Improvements in and relating to multi-hop user equipment-to-network relay communication

Abstract

A method to provide multi-hop communications between a Remote User Equipment (UE) and a telecommunication network, where the communication is conducted via a ProSe Intermediate Relay and a ProSe UE-to-Network Relay comprising the steps of authorising and provisioning service at the telecommunication network, establishing a PDU session for relaying communications, the Remote UE performing discovery of ProSe UE-to-Network Relay, the Remote UE selecting ProSe UE-to-Network Relay to establish end-to-end connection for unicast mode communication to the telecommunication network via the ProSe Intermediate Relay and the ProSe UE-to-Network Relay, the ProSe UE-to-Network Relay assigning IP addresses to the ProSe Intermediate Relay and the Remote UE, the Remote UE providing Quality of Service (QoS) info to the UE-to-Network Relay using a link modification procedure, and the ProSe UE-to-Network Relay that connects to the telecommunication network sends a Remote UE Report message to a Session Management Function (SMF) of the telecommunication network for the established PDU Session. The QoS Flow and rules may be generated the SMF based on which the UE-to-Network Relay may determine end-to-end PC5 QoS parameters.

Description

Fifth Generation, 5G, Proximity Services, ProSe, or communications have been supported by 3GPP specifications since Rel-17. Before Rel-19, 5G ProSe Direct Communication, single-hop 5G ProSe UE-to-Network Relay Communication (one relay only), single-hop 5G ProSe UE-to-UE Relay Communication (one relay only) were supported for both Layer-2 and Layer-3 relay scenarios. The procedures to support the discovery and communication via User Equipment-to-User, U2U, User Equipment to a network, U2N, and direct communication were specified. For different relaying scenarios of 5G ProSe, e.g. 5G ProSe UE-to-Network relay Discovery and 5G ProSe direct Discovery, 5G ProSe UE-to-UE relay Discovery both discovery Model A and Model B are applicable. Model A uses a single discovery protocol message (Announcement). Model B uses two discovery protocol messages (Solicitation and Response). Herein the procedure for 5G ProSe UE-to-UE Discovery is used as an example. The 5G ProSe UE-to-UE Discovery with Model A are shown in Figure 1 (taken from Figure 6.3.2.4.2-1: 5G ProSe UE-to-UE Relay Discovery with Model A of TS 23.304). The procedures are detailed in clause 6.3.2.4.2 of TS 23.304, as follows: “1. The 5G ProSe UE-to-UE Relay has discovered other UEs in proximity (e.g. via a previous 5G ProSe UE-to-UE Relay Discovery or 5G ProSe UE-to-UE Relay Communication procedures). The 5G ProSe UE-to-UE Relay obtains the User Info ID of other UEs in proximity per RSC. 2. The 5G ProSe UE-to-UE Relay sends a UE-to-UE Relay Discovery Announcement message. The UE-to-UE Relay Discovery Announcement message contains the Type of Discovery Message, User Info ID of the 5G ProSe UE-to-UE Relay, RSC and list of User Info ID of the 5G ProSe End UEs supporting the RSC. The UE-to-UE Relay Discovery Announcement message is sent using the Source Layer-2 ID and Destination Layer-2 ID as described in clause 5.8.4. The 5G ProSe UE-to-UE Relay shall only announce User Info IDs of other UEs in proximity that did not include an Announce Prohibited Indication when they were previously discovered. A 5G ProSe End UE monitors announcement messages from a 5G ProSe UE-to-UE Relay. The 5G ProSe End UEs determine the Destination Layer-2 ID for signalling reception as specified in clause 5.1. ’’ Figure 2 shows 5G ProSe UE-to-UE Relay Discovery with Model B of TS 23.304. The procedures are detailed in clause 6.3.2.4.3 of TS 23.304, as follows: “1. The discoverer 5G ProSe End UE (UE-1) sends a 5G ProSe UE-to-UE Relay Discovery Solicitation message. The 5G ProSe UE-to-UE Relay Discovery Solicitation message contains the Type of Discovery Message, User Info ID of itself, RSC and User Info ID of the discoveree 5G ProSe End UE (UE-2) and is sent using the Source Layer-2 ID and Destination Layer-2 ID as described in clause 5.8.4. A 5G ProSe UE-to-UE Relay determines the Destination Layer-2 ID for signalling reception as specified in clause 5.1. The discoverer 5G ProSe End UE may include an Announce Prohibited Indication in the UE-to-UE Relay Discovery Solicitation message. If a 5G ProSe UE-to-UE Relay receives a Relay Discovery Solicitation message with an Announce Prohibited Indication it does not consider the 5G ProSe End UE as discovered during this procedure for inclusion in 5G ProSe UE-to-UE Relay Discovery with Model A, see clause 6.3.2.4.2, step 1. 2. If the RSC contained in the solicitation message matches any of the (pre)configured RSC(s), as specified in clause 5.1.5.1, of a 5G ProSe UE-to-UE Relay, the 5G ProSe UE-to-UE Relay sends a 5G ProSe UE-to-UE Relay Discovery Solicitation message. The 5G ProSe UE-to-UE Relay Discovery Solicitation message contains the Type of Discovery Message, User Info ID of the discoverer 5G ProSe End UE (UE-1), User Info ID of UE-to-UE Relay, RSC and User Info ID of the discoveree 5G ProSe End UE (UE-2) and is sent using the Source Layer-2 ID and Destination Layer-2 ID as described in clause 5.8.4. A 5G ProSe End UE determines the Destination Layer-2 ID for signalling reception as specified in clause 5.1. 3. If the RSC contained in the solicitation message matches any of the (pre)configured RSC(s), as specified in clause 5.1.5.1, of the discoveree 5G ProSe End UE (UE-2), and the discoveree 5G ProSe End UE (UE-2) matches the User Info ID of the discoveree 5G ProSe End UE (UE-2) contained in the solicitation message, then the discoveree 5G ProSe End UE (UE-2) responds to the 5G ProSe UE-to-UE Relay with a 5G ProSe UE-to-UE Relay Discovery Response message. The 5G ProSe UE-to-UE Relay Discovery Response message contains the Type of Discovery Message, RSC, User Info ID of the discoverer 5G ProSe End UE (UE-1) and User Info ID of discoveree 5G ProSe End UE (UE-2) and is sent using the Source Layer-2 ID and Destination Layer-2 ID as described in clause 5.8.4. If the discoveree 5G ProSe End UE (UE-2) receives multiple UE-to-UE Relay Discovery Solicitation messages from different 5G ProSe UE-to-UE Relays with the same RSC and the User Info ID of the discoveree 5G ProSe End UE (UE-2), it may choose to respond or not to a 5G ProSe UE-to-UE Relay (e.g. based on the PC5 signal strength of each message received). The discoveree 5G ProSe End UE may include an Announce Prohibited Indication in the UE-to-UE Relay Discovery Response message. If a 5G ProSe UE-to-UE Relay receives a Relay Discovery Response message with an Announce Prohibited Indication it does not consider the 5G ProSe End UE as discovered during this procedure for inclusion in 5G ProSe UE-to-UE Relay Discovery with Model A, see clause 6.3.2.4.2, step 1. 4. The 5G ProSe UE-to-UE Relay sends a 5G ProSe UE-to-UE Relay Discovery Response message. The 5G ProSe UE-to-UE Relay Discovery Response message contains the Type of Discovery Message, User Info ID of UE-to-UE Relay, RSC, User Info ID of the discoverer 5G ProSe End UE (UE-1) and User Info ID of the discoveree 5G ProSe End UE (UE-2) and is sent using the Source Layer-2 ID and Destination Layer-2 ID as...” After the discovery procedures are performed or without performing the discovery procedures in some scenarios, the ProSe communication establishment might be triggered. In the prior art specification, the ProSe communication in different scenarios include: 5G ProSe Direct Communication, e.g. Broadcast, Groupcast, Unicast mode 5G ProSe Direct Communication 5G ProSe UE-to-Network Relay Communication, e.g. unicast 5G ProSe UE-to-Network Relay Communication 5G ProSe UE-to-UE Relay Communication, supported by enhanced Unicast mode 5G ProSe Direct Communication. In general, for the unicast mode 5G ProSe communication, the layer-2 link (end-to-end link) should be established, e.g. over the PC5 reference point for direct communication and 5G ProSe UE-to-UE Relay, over the PC5 and uu link for 5G ProSe UE-to-Network Relay Communication. An example of 5G ProSe Communication via 5G ProSe Layer-3 UE-to-Network Relay without N3IWF is shown in Figure 3.The procedures are detailed in clause 6.5.1.1 of TS 23.304, as follows: “1. Service authorization and provisioning are performed for the 5G ProSe Layer-3 UE-to-Network Relay (step 1a) and 5G ProSe Layer-3 Remote UE (step 1b) as described in clause 6.2. 2. The 5G ProSe Layer-3 UE-to-Network Relay may establish a PDU Session for relaying. In the case of IPv6, the 5G ProSe Layer-3 UE-to-Network Relay obtains the IPv6 prefix via prefix delegation function from the network as defined in TS 23.501 [4], NOTE 1: 5G ProSe Layer-3 UE-to-Network Relay can establish a PDU Session for any Relay Service Code it supports before the connection is established with the 5G ProSe Layer-3 Remote UE. 3. The 5G ProSe Layer-3 Remote UE performs discovery of a 5G ProSe Layer-3 UE-to-Network Relay as described in clause 6.3.2.3. As part of the discovery procedure the 5G ProSe Layer-3 Remote UE learns about the connectivity service the 5G ProSe Layer-3 UE-to-Network Relay provides. 