies, in order to support services and to satisfy performance requirements in connection with enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), there has been ongoing standardization regarding beamforming and massive MIMO for mitigating radio-wave path loss and increasing radio-wave transmission distances in mmWave, supporting numerologies (for example, operating multiple subcarrier spacings) for efficiently utilizing mmWave resources and dynamic operation of slot formats, initial access technologies for supporting multi-beam transmission and broadbands, definition and operation of BWP (BandWidth Part), new channel coding methods such as a LDPC (Low Density Parity Check) code for large amount of data transmission and a polar code for highly reliable transmission of control information, L2 pre-processing, and network slicing for providing a dedicated network specialized to a specific service.

[0004] Currently, there are ongoing discussions regarding improvement and performance enhancement of initial 5G mobile communication technologies in view of services to be supported by 5G mobile communication technologies, and there has been physical layer standardization regarding technologies such as V2X (Vehicle-to-everything) for aiding driving determination by autonomous vehicles based on information regarding positions and states of vehicles transmitted by the vehicles and for enhancing user convenience, NR-U (New Radio Unlicensed) aimed at system operations conforming to various regulation-related requirements in unlicensed bands, NR UE Power Saving, Non-Terrestrial Network (NTN) which is UE-satellite direct communication for providing coverage in an area in which communication with terrestrial networks is unavailable, and positioning.

[0005] Moreover, there has been ongoing standardization in air interface architecture / protocol regarding technologies such as Industrial Internet of Things (IIoT) for supporting new services through interworking and convergence with other industries, IAB (Integrated Access and Backhaul) for providing a node for network service area expansion by supporting a wireless backhaul link and an access link in an integrated manner, mobility enhancement including conditional handover and DAPS (Dual Active Protocol Stack) handover, and two-step random access for simplifying random access procedures (2-step RACH for NR). There also has been ongoing standardization in system architecture / service regarding a 5G baseline architecture (for example, service based architecture or service based interface) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) for receiving services based on UE positions.

[0006] As 5G mobile communication systems are commercialized, connected devices that have been exponentially increasing will be connected to communication networks, and it is accordingly expected that enhanced functions and performances of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research is scheduled in connection with eXtended Reality (XR) for efficiently supporting AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality) and the like, 5G performance improvement and complexity reduction by utilizing Artificial Intelligence (AI) and Machine Learning (ML), AI service support, metaverse service support, and drone communication.

[0007] Furthermore, such development of 5G mobile communication systems will serve as a basis for developing not only new waveforms for providing coverage in terahertz bands of 6G mobile communication technologies, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), array antennas and large-scale antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional space multiplexing technology using OAM (Orbital Angular Momentum), and RIS (Reconfigurable Intelligent Surface), but also full-duplex technology for increasing frequency efficiency of 6G mobile communication technologies and improving system networks, AI-based communication technology for implementing system optimization by utilizing satellites and AI (Artificial Intelligence) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at levels of complexity exceeding the limit of UE operation capability by utilizing ultra-high-performance communication and computing resources.

[0008] The Rel-17 3GPP RAN Study Item "Study on NR Sidelink Relay", completed in 2021 and whose outcome is captured in 3GPP TR 38.836 v17.0.0, considered both UE-to-Network Relay and UE-to-UE Relay coverage extension. However, the subsequent Rel-17 normative work in RAN focused exclusively on UE-to-Network Relay.

[0009] The present disclosure relates to a method for UE-to-UE Sidelink relaying.

[0010] It is an aim of certain examples of the present disclosure to address, solve and / or mitigate, at least partly, at least one of the problems and / or disadvantages associated with the related art, for example at least one of the problems and / or disadvantages described herein. It is an aim of certain examples of the present disclosure to provide at least one advantage over the related art, for example at least one of the advantages described herein.

[0011] There is disclosed a method of a first Remote UE in a sidelink relay network, the sidelink relay network comprising the first Remote UE, a Relay UE, and a second Remote UE, wherein the method comprises: determining a pair identifier (ID) identifying the first remote UE and a second remote UE at a sidelink relay adaptation protocol (SRAP) layer; and transmitting, to at least one of the second remote UE and a relay UE, the pair ID identifying the first remote UE and the second remote UE.

[0012] Embodiments or examples disclosed in the description and / or figures falling outside the scope of the claims are to be understood as examples useful for understanding the present invention.

[0013] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description taken in conjunction with the accompanying drawings.

[0014] The present disclosure provides a method for bearer mapping configuration for UE-to-UE Sidelink relaying.

[0015] Figure 1 illustrates the User plane protocol stacks for L2 UE-to-UE (U2U) Relay;

[0016] Figure 2 illustrates the Control plane protocol stacks for L2 UE-to-UE (U2U) Relay;

[0017] Figure 3 illustrates an example sidelink relay system;

[0018] Figure 4 illustrates a method of a first Remote UE in a sidelink relay network according to certain embodiments;

[0019] Figure 5 illustrates a method of a Relay UE in a sidelink relay network according to certain embodiments;

[0020] Figure 6 illustrates a method of a second Remote UE in a sidelink relay network according to certain embodiments;

[0021] Figure 7 illustrates a method of a Relay UE in a sidelink relay network according to certain embodiments;

[0022] Figure 8 illustrates a method of a source Remote UE in a sidelink relay network according to certain embodiments;

[0023] Figure 9 illustrates a method of a Relay UE in a sidelink relay network according to certain embodiments;

[0024] Figure 10 illustrates a method of a Relay UE 310 in a sidelink relay network according to certain embodiments; and

[0025] Figure 11 illustrates a block diagram of an example UE (e.g. Remote UE, Relay UE) according to certain embodiments.

[0026] The following description of examples of the present disclosure, with reference to the accompanying drawings, is provided to assist in a comprehensive understanding of the present invention, as defined by the claims. The description includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the examples described herein can be made.

[0027] The same or similar components may be designated by the same or similar reference numerals, although they may be illustrated in different drawings.

[0028] Detailed descriptions of techniques, structures, constructions, functions or processes known in the art may be omitted for clarity and conciseness, and to avoid obscuring the subject matter of the present disclosure.

[0029] The terms and words used herein are not limited to the bibliographical or standard meanings, but, are merely used to enable a clear and consistent understanding of the examples disclosed herein.

[0030] Throughout the description and claims, the words “comprise”, “contain” and “include”, and variations thereof, for example “comprising”, “containing” and “including”, means “including but not limited to”, and is not intended to (and does not) exclude other features, elements, components, integers, steps, processes, functions, characteristics, and the like.

[0031] Throughout the description and claims, the singular form, for example “a”, “an” and “the”, encompasses the plural unless the context otherwise requires. For example, reference to “an object” includes reference to one or more of such objects.

[0032] Throughout the description and claims, language in the general form of “X for Y” (where Y is some action, process, function, activity or step and X is some means for carrying out that action, process, function, activity or step) encompasses means X adapted, configured or arranged specifically, but not necessarily exclusively, to do Y.

[0033] Features, elements, components, integers, steps, processes, functions, characteristics, and the like, described in conjunction with a particular aspect, embodiment, example or claim are to be understood to be applicable to any other aspect, embodiment, example or claim disclosed herein unless incompatible therewith.

[0034] The following examples are applicable to, and use terminology associated with, 3GPP 5G. However, the skilled person will appreciate that the techniques disclosed herein are not limited to these examples or to 3GPP 5G, and may be applied in any suitable system or standard, for example one or more existing and / or future generation wireless communication systems or standards. The skilled person will appreciate that the techniques disclosed herein may be applied in any existing or future releases of 3GPP 5G NR or any other relevant standard. For example, the following examples may refer to a user equipment (UE), but the skilled person will appreciate that this may be applied to any terminal. For example, the following examples may refer to a PC5 channel, but the skilled person will appreciate that this may be applied to any channel or interface between terminals.

[0035] For example, the functionality of the various network entities and other features disclosed herein may be applied to corresponding or equivalent entities or features in other communication systems or standards. Corresponding or equivalent entities or features may be regarded as entities or features that perform the same or similar role, function, operation or purpose within the network. For example, the functionality of a network node in the examples below may be applied to any other suitable type of entity performing functions of a network node.

[0036] The skilled person will appreciate that certain examples of the present disclosure may not be directly related to standardization but rather proprietary implementation of some of the sidelink relay functions or non-sidelink relay related functions of NR Rel-17 and beyond networks.

[0037] The skilled person will appreciate that the present invention is not limited to the specific examples disclosed herein. For example:

[0038] - The techniques disclosed herein are not limited to 3GPP 5G.

