WO2025233233A1

WO2025233233A1 - Methods and apparatus for managing multi-hop relaying

Info

Publication number: WO2025233233A1
Application number: PCT/EP2025/062026
Authority: WO
Inventors: Pascal Lagrange; Romain Guignard
Original assignee: Canon Europe Ltd; Canon Inc
Current assignee: Canon Europe Ltd; Canon Inc
Priority date: 2024-05-10
Filing date: 2025-05-01
Publication date: 2025-11-13
Anticipated expiration: 2026-11-10
Also published as: GB202406656D0; GB2640970A

Abstract

Methods and apparatus for managing multi-hop relaying in a wireless communication system including a plurality of User Equipment, UE, and a network including a base station are disclosed. The method at a UE of the plurality of UEs includes: sending a message indicating a UE supports multi-hop relaying between a remote UE and a target node in the wireless communication system, the multi-hop relaying involving at least two relay UEs. For example, the message is sent as part of a discovery procedure.

Description

METHODS AND APPARATUS FOR MANAGING MULTI-HOP RELAYING

Field of the Invention

The present invention generally relates to managing multi-hop relaying in a wireless communication system supporting relaying between a user equipment, UE, and a target (e.g. target node) in the wireless communication system. In particular, the present invention relates to managing and/or facilitating discovery or discovery communication (for multi-hop relaying) in a wireless communication system supporting relaying.

Background

The 3rd Generation Partnership Project (3GPP) has initiated the development of new radio access technology known as fifth-generation New Radio (5G NR) to respond to requirements related to very high reliability and very low latency. The 5G NR is not referred only to the enhancement of radio access technology but also to address a wide range of new services to be enabled by future mobile communication. Three distinctive categories of use cases are defined in NR from enhanced mobile broadband (eMBB), massive machine typing communication (mMTC) to Ultra-Reliable and Low Latency communication (URLLC).

A first version of Sidelink for 5G, or New Radio (NR) Sidelink, has been developed in 3GPP Release 16 as part of the 5G V2X Work Item, to support advanced vehicle-to-anything (V2X) scenarios and commercial applications and services in addition to complement former basic safety services. NR V2X addresses advanced driving use cases where vehicles are exchanging large amount of data while respecting a low latency requirement. NR Sidelink is designed to provide three basic transmission scenarios: broadcast, groupcast and unicast communications, while considering both out-of-coverage and in-network coverage deployment scenarios.

Based on the NR sidelink technology, 3 GPP introduced the sidelink-based relaying functionality as part of the 3GPP Release 17 framework, where a relay UE may provide User Plane (UP) and Control Plane (CP) data relaying between a set of served remote UEs and the network (UE-to-network, or U2N, relay) or between a source remote UE, or source UE, and a target remote UE, or target UE (UE-to-UE, or U2U relay).

The purpose of the Release 17 sidelink relaying functionality was to both extend sidelink / network coverage and improve power efficiency, while considering a wider range of applications and services, including V2X, Public Safety and commercial applications and services. Some of these new V2X scenarios require ultra-reliability and low latency (URLLC) performance, in order to meet high-speed and high-density constraints, while requiring some network coverage extension, which may be achieved through sidelink relaying.

This first version of the sidelink relaying functionality, as defined in the Release 17 specification, mainly aimed at supporting the UE-to-network (U2N) relaying with basic functionalities and limited features. For better support of the use cases requiring sidelink relay, further enhancements are necessary in order to introduce the potential solutions identified during the Rel-17 study item. The follow-up 3GPP Release 18 work item “NR Sidelink Relay (SLR) Enhancements” has addressed several solutions considered as enhancement areas needed in NR Sidelink Relay system for the V2X, public safety and commercial use cases.

In this respect, Release 18 introduced some new features aiming at supporting the UE- to-UE (U2U) relaying, while introducing some service continuity enhancements for the UE- to-network (U2N) relaying, while some further enhancements to support multi-hop relaying are foreseen for Release 19.

So far, the discovery protocols considered in 3GPP are intended for “direct” relaying and do not support multi-hop relaying scenarios where a UE would be connected to the Network (multi-hop U2N) or to another UE (multi-hop U2U) through more than one relay UE.

Therefore, it is desirable to provide solutions to manage or facilitate multi-hop relaying in a wireless communication system.

Summary

In accordance with an aspect of the present invention, there is provided a method for managing multi-hop relaying (e.g. a method for managing discovery or discovery communication) in a wireless communication system including a plurality of User Equipment, UE, and a network including a base station, the method at a UE of the plurality of UEs including: sending a message indicating a UE supports multi-hop relaying between a remote UE and a target node in the wireless communication system, the multi-hop relaying involving at least two relay UEs.

In an example, a method for managing or facilitating multi-hop relaying (e.g. managing discovery or discovery communication) in a wireless communication system including a plurality of User Equipment, UE, and a network including a base station, is disclosed. The method at a UE of the plurality of UEs includes sending a discovery solicitation message indicating a UE is willing to support multi-hop relaying between a remote UE and a target node in the wireless communication system, the multi-hop relaying involving at least two relay UEs, In an example, a method for managing or facilitating multi-hop relaying (e.g. managing discovery or discovery communication) in a wireless communication system including a plurality of User Equipment, UE, and a network including a base station, is disclosed. The method at a UE of the plurality of UEs includes sending, after a trigger, a message indicating a UE supports multi-hop relaying between a remote UE and a target node in the wireless communication system, the multi-hop relaying involving at least two relay UEs, wherein the trigger includes at least one of: reception of multi-hop information in a discovery message or expiry of a certain time period after receipt of multi-hop information in a discovery message. The trigger may alternatively or additionally include reception of a discovery message or expiry of a certain time period after receipt of a discovery message.

In accordance with an aspect of the present invention, there is provided an apparatus for a UE as recited in claim 35 of the accompanying claims.

By sending a message indicating the UE supports (or is willing to support) multi-hop relaying, multi-hop relaying information can be shared with UEs in the communication system and one or more multi-hop relay relaying paths can be identified: for example, for U2N relaying or U2U relaying based on the discovery information included in the message sent by the UE (and other UEs).

By indicating that it is supporting multi-hop relaying, the UE allows the relay UE to know whether it should forward or not the discovery messages issued by this UE, thus optimizing the use of the bandwidth used for performing discovery signalling.

The use of a hop count information in the multi-hop information can also allow optimizing the forwarding of the discovery messages in the network as a relay UE may stop forwarding discovery messages when the number of hops has reached a limit, or maximum number of hops supported by the UE.

The use of a hop count information in the multi-hop information would also allow optimizing the performance of the UE communications as well as the relay selection process that would result from the discovery process.

For instance, if a UE has some tight latency constraints, it may limit the number of hops to be considered in a multi-hop relaying scheme it is looking for. Similarly, a UE may further select a multi-hop relaying scheme having a low hop count in order to optimize the latency of its communications with a target device (either network or UE). In another aspect, a first relay UE may advantageously indicate to a UE that is it capable of performing U2N or U2U relaying with a target device (either network node, base station, or other UE device) in case it has received from a second relay UE some multi-hop information indicating that this second relay UE is capable of performing multi-hop relaying with said target device. This would allow optimizing the number of discovery messages to be sent and thus optimizing the network bandwidth.

This would also allow connecting some legacy UE devices which do not support multihop relaying (e.g., release 17 or release 18 devices) to a multi -hop capable relay UE, which would then act as a “proxy” and handle the multi-hop relaying scheme while behaving with the legacy UE as a legacy relay UE.

Also, considering the several tiggers discussed above ( and also in relation with Figure 11), such triggers would allow limiting the number of discovery messages sent over the network, therefore optimizing the use of the network bandwidth, while ensuring the efficiency of the considered multi-hop relaying scheme (only the relay UEs having satisfied link quality or being within an acceptable hop range may be considered).

Further example features of the invention are described in other independent and dependent claims.

In the following reference will be a UE and other UE. It will however be appreciated that instead the terms first UE and second UE could be used in place of UE and other UE.

Any feature in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. In particular, method aspects may be applied to apparatus/device/unit aspects, and vice versa.

Furthermore, features implemented in hardware may be implemented in software, and vice versa. Any reference to software and hardware features herein should be construed accordingly. For example, in accordance with other aspects of the invention, there are provided a computer program comprising instructions which, when the program is executed by one or more processing units, cause the one or more processing units to carry out the method of any aspect or example described above and a computer readable storage medium carrying the computer program.

Brief Description of the Drawings

Different aspects of the invention will now be described, by way of example only, and with reference to the following drawings in which: Figure l is a schematic diagram illustrating an example wireless communication system in which the present invention may be implemented according to one or more embodiments;

Figure 2 is a schematic diagram illustrating a typical 5G Proximity-based Services (ProSe) Relay reference architecture;

Figure 3 is a schematic diagram illustrating user plane stacks of some protocol layers involved in Sidelink relay operations for UE-to-network (U2N) based relaying;

Figure 4 is a block schematic diagram of an example wireless communication device in accordance with embodiments of the present invention;

Figures 5 to 7 are schematic and simplified diagrams illustrating examples of message flows for managing multi-hop discovery in a wireless communication system in accordance with one or more embodiments of the invention;

Figure 8 to 12 are simplified flowcharts of methods performed at a UE device in accordance with one or more embodiments of the present invention.

Detailed Description

Figure 1 represents an example of a wireless communication system 100 capable of supporting relaying between a User Equipment (UE) and a base station, or between two User Equipment (UE) and shows a relay arrangement or system (or network) including a plurality of nodes including one or more relay nodes (e.g., relay User Equipment (UE)) serving one or more remote User Equipment (UE).

In the following description reference is made to a wireless communication system 100 capable of supporting Sidelink Relay where a path between a remote UE and a base station includes a sidelink connection (also known as a PC5 link) between the remote UE and a relay UE and a network connection (also known as a Uu link) between a relay UE and the base station. However, it is not intended that the present invention is limited to a PC5 link between the remote UE and the relay UE and could apply to relaying configurations where the link between the remote UE and the relay UE is via another type of connection (e.g., a non-3GPP connection), such as a WiFi or Bluetooth.

With reference to Figure 1, UE node 111 is served by network node 101 and may operate as a relay UE node relaying data between one of the UE nodes 112, 121 (referred to as remote UE nodes) and the network node 101, hence performing UE-to-network (U2N) relaying. In its turn, UE 112 may operate as a relay UE node relaying data between the UE node 113 and the network node 101 through the other relay node 111. Some multi -hop UE-to-Network relaying (multi -hop U2N) may thus be performed between network node 101 and UE 113 through relay UEs 111 and 112.

In the example of the figure 1, the UE 111 may act as a remote UE and as a relay UE. In an example where the network node 101 is part of a cellular network, the relay UE I l l is served by a cell 101a controlled by the network node 101.

UE node 131 is served by network node 101 and may operate as a relay UE node relaying data between the UE node 132 (referred to as a remote UE node) and the network node 101, hence performing UE-to-network (U2N) relaying. In its turn, UE 132 may operate as a relay UE node relaying data between the UE node 133 or 134 and the network node 101 through the other relay node 131. Some multi -hop UE-to-Network relaying (multi -hop U2N) may thus be performed between network node 101 and UEs 133 or 134 through relay UEs 131 and 132.

In an example where the network node 101 is part of a cellular network, the relay UE 131 is served by cell 101a controlled by the network node 101.

In an example where the network node 101 is part of a cellular network, the relay UE 131 and 132 are served by a cell 101a controlled by the network node 101, while remote UE 133 and 134 are out of coverage (OOC) as they are not served by any cell.

UE node 121 is served by network node 101 and may operate as a relay UE node relaying data between the UE nodes 122 (referred to as remote UE node) and the network node 101, hence performing UE-to-network (U2N) relaying. In its turn, UE 122 may operate as a relay UE node relaying between the UE node 123 and the network node 101 through the other relay node 121. In the example of the figure 1, the UE 121 may act as a remote UE and as a relay UE. In its turn, UE 123 may operate as a relay UE node relaying between the UE node 124 and the network node 101 through the other relay nodes 121 and 122. Some multi-hop UE-to- Network relaying (multi -hop U2N) may thus be performed between network node 101 and UE 123 or 124 through relay UEs 122 and 121 or through relay UEs 123, 122 and 121.

In an example where the network node 101 is part of a cellular network, the relay UE 121, 122 and 123 are served by a cell 101a controlled by the network node 101, while remote UE 124 is out of coverage (OOC) as it is not served by any cell.

UE node 151 is served by network node 102 and may operate as a relay UE node relaying data between one of the UE nodes 152, 153, 141 (referred to as remote UE nodes) and the network node 102, hence performing UE-to-network (U2N) relaying. In its turn, UE 152 may operate as a relay UE node relaying between the UE node 154 and the network node 102 through the other relay node 151. Some multi -hop UE-to-Network relaying (multi -hop U2N) may thus be performed between network node 102 and UE 154 through relay UEs 152, and

151 (and 141).

In the example of the figure 1, the UE 141 may act as a remote UE and/or as a relay UE for UE 151.

In an example where the network node 102 is part of a cellular network, the UEs 151,

152 and 141 are served by a cell 102a controlled by the network node 102, while remote UEs

153 and 154 are out of coverage (OOC) as they are not served by any cell.

The network nodes 101 and 102 may be base stations of a wireless network or network, such as a fifth-generation (5G) New Radio (NR) network or a Long-Term Evolution (LTE) network. Figure 1 only shows the base stations of the wireless network for clarity. Base stations 101 and 102 are interconnected such as through a wired link infrastructure 180, preferably based on optical fiber or any other wired means. As shown in figure 1, the base stations are also connected to a core network 170 through a wired link infrastructure 190, preferably based on optical fiber or any other wired means. For a 5GNR network, the network nodes 101, 102, are referred to as gNBs and are part of the NG-RAN.