4. The 5G ProSe Layer-3 Remote UE selects a 5G ProSe Layer-3 UE-to-Network Relay and establishes a connection for unicast mode communication as described in clause 6.4.3.6. If there is no PDU Session associated with the Relay Service Code or a new PDU Session for relaying is needed, the 5G ProSe Layer-3 UE-to-Network Relay initiates a new PDU Session establishment procedure for relaying before completing the PC5 connection establishment. When the 5G ProSe Layer-3 Remote UE sends the Direct Communication Request message including the dedicated emergency RSC, the 5G ProSe Layer-3 UE-to-Network Relay sets up an emergency PDU session for relaying the emergency service if there is not an emergency PDU Session established in step 2. The network decides that the PDU Session to be established is for relay traffic and then generates the QoS rules and QoS Flow level QoS parameters to 5G ProSe Layer-3 UE-to-Network Relay with relay consideration and can initiate the setup of QoS flows as specified in clause 5.6.2.1. The Remote UE can also initiate the setup of QoS flows by providing PC5 QoS info and (optionally) PC5 QoS rule(s) to the 5G ProSe Layer-3 UE-to-Network Relay during connection setup, according to the procedure as specified in clause 5.6.2.1. The 5G ProSe Layer-3 UE-to-Network Relay determines the PDU Session type for relaying as specified in clause 5.4.1.1. According to the PDU Session Type for relaying, the 5G ProSe Layer-3 UE-to-Network Relay performs relaying function at the corresponding layer as follows: When the IP type PDU Session is used for IP traffic over PC5 reference point, the 5G ProSe Layer-3 UE-to-Network Relay acts as an IP router. For IPv4, the 5G ProSe Layer-3 UE-to-Network Relay performs IPv4 NAT between IPv4 addresses assigned to the 5G ProSe Layer-3 Remote UE and the IPv4 address assigned to the PDU Session used for the relay traffic. When the Ethernet type PDU Session is used for Ethernet traffic over PC5 reference point, the 5G ProSe Layer-3 UE-to-Network Relay acts as an Ethernet switch. When the Unstructured type PDU Session is used for Unstructured traffic over PC5 reference point, the 5G ProSe Layer-3 UE-to-Network Relay performs traffic relaying based on a mapping between the PC5 Link Identifier and the PDU Session ID and a mapping between PFI for PC5 Layer-2 link and the QFI for the PDU Session. These mappings are created when the Unstructured type PDU Session is established for the 5G ProSe Layer-3 Remote UE. When the IP type PDU Session is used for Ethernet or Unstructured traffic over PC5 reference point, the 5G ProSe Layer-3 UE-to-Network Relay uses IP tunnelling. For this IP tunnelling, the 5G ProSe Layer-3 UE-to-Network Relay locally assigns an IP address / prefix for the 5G ProSe Layer-3 Remote UE and uses it on the Uu reference point to encapsulate and decapsulate the uplink and downlink traffic for the 5G ProSe Layer-3 Remote UE. The tunnelled traffic over Uu reference point is transported over the PC5 reference point as Ethernet or Unstructured traffic. 5. For IP PDU Session Type and IP traffic over PC5 reference point, IPv6 prefix or IPv4 address (including NAT case) is allocated for the 5G ProSe Layer-3 Remote UE as defined in clause 5.5.1.3. 6. The 5G ProSe Layer-3 Remote UE may provide PC5 QoS Info and PC5 QoS rule(s) to the 5G ProSe Layer-3 UE-to-Network Relay using Layer-2 link modification procedure as specified in clause 6.4.3.4. The 5G ProSe Layer-3 UE-to-Network Relay generates the Packet Filters used over Uu interface based on the received PC5 QoS info and QoS Rule(s) as described in clause 5.6.2.1 and may perform the UE requested PDU Session Modification as defined in TS 23.502 [5] clause 4.3.3 to setup a new QoS Flow or bind the traffic to an existing QoS Flow. From this point the uplink and downlink relaying can start. For downlink traffic forwarding, the PC5 QoS Rule is used to map the downlink packet to the PC5 QoS Flow. For uplink traffic forwarding, the 5G QoS Rule is used to map the uplink packet to the Uu QoS Flow. 7. The 5G ProSe Layer-3 UE-to-Network Relay shall send a Remote UE Report (Remote User ID, Remote UE info) message to the SMF for the PDU Session associated with the relay. The Remote User ID, as defined in TS 33.503

[29] , is an identity of the 5G ProSe Layer-3 Remote UE user that was successfully connected in step 4. The Remote UE info is used to assist identifying the 5G ProSe Layer-3 Remote UE in the 5GC. For IP PDU Session Type, the Remote UE info is Remote UE IP info. For Ethernet PDU Session Type, the Remote UE info is Remote UE MAC address which is detected by the 5G ProSe Layer-3 UE-to-Network Relay. For Unstructured PDU Session Type, the Remote UE info is not included. The SMF stores the Remote User IDs and the related Remote UE info in the 5G ProSe Layer-3 UE-to-Network Relay's SM context for this PDU Session associated with the relay. The Remote UE Report is N1 SM NAS message sent with the PDU Session ID to the AMF, in turn delivered to the SMF. ” In order to maintain the end-to-end service quality of relay services or relaying traffic, the Quality of Service, QoS, handling of layer-3 and layer-2 relays are specified by SA2. But the QoS handling of layer-2 relays are more in charge of Radio Access Network, RAN, RAN Working Groups, WGs. QoS handling for 5G ProSe Layer-3 UE-to-Network Relay without N3IWF is specified in clause 5.6.2.1 of TS 23.304, as follows, with reference to Figure 4 of the attached figures: “For a 5G ProSe Layer-3 Remote UE accessing network via 5G ProSe Layer-3 UE-to-Network Relay without N3IWF, the QoS requirement of the relay traffic between 5G ProSe Layer-3 Remote UE and UPF can be satisfied by the corresponding QoS control for the PC5 link between 5G ProSe Layer-3 Remote UE and 5G ProSe Layer-3 UE-to-Network Relay (PC5 QoS control) and the QoS control for the PDU session established between 5G ProSe Layer-3 UE-to-Network Relay and UPF (i.e. Uu QoS control). The PC5 QoS is controlled with PC5 QoS rules and PC5 QoS parameters (e.g. PQI, GFBR, MFBR, PC5 LINK-AMBR) as specified in clause 5.4 of TS 23.287 [2]. The QoS for the PDU session established between the 5G ProSe Layer-3 UE-to-Network Relay and UPF (i.e. Uu QoS control) is controlled with QoS rules and 5G QoS parameters (e.g. 5QI, GFBR, MFBR. As shown in Figure 4 Figure 5.6.2.2-1: End-to-End QoS support via Layer-3 UE-to-Network Relay with N3IWF of TS 23.304, the end-to-end QoS can be met only when the QoS requirements are properly translated and satisfied over the two legs respectively. To achieve this, the QoS mapping can be pre-configured or provided to the 5G ProSe Layer-3 UE-to-Network Relay by the PCF using Prose Policy. The QoS mapping includes combinations of the 5Qls and PQIs mapping as entries. The PQI shall have standardized values as defined in Table 1 Table 5.6.1-1: Standardized PQI values that are additionally defined to QoS characteristics mapping pf TS 23.304 and Table 5.4.4-1 ofTS 23.287.” The table 5.6.1-1 referred to above is reproduced as Figure 5 in the attached figures. If the QoS Flows setup are initiated by network, then: “the SMF can base on the PCC rules or its local configuration to generates the QoS rules and QoS Flow level QoS parameters (e.g. 5QI, GFBR, MFBR) and signal to the 5G ProSe Layer-3 UE-to-Network Relay using PDU Session Establishment / Modification procedure. For the PDU sessions used for relaying, the SMF always provides the QoS Flow level QoS parameters to the 5G ProSe Layer-3 UE-to-Network Relay when establishes a QoS Flow. Then the 5G ProSe Layer-3 UE-to-Network Relay decides the PC5 QoS parameters for the corresponding PC5 QoS Flow by determining the PQI based the QoS mapping and the GFBR and MFBR values for the PC5 GBR QoS Flow are set equal to the GFBR and MFBR values for the GBR QoS Flow respectively. The PCF differentiates the relay traffic based on either local configuration, e.g.by a dedicated DNN or S-NSSAi used for relay traffic or by the traffic filters. ” If the 5G ProSe Layer-3 Remote UE initiates PC5 QoS Flows setup or modification during the Layer-2 link establishment or modification procedure: “the 5G ProSe Layer-3 Remote UE provides the QoS Info as described in clause 6.4.3.6 of TS 23.304 to the 5G ProSe Layer-3 UE-to-Network Relay. The received PC5 QoS parameters of the QoS Info (i.e. PQI and conditionally other parameters such as MFBR / GFBR, etc.) are interpreted as the end-to-end QoS requirements by the 5G ProSe Layer-3 UE-to-Network Relay for the traffic transmission between 5G ProSe Layer-3 Remote UE and UPF. If the end-to-end QoS requirements can be supported by an entry in QoS mapping, the 5G ProSe Layer-3 UE-to-Network Relay uses the 5QI of the entry for the Uu QoS control and uses the PQI of the entry for the PC5 QoS control. If the end-to-end QoS requirements cannot be supported by any entries in QoS mapping, the 5G ProSe Layer-3 UE-to-Network Relay, based on its implementation, decides the 5QI for the Uu QoS control and PQI for the PC5 QoS control. The 5G ProSe Layer-3 UE-to-Network Relay provides the QoS Info (including PQI value chosen by the 5G ProSe Layer-3 UE-to-Network Relay) as part of the Accept message to the 5G ProSe Layer-3 Remote UE. If the 5G ProSe Layer-3 Remote UE performs the Layer-2 link modification procedure to add new PC5 QoS Flow(s) or modify the existing PC5 QoS Flow(s) for IP traffic or Ethernet traffic over PC5 reference point, the 5G ProSe Layer-3 Remote UE may also provide the PC5 QoS Rule(s) for the PC5 QoS Flow(s) to be added or modified to the 5G ProSe Layer-3 UE-to-Network Relay. The 5G ProSe Layer-3 UE-to-Network Relay may generate the Packet Filters used over Uu reference point based on the received PC5 QoS Rule(s). The 5G ProSe Layer-3 UE-to-Network Relay performs the UE requested PDU session Modification as defined in TS 23.502, clause 4.3.3 for authorizing the requested QoS including the 5QI and the Packet Filters. If the PCF authorizes the requested QoS with a different 5QI value, the 5G ProSe Layer-3 UE-to-Network Relay may further update the PQI value based on the authorized 5QI value and the 5G ProSe Layer-3 UE-to-Network Relay performs the Layer-2 link modification procedure as defined in clause 6.4.3.6 to update the corresponding PC5 QoS Flow with the updated PQI value. ” QoS handling for 5G ProSe Layer-3 UE-to-UE Relay is specified in clause 5.6.3.1 of TS 23.304, as follows: “For a 5G ProSe Layer-3 End UE connecting with another 5G ProSe Layer-3 End UE(s) via 5G ProSe Layer-3 UE-to-UE Relay, the QoS requirement of the relay traffic between the peer 5G ProSe Layer-3 End UE(s) can be satisfied by the corresponding QoS control for the PC5 link between source 5G ProSe Layer-3 End UE and 5G ProSe Layer-3 UE-to-UE Relay (i.e. first hop PC5 QoS control) and the QoS control for the PC5 link between 5G ProSe Layer-3 UE-to-UE Relay and target 5G ProSe Layer-3 End UE (i.e. second hop PC5 QoS