[0039] - One or more entities in the examples disclosed herein may be replaced with one or more alternative entities performing equivalent or corresponding functions, processes or operations.

[0040] - One or more of the messages in the examples disclosed herein may be replaced with one or more alternative messages, signals or other type of information carriers that communicate equivalent or corresponding information.

[0041] - One or more further elements, entities and / or messages may be added to the examples disclosed herein.

[0042] - One or more non-essential elements, entities and / or messages may be omitted in certain examples.

[0043] - The functions, processes or operations of a particular entity in one example may be divided between two or more separate entities in an alternative example.

[0044] - The functions, processes or operations of two or more separate entities in one example may be performed by a single entity in an alternative example.

[0045] - Information carried by a particular message in one example may be carried by two or more separate messages in an alternative example.

[0046] - Information carried by two or more separate messages in one example may be carried by a single message in an alternative example.

[0047] - The order in which operations are performed may be modified, if possible, in alternative examples.

[0048] - The transmission of information between network entities is not limited to the specific form, type and / or order of messages described in relation to the examples disclosed herein.

[0049] Certain examples of the present disclosure may be provided in the form of an apparatus / device / network entity configured to perform one or more defined network functions and / or a method therefor. Such an apparatus / device / network entity may comprise one or more elements, for example one or more of receivers, transmitters, transceivers, processors, controllers, modules, units, and the like, each element configured to perform one or more corresponding processes, operations and / or method steps for implementing the techniques described herein. For example, an operation / function of X may be performed by a module configured to perform X (or an X-module). Certain examples of the present disclosure may be provided in the form of a system (e.g. a network) comprising one or more such apparatuses / devices / network entities, and / or a method therefor. For example, in the following examples, a network may include one or more nodes.

[0050] It will be appreciated that examples of the present disclosure may be realized in the form of hardware, software or a combination of hardware and software. Certain examples of the present disclosure may provide a computer program comprising instructions or code which, when executed, implement a method, system and / or apparatus in accordance with any aspect, claim, example and / or embodiment disclosed herein. Certain embodiments of the present disclosure provide a machine-readable storage storing such a program.

[0051] While the invention has been shown and described with reference to certain examples, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention, as defined by the appended claims.

[0052] Certain examples of the present disclosure provide one or more techniques as disclosed in the appended annex to the description. The skilled person will appreciate that any of these techniques may be applied in combination with any of the techniques described above and illustrated in the Figures.

[0053] In the present disclosure, the following abbreviations and definitions may be used.

[0054] 3GPP: 3rd Generation Partnership Project

[0055] 5G: 5th Generation

[0056] DL: Downlink

[0057] DST: Destination

[0058] E2E: End-to-end

[0059] gNB: 5G base station

[0060] ID: Identity / Identification / Identifier

[0061] IP: Internet Protocol

[0062] L2: Layer 2

[0063] LCH: Logical Channel

[0064] LCID: Logical Channel ID

[0065] MAC: Medium Access Control

[0066] NR: New Radio

[0067] PC5: Air interface between terminal and terminal

[0068] PDCP: Packet Data Conversion Protocol

[0069] PHY: Physical

[0070] PQI: PC5 QoS Identifier

[0071] QoS: Quality of Service

[0072] RAN: Radio Access Network

[0073] RAN2: Radio layer 2 and Radio layer 3 Working Group

[0074] Rel: Release

[0075] RLC: Radio Link Control

[0076] RRC: Radio Resource Control

[0077] Rx: Receive(r)

[0078] SDAP: Service Data Adaption Protocol

[0079] SL: Sidelink

[0080] SLRB: Sidelink Radio Bearer

[0081] SRAP: Sidelink Relay Adaptation Protocol

[0082] SRC: Source

[0083] TR: Technical Report

[0084] TS: Technical Specification

[0085] Tx: Transmit(ter)

[0086] U2N: UE-to-Network

[0087] U2U: UE-to-UE

[0088] UE: User Equipment

[0089] UL: Uplink

[0090] Uu: Air interface between terminal and base station / access point

[0091] UE-to-UE (U2U) Relay enables the coverage extension of the sidelink (SL) transmissions between two sidelink UEs, without relying on the use of uplink or downlink. This is especially important for the partial coverage scenario whereby at least one of the UEs involved in relaying (Source UE, Relay UE, Destination UE) is in-coverage, and at least one of the UEs involved in relaying is out-of-coverage. When a Relay UE is in-coverage, it can access the network via the Uu link. Relaying of data between a Source UE and a Destination UE can occur once a PC5 link is established between the Source UE, UE-to-UE Relay, and Destination UE. Connected to a Relay UE there may be multiple destination (DST) Remote UEs for a single source (SRC) Remote UE, and there may be multiple SRC Remote UEs for a single DST Remote UE.

[0092] Figures 1 and 2 respectively show User and Control plane protocol stacks for L2 UE-to-UE (U2U) Relay, as captured in the 3GPP TR 38.836 v17.0.0. 3GPP agreed to introduce the Adapt layer on the PC5 links, as shown in the above figures in shaded boxes. The Adapt layer is also present on the Uu link, between the Relay UE and the gNB (not shown in above Figures).

[0093] The main agreed functionality of Adapt on the Uu link is mapping of UL PC5 bearers onto UL Uu bearers, and performing the inverse process on the DL. The main agreed functionality of Adapt on the PC5 link is mapping of bearers onto PC5 RLC channels.

[0094] This Adapt layer was (re)named Sidelink Relay Adaptation Protocol, or SRAP for short (TS 38.351). The following is the basic model and operation of SRAP for Rel-17 U2N SL relaying, as agreed by 3GPP:

[0095] - On the U2N Relay UE, the SRAP sublayer contains one SRAP entity at Uu interface and a separate collocated SRAP entity at the PC5 interface. On the U2N Remote UE, the SRAP sublayer contains only one SRAP entity at the PC5 interface.

[0096] - Each SRAP entity has a transmitting part and a receiving part. Across the PC5 interface, the transmitting part of the SRAP entity at the U2N Remote UE has a corresponding receiving part of an SRAP entity at the U2N Relay UE, and vice-versa. Across the Uu interface, the transmitting part of the SRAP entity at the U2N Relay UE has a corresponding receiving part of an SRAP entity at the gNB, and vice-versa.

[0097] - At the Remote UE, in the uplink (UL) direction the SRAP will determine SRAP UE ID and BEARER ID and add the SRAP header. At the Remote UE, on the downlink (DL), the SRAP will remove the SRAP header and deliver the packet to higher layers.

[0098] - At the Relay UE, on the UL the SRAP will map the packet from a PC5 channel to a Uu channel using the SRAP UE ID and BEARER ID contained in the packet itself, and the mapping configuration provided by the network. At the Relay UE, on the DL the SRAP will map the packet from a Uu channel to a PC5 channel using SRAP UE ID and BEARER ID contained in the packet itself, and the mapping configuration provided by the network.

[0099] For L2 UE-to-UE Relay, functionalities of the SRAP layer are still under discussion but it is expected that it will have the bearer mapping function (mapping of end-to-end (E2E) sidelink bearers between the source / transmitting (SRC / Tx) UE and the destination / receiving (DST / Rx) UE onto PC5 channels between SRC / Tx UE and Relay UE, and between Relay UE and DST / Rx UE). The E2E sidelink bearers can include one of data radio bearer(s) and signaling radio bearer(s) between SRC / Tx UE and DST / Rx UE. The identity information of Remote UE end-to-end sidelink Radio Bearer is included in the adaptation layer, while the identity information of Source Remote UE and / or the identity information of Destination Remote UE and / or identifier of the pair are candidate information to be included in the SRAP header.

[0100] The following agreements were made as part of Rel-18 normative work on U2U SL Relaying at RAN2#121 in February 2023:

[0101] An ID mappable to the destination remote UE is needed in the first hop (SRC / Tx remote UE to Relay UE), at least in case multiplexing of different destinations in the same RLC channel is supported.

[0102] An ID mappable to the source remote UE is needed in the second hop (Relay UE to DST / Rx remote UE).

[0103] Whether multiplexing of different destinations in the same RLC channel is supported is an open issue in 3GPP. The inventors have identified additional technical obstacles posed by multiplexing and certain embodiments of the present disclosure provide solutions in the case where multiplexing is supported.

[0104] The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present invention.