UEs 161, 162, 163 and 164 are not served by any network node. Still, UE node 162 may operate as a relay UE node relaying data between the UE node 161 (referred to as a remote UE node) and the UE node 163, hence performing UE-to-UE (U2U) relaying. In its turn, UE 163 may operate as a relay UE node relaying data between the UE node 164 and the UE node 161 through the other relay node 162. Some multi -hop UE-to-UE relaying (multi -hop U2U) may thus be performed between UE 161 and UE 164 through relay UEs 162 and 163.

Similarly, some multi-hop UE-to-UE relaying (multi-hop U2U) may be performed between UE 121 and UE 124 through relay UEs 122 and 123.

In general, the wireless communication system 100 is capable of supporting relaying and multi-hop communication (e.g. multi-hop relaying) between a remote UE node (or remote UE) and a target or target node. The target node may be a base station of the network in the case of U2N relaying or another remote UE in the case of U2U relaying.

Some examples of UEs include smartphones/tablets (such as UEs 121, 122, 123, 141 and 161), XR headsets (such as UEs 111, 112, 113), cameras (such as UEs 124 and 153), fixed video cameras (such as UEs 131, 132, 133), mobile/wearable video cameras (such as UEs 134, 162, 163, 164, 152 and 154) or Unmanned Aerial Vehicle (UAV) 151, which may also embed one or more video cameras. In general, the UE may be any portable or handheld or mobile telephone, a smartphone, a tablet, a portable or fixed computer, fixed or mobile camera, portable television, other smart devices or other similar wireless communication device. In the following description, the term UE will be used and it is not intended to limit the description to any particular type of wireless communication device.

In the following, a relay UE node will also be referred to as a relay UE, a remote UE node will also be referred to as a remote UE and a network node will be referred to as a base station or as a gNB. It will however be appreciated that the terms first and second UEs may be used instead of remote UE and relay UE. Although in the following description, embodiments and examples of embodiments of the present invention will be described with respect to a 5G NR network, it will be appreciated that it is not intended that the present invention is limited to 5G NR systems and may be used in any wireless communication systems supporting sidelink (or peer to peer) relay communications and multi-hop relaying.

In an example shown in Figure 1, in a UE-to-Network (or U2N) scenario with the UE 111 (or UE 131) operating as UE-to-Network relay UE, the UE-to-Network relay UE 111 (or relay UE131) connects the UEs 112 and 121 (or UE 132), operating as remote UEs, to the gNB 101 (or gNB 102). The remote UE 112 is connected to the relay UE 111 via or through a sidelink 112a which may be referred to as a PC5 hop or link or connection or interface 112a. Similarly, remote UE 121 and remote UE 132 have PC5 hops, or links or connections or interfaces 121b, and 132b respectively with the relay UE 111 and relay UE 131. A Uu hop or link or connection or interface I l la connects the relay UE 111 to the gNB 101, while a Uu hop or link or connection or interface 131a and 131b respectively connect the relay UE 131 to the gNB 101 and the UE 131 to the gNB 102. PC5 connections are used for the relayed traffic of the remote UEs (112, 113, 121, and 132) and the non-relayed traffic specific to the relay UE 111, 131, i.e. for the direct communications between relay UE 111, 131 and the other remote UEs (112, 121 and 132). Therefore, the remote UE 112 is connected to the gNB 101 through the relay UE 111 with a PC5 hop 112a and a Uu hop I l la. For uplink communication, the remote UE 112 is the source node (or transmitter node for transmitting data) and the gNB 101 is the destination or target node (or receiver node for receiving data) for a sidelink relay connection established between the remote UE 112 and the gNB 101 with a PC5 hop 112a and a second Uu hop I l la and for downlink communication, the remote UE 112 is the destination or target node (or receiver node) and the gNB 101 is the source node (or transmitter node). Similarly, the remote UE 132 is connected to the gNB 102 through the relay UE 131 with a PC5 hop 132b and a Uu hop 131b. The remote UE 113 for its part is connected to the gNB 101 through the relay UE 112 with a 1^st PC5 hop 113a and then through the relay UE 111 with a 2^nd PC5 hop 112a and a Uu hop I l la. It will be appreciated that the terms first and second could be used in place of source and target. At some point, the gNB 101 may decide to setup a multi-path to the UE 132. For example, to maintain the QoS despite an increase of the applicative traffic to transmit/receive from/to the UE 132. Then, based on some information such as measurement information received from the different UEs (relay, remote) in, for example, measurement reports and/or measurements made by the gNB 101 itself, the source gNB 101 may decide to add an additional path either a direct path (link 132b) or a new indirect path through the relay UE 111 (links 132a and I l la) so as to set up a multi-path between the remote UE 132 and the network.

At some other point, the gNB 101, acting as a source gNB, may decide to hand over the relay UE 131 to the gNB 102, which would then act as a target gNB. For example, in the case where the radio conditions in the serving cell 101a controlled by the source gNB 101 deteriorate such that the radio conditions in the target cell 102a controlled by the target gNB 102 are better than the serving cell 101a, the source gNB 101 may decide to handover the relay UE 131 to the target gNB 102. In such a case, the relay UE 131 would detach from the source gNB 101, thereby releasing the Uu link 131a to further connect to the target gNB 102 through Uu link 131b established as part of a re-establishment procedure.

As mentioned earlier, the remote and relay UEs are attached to the core network 170 through their serving gNB (101 or 102 in figure 1). Figure 2 represents a typical 5G Proximitybased Services (ProSe) Relay reference architecture and shows the different connections between the core network entities of the 5G core (5GC) such as the Access and Mobility Management Function (AMF) entity, the Session Management Function (SMF) entity and the User Plane Function (UPF) entity, the UEs (5G ProSe Remote and 5G ProSe Relay) and the NG-RAN (i.e. base station or gNB). The 5G ProSe Remote UE and 5G ProSe Relay may be served by the same or different PLMNs (Public Land Mobile Network). If the serving PLMNs of the 5G Remote UE and the 5G ProSe Relay are different then the NG-RAN is shared by the serving PLMNs.

In order to set up a relayed traffic between a first node (remote UE) and a second node (gNB or remote UE), a Sidelink relay architecture may be used, based on the 3GPP TR 38.836. The user plane architecture or protocol stack is shown in Figure 3 and represents the Sidelink Relay adaptation layer called SRAP that is introduced between the PDCP layer and the RLC layer at the extreme nodes and above the RLC layer in the relay UE. This architecture was first documented in the TR 38.836 and finally refined in 3GPP TS 38.300 while the SRAP layer is defined in 3GPP TS 38.351.

This architecture shown in Figure 3 shows the Sidelink relay architecture 300 for the multi-hop UE-to-Network relay scenario. As shown in Figure 3 illustrating a multi-hop UE-to- Network relay scenario, a remote UE 301, such as remote UE 113 of figure 1, has a PC5 SRAP layer or entity 311 between its Uu PDCP layer 312 and its PC5 RLC layer 313. Similarly, the gNB 304, such as gNB 101 of figure 1, has a Uu SRAP layer or entity 341 between its Uu PDCP layer 342 and its Uu RLC layer 343.

As shown in Figure 3 related to a multi-hop UE-to-Network relay scenario, at the relay UE 303, such as relay UE 111, there are two SRAP layers to interface with the PC5 hop 112a and the Uu hop I l la: the PC5 SRAP layer or entity 331 is connected to the PC5 SRAP 322 of a second relay UE 302 such as relay UE 112 through the PC 5 hop 112a; and the Uu SRAP layer or entity 332 is connected to the Uu SRAP layer 341 at the gNB side 101 through the Uu link I l la. The second relay UE 302 such as relay UE 112 has also two SRAP layers to interface with the PC5 hop 112a and the PC5 hop 113a: the PC5 SRAP layer or entity 322 is connected to the PC5 SRAP 331 of a first relay UE 303 such as relay UE 111 through the PC5 hop 112a; and the PC5 SRAP layer or entity 321 is connected to the PC5 SRAP layer 311 at the remote UE 303, such as remote UE 113 through the PC 5 link 113a.

A remote UE 301/113 establishes End-to-End radio bearers 305 with the gNB 304/101. These radio bearers could be a Signalling Radio Bearer SRB or Data Radio Bearer DRB. Figure 3 shows an E2E Uu DRB/SRB 305 between the remote UE 113 and the gNB 101 by way of example.

The PC5 SRAP layer 331 of the UE-to-Network relay UE 303/111 receives data or packets (traffic data or signalling) over or via ingress PC5 Relay RLC channels 352 through the PC5-RLC layer from remote UE 113 (at PC5 hop 112a) through a UE-to-UE relay UE 302/112 in an uplink direction and transmits the packets to the Uu SRAP entity 332 of the same relay UE 303/111.

The Uu SRAP 332 entity will map the corresponding ingress PC5 Relay RLC channels 352 to egress Uu Relay RLC channels 353a and/or 353b at Uu link 11 la. Thus, a mapping table is required for uplink and it is configured by gNB 101 at the Uu SRAP entity 332 of the relay UE 303/111.

The mapping table takes at its input an identifier of the remote UE 113 (e.g. L2-ID), an identifier of the E2E radio bearer 305 (e.g. the E2E Uu DRB ID) and an identifier of the ingress PC5 Relay RLC channel (or bearer) 352 and identifies the egress Uu Relay RLC bearer ID where the E2E radio bearers are mapped. For example, the UE E2E bearer ID and remote UE ID can be obtained from the header of a data packet received at the Uu SRAP entity 332 via the PC5-SRAP entity 331. An example of an entry for an uplink mapping table with one entry configured at the Uu SRAP entity 332 is shown in Table 1 below. It will be appreciated that the mapping table will be configured so that it has an entry for each remote UE connected to the relay UE 303/111.

Table 1

At the Uu side or link I l la, different radio bearers of the same remote UE or different remote UEs can be subject to N: 1 mapping and data multiplexing over Uu RLC channels 353a and 353b.

In the downlink direction, data or packets transmitted from gNB 101 arrive at the relay UE 303/111 through the Uu link I l la. The Uu SRAP layer 332 of the UE-to-Network relay UE 111 receives data or packets (traffic data or signalling) over or via ingress Uu Relay RLC channels 353a and 353b through the Uu-RLC layer 343 from gNB 101 and transmits the packet to the PC5 SRAP entity 331 of the same relay UE 111. Those ingress Uu Relay RLC channels 353a and 353b will be mapped at the PC5 SRAP entity 331 of the relay UE 111 to the egress PC5 Relay RLC channels 352 at PC5 hop 112a. Thus, a mapping table is required for downlink and it is configured by the gNB 101 at PC5 SRAP entity 331 of the relay UE 111. The mapping table requires at its input the remote UE 113 L2-ID, the End-to-End radio bearer 305 ID and the ingress Uu Relay RLC channel (or bearer) 353a and 353b ID and identifies the egress PC5 Relay RLC channels (or bearer) 352 ID of the PC5 hop 112a. The End-to-End Radio bearer 305 is then mapped at the PC5 hop 112a to the egress PC5 Relay RLC channels 352. For example, the UE E2E bearer ID and remote UE ID can be obtained from the header of a packet received at the PC5 SRAP entity 331 via the Uu SRAP entity 332. An example of a downlink mapping table with one entry configured at the PC5 SRAP entity 331 is shown in Table 2 below. It will be appreciated that the mapping table will be configured so that it has an entry for each remote UE connected to the relay UE 303/111.

Table 2 Similarly, the UE-to-UE relay UE 302/112 maps the ingress PC5 RLC channel 351 to the egress PC5 RLC channel 352 and vice versa. Thereby, mapping tables is also required to determine the egress RLC channel based on the ingress RLC channel the Bearer ID and the UE ID. The mapping tables at the UE-to-UE relay UE 302/112 may be configured by the network.

It is noted that in case of multi-hop UE-to-Network, the mapping table at the UE-to- Network relay may map the ingress Uu Relay RLC channel to the egress End-to-End PC5 RLC channel used by the UE-to-Network relay UE 303/111 to connect to the remote UE 301/113 through the UE-to-UE relay UE 302/112.

As mentioned in 3GPP TS 38.351, each SRAP entity has a transmitting part and a receiving part. Across the PC5 interface 113a and 112a, the transmitting part of the PC5 SRAP entity 311 at the remote UE 301/113 and the transmitting part of the PC 5 SRAP entity 322 at the relay UE 302/112 has a corresponding receiving part respectively at PC5 SRAP entity 321 at the UE-to-UE relay UE 302/112 and at PC 5 SRAP entity 331 at the UE-to-Network Relay UE 303/111, and vice-versa. Across the Uu interface I l la, the transmitting part of the Uu SRAP entity 332 at the UE-to-Network Relay UE 303/111 has a corresponding receiving part at Uu SRAP entity 341 at the gNB 304/101, and vice-versa. To summarize, the transmitting part of each SRAP entity at the UE-to-Network Relay UE 111 receives the data packet with its SRAP header from its corresponding receiving part (receiving part of the SRAP entity 332 forwards the data to the transmitting part of the SRAP entity 331 and vice-versa). The transmitting part of each SRAP entity owns a mapping table configured by the gNB 101 which allows the identification of the egress RLC channel (at Uu or PC5 link) based on the ingress RLC channel where the data packet is received and the UE and Bearer IDs carried in the SRAP header. Specific mapping rules may be applied for SRB0 and SRB1 as specified in TS38.351 and TS38.331.