control). The first hop PC5 QoS and second hop PC5 QoS is controlled with PC5 QoS rules and PC5 QoS parameters (e.g. PQI, GFBR, MFBR, PC5 LINK-AMBR) as specified in clause 5.6.1. As shown in figure 5.6.3.1-1 below, the end-to-end QoS is met only when the QoS requirements are properly translated and satisfied over the two legs respectively. ” Figure 5.6.3.1-1 is reproduced as Figure 6 of the attached figures. “To achieve this, the source 5G ProSe Layer-3 End UE initiates PC5 QoS Flows setup or modification during the Layer-2 link establishment or modification procedure, the source 5G ProSe Layer-3 End UE provides the QoS Info as described in clause 6.4.3.7.3 to the 5G ProSe Layer-3 UE-to-UE Relay. The received PC5 QoS parameters of the QoS Info (i.e. PQI and conditionally other parameters such as MFBR / GFBR, etc.) are interpreted as the end-to-end QoS requirements by the 5G ProSe Layer-3 UE-to-UE Relay for the traffic transmission between source 5G ProSe Layer-3 End UE and target 5G ProSe Layer-3 End UE. The source 5G ProSe Layer-3 End UE derives the end-to-end QoS parameters as defined in clause 5.6.1. The 5G ProSe Layer-3 UE-to-UE Relay, based on its implementation, decides the PQI for the first hop PC5 QoS control and the PQI for the second hop PC5 QoS control, by considering the received PC5 QoS parameters from the source 5G ProSe Layer-3 End UE. The 5G ProSe Layer-3 UE-to-UE Relay provides the QoS Info (including PQI value chosen by the 5G ProSe Layer-3 UE-to-UE Relay for the second hop) to the target 5G ProSe Layer-3 End UE. After accepted QoS Info of the second hop QoS from the target 5G ProSe Layer-3 End UE is received, 5G ProSe Layer-3 UE-to-UE Relay provides the QoS Info (including PQI value chosen by the 5G ProSe Layer-3 UE-to-UE Relay for the first hop) to the source 5G ProSe Layer-3 End UE with considering the received second hop QoS. If the source 5G ProSe Layer-3 End UE performs the Layer-2 link modification procedure to add new PC5 QoS Flow(s) or modify the existing PC5 QoS Flow(s) for IP traffic or Ethernet traffic over PC5 reference point, the source 5G ProSe Layer-3 End UE may also provide the PC5 QoS Rule(s) for the PC5 QoS Flow(s) to be added or modified to the 5G ProSe Layer-3 UE-to-UE Relay. The 5G ProSe Layer-3 UE-to-UE Relay may generate the Packet Filters used over the second hop based on the received PC5 QoS Rule(s). ” New Study Item, SID, on System Enhancement for Proximity-based Services in 5GS - Phase 3 was approved in SP-231798 during SA102 (Dec. 2023). The objective includes: The study item aims at further investigating 5G System enhancements to support Proximity Services (beyond what has been specified in Rel-17 and Rel-18) considering the services requirements defined in TS 22.278, TS 22.261 and TS 22.115. The detailed objectives are to investigate potential 5GS enhancements in order to support the following: WT-1: Enhance ProSe to support multi-hop over NR PC5 reference point WT-1.1: for UE-to-Network Relay WT-1.2: for UE-UE Relay NOTE 1: The UE-to-Network Relay include both Layer-3 and Layer-2 Relays. UE-to-UE Relay include L3 Relay only. NOTE 2: This study requires coordination with RAN M / Gs. In SA2 160ah e-meeting, the Key issue description of the above WTs are agreed as Kl#1 and Kl#2 separately. For WT-1.1: for UE-to-Network Relay, the KI description includes: This key issue focuses on architecture enhancements to support 5G ProSe multi-hop Layer-3 and Layer-2 UE-to-Network Relay over NR PC5 reference point. This key issue addresses scenarios where multi-hop UE-to-Network Relay(s) are in coverage and out ofcoverage. Aspects such as support for single-hop relay discovery, selection, authorization, connection establishment and data transfer for ProSe UE-to-Network Relay have been addressed in previous releases and some of those aspects may need to be enhanced to support multi-hop extensions. In Release 19, at least the following aspects need to be studied in potential solutions: Whether and how to support the authorization of multi-hop UE-to-Network Relay and Remote UE authorization and policy and parameter provisioning. Whether and how to support the multi-hop UE-to-Network Relay discovery. Whether and how to perform multi-hop UE-to-Network Relay (re-)selection. Whether and how to enhance the existing mechanisms for IP address / prefix allocation to support Layer-3 multi-hop UE-to-Network Relay. Whether and how to control the maximum number of hops supported when using multi-hop Layer-3 UE-to-Network relays. NOTE 1: For multi-hop Layer-2 UE-to-Network relays, the control of the maximum number of hops is in the scope of RAN l / l / Gs and alignment work (if any) will be made by SA WG2 based on RAN WGs conclusions. How to manage multi-hop PC5 links, at least including how to establish, modify and release Layer-2 link over PC5 reference point for multi-hop UE-to-Network Relays. Whether and how to support end-to-end QoS requirements between Remote UE and the network via multi-hop Layer-3 UE-to-Network Relay. NOTE 2: For multi-hop Layer-2 UE-to-Network relays, the support of end-to-end requirements between Remote UE and the network is in the scope by RAN M / Gs and alignment work (if any) will be made by SA WG2 based on RAN l / l / Gs conclusions. NOTE 3: Security and privacy aspects will be handled by SA I / I / G3. For VVT-1.2: for UE-to-UE Relay, the KI description includes: This key issue focuses on architecture enhancements to support ProSe multi-hop Layer-3 UE-to-UE Relay over NR PC5 reference point. This key issue intends to support multihop Layer-3 UE-to-UE Relays for in coverage and out of coverage operation. Aspects such as support for relay discovery, selection, authorization, connection establishment and data transfer for single hop ProSe UE-to-UE Relay have been addressed in previous releases and some of those aspects may need to be enhanced to support multi-hop extension. In Release 19, at least the following aspects need to be studied in potential solutions: Whether and how to enhance the existing mechanisms for multi-hop UE-to-UE Relay discovery. Whether and how to enhance the existing mechanisms for IP address / prefix allocation. Whether and how to control the maximum number of hops supported when using multi-hop UE-to-UE relays. Whether and how to support path changes or Relay (re)selections, e.g., in the case one or more UE-to-UE Relays become unavailable / suitable. Whether and how to support the network control 5G ProSe multi-hops UE-to-UE Relay operations, including at least, authorization, policy and parameters provisioning etc. How to manage multi-hop PC5 links, at least including how to establish, modify and release Layer-2 link over PC5 reference point for multi-hop UE-to-UE Relays. How to establish the connection between source UE and target UE via multiple 5G ProSe UE-to-UE Relays. How to satisfy end-to-end QoS requirements for the End UEs over the path via 5G ProSe multi-hop UE-to-UE Relays, if needed. In clause 5.1 of TR 23.700-03, the key issue description of Kl#1 Support of multi-hop UE-to-Network Relays include: Whether and how to support the authorization of multi-hop UE-to-Network Relay and Remote UE authorization and policy and parameter provisioning. Whether and how to support the multi-hop UE-to-Network Relay discovery. Whether and how to perform multi-hop UE-to-Network Relay (re-)selection. Whether and how to enhance the existing mechanisms for IP address / prefix allocation to support Layer-3 multi-hop UE-to-Network Relay. Whether and how to control the maximum number of hops supported when using multi-hop Layer-3 UE-to-Network relays. How to manage multi-hop PC5 links, at least including how to establish, modify and release Layer-2 link over PC5 reference point for multi-hop UE-to-Network Relays. Whether and how to support end-to-end QoS requirements between Remote UE and the network via multi-hop Layer-3 UE-to-Network Relay. In clause 5.2 of TR 23.700-03, the key issue description of Kl#1 Support of multi-hop UE-to-UE Relays include: Whether and how to enhance the existing mechanisms for multi-hop UE-to-UE Relay discovery. Whether and how to enhance the existing mechanisms for IP address / prefix allocation. Whether and how to control the maximum number of hops supported when using multi-hop UE-to-UE relays. Whether and how to support path changes or Relay (re)selections, e.g., in the case one or more UE-to-UE Relays become unavailable / suitable. Whether and how to support the network control 5G ProSe multi-hops UE-to-UE Relay operations, including at least, authorization, policy and parameters provisioning etc. How to manage multi-hop PC5 links, at least including how to establish, modify and release Layer-2 link over PC5 reference point for multi-hop UE-to-UE Relays. How to establish the connection between source UE and target UE via multiple 5G ProSe UE-to-UE Relays. How to satisfy end-to-end QoS requirements for the End UEs over the path via 5G ProSe multi-hop UE-to-UE Relays, if needed. It is an aim of embodiments of the present invention to address these issues and others not referred to herein. According to the present invention there is provided an apparatus and method as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows. According to a first aspect of the present invention, there is provided a method of operating a system to provide multi-hop communications between a Remote User Equipment, UE, and a telecommunication network, where the communication is conducted via at least one ProSe Intermediate Relay and a ProSe UE to network relay, disposed between the Remote UE and the telecommunication network, comprising the steps of: • authorising and provisioning service at the telecommunication network; • establishing a PDU session for relaying communications; • the Remote UE performing discovery of at least one ProSe UE-to-Network Relay; • the Remote UE selecting at least one ProSe UE-to-Network Relay to establish end-to-end connection for unicast mode communication to the telecommunication network via the at least one ProSe