[0105] Figure 3 illustrates an example sidelink relay system comprising N Remote UEs 301-30N with the possibility of connecting to the same Relay UE 310. These Remote UEs 301-30N may communicate with each other via direct 320 and / or indirect 330 (i.e. via Relay UE 310) paths. In an example, the Relay UE 310 may know the SRC L2 IDs of two Remote UEs communicating via the Relay UE 310. For example, during the Relay discovery / selection phase, both Remote UEs can report their peer UE’s SRC ID (i.e. the one used for direct communication) to the selected Relay UE 310, where peer UE’s SRC ID serves as DST ID for the reporting Remote UE. In an example, E2E bearers from a single SRC Remote UE towards multiple DST Remote UEs could be multiplexed onto a single RLC channel between the SRC Remote UE and Relay UE 310. In an example, there could also be multiplexing of E2E bearers between Relay UE 310 and DST Remote UE since multiple SRC UEs could be communicating with the same DST Remote UE via the same Relay UE 310.

[0106] As mentioned, a SRC UE may be communicating with multiple DST UEs via the same Relay UE 310. This can be done without multiplexing in the same RLC channel, but in that case more RLC channels are required (bigger LCID space). More specifically, a SRC UE would have to use subset#1 of its RLC channels towards the Relay UE 310 for traffic towards DST UE#1, non-overlapping subset#2 for traffic towards DST UE#2, and so on. Relay UE 310 would need to use subset#A of the RLC channels towards a DST UE for traffic from SRC UE#A, non-overlapping subset#B for traffic from SRC UE#B, and so on. This may lead to significant signalling overload since these subsets may often need to be reconfigured.

[0107] If multiplexing is not used, a UE ID (e.g. in the SRAP header) may not be needed so long as each individual E2E bearer is mapped onto a different channel (e.g. a PC5-RLC channel). However, in the case of bearer multiplexing, it may be necessary to identify the UE that the E2E bearer comes from / is intended for, since data from different E2E bearers can be multiplexed onto the same channel.

[0108] Assuming each of the N Remote UEs can connect to each other Remote UE, a maximum of N*(N-1) / 2 pairs would have to be identified, and this behaves as N^2 as N grows. So 2 * log2(N) bits would be needed for a local ID for the pair (i.e. single ID identifying the pair, as opposed to two IDs identifying each of the UEs, such as e.g. SRC / DST IDs). If each of individual source and destination UE IDs has M bits, the question is whether 2*M (assuming both IDs are included in the packet header) is greater than 2 * log2(N)? If the SRC L2 IDs (M = 24 bits) were to be used as UE ID in the SRAP layer, then it is clear that so long as N<224, using a pair ID gives less overhead.

[0109] Figure 4 illustrates a method of a first Remote UE 301 in a sidelink relay network according to certain embodiments. The sidelink relay network comprises the first Remote UE 301, a Relay UE 310, and a second Remote UE 302. In step 401 the method comprises determining a pair ID corresponding to the first Remote UE 301 and the second Remote UE 302. In step 402 the method comprises transmitting the pair ID to at least one of the Relay UE 310 and the second Remote UE 302. In certain embodiments, transmitting the pair ID to the second Remote UE 302 may comprise directly transmitting the pair ID to the second Remote UE 302, or may comprise transmitting the pair ID indirectly (e.g. via the Relay UE 310) to the second Remote UE 302.

[0110] Figure 5 illustrates a method of a Relay UE 310 in a sidelink relay network according to certain embodiments. The sidelink relay network comprises the Relay UE 310, a first Remote UE 301, and a second Remote UE 302. In step 501 the method comprises determining a pair ID corresponding to the first Remote UE 301 and the second Remote UE 302. In step 502 the method comprises transmitting the pair ID to at least one of the first Remote UE 301 and the second Remote UE 302.

[0111] Figure 6 illustrates a method of a second Remote UE 302 in a sidelink relay network according to certain embodiments. The sidelink relay network comprises a Relay UE 310, a first Remote UE 301, and the second Remote UE 302. In step 601 the method comprises receiving, from at least one of the first Remote UE 301 or the Relay UE 310, a pair ID corresponding to the first Remote UE 301 and the second Remote UE 302.

[0112] Figure 7 illustrates a method of a Relay UE 310 in a sidelink relay network according to certain embodiments. The sidelink relay network comprises the Relay UE 310, and a first pair of Remote UEs comprising a first Remote UE 301, and a second Remote UE 302. In step 701 the method comprises receiving, from the first Remote UE 301, a first pair ID corresponding to the first pair of Remote UEs. In certain embodiments, the method may further comprise transmitting the first pair ID to the second Remote UE 302.

[0113] According to the above embodiments (e.g. the embodiments described in relation to Figures 4 to 7), a joint / single identifier is used for a pair of Remote UEs. The pair ID may be shorter than the combined length of the individual identifiers used for the Remote UEs. For example, the pair ID may not be the individual remote UE IDs concatenated together. Use of the shorter pair ID may reduce signalling overhead. For example, instead of using individual source and destination IDs (for example the source and destination L2 IDs) in a packet header (for example the SRAP packet header), a pair ID may be used, wherein the pair ID is shorter (for example comprises less bits) than the combined length of the individual source and destination IDs.

[0114] In certain embodiments (e.g. any of the above embodiments), transmitting the pair ID from the first Remote UE 301 to at least one of the Relay UE 310 and the second Remote UE 302 may comprise transmitting the pair ID to at least one of the Relay UE 310 and the second Remote UE 302 during an initial relay discovery and / or selection phase. For example, a discovery procedure may be integrated into a PC5 link establishment procedure between the two Remote UEs, and the pair ID may be transmitted to at least one of the Relay UE 310 and the second Remote UE 302 during the discovery integrated PC5 link establishment procedure.

[0115] In certain embodiments (e.g. any of the above embodiments), the pair identifier may correspond to the existing PC5 Link Identifier as defined in 3GPP. According to state-of-the-art, when receiving user data from upper layers to be sent over SL direct link to a specific UE, the source / transmitting UE shall determine the direct link context corresponding to the application layer ID and then shall include in each outgoing protocol data unit a specific PC5 Link Identifier. For every PC5 unicast link, a UE self-assigns a distinct PC5 Link Identifier that uniquely identifies the PC5 unicast link in the UE for the lifetime of the PC5 unicast link. To avoid the need to define a new ID, in certain embodiments this higher-layer identifier may be used as the pair ID inside the SRAP header.

[0116] In certain embodiments (e.g. any of the above embodiments), if the PC5 Link Identifier is used as the pair ID then either the SRC UE’s Link identifier may be used or the DST UE’s Link identifier may be used as the pair ID, and then signalled to the Relay UE 310 and / or the other Remote UE.

[0117] In certain embodiments (e.g. any of the above embodiments), a new pair ID may be used. That is, the pair ID may not be an ID already defined in the art. In this case, any UE (e.g. source Remote UE, Relay UE 310, destination Remote UE) can assign the ID and signal it to the other UEs (e.g. Relay UE 310 / Remote UEs).

[0118] In certain embodiments (e.g. any of the above embodiments), if the pair ID is assigned by the source Remote UE, the assigned pair ID may be communicated to the destination Remote UE, and the destination Remote UE may use the same assigned pair ID for return communications to the source UE (i.e. when the source / destination roles are switched the same pair ID is used). Alternatively, each Remote UE may assign its own pair ID to each pairing (i.e. for the same pair of Remote UEs, the pair ID is different depending on which Remote UE is the source Remote UE).

[0119] In certain embodiments (e.g. any of the above embodiments), when the pair ID is determined by a Remote UE there is a potential conflict issue since the UE pair identifier is self-assigned. In certain embodiments, the Relay UE 310 may already have or may obtain the mapping between the pair ID and the corresponding SRC and DST UE IDs. For example, the Relay UE 310 may already have IDs (e.g. L2 IDs) of both Remote UEs, and may also receive from the pair ID generating Remote UE the pair ID and the ID (e.g. L2 ID) of the other Remote UE). For example, the pair ID generating Remote UE may transmit the pair ID along with the ID of the other Remote UE. In certain embodiments (e.g. any of the above embodiments), the method may further comprise detecting whether the first pair ID is the same as a second pair ID corresponding to a second pair of Remote UEs, wherein the second pair of Remote UEs is different to the first pair of Remote UEs. That is, the Relay UE 310 may detect that a different {SRC UE ID, DST UE ID} pair has the same pair ID (assigned by either the SRC UE or DST UE). A first pair may be determined to be different to a second pair if at least one Remote UE in the first pair is not included in the second pair.