In the case of the multi-path with one indirect and one direct path, the remote UE 113 and the gNB 101 may communicate with each other through both paths. Thereby, each node has two protocol stacks: one for the indirect path such as described above and one for the direct path. The split between the direct and/or the indirect path is performed at the PDCP layer of each node. For the direct path, in the downlink direction, data or packets transmitted from gNB 101 through the direct path arrive at the remote UE 113 via ingress Uu Direct Path RLC channel 354 of the Uu link 113b. On the other hand, in the uplink direction, data or packets transmitted from the remote UE 113 through the direct path arrive at the gNB 101 via ingress Uu Direct path RLC channel 354 of the Uu link 113b. Figure 4 shows a schematic representation of an example communication device or station, in accordance with one or more example embodiments of the present disclosure.

The communication device 400 may be a device such as a micro-computer, a workstation or a portable or mobile device. The communication device 400 comprises a communication bus 413 to which there are preferably connected: a central processing unit 411, such as a microprocessor, denoted CPU; memory for storing data and computer programs containing instructions for the operation of the communication device 400. The computer programs may contain a number of different program elements or sub-routines containing instructions for a variety of operations and for implementing the invention. For example, the program elements include at least one element for managing multi-path or multi-hop communication as discussed above. The at least one element when executed by the central processing unit 411 configure one or more processing units (e.g. functioning as or part of the CPU 411) to perform the method(s) as described above.

The communication device 400 may further comprise at least one communication interface 402 connected to the radio communication network 403 over which digital data packets or frames or control frames are transmitted, for example a 5G NR wireless communication network. The frames are written from a FIFO sending memory in RAM 412 to the communication interface 402 for transmission or are read from the communication interface 402 for reception and writing into a FIFO receiving memory in RAM 412 under the control of a software application running in the CPU 411.

Each of a UE and base station may comprise such a communication device 400.

The central processing unit 411 may be a single processing unit or processor or may comprise two or more processing units or processors carrying out the processing required for the operation of the communication device 400. The number of processing units or processors and the allocation of processing functions to the processing unit(s) is a matter of design choice for a skilled person.

The memory may include: a read only memory 407, denoted ROM, for storing computer programs for implementing methods according to embodiments of the invention; a random-access memory 412, denoted RAM, for storing the executable code of methods according to embodiments of the invention as well as the registers adapted to record variables and parameters necessary for implementing methods according to embodiments of the invention. Optionally, the communication device 400 may also include the following components: a data storage means 404 such as a hard disk, for storing computer programs for implementing methods according to one or more embodiments of the invention; a disk drive 405 for a disk 406, the disk drive being adapted to read data from the disk 406 or to write data onto said disk; a screen 409 for displaying decoded data and/or serving as a graphical interface with the user, by means of a keyboard 410 or any other user input means.

Preferably the communication bus 413 provides communication and interoperability between the various elements included in the communication device 400 or connected to it. The representation of the bus 413 is not limiting and in particular, the central processing unit is operable to communicate instructions to any element of the communication device 400 directly or by means of another element of the communication device 400.

The disk 406 may optionally be replaced by any information medium such as for example a compact disk (CD-ROM), rewritable or not, a ZIP disk, a USB key or a memory card and, in general terms, by an information storage means that can be read by a microcomputer or by a microprocessor, integrated or not into the apparatus, possibly removable and adapted to store one or more programs whose execution enables a method according to embodiments of the invention to be implemented.

The executable code may optionally be stored either in read only memory 407, on the hard disk 404 or on a removable digital medium such as for example a disk 406 as described previously. According to an optional variant, the executable code of the programs can be received by means of the communication network 403, via the communication interface 402, in order to be stored in one of the storage means of the communication device 400, such as the hard disk 404, before being executed.

The central processing unit 411 is preferably adapted to control and direct the execution of the instructions or portions of software code of the program or programs according to the invention, which instructions are stored in one of the aforementioned storage means. On powering up, the program or programs that are stored in a non-volatile memory, for example on the hard disk 404 or in the read only memory 407, are transferred into the random-access memory 412, which then contains the executable code of the program or programs, as well as registers for storing the variables and parameters necessary for implementing the invention.

In an example implementation, the communication device may be or may include an apparatus comprising one or more processing units or processors for performing or implementing the methods in accordance with one or more embodiments of the invention. In other words, the apparatus is capable of performing one or more functions of the communication device including performing the methods in accordance with one or more embodiments of the invention by means of the one or more processing units. For example, the one or more processing units uses software to implement the one or more embodiments of the invention as described above with reference to the central processing unit 411 of figure 4. Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, a CPU of a microcontroller Unit (MCU), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other equivalent integrated (e.g. on an Integrated Circuit) or discrete logic circuitry. In an embodiment, the apparatus is a programmable apparatus which uses software to implement the invention. However, alternatively, the one or more processing units for performing or implementing the methods in accordance with embodiments of the present invention may be implemented in hardware: for example, in the form of an Application Specific Integrated Circuit or ASIC or other hardware comprising logic element (s). In such a case, logic units or logic elements or means are configured to perform the steps of the method(s) in accordance with the present invention described above. Accordingly, the term “processing unit” as used herein may refer to any of the foregoing structure or any other structure suitable for implementation of the techniques described herein.

Referring now to figure 12 which is a flow chart showing steps of a method 1200 for managing or facilitating multi-hop relaying or a method for managing discovery/discovery communication in a wireless communication system. The wireless communication system includes a plurality of User Equipment, UE, and a network including a base station. The method is performed at a UE (e.g. a first UE) of the plurality of UEs. The wireless communication system may be, for example, the wireless communication system 100 of Figure 1. With respect to the example shown in Figure 1, the UE may be UE 111 and the base station may be base station 101 (also referred to as gNB 101). The method 1200 as shown in and described with respect to figure 12 may be performed by software elements and/or hardware elements. Thus, for example, the method as shown in and described with respect to figure 12 may be performed by an apparatus for the UE comprising one or more processing units configured to carry out the method. The UE may be implemented in a communication device 400 as shown in and described with reference to figure 4 with the method as shown in and described with respect to figure 12 being performed by one or more processing units, such as the central processing unit 411. A hop is a link or connection between two UEs in which case the hop is a PC5 hop or between a UE and a base station in which case the hop is a Uu hop.

Briefly, at step 1201, the UE 111 sends a message indicating a UE supports multi -hop relaying (e.g. the UE has multi-hop capability or connectivity) between a remote UE and a target node in the wireless communication system, where the multi-hop relaying involves or includes at least two relay UEs. The UE indicated in the message as supporting multi-hop relaying could be the UE 111 (first UE 111) and/or one or more other UEs (such as one or more second UEs such as one or more of UE 112, 113, 132, 121 of figure 1). The message may be a discovery message or a message indicating the UE is a Release 19 UE or a UE that is compatible with Release 19 where a Release 19 UE or being compatible with Release 19 implies that the UE supports multi-hop relaying.

In the case where the message is sent in a legacy message, only a Release 19 UE and a Release 19 compatible UE on receipt of the message will identify that the message indicates the UE can support multi-hop relaying. Otherwise, on receipt of such a legacy message by a legacy UE, the legacy UE will identify the UE as legacy UE.

In another case where the message is sent in a new message and not a legacy message, such a message may only be sent by a UE capable of supporting multi-hop relaying.

In an example where the message is a discovery message, the discovery message may be a discovery announcement message, such as the DISCOVERY ANNOUNCEMENT message 640a, 640b, 630a, 630b or 620, as discussed with reference to figures 6, 8, or discovery response message, such as the DISCOVERY RESPONSE message 714a, 714b, 715, 716a, 716b or 716c as discussed with reference to figures 7, 10, or or a discovery solicitation message, such as the DISCOVERY SOLICITATION message 711, 712a, 712b, or 713 as discussed with reference to figures 7, 9.

The discovery message may include discovery information associated with the UE 111 (e.g. the UE sending the discovery message) for indicating the capability of the UE 111 to perform at least one of UE-to-Network, U2N, relaying with multi -hop and UE-to-UE, U2U, relaying with multi-hop.

In an example, the discovery message includes discovery information associated with the UE 111 (e.g. the UE sending the discovery message) including at least one of: relaying connectivity information for indicating the capability of the UE 111 to perform or provide at least one of UE-to-Network, U2N, relaying and UE-to-UE, U2U, relaying; multi-hop information for indicating whether the relaying indicated by the relaying connectivity information is associated with multi -hop relaying. For example, the multi -hop information may indicate the relaying indicated by the relaying connectivity information is associated with multi-hop relaying (e.g. a multi-hop scheme) such as U2N relaying or U2U relaying or the multi-hop information may indicate the relaying indicated by the relaying connectivity information is not associated with multi-hop relaying (e.g. a multi-hop scheme) such as U2N relaying or U2U relaying. The multi-hop information may further include information relating to one or more characteristics of such multi-hop relaying (e.g. a multi-hop scheme) if there are any.

The discovery message may include a first field indicating the capability of the UE 111 to perform U2N or U2U relaying (as the relaying connectivity information) and a second field indicating the U2N or U2U relaying indicated by the relaying connectivity information of the first field is associated with multi-hop relaying. In such a case, if the UE 111 does not have the capability to perform U2N or U2U, the first field may not be included in the message (and so the second field is also not included). If the UE 111 does not support multi-hop relaying the second field may not be included. Alternatively, the discovery message may include one field indicating both the relaying connectivity information and the multi-hop information. Other means for providing the relaying connectivity information and multi-hop information in the discovery message may be used: such as configuring fields with certain values.

The relaying connectivity information is also referred to in the description as relaying capability information (e.g. with respect to the discovery announcement message). The relaying connectivity information is also referred to in the description as relaying connection information (e.g. with respect to a discovery response message sent in response to a discovery solicitation message and with respect to a discovery solicitation message).

The discovery information is also referred to in the description as relaying discovery information or UE relaying discovery information (e.g. with respect to the discovery announcement message). The discovery information is also referred to in the description as UE discovery information or discovery response information or UE discovery response information (e.g. with respect to a discovery response message sent in response to a discovery solicitation message and with respect to a discovery solicitation message).

Discovery response information and/or discovery solicitation information may be included in a discovery announcement message.

In an example, the relaying connectivity information may include U2U connection information for indicating the UE 111 is capable of U2U relaying to a specific target UE and identification information, such as a UE identifier (e.g. L2-ID), for identifying the specific target UE. In the case of the UE 111, the specific target could be UE 113. The relaying connectivity information may include U2N connection information for indicating the UE 111 is capable of U2N relaying to a specific target base station and identification information, such as an identifier of the base station or cell controlled by the base station, for identifying the specific target base station. In the case of the UE 111, the specific target could be base station or gNB 101.

The discovery information may further include at least one of: identification information, such as a L2-ID or other UE identifier, for identifying the UE 111 with/for which the discovery information is associated; RRC state information for indicating a RRC state of the UE 111, the RRC state being one of idle, inactive, connected; relay UE information, such as the relay UE list discussed below with respect to figures 6 and 8, for identifying one or more other UEs (e.g. one or more of UE 112, 113, 132, 121) of the plurality of UEs in the case where the UE has received discovery information from each of the one or more other UEs before sending the discovery message including the discovery information associated with the UE; neighbour UE information (e.g. neighbour UE list as discussed below with reference to figures 6 and 8) for identifying one or more UEs in proximity to (e.g. neighbouring) the UE and with or for which the UE is capable of performing U2U relaying.

In one example, the relay UE information (also referred to as relay UE list or relay UE list information) included or carried in DISCOVERY ANNOUNCEMENT message 630a, 630b or 620 may include at least one UE relaying discovery information, as discussed in relation to message 640a or 640b

The UE 111 may consider a UE, such as UE 112, 121, 132 as a neighbour UE and add it to the neighbour UE information if the link quality or signal quality of its PC5 link with such a UE (e.g. quality of links 112a, 121b, 132a) meets a certain condition. The certain condition may be a predefined quality range which may be configured by the gNB serving the UE 111. In one example, the PC5 quality range is defined by a minimum or low threshold and/or a maximum or high threshold. The thresholds may relate to RSRP (Reference Signal Received Power), SL-RSRP (Sidelink Reference Signal Received Power) or SD-RSRP (Sidelink Discovery Reference Signal Received Power) threshold.

In an example, the relay UE information includes for each UE of the one or more other UEs (e.g. one or more of UE 112, 113, 132, 121) at least one of: identification information (e.g. L2-ID) for identifying the other UE; RRC state information for indicating a RRC state of the other UE; multi-hop information indicating whether the other UE supports multi-hop relaying; hop information indicating the number of hops (e.g. hop count as discussed below) between the other UE and a target node and/or the UE 111; information indicating whether the other UE is in coverage of a base station (e.g. whether the other UE 112, 113, 132, 121) is located in cell lOla of gNB 101).

In an example, the neighbour UE information includes for each UE of the one or more UEs (e.g. one or more of UE 112, 113, 132, 121) in proximity to the UE 111 at least one of: identification information (e.g. L2-ID) for identifying the neighbouring UE; RRC state information for indicating a RRC state of the neighbouring UE; multi-hop information indicating whether the neighbouring UE supports multi-hop relaying; hop information indicating the number of hops (e.g. hop count as discussed below) between the neighbouring UE and a target node and/or the UE 111; information indicating whether the neighbouring UE is in coverage of a base station (e.g. whether the neighbouring UE is a U2N relay UE).