Intermediate Relay and the ProSe UE-to-Network Relay; • the ProSe UE to Network Relay assigning IP addresses to the at least one ProSe intermediate relay and the Remote UE; • the Remote UE providing QoS info to the UE-to-Network Relay using a link modification procedure; and • the ProSe UE-to-Network Relay that connects to the telecommunication network sending a Remote UE Report message to a Session Management Function, SMF, of the telecommunication network for the established PDU Session. In an embodiment, QoS flows are initiated by either the telecommunication network or the Remote UE. In an embodiment, wherein if the QoS flows are initiated by the telecommunication network, then a Session Management Function, SMF, based on Policy and Charging Control, PCC, rules or its local configuration, generates QoS rules and QoS Flow level QoS parameters and signals these to the ProSe UE to Network relay. In an embodiment, based upon the QoS rules and QoS Flow level QoS parameters the ProSe UE to Network relay determines end to end PC5 QoS parameters for a corresponding PC5 QoS flow, based on a QoS mapping. In an embodiment, a number of hops to the Remote UE is taken into account. In an embodiment, the UE to network relay provides information to a next hop ProSe intermediate relay. In an embodiment, the information comprises end-to-end PC5 QoS information, a maximum PC5 Packet Delay Budget, PDB, and the generated PC5 QoS Flow parameters. In an embodiment, a further next hop ProSe intermediate relay determines PC5 Flow QoS parameters for a next hop PC5 link towards the 5G ProSe Layer-3 Remote UE. In an embodiment, if the QoS flows are initiated by the Remote UE, then the Remote UE provides QoS information to the ProSe UE to network relay via the at least one ProSe intermediate relay. In an embodiment, the QoS information is interpreted as end-to-end QoS requirements for traffic transmission between Remote UE and the telecommunication network. In an embodiment, the UE-to-Network Relay determines 5QI for Uu QoS control and PQI for end-to-end PC5 QoS control based on a QoS mapping. In an embodiment, the Remote UE is a 5G ProSe Remote UE, the at least one ProSe Intermediate Relay is at least one 5G ProSe intermediate relay and the ProSe UE to network relay is a 5G ProSe UE to network relay. In an embodiment, QoS mapping may be pre-configured to provided to the ProSe UE to network relay by a PCF in the telecommunication network. In an embodiment, QoS mapping is performed, making use of an adjustment factor, taking to account a number of hops between the remote UE and the telecommunication network. According to a second aspect of the present invention, there is provided a system arranged to perform the method of the first aspect, comprising at least one Remote UE, at least one ProSe intermediate relay, at least one ProSe UE to network relay and a telecommunication network. Embodiments of the invention provide support for multi-hop UE-to-Network Relays, in particular focusing on the enhancements to the existing framework of 5G ProSe Communication via 5G ProSe Layer-3 UE-to-Network Relay to support the multi-hop scenarios, by supporting the communication establishment procedures with introducing one or more intermediate relay between the remote and ue-to-network relay. The QoS handling mechanism for single-hop UE-to-Network Relay scenarios is also enhanced to support the end-to-end QoS between the 5G ProSe Remote and the network via more than one relays, by supporting Qos handling and transmission procedures in multi-hop U2N relay scenarios. Throughout this application, embodiments referring to “relay”, may refer to layer-2 and / or layer-3 relay. Remote UE may indicate layer-2 and / or layer-3 remote UE. Embodiments can be applied to both layer-2 and / or layer-3 relaying services / traffic. The following definitions are useful in the reading of the following: 5G ProSe Intermediate Relay: A 5G ProSe-enabled UE that provides functionality to support connectivity to the network for 5G ProSe Remote UE(s) by using the PC5 reference point with other 5G ProSe-enabled UEs, The 5G ProSe Intermediate Relay is located on the path between 5G ProSe Remote UE and 5G ProSe UE-to-Network Relay. 5G ProSe UE-to-Network (U2N) Relay: A 5G ProSe-enabled UE that provides functionality to support connectivity to the network for 5G ProSe Remote UE(s). 5G ProSe UE-to-UE (U2U) Relay: A 5G ProSe-enabled UE that provides functionality to support connectivity between 5G ProSe End UEs. 5G ProSe Remote UE: A 5G ProSe-enabled UE that communicates with a DN via a 5G ProSe UE-to-Network Relay. 5G ProSe End UE: A 5G ProSe-enabled UE that connects with another 5G ProSe-enabled UE(s) via a 5G ProSe UE-to-UE Relay. PC5 link type 1: the PC5 link between 5G ProSe Remote UE and 5G ProSe UE-to-Network Relay in the multi-hop UE-to-Network Relays scenario PC5 link type 2: PC5 link between 5G ProSe UE-to-Network Relay and 5G ProSe UE-to-Network Relay (PC5 QoS control), or PC5 link between 5G ProSe Intermediate Relay and 5G ProSe Intermediate Relay (PC5 QoS control), in the multi-hop UE-to-Network Relays scenario UE-to-Network Relay*: 5G ProSe multi-hop Layer-3 / layer-2 UE-to-Network Relay, 5G ProSe Layer-3 / layer-2 UE-to-Network Relay, or the 5G ProSe Layer-3 / layer-2 U2N relay connects to the network directly or the UE-to-Network Relay connects to the network via UU and UE-to-Network Relay via PC5, in multi-hop U2N relay scenarios. Although a few preferred embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims. For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example only, to the accompanying diagrammatic drawings in which: Figure 1 shows 5G ProSe UE-to-UE Relay Discovery with Model A of TS 23.304; Figure 2 shows 5G ProSe UE-to-UE Relay Discovery with Model B of TS 23.304 Figure 3 shows 5G ProSe Communication via 5G ProSe Layer-3 UE-to-Network Relay without N3IWF ofTS 23.304; Figure 4 shows End-to-End QoS support via Layer-3 UE-to-Network Relay with N3IWF of TS 23.304; Figure 5 shows Table 5.6.1-1: “Standardized PQI values that are additionally defined to QoS characteristics mapping” of TS 23.304; Figure 6 shows End-to-End QoS for 5G ProSe Layer-3 UE-to-UE Relay operation of TS 23.304; Figure 7 shows Example scenario of multi-hop UE-to-Network Relay of TR 23.700-03; Figure 8 shows a multi-hop UE-to-Network Relay; Figure 9 shows multi-hop UE-to-Network Relay with PC5 type 1 and type 2 explanation; Figure 10 shows adjustment factors for PQI's PDB of different hops; Figure 11 shows overall adjustment factors for PQI's PDB of all PC5 hops; Figure 12 shows multi-hop UE-to-Network Relay with PC5 link numbers; Figure 13 shows end-to-end QoS and per-hop QoS; Figure 14 shows end-to-end QoS handling: intermediate relays determine the per-hop QoS, starting from remote UE side; Figure 15 shows end-to-end QoS handling: intermediate relays determine the per-hop QoS, starting from NW side; Figure 16 shows an example scenario of multi-hop UE-to-Network Relay; and Figure 17 shows Multi-hop 5G ProSe Communication via Layer-3 UE-to-Network Relays. Exemplary scenario of multi-hop UE-to-Network Relay is shown in Figure 6 Figure 5.1.1-1: Example scenario of multi-hop UE-to-Network Relay of TR 23.700-03 and Figure 7 multi-hop UE-to-Network Relay. These figures are reproduced here as Figures 7 and 8 respectively. For the multi-hop UE-to-Network Relay scenario, there is more than one relay UE between the network and the 5g prose remote UE, to relay the service / traffic / data between the remote UE and the network. Regarding newly introduced terms,”5G ProSe Intermediate Relay", is used in Figure 8. Note that the 5G ProSe Intermediate Relay and 5G prose ue-to-network relay (1, 2, 3...) can replace each other. In Figure 8 multi-hop UE-to-Network Relay: The 5G ProSe UE-to-Network Relay* connects the network and 5G ProSe Intermediate Relay n / 5G ProSe UE-to-Network Relay n via uu and PC5 interface / link; for 5G ProSe Intermediate Relay: o 5G ProSe Intermediate Relay (2...n): connect 5G ProSe Intermediate Relay and another 5G ProSe Intermediate Relay via PC5 interface / link; o 5G ProSe Intermediate Relay 1 connects the 5G ProSe Intermediate Relay 2 and the remote UE via PC5 and UU interface / link. In order to maintain and enforce the end-to-end QoS requirements between the 5G prose remote UE and the network, the UEs that have the capability to act as multi-hop 5G ProSe UE-to-Network (U2N) Relays (e.g. 5G ProSe UE-to-Network Relay or 5G ProSe Intermediate Relay) may indicate the one or more sets of QoS information / parameters (e.g. uu QoS and / or PC5 QoS parameters / profiles) that they support for multi-hop 5G ProSe UE-to-Network (U2N) Relaying services, e.g. via discovery messages (Discovery Announcement message, Relay Discovery Solicitation message, Relay Discovery Response message etc.) Then establishing the communication via multi-hop5G ProSe Layer-3 UE-to-Network Relays, the layer-2 link establishment will consider if the QoS (e.g. uu QoS and / or PC5 QoS) can be supported by the relays. E.g. the communication establishment will only send towards the relay UEs that can support the required QoS of the relaying traffic / service. For a 5G ProSe Layer-3 Remote UE accessing network via multiple Relay(s) or via one 5G ProSe UE-to-Network Relay and one or more 5G ProSe Intermediate Relay, the QoS requirements of the relay traffic between 5G ProSe Remote UE and UPF can be satisfied by the corresponding QoS control for: the PC5 link (PC5 link type 1) between 5G ProSe Remote UE and 5G ProSe UE-to-Network Relay (PC5 QoS control), The PC5 link (PC5 link type 2) between 5G ProSe UE-to-Network Relay and 5G ProSe UE-to-Network Relay (PC5 QoS control), or PC5 link between 5G ProSe Intermediate Relay and 5G ProSe Intermediate Relay (PC5 QoS control) the QoS control for the PDU session established between 5G ProSe UE-to-Network Relay and UPF (i.e. Uu QoS control). The PC5 link type 1 and PC5 link type 2 are illustrated in Figure 9 multi-hop UE-to-Network Relay with PC5 type 1 and type 2 explanation. The