[0120] In response to detecting that the first pair ID is the same as the second pair ID, the method may further comprise determining a third pair ID corresponding to the first pair of Remote UEs; and transmitting the third pair ID to the first Remote UE 301. The method may further comprise transmitting the third pair ID to the second Remote UE 302. That is, the Relay UE 310 may assign a new pair ID and inform the pair ID-generating UE (e.g. the first Remote UE 301) of the new pair ID to be used. The new pair ID can be communicated to the peer Remote UE (e.g. the second Remote UE 302) of the pair ID-generating UE by the Relay UE 310 or by the pair ID-generating UE.

[0121] Alternatively, in response to detecting that the first pair ID is the same as the second pair ID, the method may further comprise transmitting, to the first Remote UE 301, a request to generate a third pair ID corresponding to the first pair of Remote UEs. The request may indicate to generate the third pair ID from a predetermined set of pair IDs. That is, the Relay UE 310 may inform the pair ID-generating UE that a new pair ID is to be used and / or request a new pair ID to be generated. Accordingly, the Remote UE may receive an indication from the Relay UE 310 that a new pair ID is to be used and / or may receive a request from the Relay UE 310 to generate a new pair ID, and may generate a new pair ID.

[0122] In certain embodiments (e.g. any of the above embodiments), generating the third pair ID may comprise generating the third pair ID using the same method used to generate the first pair ID.

[0123] In certain embodiments (e.g. any of the above embodiments), to reduce the possibility of the third pair ID being the same as another pair ID, generating the third pair ID may comprise generating the third pair ID from a specific pool of IDs. The specific pool may be a different pool from the pool used to generate the first pair ID. For example, all available IDs could be split into different pools and then if a collision happened the pair-ID generating UE could be instructed to use a different or specific or default pool, to minimize further collisions.

[0124] In certain embodiments, (e.g. any of the above embodiments) the method may further comprise transmitting at least one packet (e.g. on a PC5-RLC channel) to at least one of the first Remote UE 301, the Relay UE 310, and the Second Remote UE 302. For example, when the method is performed by the first Remote UE 301, the method may further comprise transmitting at least one packet to the Relay UE 310 and / or the second Remote UE 302 (e.g. via the Relay UE 310). When the method is performed by the Relay UE 310, the method may further comprise transmitting at least one packet to the first Remote UE 301 and / or the second Remote UE (302). When the method is performed by the second Remote UE 302, the method may further comprise transmitting at least one packet to the Relay UE 310 and / or the first Remote UE 301 (e.g. via the Relay UE 310). In all of the above cases, the method may further comprise including the pair ID in a header of the at least one packet.

[0125] In certain embodiments (e.g. any of the above embodiments), the header is a SRAP packet header. That is, the pair ID may be included in a SRAP packet header, and the layer at which the pair ID is inserted may be the SRAP layer. When the pair ID is used as SRAP ID (i.e. the identifier in the SRAP header that is to be used for routing), the SRAP entity may be configured with the pair ID as SRAP ID and other information by inserting it e.g. in sl-LocalIdentity field (existing in legacy but containing different information) of the SRAP configuration delivered via RRC.

[0126] As set out above, the weak point of SRC L2 ID as SRAP ID is the size (24bits). Consequently, in the present disclosure a new SRAP ID for the UE pair is defined. As set out above, use of the pair ID may be particularly advantageous in the case of multiplexing. Accordingly, the methods set out above may be applied to the case of multiplexing. For example, in certain embodiments (e.g. any of the above embodiments) the methods may further comprise multiplexing a plurality of bearers (e.g. E2E bearers) onto a channel (e.g. PC5-RLC channel), and including the pair ID in a header (e.g. a SRAP header) of at least one packet carrying (e.g. from the source remote UE to the destination Remote UE via the Relay UE 310, or from the Relay UE 310 to the destination Remote UE) the multiplexed bearers via the channel.

[0127] As an alternative solution to using the pair ID, new smaller individual UE IDs of M bits for each of the source and destination Remotes UEs could be defined and used, such that 2*M is less than 2 * log2(N).

[0128] In certain embodiments (e.g. any of the above embodiments), a method is provided where SRC Remote UE and / or Relay UE 310 decide on & configure QoS split and SLRB configuration for layer 2 relaying (including bearer mapping and any multiplexing). According to state-of-the-art, there is a PC5 unicast link and the corresponding PC5 RRC connection between SRC Remote UE and Relay UE 310, and a PC5 unicast link and the corresponding PC5 RRC connection between Relay UE 310 and DST Remote UE. E2E QoS (PQI) is split into per-hop QoS (PQI). For E2E QoS, SRC Remote UE obtains sidelink radio bearer (SLRB) configuration (SDAP, PDCP) using legacy principles and shares with DST Remote UE via RRCReconfigurationSidelink. For per-hop QoS, SRC Remote UE or Relay UE 310 obtain SLRB configuration (SRAP, RLC, MAC, PHY) using legacy principles and shares with Relay UE 310 (if SRC Remote UE obtains the config) / DST Remote UE. The obtained E2E SLRB configuration and the obtained per-hop SLRB configuration correspond to the SLRB configuration for one of signaling radio bearer(s) and data radio bearer(s) between SRC Remote UE and DST Remote UE.

[0129] An example of E2E SLRB configuration:

[0130] SL-RadioBearerConfig ::= SEQUENCE {

[0131] slrb-ConfigIndex SLRB-ConfigIndex, / this field indicates the index of SL-SRB configuration and / or SL-DRB configuration.

[0132] sl-SDAP-Config SL-SDAP-Config OPTIONAL, -- Cond SLRBSetup / this field indicates how to map sidelink E2E QoS flow to sidelink DRB.

[0133] sl-PDCP-Config SL-PDCP-Config OPTIONAL, -- Cond SLRBSetup / this field indicates the PDCP parameters for the SL-SRB or SL-DRB.

[0134] ...

[0135] }

[0136] To indicate the radio bearer identity for E2E SL-SRB and / or E2E SL-DRB corresponding to the SLRB configuration, some field for the radio bearer identity for E2E SL-SRB and / or E2E SL-DRB can be included.

[0137] An example of per-hop SLRB configuration: this configuration is used to configure per-hop SLRB configuration to forward traffic via a Relay UE 310 between SRC Remote UE and DST Remote UE. This configuration can be also used to configure per-hop SLRB configuration to support multiplexing of one SRC UE to more than one DST Remote UE via the same Relay UE 310 and more than SRC UE to one DST Remote UE via the same Relay UE 310.

[0138] SL-SRAP-Config ::= SEQUENCE {

[0139] Mapping configuration between E2E SLRB (SL-SRB and / or SL-DRB) and SL RLC chnnel (between SRC UE and Relay UE 310 or between Relay UE 310 and DST UE) for a pair of SRC Remote UE and DST Remote UE

[0140] }

[0141] / The configuration information for PC5 RLC channel between Remote UE (SRC UE / DST UE) and Relay UE 310

[0142] SL-RLC-ChannelConfig ::= SEQUENCE {

[0143] sl-RLC-ChannelID SL-RLC-ChannelID,

[0144] sl-RLC-Config SL-RLC-Config OPTIONAL, -- Need M

[0145] sl-MAC-LogicalChannelConfig SL-LogicalChannelConfig OPTIONAL, -- Need M

[0146] ...}

[0147] In U2U Relaying there may not always be a central entity (e.g. gNB) that has information on and / or configures both E2E QoS requirement and per-hop QoS requirements. Even for the in-coverage case where the gNB could do it, signaling load towards the network may be reduced by configuring these parameters locally instead.

[0148] When there is multiplexing and SRC Remote UE decides on & configures QoS split and SLRB configuration for layer 2 relaying, SRAP layer at SRC Remote UE performs the multiplexing of E2E bearers onto PC5 channels on the first hop (towards the Relay UE 310), while potentially having no knowledge of the per-hop QoS of the second hop. If multiplexing for multiple DST Remote UE is used on the first hop, then SLRB configurations satisfying a predetermined condition (for example, with the same per-QoS on the two hops) should be used. If there is no SLRB configuration satisfying the predetermined condition (for example, there is no SLRB configuration with the same per-QoS on the second hop), a separate SLRB configuration may be configured (e.g. upon request from Relay UE 310; based on indication of second hop QoS received by SRC Remote UE).