In an example and as discussed above and below, the discovery message includes discovery information associated with the UE 111, which may be referred to as a first UE, and/or discovery information associated with at least one other UE (e.g. UE 112, 113, 132, 121) of the plurality of UEs, which at least one other UE may be referred to as a second UE. As with the discovery information for the UE 111, the discovery information associated with at least one other UE may indicate for each other UE of the at least one other UE, the capability of the other UE to perform at least one of UE-to-Network, U2N, relaying with multi -hop and UE-to-UE, U2U, relaying with multi -hop. As with the discovery information for the UE 111, the discovery information associated with at least one other UE may include for each other UE of the at least one other UE at least one of: relaying connectivity information for indicating the capability of the other UE to perform at least one of UE-to-Network, U2N, relaying and UE- to-UE, U2U, relaying; multi-hop information for indicating whether the relaying indicated by the relaying connectivity information is associated with multi-hop relaying. The description of the discovery information, relaying connectivity information, multi-hop information provided above for UE 111 applies for the discovery information for each of the at least one other UEs.

For example, the multi -hop information may indicate the relaying indicated by the relaying connectivity information is associated with multi-hop relaying (e.g. a multi-hop scheme) such as U2N relaying or U2U relaying or the multi-hop information may indicate the relaying indicated by the relaying connectivity information is not associated with multi-hop relaying (e.g. a multi-hop scheme) such as U2N relaying or U2U relaying. The multi-hop information may further include information relating to one or more characteristics of such multi-hop relaying (e.g. a multi-hop scheme) if there are any.

The multi-hop information (e.g. included in the discovery information) may include at least one of: relaying information, such as local relaying information or multi -hop relaying information as described with reference to figure 6, for indicating to which UE the relaying connectivity information is associated hop information for indicating the number of hops (e.g. hop count) between the UE and the UE to which the relaying connectivity information is associated; hop information for indicating the number of hops (e.g. hop count) between the UE to which the relaying connectivity information is associated and the UE to which the discovery message is to be sent; prohibit information for indicating to another UE receiving the discovery information that the other UE cannot forward the discovery information to any other UE.

The method at the UE 111 (or first UE) may further comprise receiving discovery information associated with at least one other UE (or second UEs) of the plurality of UEs. For example, UE 111 may receive discovery information, such as that described above, from one or more of UEs 112, 113, 121, 122, 132, etc.). The UE 111 may then update the received discovery information to provide updated discovery information and the discovery message sent by the UE 111 may include the updated discovery information. The UE 111 may update at least part or some of the received discovery information. For example, when the received discovery information includes hop information, the UE 111 may update the number of hops included in the hop information (e.g. update by incrementing or decrementing the hop count to account for the hop to or through the UE 111). Additionally or alternatively, the UE 111 may update the received discovery information by adding discovery information associated with the UE to the received discovery information or updated received discovery information to provide the updated discovery information. Updating, by the UE 111, the discovery information to be included in the discovery message sent by the UE I l l is discussed in more detail below.

As discussed above, the discovery message sent by the UE 111 may be a discovery announcement message or a discovery response message. In the example, where the discovery message sent by the UE 111 is a discovery response message (e.g. in response to a discovery solicitation message), the multi-hop information includes at least one of: hop information indicating the number of hops (e.g. hop count) between the UE to which the relaying connectivity information is associated and a target node (which may be another UE or a base station); path identification information for identifying a multi-hop relaying path (e.g. a path identifier for uniquely identifying a multi-hop relay path between a remote UE and the target node - in the case where there are multiple multi-hop relaying paths, the path identification information includes a path identifier for each path); relay routing information, such as routing table information as discussed below with reference to figures 7 and 10, for identifying one or more other UEs which are involved or included in the multi-hop relaying path (e.g. including the UE 111). In another example, the discovery message sent by the UE 111 may be a discovery solicitation message, such as the DISCOVERY SOLICITATION message 711, 712a, 712b, or 713 as discussed with reference to figures 7 and 9, including discovery solicitation information associated with the UE 111. For a discovery solicitation message, the discovery solicitation information is also referred to in the description as UE discovery solicitation information.

The discovery solicitation information associated with the UE 111 may include at least one of: relaying connection information for indicating the UE 111 is seeking at least one of UE-to-Network, U2N, relaying and UE-to-UE, U2U, relaying; multi-hop information for indicating the UE 111 is supporting (e.g. willing to support) multi-hop relaying. For example, the multi-hop information may indicate the UE I l l is supporting (e.g. willing to support) multihop relaying (e.g. a multi-hop scheme) such as U2N relaying or U2U relaying or the multi-hop information may indicate the UE I l l is not supporting (e.g. not willing to support) multi-hop relaying (e.g. a multi-hop scheme) such as U2N relaying or U2U relaying. The multi-hop information may further include information relating to one or more characteristics of such multi-hop relaying (e.g. a multi-hop scheme) if there are any.

In an example, the relaying connection information may include U2U connection information for indicating the UE 111 is capable of U2U relaying to a specific target UE and identification information, such as a UE identifier (e.g. L2-ID), for identifying the specific target UE. In the case of the UE 111, the specific target could be UE 113. The relaying connectivity information may include U2N connection information for indicating the UE 111 is capable of U2N relaying to a specific target base station and identification information, such as an identifier of the base station or cell controlled by the base station, for identifying the specific target base station. In the case of the UE 111, the specific target could be base station or gNB 101.

In an example and as discussed above and below, the discovery solicitation message includes discovery solicitation information associated with the UE 111, which may be referred to as a first UE, and/or discovery information associated with at least one other UE (e.g. UE 112, 113, 132, 121) of the plurality of UEs, which at least one other UE may be referred to as a second UE. As with the discovery solicitation information for the UE 111, the discovery information associated with at least one other UE includes for each other UE of the at least one other UE: relaying connection information for indicating the other UE (e.g. UE 112, 113, 132, 121) is seeking at least one of UE-to-Network, U2N, relaying and UE-to-UE, U2U, relaying; multi-hop information for indicating the other UE (e.g. UE 112, 113, 132, 121) is supporting (e.g. willing to support) multi-hop relaying. The discovery solicitation information may further include: identification information for identifying the UE (e.g. a first UE and/or second UE) to/with which the discovery solicitation information is associated; RRC state information for indicating a RRC state of the UE (e.g. a first UE and/or second UE); relay UE information (e.g. relay UE list information or relay UE list as discussed above and below with respect to the discovery announcement message and discovery response message and also with respect to the DISCOVERY SOLICITATION message 711, 712a, 712b, or 713) for identifying one or more other UEs of the plurality of UEs in the case where each of the one or more other UEs have forwarded at least some discovery information included in the discovery solicitation information associated with the UE.

In an example, the relay UE information includes for each UE of the one or more other UEs: identification information for identifying the UE; RRC state information for indicating a RRC state of the UE; multi-hop information indicating whether the UE supports multi-hop relaying; hop information indicating the number of hops (e.g. hop count) between the UE and a target node; information indicating whether the UE is in coverage of a base station (e.g. whether the UE is a U2N relay UE).

The multi -hop information may include at least one of: multi -hop support information for indicating the UE is supporting multi-hop relaying; maximum hop information for indicating the maximum number of hops, supported (or allowed or permitted) by the UE, between the UE and a target node (in an example such maximum hop information may be configured at the UE by the network); hop information for indicating to another UE receiving the discovery solicitation information the number of hops (e.g. hop count) to the other UE; authorization information for indicating to another UE receiving the discovery solicitation information that the other UE can forward the discovery solicitation information; prohibit information for indicating to another UE receiving the discovery solicitation information that the other UE cannot forward the discovery solicitation information to any other UE.

The method at the UE 111 (or first UE) may further comprise receiving discovery solicitation information associated with at least one other UE (or second UEs) of the plurality of UEs. For example, UE 111 may receive discovery solicitation information, such as that described above, from one or more of UEs 112, 113, 121, 122, 132, etc.). The UE 111 may then update the received discovery solicitation information to provide updated discovery solicitation information and the discovery solicitation message sent by the UE 111 may include the updated discovery solicitation information. The UE 111 may update at least part or some of the received discovery solicitation information. For example, when the received discovery solicitation information includes hop information, the UE 111 may update the number of hops included in the hop information (e.g. update by incrementing or decrementing the hop count to account for the hop to or through the UE 111). Additionally or alternatively, the UE 111 may update the received discovery solicitation information by adding discovery solicitation information associated with the UE 111 to the received discovery solicitation information or updated received discovery solicitation information to provide the updated discovery solicitation information. Updating, by the UE 111, the discovery solicitation information to be included in the discovery solicitation message sent by the UE 111 is discussed in more detail below.

The UE 111 may send the message, such as the discovery announcement message, the discovery response message, the discovery solicitation message, after a trigger (which may also be referred to as a trigger event, trigger condition). For example, the UE 111 may send the message (e.g. including the discovery information) to other UEs (e.g. in proximity to the UE 111) after detecting a trigger event or an occurrence of a trigger event or a trigger condition being met. The trigger may include at least one of: link quality or signal quality of at least one link to the UE 111 (e.g. a PC5 link 112a and/or PC5 link 121b and/or Uu link I l la) meets a certain condition; reception of multi-hop information; reception of a discovery message such as a discovery announcement message, discovery response message, discovery solicitation message; timing information (e.g. on expiry of a certain period). For example, a trigger to send the discovery solicitation message and/or the discovery response message, is receipt of discovery solicitation information from UEs in its proximity. The certain condition for the link quality or signal quality may be a predefined quality range which may be configured by the gNB serving the UE 111. In one example, the quality range is defined by a minimum or low threshold and/or a maximum or high threshold. The thresholds may relate to RSRP (Reference Signal Received Power), SL-RSRP (Sidelink Reference Signal Received Power) or SD-RSRP (Sidelink Discovery Reference Signal Received Power) threshold. The timing information may indicate a time period and the UE 111 sends the message on expiry of the time period. The time period may be a periodic time period such that the UE 111 sends the message periodically. The time period may be a certain time period after receipt of a discovery message or a certain time period after receipt of multi-hop information. The description with respect to figure 11 provides additional details regarding the trigger which triggers the UE 111 to send the message.

In one example, the discovery information associated with UE 111 and discovery information associated with at least one other UE may be sent in one discovery message or may be sent in separate messages. Referring now to figure 8 which is a flowchart of an example method 800 for managing discovery in a multi-hop network in accordance with one or more embodiments of the present invention.

The method 800 of Figure 8 is performed at a UE node or UE. For example, with reference to the wireless communication system shown in and described with respect to Figure 1, the UE performing the method 800 may be UE 112 of system 100. The method 800 as shown in and described with respect to Figure 8 may be performed by software elements and/or hardware elements. The UE node may be implemented in a communication device 400 as shown in and described with reference to Figure 4 with the method as shown in and described with respect to Figure 8 being performed by one or more processing units, such as the processing unit 411.

Briefly, in a first step 801, a UE device may send to the UE(s) in proximity an announcement message, which may include some relaying discovery information.

To do so, the UE device may broadcast a DISCOVERY ANNOUNCEMENT message 640a, 640b, 630a, 630b or 620, as discussed in figure 6, where a DISCOVERY ANNOUNCEMENT message may include some relaying discovery information. The DISCOVERY ANNOUNCEMENT message may be any message capable of having information incorporated therein, for example the UE-to-Network Relay Discovery Announcement message or the UE-to-UE Relay Discovery Announcement message. Preferably the DISCOVERY ANNOUNCEMENT message may be any message(s) defined in the 3GPP standards and/or 5G NR standards which is capable of having relaying discovery information incorporated therein or having other information which may be associated with relaying discovery information incorporated therein. The message(s) discussed in relation to embodiment(s) described herein are examples and it is not intended to limit the present invention to the specific messages described.

In one example, the announcement message may carry relaying discovery information associated to a single UE device, which may be the UE device sending the announcement message.

In one example, the announcement message may carry relaying discovery information associated to a plurality of UE devices, which may include the UE device sending the announcement message.

In one aspect of the invention, the relaying discovery information associated to a given UE includes at least one of: A UE Identifier information, which identifies the given UE to which the relaying discovery information is associated;

The RRC state of the given UE device;

A relay UE list, which identifies the one or more UEs which have forwarded the relaying discovery information of the given UE. In one example, the relay UE list may include the RRC state of the UEs in the relay UE list; a relaying capability information or relay connectivity information, which indicates the capability of the UE to perform UE-to-Network (U2N) relaying or UE-to-UE relaying.

In one example, the given UE indicates that it is capable of performing UE-to- Network (U2N) relaying if it has received from another UE some relaying discovery information associated to a UE that is capable of performing UE-to-Network (U2N) relaying.

In one example, the given UE indicates that it is capable of performing UE-to-UE (U2U) relaying if it has received from another UE some relaying discovery information associated to a UE that is capable of performing UE-to-UE (U2U) relaying. multi-hop information, which indicates if the relaying capability information is associated to a multi-hop scheme (either U2U or U2N).

In one example, the multi-hop information may include some information indicating if the relaying capability information is associated to the UE that sent the broadcast announcement message carrying the relaying discovery information or to another relay UE.

In one example, the multi-hop information may include some information indicating if the relaying capability information is associated to a multi-hop relaying scheme (e.g. multi-hop U2U or U2N relaying).

In one example, the multi-hop information may include an information on the number of hops between the UE to which the relaying capability information is associated and the UE which is sending the broadcast announcement message carrying the relaying capability information, or an information on the number of hops between the UE to which the relaying capability information is associated and the UE which is to receive the broadcast announcement message carrying the relaying capability information. In one example, the multi-hop information may include a prohibit indication information used to prevent a relay UE receiving a relaying discovery information to forward it to other UE(s) in proximity;

Neighbor UE list information, which indicates one or more UEs in proximity of the UE, for which the given UE is capable of performing UE-to-UE relaying.

In one example the relaying discovery information in a DISCOVERY ANNOUNCEMENT message is only sent by a UE having UE-to-Network (U2N) relaying capability and is forwarded by one or more relay UEs.