PC5 QoS might be controlled with PC5 QoS rules and PC5 QoS parameters (e.g. PQI, GFBR, MFBR, PC5 LINK-AMBR) as specified in clause 5.4 of TS 23.287. The QoS for the PDU session established between the 5G ProSe UE-to-Network Relay and UPF (i.e. Uu QoS control) is controlled with QoS rules and 5G QoS parameters (e.g. 5QI, GFBR, MFBR) as specified in clause 5.7 of TS 23.501. The end-to-end QoS can be met only when the QoS requirements are properly translated and satisfied over the multiple legs / paths between the 5G ProSe Remote UE and network, including the PC5 legs (PC5 type 1 and type2) and UU leg, in Error! Reference source not found.. The QoS mapping can be pre-configured or provided to the 5G ProSe UE-to-Network Relay, 5G ProSe Intermediate Relay, or 5G ProSe Remote UE by the PCF using Prose Policy, e.g. the policy for multi-hop UE-to-Network Relays and multi-hop UE-to-Network remote UEs, e.g. in step 0: Authorization and Provisioning for multi-hop UE-to-Network Relays and Remote UE. The QoS mapping includes combinations of the 5Qls and PQIs mapping as entries. The PQI may have standardized values as defined in Table 5.6.1-1 and in Table 5.4.4-1 of TS 23.287, similar to the single hop UE-to-Network Relays, or new PQI might be defined / standardized for multi-hop UE-to-Network Relays scenarios. The 5QI might the have standardized values as defined in TS 23.501 clause 5.7.4, or new 5QI might be defined / standardized for multi-hop UE-to-Network Relays scenarios. The QoS mapping may also include an adjustment factor for PQI's PDB (packet delay budget). The end-to-end PDB is accumulated by the all the legs / links, tunnels paths, including the PC5 and UU legs between the remote UE and the network, and also the delay within the RAN node, 5GC, the delay between the 5GC to the DNN etc. For single-hop UE-to-Network Relays, the PQI's PDB only needs one value, e.g. 1 / 4 of the standardized PDB value in Table 5.6.1-1 and Table 5.4.4-1 of TS 23.287. However, for the multi-hop UE-to-Network Relays, the adjustment factor needs to consider the potential delay budget of the multiple hops. As the U2N relays have different capability and covered by diverse radio conditions, or no gNB coverage at all, the adjustment factor might be the same or different of each hop between remote UE and nw, the hops as shown in Figure 9 multi-hop UE-to-Network Relay with PC5 type 1 and type 2 explanation. There are many possibilities of how to split the PDB associated to the PQI or 5QI for the multiple hops between the remote UE and network (network) or UE-to-Network Relay: The adjustment factors for PQI's PDB of different I each / every hop(s) are included in the QoS mapping information, as shown in Figure 10 - adjustment factors for PQI's PDB of different hops. adjustment factors for PQI's PDB of different / each / every hops: 1 / x for pc5(1), 1 Zy for PC5(2), 1 / z for PC5(n), etc. The network may determine the adjustment factors for PQI's PDB of different hops based on its implementation. The adjustment factors for PQI's PDB of different PC5 hops might be equal The network might be aware of the number of hops. The number of hops might be also included in the QoS mapping information. For different number of hops of the multiple hop U2N case, the adjustment factors for PQI's PDB of different / each / every hop(s) might be different. The overall adjustment factor for PQI's PDB of all of the PC5 hops are included in the QoS mapping information, in Figure 11 overall adjustment factors for PQI's PDB of all PC5 hops. When provisioning the QoS mapping information, the network has no idea about the potential hops will be deployed or are needed for the communication via multihop U2N relays. The network may indicate an overall adjustment factor for PQI's PDB of all of the PC5 hops, e.g. overall adjustment factor of the all the pc5 hops is (1 / 6) of the standardized PDB value of a PQI in Table 5.6.1-1 of TS 23.304. If the number of the hops are large in a real case, the delay of pc5 links will be longer. To avoid this, each PC5 may be required to achieve a very low PDB and the number of hops might be also considered in the overall adjustment factor. Different number of hops associated to the different adjustment factor of the same PDB in a PQI, which means the number of hops might be determined by the QoS requirements / parameters. E.g. for 8 hops, the adjustment factor is 1 / 2; for 5 hops, the adjustment factors 1 / 3. The UE-to-Network Relay*, the UE-to-Network Relay connects to the network via UU and the UE-to-Network Relay, determines the adjustment factors for PDB for all or each the hops. UE-to-Network Relay* knows the number of PC5 hops between the UE-to-Network Relay* and remote UE. The UE-to-Network Relay* determines the adjustment factor for PDB of each hop, e.g. adjustment factor 1 for PC5 (1), adjustment factor 2 for PC5 (2).... adjustment factor n for PC5 (n) Figure 12 - multi-hop UE-to-Network Relay with PC5 link numbers. UE-to-Network Relay* informs the other UE-to-Network Relay(s) / 5G ProSe Intermediate Relay(s). The UE-to-Network Relay* may indicate all the adjustment factors of the hops to the next UE-to-Network Relay / the 1st 5G ProSe Intermediate Relay. The 1st 5G ProSe Intermediate Relay deploy, store, implement the adjustment factor n for PC5 (n) link, and remove the adjustment factor n of PC5 (n) link from the list. Then 1st 5G ProSe Intermediate Relay inform the remaining list of adjustment factors of the remaining hops to the next UE-to-Network Relay / 5G ProSe Intermediate Relay. The next UE-to-Network Relay / the5G ProSe Intermediate Relay repeat the 1st 5G ProSe Intermediate Relay actions, e.g. deploy, store, implement the adjustment factor n-1 for PC5 (n-1) link, and remove the adjustment factor n of PC5 (n-1) link from the list. This 5G ProSe Intermediate Relay inform the remaining list of adjustment factors of the remaining hops to the next UE-to-Network Relay / 5G ProSe Intermediate Relay. The other UE-to-Network Relay / 5G ProSe Intermediate Relay until the information / notification reaches the UE-to-Network Relay / 5G ProSe Intermediate Relay directly connects to the 5G ProSe Remote UE. Based on the above procedure, the PDB associated to the PQI of the services transmitted via multi-hop UE-to-Network Relays are split and configured to all the involved UE-to-Network Relays and / or 5G ProSe Intermediate Relay. The (PC5) QoS Flows setup can be initiated by the network or the remote UE. The remote UE may also trigger the PC5 QoS Flows modification at some scenarios. Network initiated QoS Flows setup: If the QoS Flows setup are initiated by network, the SMF can use the Policy and Charging Control, PCC, rules or its local configuration to generate the QoS rules and QoS Flow level QoS parameters (e.g. 5QI, GFBR, MFBR) and signal to the 5G ProSe UE-to-Network Relay using PDU Session Establishment / Modification procedure. For multi-hop U2N relay scenarios, the PDU session is between the network and the UE-to-Network Relay*, the U2N relay connects to the network directly, the UE-to-Network Relay connects to the network via UU and UE-to-Network Relay via PC5. For the PDU sessions used for relaying, the SMF always provides the QoS Flow level QoS parameters to the 5G ProSe UE-to-Network Relay* when establishes a QoS Flow. Then the multiple 5G ProSe UE-to-Network Relay or 5G ProSe Intermediate Relay(s) decide the PC5 QoS parameters for the corresponding PC5 QoS Flow by determining the PQI based the QoS mapping and the GFBR and MFBR values for the PC5 GBR QoS Flow are set equal to the GFBR and MFBR values for the GBR QoS Flow respectively. Then the 5G ProSe UE-to-Network Relay* / the U2N relay connects to the network directly decides the PC5 QoS parameters for the corresponding PC5 QoS Flow by determining the PQI based the QoS mapping and the GFBR and MFBR values for the PC5 GBR QoS Flow are set equal to the GFBR and MFBR values for the GBR QoS Flow respectively. There are different possibilities: 5G ProSe UE-to-Network Relay* / the U2N relay connects to the network directly decides the PC5 QoS parameters for the corresponding PC5 QoS Flow of all the PC5 hop of all the multiple U2N relays deployed / connected. 5G ProSe UE-to-Network Relay* / the U2N relay connects to the network directly then informs the next U2N relay about the determined PC5 QoS flow of each PC5 hop. The determined PC5 QoS is transferred successively to the next U2N relays, until the determined PC5 QoS information reaches the U2N relay which connects to the remote directly. Each U2N relay and / or the intermediate relay(s) determines the PC5 QoS parameters for the corresponding PC5 QoS Flow for the next PC5 hop / its own PC5 hop, and also the QoS of the remaining hops. Once the QoS requirements / parameters of the next PC5 hop / its own PC5 hop are determined, the QoS of the remaining hops are determined, as the QoS of the remaining hops are the overall end-to-end QoS requirements / parameters minus / deduct the QoS requirements / requirement that to be satisfied / met by the hops with determined QoS. This is shown in Figure 14 - end-to-end QoS handling: intermediate relays determines the per-hop QoS: ■ the remote UE may send the e2e QoS or the PC5 QoS to the intermediate relay (intermediate relay 1) which connects to the remote UE. intermediate relay 1 may determine the per hop QoS of PC5(1) (between remote UE and intermediate relay 1) and / or PC5(2) (between intermediate relay 1 and the next intermediate relay) if the remote UE does not determine the per hop QoS of PC5(1) (between remote and intermediate relay 1). Then the intermediate relay 1 deducts the determined per hop QoS from the overall QoS, and sends the remaining QoS to the next intermediate relay, intermediate relay 2. The intermediate relay 2 determines the per-hop QoS of PC5(2) (between intermediate relay 1 and the next intermediate relay 2) and / or PC5(3) (between intermediate relay 2 and the next intermediate relay 3). Then the intermediate relay 2 deducts the determined per hop