[0149] Figure 8 illustrates a method of a source Remote UE in a sidelink relay network according to certain embodiments. The sidelink relay network comprises the source Remote UE (e.g. first Remote UE 301), a Relay UE 310, and a plurality of destination Remote UEs (e.g. second Remote UE 302, third Remote UE 303, … Nth Remote UE 30N). In step 801 the method comprises determining if a respective first SLRB configuration satisfying a predetermined condition exists for at least one destination Remote UE, the respective first SLRB configuration for each destination Remote UE having a first QoS for a first hop between the source Remote UE and the Relay UE 310 and a second QoS for a second hop between the Relay UE 310 and the destination Remote UE. In step 802 the method comprises, in response to determining that a respective first SLRB configuration satisfying the predetermined condition exists for at least two destination Remote UEs, multiplexing E2E bearers for the at least two destination Remote UEs onto a PC5 channel on the first hop, based on the respective first SLRB configurations. In step 803 the method comprises, in response to determining that a respective first SLRB configuration satisfying the predetermined condition does not exist for at least one destination Remote UE, configuring a respective second SLRB configuration for each of the at least one destination Remote UEs for which a respective first SLRB configuration satisfying the predetermined condition does not exist, and mapping E2E bearers for each of the at least one destination Remote UE for which a respective first SLRB configuration satisfying the predetermined condition does not exist onto respective PC5 channels on the first hop without multiplexing, based on the respective second SLRB configurations.

[0150] When the source Remote UE determines the first hop SLRB configuration, then it refers to the first hop’s QoS (e.g. PQI) for at least one destination Remote UE. When the source Remote UE determines the second hop SLRB configuration, it refers to the second hop’s QoS (e.g. PQI) for one destination Remote UE. That is, if multiplexing of bearers intended for multiple destination Remote UEs occurs on the first hop between the source Remote UE and the Relay UE 310, then each bearer has an individual second hop between the Relay UE 310 and the corresponding destination Remote UE.

[0151] Determining if a respective first SLRB configuration satisfying a predetermined condition exists for at least one destination Remote UE may comprise determining based on an indication or request received from the Relay UE 310. For example, the Relay UE 310 may indicate that respective first SLRB configurations satisfying a predetermined condition do not exist for at least one destination Remote UE and / or may request that respective second SLRB configurations be configured for each of the at least one destination Remote UEs. In another example, the Relay UE 310 may provide information (for example, information on a second QoS for the second hop for each destination Remote UE), and the source Remote UE may determine if the respective first SLRB configuration satisfying a predetermined condition exists for at least one destination Remote UE based on the provided information.

[0152] The predetermined condition may be that the first QoS for the first hop is the same as the second QoS for the second hop. That is, if multiplexing for multiple DST Remote UE is used on the first hop, then SLRB configurations with the same per-QoS on the two hops may be used.

[0153] The predetermined condition may be that the first QoS for the first hop is within a certain range of the second QoS for the second hop, or that the first QoS is in the same group or range of QoS values as the second QoS. That is, multiplexing may still be used with similar QoS on first hop and second hop, where QoS ranges could be defined into groups to define similar i.e. tolerable deviation.

[0154] The predetermined condition may be that the first QoS for the first hop and the second QoS for the second hop are each greater than or equal to an E2E QoS (e.g. the combined packet delay is expected to be within the E2E packet delay limit). That is, per-hop QoS values are chosen to meet or exceed E2E QoS even if they are not similar (or close enough)

[0155] For E2E signaling radio bearer whose E2E QoS requirement / per-hop QoS requirement is not defined, multiplexing can be used based on the identity of a signaling bearer (e.g., 0, 1, 2, 3, …). So the signaling radio bearer with the same identity from more than one SRC Remote UE to one DST Remote UE can be multiplexed or the signaling radio bearer with the same identity from one SRC Remote UE to more than one DST Remote UE can be multiplexed.

[0156] When it is the Relay UE 310 that decides on & configures QoS split and SLRB configuration to be then used at SRAP for bearer mapping, similar issues as above apply, however there may be lower signaling overhead since a step of informing the SRC Remote UE and / or DST Remote UE of the second QoS or that a separate SLRB configuration (not containing multiplexing) is needed, may not be required.

[0157] Figure 9 illustrates a method of a Relay UE 310 in a sidelink relay network according to certain embodiments. The sidelink relay network comprises a plurality of source Remote UEs (e.g. first Remote UE 301, third remote UE 303, … Nth Remote UE 30N), the Relay UE 310, and a destination Remote UE (e.g. second Remote UE 302). In step 901 the method comprises determining if a respective first SLRB configuration satisfying a predetermined condition exists for at least one source Remote UE, the respective first SLRB configuration for each source Remote UE having a first QoS for a first hop between the source Remote UE and the Relay UE 310 and a second QoS for a second hop between the Relay UE 310 and the destination Remote UE. In step 902 the method comprises, in response to determining that a respective first SLRB configuration satisfying the predetermined condition exists for at least two source Remote UEs, multiplexing corresponding E2E bearers from the at least two source Remote UEs to the destination Remote UE onto a PC5 channel on the second hop, based on the respective first SLRB configurations. In step 903 the method comprises, in response to determining that a respective first SLRB configuration satisfying the predetermined condition does not exist for at least one source Remote UE, configuring a respective second SLRB configuration for each of the at least one source Remote UEs for which a respective first SLRB configuration satisfying the predetermined condition does not exist, and mapping E2E bearers from each of the at least one source Remote UEs for which a respective first SLRB configuration satisfying the predetermined condition does not exist onto respective PC5 channels on the second hop without multiplexing, based on the respective second SLRB configurations.

[0158] When the Relay UE 310 determines the second hop SLRB configuration, it refers to the second hop’s QoS (e.g. PQI) between at least one source Remote UE and a destination Remote UE. That is, each bearer has an individual first hop between its respective source Remote UE and the Relay UE 310, and multiplexing of bearers intended for a destination Remote UE occurs on the second hop between the Relay UE 310 and the destination Remote UE.

[0159] Figure 10 illustrates a method of a Relay UE 310 in a sidelink relay network according to certain embodiments. The sidelink relay network comprises a source Remote UE (e.g. first Remote UE 301), the Relay UE 310, and a plurality of destination Remote UEs (e.g. second Remote UE 302, third Remote UE 303, … Nth Remote UE 30N). In step 1001 the method comprises determining if a respective first SLRB configuration satisfying a predetermined condition exists for at least one destination Remote UE, the respective first SLRB configuration for each destination Remote UE having a first QoS for a first hop between the source Remote UE and the Relay UE 310 and a second QoS for a second hop between the Relay UE 310 and the destination Remote UE. In step 1002 the method comprises, in response to determining that a respective first SLRB configuration satisfying the predetermined condition exists for at least two destination Remote UEs, transmitting, to the source Remote UE the respective first SLRB configurations and an indication to multiplex, based on the respective first SLRB configurations, E2E bearers for the at least two destination Remote UEs onto a PC5 channel on the first hop. In step 1003 the method comprises, in response to determining that a respective first SLRB configuration satisfying the predetermined condition does not exist for at least one destination Remote UE, configuring a respective second SLRB configuration for each of the at least one destination Remote UEs for which a respective first SLRB configuration satisfying the predetermined condition does not exist, and transmitting, to the source Remote UE, the respective second SLRB configurations and an indication to map, based on the respective second SLRB configurations, E2E bearers for each of the at least one destination Remote UE for which a respective first SLRB configuration satisfying the predetermined condition does not exist onto respective PC5 channels on the first hop without multiplexing.

[0160] When the Relay UE 310 determines the first hop SLRB configuration, it refers to the first hop’s QoS (e.g. PQI) between a source Remote UE and at least one destination Remote UE. That is, if multiplexing of bearers intended for multiple destination Remote UEs occurs on the first hop between the source Remote UE and the Relay UE 310, then each bearer has an individual second hop between the Relay UE 310 and the corresponding destination Remote UE.

[0161] In certain embodiments (e.g. any of the above embodiments), when multiplexing of bearers (e.g. E2E bearers) occurs based on the SLRB configuration as described above, the pair ID (obtained as described above) may be included in a header (e.g. a SRAP packet header) of at least one packet carrying multiple (multiplexed) bearers. In certain embodiments (e.g. any of the above embodiments), the pair ID may also be included in a header of a packet that is transmitted without multiplexing. For example, the layer at which the pair ID is inserted may be the SRAP layer.

[0162] Figure 11 illustrates a block diagram of an example UE (e.g. Remote UE, Relay UE) according to certain embodiments. The UE 1100 comprises a receiver 1110, a processor (or controller) 1120, and a transmitter 1130. The receiver 1110 is configured for receiving one or more signals or messages from one or more UEs (e.g. Remote UEs, Relay UE) or other network entities. The transmitter 1130 is configured for transmitting one or more signals or messages to one or more UEs (e.g. Remote UEs, Relay UE) or other network entities. The processor 1130 is configured for performing operations as described above, for example any of the methods described above in relation to Figures 4-10.