In one aspect of the invention, a relay UE may update all or part of the relaying discovery information of a DISCOVERY ANNOUNCEMENT message when forwarding this information, as further discussed in relation with Figure 6. In one example, the relay UE forwarding a DISCOVERY ANNOUNCEMENT message received from another relay UE may increment or decrement the information on the number of hops included in the multi -hop information. In one example, the relay UE forwarding a DISCOVERY ANNOUNCEMENT message received from another relay UE may update prohibit indication information in the multi-hop information.

In one example, the relaying discovery information in an announcement message sent by a relay UE may carry the relaying discovery information associated to this relay UE and / or the information associated to one or more other relay UEs, as also discussed in relation with Figure 6.

More details on the relaying discovery information included in the DISCOVERY ANNOUNCEMENT message 640a, 640b, 630a or 620 sent by the UE is given hereafter in relation to Figure 6.

Figure 9 is a flowchart of an example method 900 for managing discovery in a multi-hop network in accordance with one or more embodiments of the present invention.

The method 900 of Figure 9 is performed at a UE node or UE. For example, with reference to the wireless communication system shown in and described with respect to Figure 1, the UE performing the method 900 may be UE 112 of system 100. The method 900 as shown in and described with respect to Figure 9 may be performed by software elements and/or hardware elements. The UE node may be implemented in a communication device 400 as shown in and described with reference to Figure 4 with the method as shown in and described with respect to Figure 9 being performed by one or more processing units, such as the processing unit 411. Briefly, in a first step 901, a UE device may send to the UE(s) in proximity a solicitation message, which may include some discovery solicitation information.

In one example, the sending by a UE device of a solicitation message including some discovery solicitation information may be triggered by the reception of a solicitation message from one or more UEs in proximity.

In one example, the UE device may broadcast a DISCOVERY SOLICITATION message 711, 712a, 712b, or 713 as discussed in figure 7, where a DISCOVERY SOLICITATION message may include some discovery solicitation information. The DISCOVERY SOLICITATION message may be any message capable of having information incorporated therein, for example the UE-to-Network Relay Discovery Solicitation message or the UE-to- UE Relay Discovery Solicitation message. Preferably the DISCOVERY SOLICITATION message may be any message(s) defined in the 3GPP standards and/or 5GNR standards which is capable of having relaying discovery information incorporated therein or having other information which may be associated with relaying discovery information incorporated therein. The message(s) discussed in relation to embodiment(s) described herein are examples and it is not intended to limit the present invention to the specific messages described.

In one example, the solicitation message may carry discovery solicitation information associated to a single UE device, which may be the UE device sending the discovery solicitation message.

In one example, the solicitation message may carry discovery solicitation information associated to a plurality of UE devices, which may include the UE device sending the solicitation message.

In one aspect of the invention, the discovery solicitation information associated to a given UE includes at least one of:

A UE Identifier information, which identifies the given UE to which the discovery solicitation information is associated;

The RRC state of the given UE device;

A relay UE list, which identifies the one or more UEs which have forwarded the discovery solicitation information of the given UE. In one example, the relay UE list may include the RRC state of the UEs in the relay UE list;

A relaying connection information or relay connectivity information, which indicates the type of relaying connectivity, i.e., UE-to-Network (U2N) relaying or UE-to-UE (U2U) relaying, the given UE is seeking. In one example, the given UE may indicate that it is looking for some connectivity with the network, thus looking for a relay UE that is capable of performing UE-to- Network (U2N) relaying.

In one example, the given UE may indicate that it is looking for some connectivity with a specific target UE device, thus looking for a relay UE that is capable of performing UE-to-UE (U2U) relaying. In one example, the relaying connection information may include the identifier of the target UE device. multi-hop information (which may also be referred to as multi-hop relaying scheme information), which indicates if the UE is willing to support multi-hop relaying (either U2U or U2N) or not along with the characteristics of the multi-hop relaying scheme supported by the UE.

In one example, the multi-hop information may include an information on the maximum number of hops to be supported by the UE device in case of multi-hop relaying between the UE and its target, i.e., the network (in case of UE-to-Network relaying) or another UE device (in case of UE-to-UE relaying).

In one example, the multi-hop information may include an authorization indication used to allow a relay UE receiving the discovery solicitation information to look for a multi-hop relaying scheme by forwarding the discovery solicitation information to other UE(s) in proximity;

In one example, the multi-hop information may include a prohibit indication information used to prevent a relay UE receiving the discovery solicitation information to forward it to other UE(s) in proximity;

In one example, the multi-hop information may include a hop count information to be used by the relay UE(s) receiving the discovery solicitation information to count the number of hops to be considered in case of a multi -hop relaying scheme.

In one example the discovery solicitation information associated to a given UE included in a DISCOVERY SOLICITATION message may be forwarded by one or more relay UEs that received this information.

In one aspect of the invention, a relay UE may update all or part of the discovery solicitation information of a DISCOVERY SOLICITATION message when forwarding this information, as further discussed in relation with Figure 7. In one example, the relay UE forwarding the discovery solicitation information of a DISCOVERY SOLICITATION message received from another relay UE may increment or decrement the hop count information in the multi-hop information. In one example, the relay UE forwarding the discovery solicitation information received from another relay UE may update the prohibit indication information in the multi-hop information. In one example, a relay UE may do so if the value of the hop count information has reached the maximum number of hops to be supported by the UE device. In one example, a relay UE may do so if the value of the hop count information has reached a zero value.

In one example, the discovery solicitation information in a discovery solicitation message sent by a relay UE may carry the discovery solicitation information associated with this relay UE and / or the discovery solicitation information associated to one or more other relay UEs, as also discussed in relation with Figure 6.

More details on the discovery solicitation information included in the DISCOVERY SOLICITATION message 711, 712a, 712b, or 713 sent by a UE device is given hereafter in relation to Figure 7.

Figure 10 is a flowchart of an example method 1000 for managing discovery in a multihop network in accordance with one or more embodiments of the present invention.

The method 1000 of Figure 10 is performed at a UE node or UE. For example, with reference to the wireless communication system shown in and described with respect to Figure 1, the UE performing the method 1000 may be UE 112 of system 100. The method 1000 as shown in and described with respect to Figure 10 may be performed by software elements and/or hardware elements. The UE node may be implemented in a communication device 400 as shown in and described with reference to Figure 4 with the method as shown in and described with respect to Figure 10 being performed by one or more processing units, such as the processing unit 411.

Briefly, in a first step 1001, upon reception by a UE device of some discovery solicitation information from one or more UEs in its proximity, the UE device may transmit some discovery response information.

In one example, the UE device may send a DISCOVERY RESPONSE message 714a, 714b, 715, 716a, 716b or 716c as discussed in figure 7, where a DISCOVERY RESPONSE message may include some discovery response information. The DISCOVERY RESPONSE message may be any message capable of having information incorporated therein, for example the UE-to-Network Relay Discovery Response message or the UE-to-UE Relay Discovery Response message. Preferably the DISCOVERY RESPONSE message may be any message(s) defined in the 3GPP standards and/or 5G NR standards which is capable of having relaying discovery information incorporated therein or having other information which may be associated with relaying discovery information incorporated therein. The message(s) discussed in relation to embodiment s) described herein are examples and it is not intended to limit the present invention to the specific messages described.

In one example, the discovery response message may carry discovery response information associated to a single UE device, which may be the UE device sending the discovery response message.

In one example, the discovery response message may carry discovery response information associated to a plurality of UE devices, which may include the UE device sending the discovery response message.

In one aspect of the invention, the discovery response information associated to a given UE includes at least one of

A UE Identifier information, which identifies the given UE to which the discovery response information is associated;

The RRC state of the given UE device;

A relaying connection information or relay connectivity information, which indicates the type of relaying connectivity, i.e., UE-to-Network (U2N) relaying or UE-to-UE (U2U) relaying, the given UE is capable of providing.

In one example, the given UE may indicate that it is capable of connecting to the network, i.e., capable of performing UE-to-Network (U2N) relaying.

In one example, the given UE may indicate that it is capable of connecting with a specific target UE device, i.e., it is capable of performing UE-to-UE (U2U) relaying. In one example, the relaying connection information may include the identifier of the target UE device. multi-hop information (which may also be referred to as multi-hop relaying scheme information), which indicates if the above relaying connection information relates to a multi-hop relaying scheme (either U2U or U2N) or not along with the characteristics of the multi-hop relaying scheme (if any).

In one example, the multi-hop information may include an information associated to the distance, in terms of hops, between the UE device and the target, i.e., the network (in case of UE-to-Network relaying) or another UE device (in case of UE-to-UE relaying).

In one example, the multi-hop information may include a hop count information to be used by the relay UE(s) receiving the discovery response information to count the number of hops to be considered in case of a multi-hop relaying scheme. In one example, the hop count information in the discovery response information is a function of the value of the hop count information in the discovery solicitation information received from another UE device. In one example, the hop count information in the discovery response information is equal to the value of the hop count information in the discovery solicitation information received from another UE device. In one example, the hop count information in the discovery response information is equal to the value of the hop count information in the discovery solicitation information received from another UE device incremented by one.

In one example, the hop count information in the discovery response information is equal to the difference between the values of the maximum number of hops information and the hop count information in the discovery solicitation information received from another UE device.

In one example, the multi-hop information may include a Path identifier information which is used to uniquely identify the multi-hop relay relaying path, i.e., the succession of the one or more relay UEs involved in the multi-hop relaying scheme. In one example, the multi-hop information may include a relay UE list, also referred to as relay routing table information, which identifies the one or more UEs which are involved in the multi-hop relay relaying path;

In one example the discovery response information associated to a given UE included in a DISCOVERY RESPONSE message may be forwarded by one or more relay UEs that received this information.

In one aspect, a relay UE may update all or part of the discovery response information of a DISCOVERY RESPONSE message when forwarding this information, as further discussed in relation with Figure 7.

In one example, the discovery response information in an announcement message sent by a relay UE may carry the discovery response information associated with this relay UE and / or the discovery solicitation information associated to one or more other relay UEs, as also discussed in relation with Figure 7.

In one example, a UE may indicate in its own discovery response information that it is capable of performing UE-to-Network (U2N) relaying if it has received discovery response information from another relay UE indicating that a UE is capable of performing UE-to- Network (U2N) relaying.

In one example, a UE may indicate in its own discovery response information that it is capable of performing UE-to-UE (U2U) relaying if it has received discovery response information from another relay UE indicating that a UE is capable of performing UE-to-UE (U2U) relaying.

More details on the discovery response information included in the DISCOVERY RESPONSE message 714a, 714b, 715, 716a, 716b or 716c sent by a UE device is given hereafter in relation to Figure 7.

Figure 11 is a flowchart of an example method 1100 for managing discovery in a multihop network in accordance with one or more embodiments of the present invention.

The method 1100 of Figure 11 is performed at a UE node or UE. For example, with reference to the wireless communication system shown in and described with respect to Figure 1, the UE performing the method 1100 may be UE 112 of system 100. The method 1100 as shown in and described with respect to Figure 11 may be performed by software elements and/or hardware elements. The UE node may be implemented in a communication device 400 as shown in and described with reference to Figure 4 with the method as shown in and described with respect to Figure 11 being performed by one or more processing units, such as the processing unit 411.

Briefly, in a first step 1101, upon detection by a UE device of a discovery trigger (or after a trigger or trigger event or after an occurrence of a trigger condition/event), the UE device may transmit some discovery information to other UE(s) in proximity.

In one aspect, the discovery trigger may include at least one of, or any combination thereof:

A signal quality.

In one example, a UE device may send some discovery information if the quality of its Uu link (such as Uu link 121a of Figure 1) with a base station, or gNB (such as gNB 101 of Figure 1), is within a predefined quality range. In one example, this Uu quality range is configured by the gNB serving the relay UE 604. In one example, Uu quality range is defined by a minimum and / or a maximum RSRP (Reference signal received power) threshold.

In one example, a UE device may send some discovery information if the quality of its PC5 link (such as PC5 links 122a or 121b of Figure 1) with another UE (such as UE 122 or UE 111 of Figure 1), is within a predefined quality range. In one example, this PC5 quality range is configured by the gNB serving the relay UE 604. In one example, the PC5 quality range is defined by a minimum and / or a maximum RSRP (Reference Signal Received Power), SL-RSRP (Sidelink Reference Signal Received Power) or SD-RSRP (Sidelink Discovery Reference Signal Received Power) threshold.

The reception of a discovery message.

In one example, the discovery message which reception may trigger the sending of some discovery information by the UE device may be the DISCOVERY ANNOUNCEMENT message, as discussed in relation with figure 6 and Figure 8.

In one example, the discovery message which reception may trigger the sending of some discovery information by the UE device may be the DISCOVERY SOLICITATION message, as discussed in relation with figure 7 and Figure 9.

In one example, the discovery message which reception may trigger the sending of some discovery information by the UE device may be the DISCOVERY RESPONSE message, as discussed in relation with figure 7 and Figure 10.

The reception of a multi-hop relay information in a discovery message.

In one example, this multi-hop relay information is the multi-hop information in the relaying discovery information included in a discovery announcement message, as discussed in relation with figure 8.

In one example, this multi-hop relay information is the multi-hop information in the discovery solicitation information included in a discovery solicitation message, as discussed in relation with figure 9.

In one example, this multi-hop relay information is the multi-hop information in the discovery response information included in a discovery response message, as discussed in relation with figure 10.

A timing information.

In one example, a UE device may send some discovery information on a periodic basis.

In one example, a UE device may send some discovery information after a specific time period after the reception of a discovery message or after the reception of a multi-hop relay information.