QoS from the QoS it receives and sends the remaining QoS to the next intermediate relay , intermediate relay 3. Each intermediate relay repeats the above QoS determination and split procedure, until the QoS is propagated to the UE-to-Network relay or the NG-RAN node. ■ Alternatively, the remote UE may send one or more of the following to intermediate relay (intermediate relay 1): the e2e QoS, PC5 QoS, per-hop QoS of PC5(1) (between remote and intermediate relay 1), remaining QoS of the other PC5 hops (exclude the QoS of PC5(1) from PC5 QoS or end-to-end QoS) and / or UU QoS. The determination of per hop QoS might be made from the UE-to-Network relay or the intermediate relay closer to the network side, as shown in Figure 15 end-to-end QoS handling: intermediate relays determines the per-hop QoS, starting from NW side . ■ the network / NG-RAN may send the e2e QoS or the PC5 QoS to the UE-to-network relay that connects to the network and intermediate relay n. The UE-to-network relay may determine the per hop QoS of PC5(n+1) (between network and intermediate relay n) and / or UU QoS) (between network and ue-to-network relay). Then the ue-to-network relay deduct the determined per hop QoS from the overall PC5 QoS, and sends the remaining QoS to the intermediate relay n that connects to the ue-to-network relay, intermediate relay n. The intermediate relay n determines the per-hop QoS of PC5(n+1) (between intermediate relay n and the UE-to-network relay) and / or PC5(n) (between intermediate relay n and the intermediate relay n-1 on the left). Then the intermediate relay n deducts the determined per hop QoS from the overall / remaining (PC5) QoS it receives from the previous relay and sends the remaining QoS to the next intermediate relay, intermediate relay n-1. Each intermediate relay repeats the above QoS determination and split procedure, until the QoS is propagated to the remote UE. 5G ProSe UE-to-Network Relay* / the U2N relay connects to the network directly determines the PC5 QoS Flow of the PC5 link between itself and the next U2N relay. Then the next U2N relay determines the PC5 QoS Flow of the PC5 between itself and another U2N relay connects to it. This next U2N relay informs the other U2N relay about the determined PC5 QoS Flow and / or U2N relay about the E2E QoS requirements / parameters. This decision and notification are transferred successively to the next U2N relays, until the U2N relay that connects to the remote UE directly. The U2N relay that connects to the remote UE directly determines the PC5 QoS Flow of the PC5 link between remote UE and itself. The PCF differentiates the relay traffic via multiple relays based on either local configuration, e.g.by a dedicated DNN or S-NSSAI used for relay traffic or by the traffic filters, number of hops. If the 5G ProSe Remote UE initiates PC5 QoS Flows setup or modification during the Layer-2 link establishment or modification procedure, the 5G ProSe Remote UE provides the QoS Info to the 5G ProSe UE-to-Network Relays. As there are multiples / more than one U2N relays between the remote UE and the network, the remote UE indicate the QoS Info to the U2N relay that connects to the remote UE directly. Then this U2N relay relays the QoS Info to the next relay. The QoS info is transferred successively from among the U2N relays, until the QoS info arrives the network. The QoS Info might be transparent to the multiple U2N relays; The QoS Info might be transparent to all the 5G ProSe Intermediate Relays, but not to the U2N relay directly connects to the network. The QoS info might be carried by a container when transferring between U2N relays / 5G ProSe Intermediate Relays, e.g. via layer-2 link modification or establishment messages, direct communication request messages, etc. The received PC5 QoS parameters of the QoS Info (i.e. PQI(s) and conditionally other parameters such as MFBR / GFBR, etc.) by the U2N relay that connects the network directly / UE-to-Network Relay* are interpreted as the end-to-end QoS requirements by the 5G ProSe (layer-2 or layer-3) UE-to-Network Relay* / 5G ProSe (layer-2 or layer-3) U2N relay that connects the network directly for the data / traffic transmission between 5G ProSe (layer-2 or layer-3) Remote UE and UPF. The end-to-end QoS requirements indicate the QoS between the UPF and the remote UE via multiple U2N relays. The PQI might be the same for all the PC5 links. In this case, the Remote indicated one PQI and conditionally other parameters such as MFBR / GFBR, etc. to the relay(s). The PQI might be different for PC5 links. In this case, the Remote indicated a set / list of PQI(s) and conditionally other parameters associated to different PQI(s), such as MFBR / GFBR, etc. to the relay(s). If the end-to-end QoS requirements can be supported by an entry in QoS mapping, optionally consider the number of hops / U2N relays, the 5G ProSe UE-to-Network Relay* / 5G ProSe (layer-2 or layer-3) U2N relay that connects the nw / or any U2N relay among the multiple deployed relays use the 5QI of the entry for the Uu QoS control and uses the PQI of the entry for the PC5 QoS control. If the end-to-end QoS requirements cannot be supported by any entries in QoS mapping, the 5G ProSe UE-to-Network Relay, based on its implementation, decides the 5QI for the Uu QoS control and PQI for the PC5 QoS control. The 5G ProSe UE-to-Network Relay that makes this decision might be the 5G ProSe UE-to-Network Relay* / 5G ProSe (layer-2 or layer-3) U2N relay that connects the nw / any U2N relay among the multiple deployed relays. The 5G ProSe UE-to-Network Relay provides the QoS Info (including PQI value chosen by the 5G ProSe UE-to-Network Relay) as part of the Accept message to the next U2N relay / the 1st 5G ProSe Intermediate Relay / 5G ProSe Remote UE. The next U2N relay / the 1st 5G ProSe Intermediate Relay needs to check whether the update / new PQI is acceptable or not. o If yes, the next U2N relay / the 1st 5G ProSe Intermediate Relay will include the PQI and other optional PC5 QoS information to the next U2N relay / 5G ProSe Intermediate Relay, e.g. via accept message. The next relay will behave in the same way. Until the PQI reaches the remote UE or the U2N relay connects to the remote UE directly. o If any of the relays cannot accept the PQI and other optional PC5 QoS information, this relay will send rejection to the previous relay, optionally include the PQI(s) and other optional PC5 QoS information it can accept, and UE info ID or any other can identify this UE, its index / hop number that can identify where is the relay UE / relay order / sequence among all the U2N relays. Based on the request from remote UE, the 5G ProSe UE-to-Network Relay* / 5G ProSe (layer-2 or layer-3) U2N relay that connects the network performs the UE requested PDU session Modification as defined in TS 23.502 , clause 4.3.3 for authorizing the requested QoS including the 5QI and the Packet Filters. If the PCF authorizes the requested QoS with a different 5QI value, the 5G ProSe UE-to-Network Relay may further update the PQI value based on the authorized 5QI value and the all of the 5G ProSe UE-to-Network Relays deployed will perform the Layer-2 link modification procedure to update the corresponding PC5 QoS Flow with the updated PQI value. The reflective QoS control over Uu as defined in TS 23.501, clause 5.6.5.3 can be applied to multiple hop U2N relay scenarios, by leveraging for dynamic QoS handling of 5G ProSe Remote UE to save on signalling between SMF and 5G ProSe UE-to-Network Relay, e.g. between SMF and the 5G ProSe UE-to-Network Relay* / 5G ProSe (layer-2 or layer-3) U2N relay that connects the nw, between 5G ProSe UE-to-Network Relay and 5G ProSe UE-to-Network Relay, between 5G ProSe Remote UE and 5G ProSe UE-to-Network Relay. In detail: Upon reception of a DL packet with RQI on the Uu for the 5G ProSe Remote UE via multi-hop U2N relays, based on the indicated QFI, the 5G ProSe UE-to-Network Relay* / 5G ProSe (layer-2 or layer-3) U2N relay that connects the nw / any U2N relay creates a new derived QoS rule or updates existing derived QoS rule corresponding to the remote UE. The derived QoS rule is for UL packets from the 5G ProSe Remote UE at Uu interface. The 5G ProSe UE-to-Network Relay* / 5G ProSe (layer-2 or layer-3) U2N relay that connects the network will indicate the QoS rules to other U2N relays and optionally the remote UE. Based on signalled QoS rules (via SMF) or derived QoS rules (e.g. Uplink Uu via reflective QoS), the 5G ProSe UE-to-Network Relay* / 5G ProSe (layer-2 or layer-3) U2N relay that connects the nw / any U2N relay may generate the Packet Filters used over PC5 reference point and use the L2 Link Modification procedures to either update existing PC5 QoS Flow(s) or to set up new PC5 QoS Flow(s) (e.g. when the QFI to PC5 QoS Flow mapping does not exist). The 5G ProSe UE-to-Network Relay* / 5G ProSe (layer-2 or layer-3) U2N relay that connects the nw / any U2N relay may also provide the PC5 QoS Rule(s) for the PC5 QoS Flow(s) to be added or modified to the 5G ProSe Remote UE, other U2N relays, other 5G ProSe Intermediate Relays. When the 5G ProSe UE-to-Network Relay* / 5G ProSe (layer-2 or layer-3) U2N relay that connects the nw / any U2N relay deletes the derived QoS rule e.g. after the RQ Timer expires, the 5G ProSe UE-to-Network Relay* / 5G ProSe (layer-2 or layer-3) U2N relay that connects the nw / any U2N relay may perform L2 Link Modification procedures using the PQI mapped from the 5QI of the currently used QoS rule after the deletion of the derived QoS rule(s), and provide the PC5 QoS Rule(s) for the PC5 QoS Flow(s) to be added or modified to the 5G ProSe Remote UE, other U2N relays, other 5G ProSe Intermediate Relays. Enhancements to QoS handling: For a 5G ProSe Layer-3 Remote UE accessing the network via one 5G ProSe UE-to-Network Relay and one or more 5G ProSe Intermediate Relay(s), the end-to-end QoS requirements of the relay traffic between 5G ProSe Remote UE and UPF can be satisfied by the corresponding QoS control of the following