[0163] In a first example, there is provided a method of a first Remote UE in a sidelink relay network, the sidelink relay network comprising the first Remote UE, a Relay UE, and a second Remote UE, wherein the method comprises: determining a pair ID corresponding to the first Remote UE and the second Remote UE; and transmitting the pair ID to at least one of the Relay UE and the second Remote UE.

[0164] In a second example, there is provided a method of a second Remote UE in a sidelink relay network, the sidelink relay network comprising a Relay UE, a first Remote UE, and the second Remote UE, wherein the method comprises: receiving, from at least one of the first Remote UE or the Relay UE, a pair ID corresponding to the first Remote UE and the second Remote UE.

[0165] In a third example, there is provided the method according to the first or second examples, wherein the pair ID is a PC5 Link Identifier of the first Remote UE and the second Remote UE.

[0166] In a fourth example, there is provided a method of a Relay UE in a sidelink relay network, the sidelink relay network comprising the Relay UE, and a first pair of Remote UEs comprising a first Remote UE, and a second Remote UE, wherein the method comprises: receiving, from the first Remote UE, a first pair ID corresponding to the first pair of Remote UEs.

[0167] In a fifth example, there is provided the method of the fourth example, further comprising: detecting whether the first pair ID is the same as a second pair ID corresponding to a second pair of Remote UEs, wherein the second pair of Remote UEs is different to the first pair of Remote UEs.

[0168] In a sixth example, there is provided the method of the fifth example, further comprising: determining, in response to detecting that the first pair ID is the same as the second pair ID, a third pair ID corresponding to the first pair of Remote UEs; and transmitting the third pair ID to the first Remote UE.

[0169] In a seventh example, there is provided the method of the sixth example, further comprising transmitting the third pair ID to the second Remote UE.

[0170] In an eighth example, there is provided the method of the fifth example, further comprising transmitting, in response to detecting that the first pair ID is the same as the second pair ID, a request to the first Remote UE to generate a third pair ID corresponding to the first pair of Remote UEs.

[0171] In a ninth example, there is provided the method of the eighth example, wherein the request indicates to generate the third pair ID from a predetermined set of pair IDs.

[0172] In a tenth example, there is provided the method of any of the fourth to ninth examples, wherein the first pair ID is a PC5 Link Identifier of the first Remote UE and the second Remote UE.

[0173] In an eleventh example, there is provided a method of a Relay UE in a sidelink relay network, the sidelink relay network comprising the Relay UE, a first Remote UE, and a second Remote UE, wherein the method comprises: determining a pair ID corresponding to the first Remote UE and the second Remote UE; and transmitting the pair ID to at least one of the first Remote UE and the second Remote UE.

[0174] In a twelfth example, there is provided the method of any of the first to eleventh examples, wherein the method further comprises transmitting at least one packet to at least one of the first Remote UE, the Relay UE, and the Second Remote UE, and including the pair ID in a header of the at least one packet.

[0175] In a thirteenth example, there is provided the method of the twelfth example, wherein the header is a SRAP packet header.

[0176] In a fourteenth example, there is provided the method of any of the first to thirteenth examples, wherein the method further comprises: multiplexing a plurality of bearers onto a channel; and including the pair ID in a header of at least one packet carrying the multiplexed bearers via the channel.

[0177] In a fifteenth example, there is provided the method of any of the first to fourteenth examples, wherein the header is a SRAP packet header

[0178] In a sixteenth example, there is provided a method of a source Remote UE in a sidelink relay network, the sidelink relay network comprising the source Remote UE, a Relay UE, and a plurality of destination Remote UEs, wherein the method comprises: determining if a respective first SLRB configuration satisfying a predetermined condition exists for at least one destination Remote UE, the respective first SLRB configuration having a first QoS for a first hop between the source Remote UE and the Relay UE and a second QoS for a second hop between the Relay UE and the destination Remote UE; in response to determining that a respective first SLRB configuration satisfying the predetermined condition exists for at least two destination Remote UEs, multiplexing E2E bearers for the at least two destination Remote UEs onto PC5 channels on the first hop, based on the respective first SLRB configurations; and in response to determining that a respective first SLRB configuration satisfying the predetermined condition does not exist for at least one destination Remote UE, configuring a respective second SLRB configuration for each of the at least one destination Remote UEs, and mapping E2E bearers for the at least one destination Remote UE onto PC5 channels on the first hop without multiplexing, based on the respective second SLRB configurations.

[0179] In a seventeenth example, there is provided the method of the sixteenth example, wherein determining if a respective first SLRB configuration satisfying a predetermined condition exists for at least one destination Remote UE comprises determining based on an indication or request received from the Relay UE.

[0180] In an eighteenth example, there is provided the method of the sixteenth or seventeenth examples, wherein the predetermined condition is one of: the first QoS for the first hop is the same as the second QoS for the second hop; the first QoS for the first hop is within a certain range of the second QoS for the second hop; the first QoS is in the same group or range of QoS values as the second QoS; or the first QoS for the first hop and the second QoS for the second hop are each greater than or equal to an E2E QoS.

[0181] In a nineteenth example, there is provided a method of a Relay UE in a sidelink relay network, the sidelink relay network comprising a plurality of source Remote UEs, the Relay UE, and a destination Remote UE, wherein the method comprises: determining if a respective first SLRB configuration satisfying a predetermined condition exists for at least one source Remote UE, the respective first SLRB configuration for each source Remote UE having a first QoS for a first hop between the source Remote UE and the Relay UE and a second QoS for a second hop between the Relay UE and the destination Remote UE; in response to determining that a respective first SLRB configuration satisfying the predetermined condition exists for at least two source Remote UEs, multiplexing corresponding E2E bearers from the at least two source Remote UEs to the destination Remote UE onto a PC5 channel on the second hop, based on the respective first SLRB configurations; and in response to determining that a respective first SLRB configuration satisfying the predetermined condition does not exist for at least one source Remote UE, configuring a respective second SLRB configuration for each of the at least one source Remote UEs for which a respective first SLRB configuration satisfying the predetermined condition does not exist, and mapping E2E bearers from each of the at least one source Remote UEs for which a respective first SLRB configuration satisfying the predetermined condition does not exist onto respective PC5 channels on the second hop without multiplexing, based on the respective second SLRB configurations.

[0182] In a twentieth example, there is provided a method of a Relay UE in a sidelink relay network, the sidelink relay network comprising a source Remote UE, the Relay UE, and a plurality of destination Remote UEs, wherein the method comprises: determining if a respective first SLRB configuration satisfying a predetermined condition exists for at least one destination Remote UE, the respective first SLRB configuration for each destination Remote UE having a first QoS for a first hop between the source Remote UE and the Relay UE and a second QoS for a second hop between the Relay UE and the destination Remote UE; in response to determining that a respective first SLRB configuration satisfying the predetermined condition exists for at least two destination Remote UEs, transmitting, to the source Remote UE the respective first SLRB configurations and an indication to multiplex, based on the respective first SLRB configurations, E2E bearers for the at least two destination Remote UEs onto a PC5 channel on the first hop; and in response to determining that a respective first SLRB configuration satisfying the predetermined condition does not exist for at least one destination Remote UE, configuring a respective second SLRB configuration for each of the at least one destination Remote UEs for which a respective first SLRB configuration satisfying the predetermined condition does not exist, and transmitting, to the source Remote UE, the respective second SLRB configurations and an indication to map, based on the respective second SLRB configurations, E2E bearers for each of the at least one destination Remote UE for which a respective first SLRB configuration satisfying the predetermined condition does not exist onto respective PC5 channels on the first hop without multiplexing.

[0183] In a twenty-first example, there is provided the method of any of the sixteenth to twentieth examples, further comprising including a pair ID corresponding to the source Remote UE and the destination Remote UE in a header of at least one packet carrying the multiplexed bearers or at least one packet transmitted without multiplexing.

[0184] In a twenty-second example, there is provided the method of the twenty-first example, wherein the header is a sidelink relay adaptation protocol (SRAP) packet header.

[0185] In a twenty-third example, there is provided the method of the twenty-first or twenty-second examples, wherein the pair ID is obtained via the method of any of the first to fifteenth examples.