In one example, the discovery information transmitted to other UE(s) in proximity is the relaying discovery information, as discussed in relation with Figure 8 and Figure 6.

In one example, the discovery information transmitted to other UE(s) in proximity is the discovery solicitation information, as discussed in relation with Figure 9 and Figure 7.

In one example, the discovery information transmitted to other UE(s) in proximity is the discovery response information, as discussed in relation with Figure 9 and Figure 7. Referring to Figure 5, a schematic and simplified diagram illustrating an example message flow for use in managing discovery in a multi-hop relay wireless communication system in accordance with one or more embodiments and which may be used for performing discovery announcement by a relay UE node or UE is shown.

A relay UE, such relay UEs 502, 503 may check in a step 507 whether it supports U2U relaying function and/or multi-hop U2U and/or multi-hop U2N capabilities, and whether it is authorized to act as a U2U and/or multi-hop U2U relay and/or multi-hop U2N relay. This authorization may be provided by the network during the step 507. For example, step 507 is a service authorization and parameter provisioning procedure such as that described in 3GPP Release 18 (e.g. TS23.304 clause 6.2). In one example, the network may configure a relay UE as a Release 19 relay UE or as a relay UE compatible with a Release 19 relay UE, indicating that this relay UE is capable of operating as U2U or multi-hop U2U relay or multi-hop U2N relay.

UE nodes or UEs 501, 502, 503, and 504 (which may correspond to UE nodes or UEs 124, 123, 122 and 121 of Figure 1 as described above, or correspond to other examples of UE nodes or UEs discussed herein) perform a Discovery procedure 506. In one example, UE nodes 502, 503, and 504 may act as relay UE nodes. As a result of this discovery process, relay UE nodes 502, 503, and 504 may have discovered other UEs in proximity.

In one example, the Discovery procedure 506 performed by UE nodes 501, 502, 503, and 504 is the Model A announcement-based discovery procedure 600, as further discussed in relation with Figure 6.

In one example, the Discovery procedure 506 performed by UE nodes 501, 502, 503, and 504 is the Model B solicitation-based discovery procedure 700, as further discussed in relation with Figure 7.

As a result of this discovery procedure, the relay UE 502 may send one or more DISCOVERY messages 505a, 505b or 505c, which may be received by the Remote UE 501. In one example, relay UE 502 may broadcast one or more DISCOVERY messages 505a, 505b or 505c.

In one example, the broadcast one or more DISCOVERY messages 505a, 505b or 505c are similar to the DISCOVERY ANNOUNCEMENT message 620, discussed in relation with Figure 6.

In one example, relay UE 502 may send to Remote UE 501 one or more DISCOVERY messages 505a, 505b or 505c. In one example, one or more DISCOVERY messages 505a, 505b or 505c sent by relay UE 502 to Remote UE 501 are similar to the DISCOVERY RESPONSE messages 716a, 716b or 716c, discussed in relation with Figure 7.

Referring to Figure 6, a schematic and simplified diagram illustrating an example message flow for use in managing discovery in a multi-hop relay wireless communication system in accordance with one or more embodiments and which may be used for performing discovery announcement by a relay UE node is shown.

A relay UE node 604 (which may correspond to relay UE node 121 of Figure 1 as described above, or correspond to other examples of relay UE nodes or relay UEs discussed herein) may share some relaying discovery information by broadcasting a DISCOVERY ANNOUNCEMENT message, which may be received as DISCOVERY ANNOUNCEMENT message 640a by relay UE node 603 (which may correspond to relay UE node 122 of Figure 1 as described above, or correspond to other examples of relay UE nodes or UEs discussed herein) and as DISCOVERY ANNOUNCEMENT message 640b by relay UE 602 (which may correspond to relay UE node 123 of Figure 1 as described above, or correspond to other examples of relay UE nodes or UEs discussed herein).

In one aspect, the relay UE 604 may broadcast a DISCOVERY ANNOUNCEMENT message if the quality of its Uu link (such as Uu link 121a of Figure 1) with a base station, or gNB (such as gNB 101 of Figure 1), is within a predefined quality range. In one example, this Uu quality range is configured by the gNB serving the relay UE 604. In one example, Uu quality range is defined by a minimum and / or a maximum RSRP (Reference signal received power) threshold.

The relaying discovery information carried in DISCOVERY ANNOUNCEMENT message 640b or 640a may, in some examples, include at least one UE relaying discovery information, where a UE relaying discovery information includes at least one of:

UE Identifier information. This information indicates the unique identifier of the UE to which the UE relaying discovery information is associated (e.g., UE 604).

RRC state information. This information indicates the RRC state of the UE 604;

Relaying Capability information or relaying connectivity information. This information indicates the capability of the UE 604 to perform UE-to-Network (U2N) relaying.

- Multi-hop information. This information is used to manage multi-hop discovery (either U2U or U2N). Neighbor UE list information. This information is used to indicate the identifier of one or more UEs in proximity of the relay UE 604. In one aspect of the invention, the relay UE 604 may consider a UE as a neighbor UE, and add it to the Neighbor UE list information if the quality of its PC5 link (such as PC5 links 122a or 121b of Figure 1) with another UE (such as UE 122 or UE 111 of Figure 1), is within a predefined quality range. In one example, this PC5 quality range is configured by the gNB serving the relay UE 604. In one example, the PC5 quality range is defined by a minimum and / or a maximum RSRP (Reference Signal Received Power), SL- RSRP (Sidelink Reference Signal Received Power) or SD-RSRP (Sidelink Discovery Reference Signal Received Power) threshold.

In one example, the Neighbor UE list information may include the RRC state of the UEs in the Neighbor UE list.

The Multi-hop information may, in some examples, include at least one of:

Local relaying information. This information indicates if the Relaying Capability information is associated to the UE 604 that sent the broadcast announcement message carrying the UE relaying discovery information or to another relay UE. In one example, the Local relaying information is a Boolean information set to true to indicate that the Relaying Capability information is associated to the UE 604.

- Multi-hop relaying information. This information indicates that the Relaying Capability information (either UE-to-Network or UE-to-UE) is refers to a multi-hop relaying scheme.

- Hop Count information. This information is used by a UE that receives the broadcast announcement message carrying the relaying capability information to determine the number of hops between the UE to which the relaying capability information is associated (here UE 604) and the UE that is receiving the broadcast DISCOVERY ANNOUNCEMENT message carrying the relaying capability information. In one example, the relay UE 604 may set the value of the Hop Count information to a maximum value (e.g. a maximum value configured by the network). In one example, the relay UE 604 may set the value of the Hop Count information to zero.

Discovery forwarding prohibit information. This information is used to prevent a relay UE receiving a UE relaying discovery information from another relay UE to forward it to other UE(s) in proximity. For instance, the relay UE 604 may set Discovery forwarding prohibit information to a true value to indicate to the relay UEs 603 and 602 that they should not forward the relaying discovery information carried in DISCOVERY ANNOUNCEMENT message 640b or 640a.

Similar to UE 604, relay UE 603 may share some relaying discovery information by broadcasting a DISCOVERY ANNOUNCEMENT message, which may be received as DISCOVERY ANNOUNCEMENT message 630a by relay UE node 604 and as DISCOVERY ANNOUNCEMENT message 630b by relay UE 602.

In one example, the relaying discovery information carried in DISCOVERY ANNOUNCEMENT message 630b or 630a may include at least one UE relaying discovery information, as defined above in relation with message 640a or 640b.

Similar to UE 604 or relay UE 603, relay UE 602 may share some relaying discovery information by broadcasting a DISCOVERY ANNOUNCEMENT message, which may be received as DISCOVERY ANNOUNCEMENT message 620 by remote UE node 601 (such as UE node 124 of Figure 1). The DISCOVERY ANNOUNCEMENT message 620 may be received by other UE nodes (e.g., relay UE 603), even though this is not depicted on Figure 6.

In one example, the relaying discovery information carried in DISCOVERY ANNOUNCEMENT message 620 may include at least one UE relaying discovery information, as defined above in relation with message 640a, 640b, 630a or 630b.

In one example, relay UE 602 may add to the relaying discovery information carried in DISCOVERY ANNOUNCEMENT message 620 the following information: relay UE list information. This information identifies the one or more UEs which have forwarded some of the relaying discovery information carried in DISCOVERY ANNOUNCEMENT message 620. For instance, if DISCOVERY ANNOUNCEMENT message 620 carries the relaying discovery information issued by relay UE 604 in DISCOVERY ANNOUNCEMENT message 640a and forwarded to relay UE 602 by relay UE 603 through DISCOVERY ANNOUNCEMENT message 630b, relay UE 602 may add the Identifier of relay UE 603 and relay UE 602 to the relay UE list information associated to the forwarded relay UE 604’ s relaying discovery information.

In one example, the relay UE list information may include the RRC state of the UEs in the relay UE list.

In one example, the relaying discovery information carried in DISCOVERY ANNOUNCEMENT message 630a, 630b or 620 may include at least one UE relaying discovery information, as defined above in relation with message 640a or 640b. In one example, the relaying discovery information carried in DISCOVERY ANNOUNCEMENT message 630a, 630b may include at least one of:

UE relaying discovery information associated to relay UE 603.

UE relaying discovery information associated to other relay UE(s).

In one example, the relaying discovery information carried in DISCOVERY ANNOUNCEMENT message 630a or 630b may include the UE relaying discovery information associated to relay UE 604, which was previously received in DISCOVERY ANNOUNCEMENT message 640a.

In one example, the relaying discovery information carried in DISCOVERY ANNOUNCEMENT message 620 may include the UE relaying discovery information associated to relay UE 604, which was previously received in DISCOVERY ANNOUNCEMENT message 640b, and / or the UE relaying discovery information associated to relay UE 603, which was previously received in DISCOVERY ANNOUNCEMENT message 630b.

In one example, relay UE 603 may send the UE relaying discovery information associated to relay UE 603 and the UE relaying discovery information associated to other relay UE(s), such as UE relaying discovery information associated to relay UE 604, in different DISCOVERY ANNOUNCEMENT messages (not represented on Figure 6).

In one example, relay UE 602 may send the UE relaying discovery information associated to relay UE 602 and the UE relaying discovery information associated to other relay UE(s), such as UE relaying discovery information associated to relay UE 604 and / or UE relaying discovery information associated to relay UE 603, in different DISCOVERY ANNOUNCEMENT messages (not represented on Figure 6).

In one example, relay UE 603 may update the value of the Hop Count information in the UE relaying discovery information associated to other relay UE(s), such as UE relaying discovery information associated to relay UE 604, before broadcasting this information in a DISCOVERY ANNOUNCEMENT message, such as 630b or 630a. In one example, the update of the Hop Count information consists in incrementing the Hop Count information received from relay UE 604. In one example, the update of the Hop Count information consists in decrementing the Hop Count information received from relay UE 604.

In one example, relay UE 602 may update the value of the Hop Count information in the UE relaying discovery information associated to other relay UE(s), such as UE relaying discovery information associated to relay UE 604 and/or UE relaying discovery information associated to relay UE 603 before broadcasting this information in a DISCOVERY ANNOUNCEMENT message, such as 620. In one example, the update of the Hop Count information consists in incrementing the Hop Count information received from relay UE 604 or relay UE 603. In one example, the update of the Hop Count information consists in decrementing the Hop Count information received from relay UE 604 or relay UE 603.

In one example, relay UE 603, respectively relay UE 602, will not send the UE relaying discovery information associated to another relay UE in a DISCOVERY ANNOUNCEMENT message in case the received Hop Count information associated to this other relay UE has reached a threshold value. In one example, this threshold value is a minimum threshold value (e.g., zero). In one example, this threshold value is a maximum threshold value.

In one example, the relay UE 604 may broadcast a DISCOVERY ANNOUNCEMENT message only if it is capable of performing UE-to-Network relaying.

In one example, the relay UE 603 or the relay UE 602 may broadcast a DISCOVERY ANNOUNCEMENT message only if it is capable of performing UE-to-Network relaying and/or UE-to-UE relaying or if it has received some UE relaying discovery information from another relay UE (e.g., relay UE 604) indicating that this other relay UE is capable of performing UE-to-Network and/or UE-to-UE relaying.

In one example, relay 603 may indicate that it is capable of performing UE-to-Network relaying if it has received some UE relaying discovery information from another relay UE node that is capable of performing UE-to-Network relaying (for instance relay UE 604). Relay 603 will do so by setting the Relaying Capability information accordingly in the UE relaying discovery information of relay UE 603 in DISCOVERY ANNOUNCEMENT message 630a or 630b or DISCOVERY ANNOUNCEMENT message 630a or 630b.

In one example, relay UE 602 may indicate that it is capable of performing UE-to- Network relaying if it has received some UE relaying discovery information from another relay UE node that is capable of performing UE-to-Network relaying (for instance relay UE 604 and / or relay UE 603). Relay UE 602 will do so by setting the Relaying Capability information accordingly in the UE relaying discovery information of relay UE 602 in DISCOVERY ANNOUNCEMENT message 620.

In one example, relay UE 603 or relay UE 602 may indicate that it is capable of performing UE-to-UE relaying if it has received some UE relaying discovery information from another relay UE node that is capable of performing UE-to-UE relaying (for instance relay UE 604). Relay 603 will do so by updating the Relaying Capability information accordingly in the UE relaying discovery information of relay UE 603 in DISCOVERY ANNOUNCEMENT message 630a or 630b. Relay UE 602 will do so by updating the Relaying Capability information accordingly in the UE relaying discovery information of relay UE 602 in DISCOVERY ANNOUNCEMENT message 620.