legs in Figure 16: PC5 QoS control for the PC5 link 1 between 5G ProSe Remote UE and 5G ProSe Intermediate Relay 1; PC5 QoS control for the PC5 link (2,..., n): the PC5 link(s) between 5G ProSe Intermediate Relays, if applicable; and the PC5 link between a ProSe Intermediate Relay and UE-to-Network Relay; QoS control for PDU session established between 5G ProSe UE-to-Network Relay and UPF (e.g. Uu QoS control). For the single-hop UE-to-Network relay scenarios, as specified in TS 23.304, the PC5 QoS can be controlled by PC5 QoS rules and PC5 QoS parameters (e.g. PQI, GFBR, MFBR, PC5 LINK-AMBR), and the QoS of the PDU session established between the 5G ProSe UE-to-Network Relay and UPF (i.e. Uu QoS control) is controlled with QoS rules and 5G QoS parameters (e.g. 5QI, GFBR, MFBR) as specified in clause 5.7 ofTS 23.501. For the multi-hop UE-to-Network relay scenarios as shown in Figure 16, the end-to-end QoS can be met only when the QoS requirements are properly translated and satisfied over the multiple legs. To control and maintain the end-to-end QoS, the QoS mapping mechanism for single-hop relay scenarios can be still applied in the multiple-hop U2N scenarios. The QoS mapping might be pre-configured or provided to the 5G ProSe Layer-3 UE-to-Network Relay and Intermediate Relay(s) by the PCF using multi-hop Prose Policy. The QoS mapping may include the combinations of the 5Qls and PQIs mapping as entries. The PQI(s) can have standardized values as defined in Table 5.6.1-1 of TS 23.304 and in Table 5.4.4-1 of TS 23.287, or new values. The 5QI are standardized values as defined in TS 23.501 clause 5.7.4. The QoS mapping may also include adjustment factor(s) for the PQI's PDB. Compared to the single-hop U2N relay, for the multi-hop U2N relay scenarios, the bigger number of PC5 hops may increase the overall end-to-end delay between the remote UE and UPF. Therefore, the PDB of a PQI might be varied with the numbers of hops, e.g. the scenario with larger number of PC5 hops may be associated with a higher PDB. The adjustment factor(s) associated to a PQI or PDB might be configured as an overall number for all of the PC5 links, e.g. 3 / 4 of the standardised PDB value over all of the PC5 links in Figure 16, then the UE-to-Network Relay determines the adjustment factors of each PC5 link, e.g. evenly and / or based on the number of hops, the air interface quality and capability of different relays, etc. or the adjustment factor is for each single PC5 hop, e.g. the same for every PC5 hops in the multi-hop case: e.g. 1 / 7 of the standardised PDB value over every PC5 link in Figure 16, if the number of hops is 5; or different adjustment factors might be configured for different PC5 hop (e.g. based on the air interface quality and capability of different relays). In the current framework of U2N relay communication, the QoS flow setup and modification can be initiated either by the Remote UE and the U2N Relay. A similar mechanism with enhancements may be applied to the multi-hop U2N relay scenarios. QoS Flows setup are initiated by network: The SMF can use the PCC rules or its local configuration to generate the QoS rules and QoS Flow level QoS parameters (e.g. 5QI, GFBR, MFBR) and signal them to the 5G ProSe UE-to-Network Relay using PDU Session Establish ment / Modification procedure, similar to the singlehop U2N relay case. Then the 5G ProSe UE-to-Network Relay may decide the PC5 QoS parameters for the corresponding PC5 QoS Flow by determining the PQI based the QoS mapping. In the multihop U2N relay scenarios, for the GBR QoS flow, the values of the GFBR and MFBR of the PC5 GBR QoS Flow over every PC5 link might be configured the same as those for the GBR QoS Flow. Then the 5G ProSe UE-to-Network Relay will indicate the determined PQI and any other QoS related parameters to the ProSe Intermediate Relay. If the ProSe Intermediate Relay accepts the PC5 QoS configuration, it will indicate to the parameters to the next ProSe Intermediate Relay. The QoS parameters will be transferred successively until the last ProSe Intermediate Relay that connects to the Remote UE is reached. PC5 QoS flows setup or modification is initiated by the 5G ProSe Layer-3 Remote UE: The Remote UE may initiate the PC5 QoS Flows setup or modification during the Layer-2 link establishment or modification procedure. In this case, the 5G ProSe Remote UE provides the QoS Info to the 5G ProSe UE-to-Network Relay, via the intermediate relay(s). The PC5 QoS parameters of the QoS Info (i.e. PQI and conditionally other parameters such as MFBR / GFBR, etc.) are interpreted as the end-to-end QoS requirements by the 5G ProSe Layer-3 UE-to-Network Relay for the traffic transmission between 5G ProSe Layer-3 Remote UE and UPF. If the end-to-end QoS requirements can be supported by an entry of QoS mapping, the 5G ProSe Layer-3 UE-to-Network Relay uses the 5QI of the entry for the Uu QoS control and uses the PQI of the entry for the PC5 QoS control. The same PQI might be applied to all the PC5 links in the multi-hop U2N relay scenario. The determined PQI will be transferred from the UE-to-Network Relay successively to the remote UE via successive intermediate relay(s) to. If any of the intermediate relays cannot accept the PQI, it sends the reject message to the Layer-3 UE-to-Network Relay, e.g. via intermediate relay(s) if applicable. If the end-to-end QoS requirements cannot be supported by any entries of QoS mapping, the 5G ProSe Layer-3 UE-to-Network Relay, based on its implementation, decides the 5QI for the Uu QoS control and PQI for the PC5 QoS control of all the PC5 hops in the multi-hop relay scenario. The 5G ProSe Layer-3 UE-to-Network Relay provides the QoS Info (including PQI value chosen by the 5G ProSe Layer-3 UE-to-Network Relay) as part of the Accept message to the Intermediate relay connects to it. If the 1st Intermediate relay accepts the QoS Info, it will provide QoS Info to the successive Intermediate relay until the QoS info reaches the Remote UE. The 5G ProSe Layer-3 UE-to-Network Relay performs the UE requested PDU session Modification as defined in TS 23.502, clause 4.3.3 for authorizing the requested QoS including the 5QI and the Packet Filters. If the PCF authorizes the requested QoS with a different 5QI value, the 5G ProSe Layer-3 UE-to-Network Relay may further update the PQI value based on the authorized 5QI value to the intermediate relay(s) and Remote UE, e.g. by performing Layer-2 link modification procedure to update the corresponding PC5 QoS Flow with the updated PQI value. Figure 17 shows Multi-hop 5G ProSe Communication via Layer-3 UE-to-Network Relays, using 5G ProSe Communication via multi-hop 5G ProSe Layer-3 UE-to-Network Relay without N3IWF as an example, but 5G ProSe Communication via multi-hop 5G ProSe Layer-3 UE-to-Network Relay with N3IWF can be also supported based on this call flow. The steps and messages shown in Figure 17 are described in detail below: 1. Service authorization and provisioning are performed for the 5G ProSe Layer-3 UE-to-Network Relay(s), including the 5G ProSe multi-hop Layer-3 UE-to-Network Relay (the 5G ProSe Layer-3 UE-to-Network Relay connects to the network directly) in step 1a and 5G ProSe Intermediate Relay(s) in step 1b, and 5G ProSe Layer-3 Remote UE in step 1c. 2. The 5G ProSe Layer-3 UE-to-Network Relay may establish a PDU Session for relaying. 3. The 5G ProSe Layer-3 Remote UE performs discovery of one or more 5G ProSe Layer-3 UE-to-Network Relay(s). As part of the discovery procedure the 5G ProSe Layer-3 Remote UE and 5G ProSe Layer-3 UE-to-Network Relay(s) may learn about the connectivity service and capability the 5G ProSe Layer-3 UE-to-Network Relay can support. 4. The 5G ProSe Layer-3 Remote UE selects one or more 5G ProSe Layer-3 UE-to-Network Relay(s) to establish end-to-end connection for unicast mode communication to the network via 5G ProSe Intermediate Relay and a 5G ProSe multi-hop Layer-3 UE-to-Network Relay. If there is no PDU Session associated with the Relay Service Code or a new PDU Session for relaying is needed, the 5G ProSe Layer-3 UE-to-Network Relay connects the network directly / 5G ProSe multi-hop Layer-3 UE-to-Network Relay / UE-to-Network Relay that may initiate a new PDU Session establishment procedure for relaying. This may happen before completing the PC5 connection establishment between the 5G ProSe Layer-3 Remote UE and 5G ProSe Intermediate Relay, between 5G ProSe Layer-3 UE-to-Network Relay and5G ProSe Intermediate Relay, between 5G ProSe Intermediate Relays, if more than one 5G ProSe Layer-3 UE-to-Network Relays are selected for multi-hop U2N relay case. If there is no PDU Session associated with the Relay Service Code or a new PDU Session for relaying is needed, the 5G ProSe Layer-3 UE-to-Network Relay may initiate a new PDU Session establishment procedure for relaying. This may happen before completing the PC5 connection establishment between the 5G ProSe Layer-3 Remote UE and 5G ProSe Intermediate Relay, between 5G ProSe Layer-3 UE-to-Network Relay and5G ProSe Intermediate Relay(s) if applicable, and between 5G ProSe Intermediate Relay and 5G ProSe Remote UE. When the 5G ProSe Layer-3 Remote UE sends the Direct Communication Request message including the dedicated emergency RSC, the 5G ProSe Layer-3 UE-to-Network Relay that connects to the network directly sets up an emergency PDU session for relaying the emergency service if there is not an emergency PDU Session established in step 2. The network decides that the PDU Session to be established is for relay traffic and then generates the QoS rules and QoS Flow level QoS parameters to 5G ProSe Layer-3 UE-to-Network Relay(s) with relay consideration (e.g. the number of PC5 hops, etc.) and can initiate the setup of QoS flows. The Remote UE may also initiate the setup of QoS flows by providing PC5 QoS info and (optionally) PC5 QoS rule(s) to the 5G ProSe Layer-3 UE-to-Network Relay(s). The PC5 QoS info and (optionally) PC5 QoS rule(s) will be transferred to the network via multiple 5G ProSe Layer-3 UE-to-Network Relays, including the 5G ProSe Intermediate Relay(s) and a 5G ProSe Layer-3 UE-to-Network Relay that connects to the network directly, during connection setup. The PDU Session type for relaying might be determined by the 5G ProSe Layer-3 UE-to-Network Relay that connects to the network directly. According to the PDU Session Type for relaying, the 5G ProSe Layer-3 UE-to-Network Relays, including the 5G ProSe Intermediate Relay(s) and a 5G ProSe Layer-3 UE-to-Network Relay that connects to the network directly, performs relaying function at the corresponding layer as follows: When the IP type PDU Session is used for IP traffic over PC5 reference point, the 5G ProSe Layer-3 UE-to-Network Relay, e.g. the 5G ProSe Layer-3 UE-to-Network Relay that connects to the network directly, acts as an IP router. For IPv4, the 5G ProSe Layer-3 UE-to-Network Relay, e.g. the 5G ProSe Layer-3 UE-to-Network Relay that connects to the network directly, performs IPv4 NAT between IPv4 addresses assigned to the 5G ProSe Layer-3 Remote UE and the IPv4 address assigned to the PDU Session used for the relay traffic. When the Ethernet type PDU Session is used for Ethernet traffic over PC5 reference point, the 5G ProSe Layer-3 UE-to-Network Relay that connects to the network directly acts as an Ethernet switch. 