[0186] In a twenty-fourth example, there is provided a method of a Relay user equipment (UE) in a UE-to-UE (U2U) sidelink relay network, the U2U sidelink relay network comprising the Relay UE, a first Remote UE, and a second Remote UE, wherein the method comprises: determining a first identifier (ID) identifying the first Remote UE and a second ID identifying the second Remote UE; and transmitting the first ID and the second ID to at least one of the first Remote UE and the second Remote UE.

[0187] In a twenty-fifth example, there is provided the method of the twenty-fourth example, wherein the first ID has fewer bits than the first Remote UE Layer 2 (L2) ID; and wherein the second ID has fewer bits than the second Remote UE L2 ID.

[0188] In a twenty-sixth example, there is provided the method of the twenty-fourth or twenty-fifth examples, wherein the method further comprises: transmitting at least one packet to at least one of the first Remote UE and the second Remote UE, and including the first ID and the second ID in a header of the at least one packet; wherein the header is a sidelink relay adaptation protocol (SRAP) packet header.

[0189] In a twenty-seventh example, there is provided the method of any of the twenty-fourth to twenty-sixth examples, wherein the method further comprises: multiplexing a plurality of bearers onto a channel; and including the first ID and the second ID in a header of at least one packet carrying the multiplexed bearers via the channel; wherein the header is a sidelink relay adaptation protocol (SRAP) packet header.

[0190] In a twenty-eighth example, there is provided a method of a first Remote UE in a UE-to-UE (U2U) sidelink relay network, the UE-to-UE (U2U) sidelink relay network comprising a Relay UE, the first Remote UE, and a second Remote UE, wherein the method comprises: receiving, from the Relay UE, a first identifier (ID) identifying the first Remote UE and a second ID identifying the second Remote UE.

[0191] In a twenty-ninth example, there is provided the method of the twenty-eighth example, wherein the first ID has fewer bits than the first Remote UE Layer 2 (L2) ID; and wherein the second ID has fewer bits than the second Remote UE L2 ID.

[0192] In a thirtieth example, there is provided the method of the twenty-eighth or twenty-ninth examples, wherein the method further comprises receiving at least one packet from the Relay UE, wherein the first ID and the second ID are included in a header of the at least one packet, wherein the header is a sidelink relay adaptation protocol (SRAP) packet header

[0193] In a thirty-first example, there is provided a method of a first Remote user equipment (UE) in a UE-to-UE (U2U) sidelink relay network, the U2U sidelink relay network comprising a Relay UE, the first Remote UE, and a second Remote UE, wherein the method comprises: determining a first identifier (ID) identifying the first Remote UE and a second ID identifying the second Remote UE; and transmitting the first ID and the second ID to at least one of the Relay UE and the second Remote UE.

[0194] In a thirty-second example, there is provided the method of the thirty-first example, wherein the first ID has fewer bits than the first Remote UE Layer 2 (L2) ID; and wherein the destination ID has fewer bits than the destination Remote UE L2 ID.

[0195] In a thirty-third example, there is provided the method of any of the twenty-eighth to thirty-second examples, wherein the method further comprises transmitting at least one packet to the Relay UE, and including the first ID and the second ID in a header of the at least one packet, wherein the header is a sidelink relay adaptation protocol (SRAP) packet header

[0196] In a thirty-fourth example, there is provided the method of any of the twenty-eighth to thirty-third examples wherein the method further comprises: multiplexing a plurality of bearers onto a channel; and including the first ID and the secondID in a header of at least one packet carrying the multiplexed bearers via the channel, wherein the header is a sidelink relay adaptation protocol (SRAP) packet header.

[0197] In a thirty-fifth example, there is provided a method of a source Remote user equipment (UE) in a sidelink relay network, the sidelink relay network comprising the source Remote UE, a Relay UE, and a plurality of destination Remote UEs, wherein the method comprises: determining if a respective first sidelink radio bearer (SLRB) configuration satisfying a predetermined condition exists for at least one destination Remote UE, the respective first SLRB configuration having a first quality of service (QoS) for a first hop between the source Remote UE and the Relay UE and a second QoS for a second hop between the Relay UE and the destination Remote UE.

[0198] In a thirty-sixth example, there is provided the method of the thirty-fifth example, further comprising at least one of: in response to determining that a respective first SLRB configuration satisfying the predetermined condition exists for at least two destination Remote UEs, multiplexing end-to-end (E2E) bearers for the at least two destination Remote UEs onto PC5 channels on the first hop, based on the respective first SLRB configurations; and in response to determining that a respective first SLRB configuration satisfying the predetermined condition does not exist for at least one destination Remote UE, configuring a respective second SLRB configuration for each of the at least one destination Remote UEs, and mapping E2E bearers for the at least one destination Remote UE onto PC5 channels on the first hop without multiplexing, based on the respective second SLRB configurations.

[0199] In a thirty-seventh example, there is provided the method of the thirty-fifth or thirty-sixth examples, wherein determining if a respective first SLRB configuration satisfying a predetermined condition exists for at least one destination Remote UE comprises determining based on an indication received from the Relay UE.

[0200] In a thirty-eighth example, there is provided the method of the thirty-seventh example, wherein the indication received from the Relay UE comprises at least one of information on the first QoS for the first hop and information on the second QoS for the second hop.

[0201] In a thirty-ninth example, there is provided a method of a Relay user equipment (UE) in a UE-to-UE (U2U) sidelink relay network, the UE-to-UE (U2U) sidelink relay network comprising a plurality of source Remote UEs, the Relay UE, and a destination Remote UE, wherein the method comprises: determining a quality of service (QoS) split, the QoS split comprising a first QoS for a first hop between the source Remote UE and the Relay UE and a second QoS for a second hop between the Relay UE and the destination Remote UE; and transmitting, to at least one of the plurality of source Remote UEs, at least one of information on the first QoS for the first hop and information on the second QoS for the second hop.

[0202] In a fortieth example, there is provided the method of the thirty-ninth example, further comprising: determining if a respective first sidelink radio bearer (SLRB) configuration for Layer 2 (L2)_relaying satisfying a predetermined condition exists for at least one source Remote UE, the respective first SLRB configuration for each source Remote UE having the first QoS) for the first hop between the source Remote UE and the Relay UE and the second QoS for the second hop between the Relay UE and the destination Remote UE; in response to determining that a respective first SLRB configuration satisfying the predetermined condition exists for at least two source Remote UEs, multiplexing corresponding end-to-end (E2E) bearers from the at least two source Remote UEs to the destination Remote UE onto a PC5 channel on the second hop, based on the respective first SLRB configurations; and in response to determining that a respective first SLRB configuration satisfying the predetermined condition does not exist for at least one source Remote UE, configuring a respective second SLRB configuration for L2_relaying for each of the at least one source Remote UEs for which a respective first SLRB configuration satisfying the predetermined condition does not exist, and mapping E2E bearers from each of the at least one source Remote UEs for which a respective first SLRB configuration satisfying the predetermined condition does not exist onto respective PC5 channels on the second hop without multiplexing, based on the respective second SLRB configurations.

[0203] In a forty-first example, there is provided a method of a Relay user equipment (UE) in a UE-to-UE (U2U) sidelink relay network, the UE-to-UE (U2U) sidelink relay network comprising a source Remote UE, the Relay UE, and a plurality of destination Remote UEs, wherein the method comprises: determining a quality of service (QoS) split, the QoS split comprising a first QoS for a first hop between the source Remote UE and the Relay UE and a second QoS for a second hop between the Relay UE and the destination Remote UE; and transmitting, to the source Remote UE, at least one of information on the first QoS for the first hop and information on the second QoS for the second hop.

[0204] In a forty-second example, there is provided the method of the forty-first example, further comprising: determining if a respective first sidelink radio bearer (SLRB) configuration for Layer 2 (L2)_relaying satisfying a predetermined condition exists for at least one destination Remote UE, the respective first SLRB configuration for each destination Remote UE having the first QoS for the first hop between the source Remote UE and the Relay UE and a second QoS for the second hop between the Relay UE and the destination Remote UE; in response to determining that a respective first SLRB configuration satisfying the predetermined condition exists for at least two destination Remote UEs, transmitting, to the source Remote UE the respective first SLRB configurations and an indication to multiplex, based on the respective first SLRB configurations, end-to-end (E2E) bearers for the at least two destination Remote UEs onto a PC5 channel on the first hop; and in response to determining that a respective first SLRB configuration satisfying the predetermined condition does not exist for at least one destination Remote UE, configuring a respective second SLRB configuration for L2 relaying for each of the at least one destination Remote UEs for which a respective first SLRB configuration satisfying the predetermined condition does not exist, and transmitting, to the source Remote UE, the respective second SLRB configurations and an indication to map, based on the respective second SLRB configurations, E2E bearers for each of the at least one destination Remote UE for which a respective first SLRB configuration satisfying the predetermined condition does not exist onto respective PC5 channels on the first hop without multiplexing.