In one example, relay UE 603 or relay UE 602 may indicate that its Relaying Capability information (either UE-to-Network or UE-to-UE) refers to a multi-hop relaying scheme if it has received some UE relaying discovery information from another relay UE node that is capable of performing UE-to-Network or UE-to-UE relaying (for instance relay UE 604). Relay UE 603 will do so by setting the Multi-hop relaying information accordingly (e.g., setting the Multi-hop relaying information to a TRUE value) in the UE relaying discovery information of relay UE 603 in DISCOVERY ANNOUNCEMENT message 630a or 630b. Relay UE 602 will do so by setting the Multi-hop relaying information accordingly (e.g., setting the Multihop relaying information to a TRUE value) in the UE relaying discovery information of relay UE 602 in DISCOVERY ANNOUNCEMENT message 620.

In some examples, the announcement of the relaying discovery information is performed upon or as part of 5G ProSe UE-to-UE or UE-to-Network Discovery with Model A procedure.

In some examples, the announcement of the relaying discovery information is performed upon or as part of 5G ProSe UE-to-Network Discovery with Model A procedure, in such cases, the DISCOVERY ANNOUNCEMENT message sent by relay UE 604, such as message 640a or 640b, or by relay UE 603, such as message 630b or 630a, or by relay UE 602, such as message 620, is the UE-to-Network Relay Discovery Announcement message, as specified in 3GPP TS 23.304.

In one example, the announcement of the relaying discovery information is performed upon or as part of a 5G ProSe UE-to-UE Discovery with Model A procedure, in such cases, the DISCOVERY ANNOUNCEMENT message sent by relay UE 604, such as message 640a or 640b, or by relay UE 603, such as message 630b or 630a, or by relay UE 602, such as message 620, is the UE-to-UE Relay Discovery Announcement message, as specified in 3GPP TS 23.304.

Referring to Figure 7, a schematic and simplified diagram illustrating an example message flow for use in managing discovery in a multi-hop relay wireless communication system in accordance with one or more embodiments and which may be used for performing discovery announcement by a relay UE node is shown.

A UE node or UE 701 (which may correspond to relay UE node 124 of Figure 1 as described above, or correspond to other examples of relay UE nodes or relay UEs discussed herein) may try to discover some UE device in proximity and further establish a connection with the network or another UE by broadcasting a DISCOVERY SOLICITATION message 711, which may be received by relay UE node 702 (which may correspond to relay UE node 123 of Figure 1 as described above, or correspond to other examples of relay UE nodes or relay UEs discussed herein). In one example, the DISCOVERY SOLICITATION message 711 may carry discovery solicitation information.

The discovery solicitation information carried in DISCOVERY SOLICITATION message 711 may, in some examples, include a UE discovery solicitation information, where a UE discovery solicitation information includes at least one of:

A UE Identifier information. This information identifies the UE to which the UE discovery solicitation information is associated (here, UE 701);

A relaying connection information or relay connectivity information. This information indicates the type of relaying connectivity, i.e., UE-to-Network (U2N) relaying or UE-to-UE (U2U) relaying, the UE is looking for.

In one example, the relaying connection information may include a U2N connection information, used by UE 701 to indicate that it is looking for some connectivity with the network, thus looking for a relay UE that is capable of performing UE-to-Network (U2N) relaying.

In one example, the relaying connection information may include a U2U connection information, used by UE 701 to indicate that it is looking for some connectivity with a specific target UE device, thus looking for a relay UE that is capable of performing UE-to-UE (U2U) relaying. In one example, the relaying connection information may also include the identifier of the target UE device.

A multi-hop information. This information indicates if UE 701 is willing to support multi-hop relaying (either U2U or U2N) or not along with the characteristics of the multi-hop relaying scheme supported by the UE.

In one example, the multi-hop information may include at least one of:

A multi-hop support information. This information is used to indicate that UE 701 is supporting multi-hop relaying. This information may be used to allow a relay UE, such as relay UE 702, receiving UE 701’s discovery solicitation information to look for a multi -hop relaying scheme by forwarding the UE 701 ’s UE discovery solicitation information to other UE(s) in proximity (such as relay UEs 703);

In one example, the presence of the multi-hop information in a DISCOVERY SOLICITATION message, such as message 711, even without the multi-hop support information, indicates that UE 701 is actually supporting multi -hop relaying. A maximum number of hops information. This information is used to indicate the maximum number of hops to be supported (or allowed or permitted) by the UE device 701 in case of multi-hop relaying between the UE and its target, i.e., the network (in case of UE-to-Network relaying) or another UE device (in case of UE-to-UE relaying).

A multi-hop prohibited information. This information may be used to prevent a relay UE receiving UE 701’ s discovery solicitation information to forward it to other UE(s) in proximity;

A hop count information. This information may be used by other relay UE(s) (such as relay UEs 702, 703 or 704) receiving the discovery solicitation information to count the number of hops to be considered in case of a multi -hop relaying scheme.

Upon reception of the DISCOVERY SOLICITATION message 711, relay UE 702 may broadcast a DISCOVERY SOLICITATION message, which may be received as DISCOVERY SOLICITATION message 712a by relay UE node 703 (which may correspond to relay UE node 122 of Figure 1 as described above, or correspond to other examples of relay UE nodes or relay UEs discussed herein) and as DISCOVERY SOLICITATION message 712b by relay UE 704 (which may correspond to relay UE node 121 of Figure 1 as described above, or correspond to other examples of relay UE nodes or relay UEs discussed herein).

In one example, the discovery solicitation information carried in DISCOVERY SOLICITATION message 712a or 712b may include at least one UE discovery solicitation information, as defined above in relation with message 711.

Similar to UE 701 or relay UE 702, relay UE 703 may share some discovery solicitation information by broadcasting a DISCOVERY SOLICITATION message, which may be received as DISCOVERY ANNOUNCEMENT message 713 by relay UE node 704 (which may correspond to relay UE node 121 of Figure 1 as described above, or correspond to other examples of relay UE nodes or relay UEs discussed herein). The DISCOVERY ANNOUNCEMENT message 713 may be received by other UE nodes (e.g., relay UE 702), even though this is not depicted on Figure 7.

In one example, the discovery solicitation information carried in DISCOVERY SOLICITATION message 713 may include at least one UE discovery solicitation information, as defined above in relation with message 711.

In one example, relay UE 702 and / or relay 703 may add to the UE discovery solicitation information carried in DISCOVERY SOLICITATION message 712a, 712b or 713 the following information: A relay UE list information. This information identifies the one or more UEs which have forwarded some of the UE discovery solicitation information carried in DISCOVERY SOLICITATION message 712a, 712b or 713. For instance, if DISCOVERY ANNOUNCEMENT message 713 carries the UE discovery solicitation information issued by relay UE 701 in DISCOVERY SOLICITATION message 711 and forwarded to relay UE 703 by relay UE 702 through DISCOVERY SOLICITATION message 712a, relay UE 703 may add the Identifier of relay UE 702 and relay UE 703 to the relay UE list information associated to the forwarded relay UE 701 ’s UE discovery solicitation information.

In one example, the UE discovery solicitation information carried in DISCOVERY SOLICITATION message 712a, 712b or 713 may include at least one UE discovery solicitation information, as defined above in relation with message 711.

In one example, the discovery solicitation information carried in DISCOVERY SOLICITATION message 713 may include at least one of:

UE discovery solicitation information associated to relay UE 703.

UE discovery solicitation information associated to other UE(s).

In one example, the discovery solicitation information carried in DISCOVERY SOLICITATION message 713 may include the UE discovery solicitation information associated to relay UE 702, which was previously received in DISCOVERY SOLICITATION message 712a and / or the UE discovery solicitation information associated to UE 701, which was previously forwarded by relay UE 702 and received in DISCOVERY SOLICITATION message 712a.

In one example, relay UE 702 may send the UE discovery solicitation information associated to relay UE 702 and the UE discovery solicitation information associated to other UE(s), such as UE discovery solicitation information associated to UE 701, in different DISCOVERY SOLICITATION messages (not represented on Figure 7).

In one example, relay UE 703 may send the UE discovery solicitation information associated to relay UE 703 and the UE discovery solicitation information associated to other UE(s), such as UE discovery solicitation information associated to UE 701 and / or UE discovery solicitation information associated to relay UE 702, in different DISCOVERY SOLICITATION messages (not represented on Figure 7). In one example, relay UE 702 may update the value of the Hop Count information in the UE discovery solicitation information associated to other relay UE(s), such as UE discovery solicitation information associated to UE 701, before broadcasting this information in a DISCOVERY SOLICITATION message, such as 712b or 712a. In one example, the update of the Hop Count information consists in incrementing the Hop Count information received from UE 701. In one example, the update of the Hop Count information consists in decrementing the Hop Count information received from UE 701.

In one example, relay UE 703 may update the value of the Hop Count information in the UE discovery solicitation information associated to other relay UE(s), such as UE discovery solicitation information associated to relay UE 702 and/or UE discovery solicitation information associated to UE 701 before broadcasting this information in a DISCOVERY SOLICITATION message, such as message 713. In one example, the update of the Hop Count information consists in incrementing the Hop Count information received from UE 70 lor relay UE 702. In one example, the update of the Hop Count information consists in decrementing the Hop Count information received from UE 701 or relay UE 702.

In one example, relay UE 703, respectively relay UE 702, will not send the UE discovery solicitation information associated to another UE/ relay UE in a DISCOVERY SOLICITATION message in case the received Hop Count information associated to this other UE / relay UE has reached a threshold value. In one example, this threshold value is a minimum threshold value (e.g., zero). In one example, this threshold value is a maximum threshold value (e.g. a maximum value configured at the relay UE by the network). In one example the maximum threshold value is the above maximum number of hops information or the above maximum number of hops information minus one.

In one aspect of the invention, relay UE 702 or 703 may update all or part of a UE discovery solicitation information of a DISCOVERY SOLICITATION message when forwarding this information. In one example, when forwarding UE’s 701 UE discovery solicitation information received from relay UE 702 in DISCOVERY SOLICITATION message 712a, relay UE 703 may increment or decrement the hop count information in the multi -hop information. In one example, when forwarding UE’s 701 UE discovery solicitation information received from relay UE 702 in DISCOVERY SOLICITATION message 712a, relay UE 703 may update the multi-hop prohibited information in the multi-hop information. In one example, a relay UE 703 may do so if the value of the hop count information in UE’s 701 UE discovery solicitation information has reached the maximum number of hops to be supported by the UE 701 device. In one example, relay UE 703 may do so if the value of the hop count information has reached a zero value.

In one example, relay UE 703 will not forward in message 713 some UE discovery solicitation information associated to a UE for which the multi-hop support information or the multi-hop prohibited information indicates that the UE is not supporting multi-hop relaying.

In some examples, the sending of the discovery solicitation information through a discovery solicitation message is performed upon or as part of 5G ProSe UE-to-UE or UE-to- Network Discovery with Model B procedure.

In some examples, the sending of the discovery solicitation information through a discovery solicitation message is performed upon or as part of 5G ProSe UE-to-Network Discovery with Model B procedure. In such cases, the DISCOVERY SOLICITATION message sent by UE 701, such as message 711, or by relay UE 702, such as message 712b or 712a, or by relay UE 703, such as message 713, is the UE-to-Network Relay Discovery Solicitation message, as specified in 3GPP TS 23.304.

In one example, the sending of the discovery solicitation information through a discovery solicitation message is performed upon or as part of a 5G ProSe UE-to-UE Discovery with Model B procedure, in such cases, the DISCOVERY SOLICITATION message sent by UE 701, such as message 711, or by relay UE 702, such as message 712b or 712a, or by relay UE 703, such as message 713, is the UE-to-UE Relay Discovery Solicitation message, as specified in 3 GPP TS 23.304.

Upon reception of a discovery solicitation message (e.g., DISCOVERY SOLICITATION message 712b or 713), relay UE 704 may send back a DISCOVERY RESPONSE message 714a to relay UE 703 and a DISCOVERY RESPONSE message 714b to relay UE 702. In one example, the DISCOVERY RESPONSE message 714a or 714b may carry discovery response information.

The discovery response information carried in DISCOVERY RESPONSE message 714a or 714b may, in some examples, include a UE discovery response information, where a UE discovery response information includes at least one of:

A UE Identifier information, which identifies the UE to which the discovery response information is associated (here, UE 704);

RRC state information. This information indicates the RRC state of the UE 704;

A relaying connection information or relaying connectivity information. This information indicates the type of relaying connectivity, i.e., UE-to-Network (U2N) relaying or UE-to-UE (U2U) relaying, the relay UE 704 is capable of providing. In one example, the relaying connection information may include a U2N connection information, used by UE 704 to indicate that it is capable of connecting to the network, i.e., capable of performing UE-to-Network (U2N) relaying.

In one example, the relaying connection information may include a U2U connection information, used by UE 704 to indicate that it is capable of connecting with a specific target UE device, i.e., it is capable of performing UE-to-UE (U2U) relaying. In one example, the relaying connection information may include the identifier of the target UE device.

A multi-hop information. This information indicates if the above relaying connection information relates to a multi -hop relaying scheme (either U2U or U2N) or not, along with the characteristics of the multi-hop relaying scheme (if any).

In one example, the multi-hop information may include at least one of:

A hop count information. This information is used to provide the distance, in terms of hops, between the UE device identified by the UE Identifier information and a target, i.e., the network (in case of UE-to-Network relaying) or another UE device (in case of UE-to-UE relaying).

In one example, the hop count information in the UE discovery response information sent by relay UE 704 is based on the value of the hop count information in the UE 701’s UE discovery solicitation information previously received from relay UE 703 through DISCOVERY SOLICITATION message 713.

In one example, the hop count information in the UE discovery response information is equal to the value of the hop count information in the discovery solicitation information received from relay UE 703 or is equal to the value of the hop count information in the discovery solicitation information received from relay UE 703 incremented by one. This may apply to the case where the hop count value is to be incremented at relay UE level. For instance, the hop count value for UE 701’s UE discovery solicitation information was ‘2’ . The relay UE 704 may set the value of the hop count information in the UE discovery response information equal to ‘2’ or ‘3’.

In one example, the hop count information in the UE discovery response information is equal to the difference between the value of the maximum number of hops information and the value of the hop count information in the discovery solicitation information received from relay UE 703. This may apply to the case where the hop count value is set to the maximum number of hops value by the originating UE (e.g., UE 701) and is further decremented at relay UE level. For instance, the hop count value for UE 701’s UE discovery solicitation information was ‘2’ while the maximum number of hops value was ‘4’. The relay UE 704 may set the value of the hop count information in the UE discovery response information equal to ‘2’. In one example, the relay UE may set this value to ‘3’ to reflect the last hop between relay UE 704 and the target (i.e., the network or another UE).

A Path identifier information which is used to uniquely identify the multi-hop relay relaying path, i.e., the succession of the one or more relay UEs involved in the multihop relaying scheme or multi-hop relay relaying path.

A relay UE list information, or Relay routing table information. This information identifies the one or more UEs which are involved in the multi-hop relay relaying path. For instance, the relay UE 704 having received UE 701’s UE discovery solicitation information through relay UE devices 702 and 703 via DISCOVERY SOLICITATION messages 712a and 713 may add the identifiers of relay UE 702 and 703 to the Relay routing table information. In one example, the relay UE 704 may rely on the relay UE list information in the DISCOVERY SOLICITATION message 713 to set the Relay routing table information. In one example, the relay UE 704 may also add its own identifier to the Relay routing table information.

Upon reception of the DISCOVERY RESPONSE message 714a, relay UE 703 may send a DISCOVERY RESPONSE message 715 to relay UE 702.

In a similar way, upon reception of the DISCOVERY RESPONSE message 714b and / or DISCOVERY RESPONSE message 715, relay UE 702 may send a DISCOVERY RESPONSE message 716 to UE 701.

In one example, the UE discovery response information carried in DISCOVERY RESPON SE message 715 or 716a may include at least one UE discovery response information, as defined above in relation with message 714a or 714b.

In one example, the discovery response information carried in DISCOVERY RESPONSE message 716a may include at least one of:

UE discovery response information associated to relay UE 702.

UE discovery response information associated to other relay UE(s).

In one example, the discovery response information carried in DISCOVERY RESPONSE message 716a may include the UE discovery response information associated to relay UE 703, which was previously received in DISCOVERY RESPONSE message 715 and / or the UE discovery response information associated to UE 704, which was previously forwarded by relay UE 703 and received in DISCOVERY RESPONSE message 715.

In one example, relay UE 702 may send the UE discovery response information associated to relay UE 702 and the UE discovery response information associated to other UE(s), such as UE discovery response information associated to relay UE 704, in different DISCOVERY SOLICITATION messages (such as messages 716b or 716c on Figure 7).

In one example, when receiving from relay UE 704 (either directly through message 714b, or indirectly, through message 715) some UE discovery response indicating that relay UE 704 is capable of performing multi-hop relaying with a specific target; i.e., the network (multi-hop U2N) or a specific UE (multi-hop U2U), the relay UE 702 may send a single DISCOVERY RESPONSE message 716a to UE 701, indicating that relay UE 702 is capable of performing multi -hop relaying with the specific target; i.e., the network (multi -hop U2N) or a specific UE (multi-hop U2U). In such case, relay UE 702 may set the hop count information value in DISCOVERY RESPONSE message 716a to the value of the hop count information received from relay UE 704.

In some examples, the sending of the discovery response information through a discovery response message is performed upon or as part of 5G ProSe UE-to-UE or UE-to-Network Discovery with Model B procedure.

In some examples, the sending of the discovery response information through a discovery response message is performed upon or as part of 5G ProSe UE-to-Network Discovery with Model B procedure. In such cases, the DISCOVERY RESPONSE message sent by UE 704, such as message 714a or 714b, or by relay UE 703, such as message 715, or by relay UE 702, such as message 716a, 716b or 716c, is the UE-to-Network Relay Discovery Response message, as specified in 3GPP TS 23.304.

In one example, the sending of the discovery response information through a discovery response message is performed upon or as part of a 5G ProSe UE-to-UE Discovery with Model B procedure. In such cases, the DISCOVERY RESPONSE message sent by UE 704, such as message 714a or 714b, or by relay UE 703, such as message 715, or by relay UE 702, such as message 716a, 716b or 716c, is the UE-to-UE Relay Discovery Response message, as specified in 3GPP TS 23.304.

While the present invention has been described with reference to embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. It will be appreciated by those skilled in the art that various changes and modification might be made without departing from the scope of the invention, as defined in the appended claims. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that different features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be advantageously used.

In the preceding embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over, as one or more instructions or code, a computer-readable medium and executed by a hardware-based processing unit.

Computer-readable media may include computer-readable storage media, which corresponds to a tangible medium such as data storage media, or communication media including any medium that facilitates transfer of a computer program from one place to another, e.g., according to a communication protocol. In this manner, computer-readable media generally may correspond to (1) tangible computer-readable storage media which is non- transitory or (2) a communication medium such as a signal or carrier wave. Data storage media may be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, code and/or data structures for implementation of the techniques described in this disclosure. A computer program product may include a computer- readable medium.

By way of example, and not limitation, such computer-readable storage media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage, or other magnetic storage devices, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if instructions are transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. It should be understood, however, that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transient media, but are instead directed to non-transient, tangible storage media. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

Claims

1. A method for managing multi -hop relaying in a wireless communication system including a plurality of User Equipment, UE, and a network including a base station, the method at a UE of the plurality of UEs including: sending a message indicating a UE supports multi-hop relaying between a remote UE and a target node in the wireless communication system, the multi-hop relaying involving at least two relay UEs.

2. The method of claim 1, wherein sending a message includes sending a discovery message.

3. The method of claim 2, wherein the discovery message includes discovery information associated with the UE for indicating the capability of the UE to perform at least one of UE- to-Network, U2N, relaying with multi-hop and UE-to-UE, U2U, relaying with multi-hop.

4. The method of claim 2, wherein the discovery message includes discovery information associated with the UE including at least one of: relaying connectivity information for indicating the capability of the UE to perform at least one of UE-to-Network, U2N, relaying and UE-to-UE, U2U, relaying; multi-hop information for indicating whether the relaying indicated by the relaying connectivity information is associated with multi-hop relaying.

5. The method of claim 4, wherein the relaying connectivity information includes:

U2U connection information for indicating the UE is capable of U2U relaying to a specific target UE; identification information for identifying the specific target UE.

6. The method of claim 4 or claim 5, wherein the discovery information further includes at least one of: identification information for identifying the UE with which the discovery information is associated;

RRC state information for indicating a RRC state of the UE; relay UE information for identifying one or more other UEs of the plurality of UEs in the case where the UE has received discovery information from each of the one or more other UEs before sending the discovery message including the discovery information associated with the UE; neighbour UE information for identifying one or more UEs in proximity to the UE and with which the UE is capable of performing U2U relaying.

7. The method of claim 6, wherein at least one of the relay UE information and neighbour UE information includes for each UE at least one of: identification information for identifying the UE;

RRC state information for indicating a RRC state of the UE; multi-hop information indicating whether the UE supports multi-hop relaying; hop information indicating the number of hops between the UE and a target node; information indicating whether the UE is in coverage of a base station.

8. The method of any one of claims 2 to 7, wherein the discovery message includes discovery information associated with at least one other UE of the plurality of UEs for indicating, for each other UE of the at least one other UE, the capability of the other UE to perform at least one of UE-to-Network, U2N, relaying with multi-hop and UE-to-UE, U2U, relaying with multi-hop.

9. The method of any one of claims 3 to 7, wherein the discovery message includes discovery information associated with the at least one other UE including, for each other UE of the at least one other UE at least one of: relaying connectivity information for indicating the capability of the other UE to perform at least one of UE-to-Network, U2N, relaying and UE-to-UE, U2U, relaying; multi-hop information for indicating whether the relaying indicated by the relaying connectivity information is associated with multi-hop relaying.

10. The method of any one of claims 4, 5, 6, 7 or 9, wherein the multi -hop information includes at least one of: relaying information for indicating to which UE the relaying connectivity information is associated; hop information for indicating the number of hops between the UE and the UE to which the relaying connectivity information is associated; hop information for indicating the number of hops between the UE to which the relaying connectivity information is associated and the UE to which the discovery message is to be sent; prohibit information for indicating to another UE receiving the discovery information that the other UE cannot forward the discovery information to any other UE.

11. The method of claim 10, wherein the multi -hop information includes at least one of: hop information indicating the number of hops between the UE to which the relaying connectivity information is associated and a target node; path identification information for identifying a multi-hop relaying path; relay routing information for identifying one or more other UEs which are involved in the multi-hope relaying path.

12. The method of any one of claims 3 to 11, further comprising: receiving discovery information associated with at least one other UE of the plurality of UEs; updating the received discovery information to provide updated discovery information, wherein sending a discovery message includes sending a discovery message including the updated discovery information.

13. The method of claim 12, wherein updating includes updating at least part of the received discovery information.

14. The method of claim 11 and claim 10 or claim 12 and claim 10 or claim 13 and claim 10, wherein updating includes updating the number of hops included in the hop information.

15. The method of any one of claims 12 to 14, wherein updating includes adding discovery information associated with the UE to the received discovery information or updated received discovery information to provide the updated discovery information.

16. The method of any one of the preceding claims, wherein sending a message includes sending a discovery response message.

17. The method of claim 1 or claim 2, wherein sending a message includes sending a message including discovery solicitation information.

18. The method of any one of claims 1 to 15 or claim 17, wherein sending a message includes sending a discovery announcement message.

19. The method of claim 17 or claim 17 and claim 18, wherein the discovery solicitation information is associated with the UE and includes at least one of: relaying connection information for indicating the UE is seeking at least one of UE-to- Network, U2N, relaying and UE-to-UE, U2U, relaying; multi-hop information for indicating the UE is supporting multi-hop relaying.

20. The method of claim 19, wherein the relaying connection information includes:

U2U connection information for indicating the UE is seeking UE-to-UE, U2U, relaying to a specific target UE; identification information for identifying the specific target UE.

21. The method of any one of claim 17, or claim 17 and claim 18 or claim 19 or claim 20, wherein the discovery solicitation information is associated with at least one other UE including, for each other UE of the at least one other UE at least one of: relaying connection information for indicating the other UE is seeking at least one of UE- to-Network, U2N, relaying and UE-to-UE, U2U, relaying; multi-hop information for indicating the other UE is supporting multi-hop relaying.

22. The method of any one of claims 19 to 21, wherein the discovery solicitation information further includes: identification information for identifying the UE to which the discovery solicitation information is associated;

RRC state information for indicating a RRC state of the UE; relay UE information for identifying one or more other UEs of the plurality of UEs in the case where each of the one or more other UEs have forwarded at least some discovery information included in the discovery solicitation information associated with the UE.

23. The method of claim 22, wherein the relay UE information includes for each UE of the one or more other UEs: identification information for identifying the UE; RRC state information for indicating a RRC state of the UE; multi-hop information indicating whether the UE supports multi-hop relaying; hop information indicating the number of hops between the UE and a target node; information indicating whether the UE is in coverage of a base station.

24. The method of any one of claims 19 to 23, wherein the multi-hop information includes at least one of: multi-hop support information for indicating the UE is supporting multi-hop relaying; maximum hop information for indicating the maximum number of hops, supported by the UE, between the UE and a target node; hop information for indicating to another UE receiving the discovery solicitation information the number of hops to the other UE; authorization information for indicating to another UE receiving the discovery solicitation information that the other UE can forward the discovery solicitation information; prohibit information for indicating to another UE receiving the discovery solicitation information that the other UE cannot forward the discovery solicitation information to any other UE.

25. The method of any one of claims 19 to 24, further comprising: receiving discovery solicitation information associated with at least one other UE of the plurality of UEs; updating the received discovery solicitation information to provide updated discovery solicitation information, wherein sending a discovery solicitation message includes sending a discovery solicitation message including the updated discovery solicitation information.

26. The method of claim 25, wherein updating includes updating at least part of the received discovery solicitation information.

27. The method of claim 25 or claim 26, wherein updating includes updating the number of hops included in the hop information.

28. The method of any one of claims 25 to 27, wherein updating includes adding discovery solicitation information associated with the UE to the received discovery solicitation information or updated received discovery solicitation information to provide the updated discovery solicitation information.

29. The method of any one of the preceding claims, wherein sending a message comprises sending a message after a trigger.

30. The method of claim 29, wherein the trigger includes at least one of: link quality of at least one link to the UE meets a certain condition; reception of multi-hop information; reception of a discovery message; timing information.

31. The method of any one of the preceding claims, wherein the target node is another UE of the plurality of UEs.

32. The method of any one of the claims 1 to 30, wherein the target node is the base station.

33. A computer program comprising instructions which, when the program is executed by one or more processing units, cause the one or more processing units to carry out the method according to any one of claims 1 to 32.

34. A computer-readable medium carrying a computer program according to claim 33.

35. Apparatus for a User Equipment, UE, for a wireless communication system including a plurality of UEs and a network, the apparatus comprising: one or more processing units and configured to perform the method as recited in any one of claims 1 to 32.