[0205] In a forty-third example, there is provided the method of any of the thirty-fifth to forty-second examples, wherein the predetermined condition is that the first QoS for the first hop and the second QoS for the second hop are each greater than or equal to an E2E QoS.

[0206] In a forty-fourth example, there is provided the method of any of the thirty-fifth to forty-third examples, wherein the predetermined condition is that the combined packet delay is expected to be within the E2E packet delay limit.

[0207] In a forty-fifth example, there is provided the method of any of the thirty-fifth to forty-fourth examples, further comprising: including at least one source identifier (ID) identifying the at least one source Remote UE and at least one destination ID identifying the at least one destination Remote UE in a header of at least one packet carrying the multiplexed bearers or at least one packet transmitted without multiplexing; wherein the header is a sidelink relay adaptation protocol (SRAP) packet header.

[0208] In a forty-sixth example, there is provided the method of the forty-fifth example, wherein the at least one source ID and at least one destination ID are at least one first ID and at least one second ID obtained via the method of any of the twenty-fourth to thirty-fourth examples.

[0209] In a forty-seventh example, there is provided a method of a Relay user equipment (UE) in a UE-to-UE (U2U) sidelink relay network, the U2U sidelink relay network comprising the Relay UE, a first Remote UE, and a second Remote UE, wherein the method comprises: determining a single identifier (ID) identifying the first Remote UE and the second Remote UE; and transmitting the single ID to at least one of the first Remote UE and the second Remote UE.

[0210] In a forty-eighth example, there is provided the method of the forty-seventh example, wherein the single ID has fewer bits than the combined number of bits in the source Remote UE Layer 2 (L2) ID and the destination Remote UE L2 ID.

[0211] In a forty-ninth example, there is provided the method of the forty seventh or forty-eighth examples, wherein the method further comprises transmitting at least one packet to at least one of the first Remote UE and the second Remote UE, and including the single ID in a header of the at least one packet, wherein the header is a sidelink relay adaptation protocol (SRAP) packet header.

[0212] In a fiftieth example, there is provided the method of any of the forty-seventh to forty-ninth examples, wherein the method further comprises: multiplexing a plurality of bearers onto a channel; and including the single ID in a header of at least one packet carrying the multiplexed bearers via the channel, wherein the header is a sidelink relay adaptation protocol (SRAP) packet header.

[0213] In a fifty-first example, there is provided a method of a first Remote UE in a UE-to-UE (U2U) sidelink relay network, the UE-to-UE (U2U) sidelink relay network comprising a Relay UE, the first Remote UE, and a second Remote UE, wherein the method comprises: receiving, from the Relay UE, a single identifier (ID) identifying the first Remote UE and the second Remote UE.

[0214] In a fifty-second example, there is provided he method of the fifty-first example, wherein the method further comprises receiving at least one packet from the Relay UE, wherein the single ID is included in a header of the at least one packet, wherein the header is a sidelink relay adaptation protocol (SRAP) packet header

[0215] In a fifty-third example, there is provided the method of the fifty-first or fifty-second examples, wherein the method further comprises transmitting at least one packet to the Relay UE, and including the single ID in a header of the at least one packet, wherein the header is a sidelink relay adaptation protocol (SRAP) packet header

[0216] In a fifty-fourth example, there is provided the method of any of the fifty-first to fifty-third examples, wherein the method further comprises: multiplexing a plurality of bearers onto a channel; and including the single ID in a header of at least one packet carrying the multiplexed bearers via the channel, wherein the header is a sidelink relay adaptation protocol (SRAP) packet header.

[0217] In a fifty-fifth example, there is provided the method of any of the fifty-first to fifty-fourth examples, wherein the single ID has fewer bits than the combined number of bits in the source Remote UE Layer 2 (L2) ID and the destination Remote UE L2 ID.

[0218] In a fifty-sixth example, there is provided a first UE (e.g. a Remote UE or a Relay UE) configured to operate according to a method of any of the first to fifty-fifth examples.

[0219] In a fifty-seventh example, there is provided a second UE (e.g. e.g. a Remote UE or a Relay UE) configured to cooperate with a first UE of the fifty-sixth example according to a method of any of the first to fifty-fifth examples.

[0220] In a fifty-eighth example, there is provided a network or wireless communication system comprising a first UE according to the fifty-sixth example and a second UE according to the fifty-seventh example.

[0221] In a fifty-ninth example, there is provided a computer program comprising instructions which, when the program is executed by a computer or processor, cause the computer or processor to carry out a method according to any of the first to fifty-fifth examples.

[0222] In a sixtieth example; there is provided a computer or processor-readable data carrier having stored thereon a computer program according to the fifty-ninth example.

Claims

1.A method of a first remote user equipment (UE) in a UE-to-UE (U2U) sidelink relay network, the method comprising:determining a pair identifier (ID) identifying the first remote UE and a second remote UE at a sidelink relay adaptation protocol (SRAP) layer; andtransmitting, to at least one of the second remote UE and a relay UE, the pair ID identifying the first remote UE and the second remote UE.2.The method of claim 1, wherein the pair ID has fewer bits than a sum of a first UE Layer 2 (L2) ID of the first remote UE and a second UE L2 ID of the second remote UE.3.The method of claim 1,wherein the pair ID identifying the first remote UE and the second remote UE is included in a SRAP packet header.4.The method of claim 1, further comprising:multiplexing a plurality of bearers onto a channel; andconfiguring the pair ID including first ID for the first remote UE and second ID for the second remote UE in a SRAP packet header of at least one packet carrying the multiplexed bearers via the channel.5.The method of claim 1, wherein a first hop is between the first remote UE and the relay UE, and a second hop is between the relay UE and the second remote UE, andwherein a first QoS for the first hop and a second QoS for the second hop are each greater than or equal to an end-to-end (E2E) QoS.6.A method of a second remote user equipment (UE) in a UE-to-UE (U2U) sidelink relay network, the method comprising:receiving, from a first remote UE, a pair identifier (ID) identifying the first remote UE and a second remote UE at a sidelink relay adaptation protocol (SRAP) layer; andidentifying the pair ID identifying the first remote UE and the second remote UE.7.The method of claim 6, wherein the pair ID has fewer bits than a sum of a first UE Layer 2 (L2) ID of the first remote UE and a second UE L2 ID of the second remote UE.8.The method of claim 6, wherein the pair ID identifying the first remote UE and the second remote UE is included in a SRAP packet header.9.The method of claim 6, wherein a first hop is between the first remote UE and the relay UE, and a second hop is between the relay UE and the second remote UE, andwherein a first QoS for the first hop and a second QoS for the second hop are each greater than or equal to an end-to-end (E2E) QoS.10.A first remote user equipment (UE) in a UE-to-UE (U2U) sidelink relay network, the first remote UE comprising:a transceiver; anda controller coupled with the transceiver and configured to control to:determine a pair identifier (ID) identifying the first remote UE and a second remote UE at a sidelink relay adaptation protocol (SRAP) layer, andtransmit, to at least one of the second remote UE and a relay UE, the pair ID identifying the first remote UE and the second remote UE.11.The first remote UE of claim 10, wherein the pair ID has fewer bits than a sum of a first UE Layer 2 (L2) ID of the first remote UE and a second UE L2 ID of the second remote UE.12.The first remote UE of claim 10, wherein the pair ID identifying the first remote UE and the second remote UE is included in a SRAP packet header.13.The first remote UE of claim 10, wherein the controller is configured to control to:multiplex a plurality of bearers onto a channel, andconfigure the pair ID including first ID for the first remote UE and second ID for the second remote UE in a SRAP packet header of at least one packet carrying the multiplexed bearers via the channel.14.A second remote user equipment (UE) in a UE-to-UE (U2U) sidelink relay network, the second remote UE comprising:a transceiver; anda controller coupled with the transceiver and configured to control to:receive, from a first remote UE, a pair identifier (ID) identifying the first remote UE and a second remote UE at a sidelink relay adaptation protocol (SRAP) layer; andidentify the pair ID identifying the first remote UE and the second remote UE.15.The second remote UE of claim 14, wherein the pair ID has fewer bits than a sum of a first UE Layer 2 (L2) ID of the first remote UE and a second UE L2 ID of the second remote UE, andwherein the pair ID identifying the first remote UE and the second remote UE is included in a SRAP packet header.

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