5. For IP PDU Session Type and IP traffic over PC5 reference points, IPv6 prefix or IPv4 address (including NAT case) is allocated for the 5G ProSe Layer-3 Remote UE. 6. The 5G ProSe Layer-3 Remote UE may provide PC5 QoS Info and PC5 QoS rule(s) to the 5G ProSe (multi-hop) Layer-3 UE-to-Network Relay using Layer-2 link modification procedure. The 5G ProSe Layer-3 UE-to-Network Relay (e.g. the 5G ProSe Layer-3 UE-to-Network Relay connects to the nw) generates the Packet Filters used over Uu interface based on the received PC5 QoS Info and QoS Rule(s), e.g. based on QoS mapping. And the 5G ProSe Layer-3 UE-to-Network Relay (e.g. the 5G ProSe Layer-3 UE-to-Network Relay connects to the nw) may perform the UE requested PDU Session Modification as defined in TS 23.502 clause 4.3.3 to setup a new QoS Flow or bind the traffic to an existing QoS Flow. From this point the uplink and downlink relaying can start between the remote UE and the network via multiple Layer-3 relays. For downlink traffic forwarding, the PC5 QoS Rule is used to map the downlink packet to the PC5 QoS Flow. For uplink traffic forwarding, the 5G QoS Rule is used to map the uplink packet to the Uu QoS Flow. 7. The 5G ProSe Layer-3 UE-to-Network Relay that connects to the network shall send a Remote UE Report (Remote User ID, Remote UE info) message to the SMF for the PDU Session associated with the relay. The Remote User ID, as defined in TS 33.503, is an identity of the 5G ProSe Layer-3 Remote UE user that was successfully connected in step 4. The Remote UE info is used to assist identifying the 5G ProSe Layer-3 Remote UE in the 5GC. Optionally, the user ID, user info of the one or more 5G ProSe Intermediate Relay(s) and / or the 5G ProSe Layer-3 UE-to-Network Relay that connects to the network are indicated to the SMF. For IP PDU Session Type, the Remote UE info is Remote UE IP info. For Ethernet PDU Session Type, the Remote UE info is Remote UE MAC address which is detected by the 5G ProSe Layer-3 UE-to-Network Relay(s) (including the one or more 5G ProSe Intermediate Relay(s) and / or the 5G ProSe Layer-3 UE-to-Network Relay that connects to the network). For Unstructured PDU Session Type, the Remote UE info is not included. The SMF stores the Remote User IDs and the related Remote UE info in the 5G ProSe Layer-3 UE-to-Network Relay's (e.g. the 5G ProSe Layer-3 UE-to-Network Relay that connects to the network) SM context for this PDU Session associated with the relay. The Remote UE Report is N1 SM NAS message sent with the PDU Session ID to the AMF, in turn delivered to the SMF. For IP info the following principles apply: for IPv4, the 5G ProSe Layer-3 UE-to-Network Relay (e.g. the 5G ProSe Layer-3 UE-to-Network Relay that connects to the network) shall report TCP / UDP port ranges assigned to individual 5G ProSe Layer-3 Remote UE(s) (along with the Remote User ID); for IPv6, the 5G ProSe Layer-3 UE-to-Network Relay (e.g. the 5G ProSe Layer-3 UE-to-Network Relay that connects to the network) shall report IPv6 prefix(es) assigned to individual 5G ProSe Layer-3 Remote UE(s) (along with the Remote User ID). If the PDU Session for relaying is released by the UE-to-Network Relay (e.g. the 5G ProSe Layer-3 UE-to-Network Relay that connects to the network) or the network as described in clause 4.3.4 of TS 23.502, the UE-to-Network Relay (e.g. the 5G ProSe Layer-3 UE-to-Network Relay that connects to the network) should initiate the release of the layer-2 links associated with the released PDU Session, The PDU Session(s) used for relaying should be released as described in clause 4.3.4 of TS 23.502 (e.g. by 5G ProSe Layer-3 UE-to-Network Relay that connects to the network), if the service authorization for acting as a 5G ProSe Layer-3 UE-to-Network Relay in the serving PLMN is revoked. In this case: The layer-2 link associated to the PDU Session(s) used for relaying should be released. The PC5 links establishment for this communication might be also released or updated / modified. The 5G ProSe Layer-3 UE-to-Network Relay (e.g. the 5G ProSe Layer-3 UE-to-Network Relay that connects to the network) shall send the Remote UE Report message when the 5G ProSe Layer-3 Remote UE disconnects from the 5G ProSe Layer-3 UE-to-Network Relay (e.g. upon explicit layer-2 link release or based on the absence of keep alive messages over PC5), to inform the SMF that the 5G ProSe Layer-3 Remote UE(s) have left. The 5G ProSe Layer-3 UE-to-Network Relay may send the Remote UE Report message when the 5G ProSe Layer-3 Remote UE or any 5G ProSe Intermediate Relay disconnects from the multi-hop 5G ProSe Layer-3 UE-to-Network Relay chain, to inform the SMF that the 5G ProSe Layer-3 Remote UE(s) have left. The 5G ProSe Layer-3 UE-to-Network Relay (e.g. the 5G ProSe Layer-3 UE-to-Network Relay that connects to the network) shall send the 5G ProSe Intermediate Relay report message when any of the 5G ProSe Intermediate Relay is disconnected for the multiple U2N relay chain, to inform the SMF that the 5G ProSe Layer-3 Remote UE(s) have left. The disconnection might be triggered by remote ue, 5G ProSe Intermediate Relay itself, the 5G ProSe Layer-3 UE-to-Network Relay that connects to the network, any other 5G ProSe Intermediate Relay, or the network. E.g. upon explicit layer-2 link release or based on the absence of keep alive messages over PC5. It is up to 5G ProSe Layer-3 UE-to-Network Relay implementation how PDU Session(s) used for relaying are released or QoS Flow(s) used for relaying are removed by the 5G ProSe Layer-3 UE-to-Network Relay when 5G ProSe Layer-3 Remote UE(s) disconnect from the 5G ProSe Layer-3 UE-to-Network Relay. At least some of the example embodiments described herein may be constructed, partially or wholly, using dedicated special-purpose hardware. Terms such as ‘component’, ‘module’ or ‘unit’ used herein may include, but are not limited to, a hardware device, such as circuitry in the form of discrete or integrated components, a Field Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC), which performs certain tasks or provides the associated functionality. In some embodiments, the described elements may be configured to reside on a tangible, persistent, addressable storage medium and may be configured to execute on one or more processors. These functional elements may in some embodiments include, by way of example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. Although the example embodiments have been described with reference to the components, modules and units discussed herein, such functional elements may be combined into fewer elements or separated into additional elements. Various combinations of optional features have been described herein, and it will be appreciated that described features may be combined in any suitable combination. In particular, the features of any one example embodiment may be combined with features of any other embodiment, as appropriate, except where such combinations are mutually exclusive. Throughout this specification, the term “comprising” or “comprises” means including the component(s) specified but not to the exclusion of the presence of others. Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. 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. The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A method of operating a system to provide multi-hop communications between a Remote User Equipment, UE, and a telecommunication network, where the communication is conducted via at least one ProSe Intermediate Relay and a ProSe UE to network relay, disposed between the Remote UE and the telecommunication network, comprising the steps of:• authorising and provisioning service at the telecommunication network;• establishing a PDU session for relaying communications;• the Remote UE performing discovery of at least one ProSe UE-to-Network Relay;• the Remote UE selecting at least one ProSe UE-to-Network Relay to establish end-to-end connection for unicast mode communication to the telecommunication network via the at least one ProSe Intermediate Relay and the ProSe UE-to-Network Relay;• the ProSe UE to Network Relay assigning IP addresses to the at least one ProSe intermediate relay and the Remote UE;• the Remote UE providing QoS info to the UE-to-Network Relay using a link modification procedure; and• the ProSe UE-to-Network Relay that connects to the telecommunication network sending a Remote UE Report message to a Session Management Function, SMF, of the telecommunication network for the established PDU Session.

2. The method of claim 1 wherein QoS flows are initiated by either the telecommunication network or the Remote UE.

3. The method of claim 2, wherein if the QoS flows are initiated by the telecommunication network, then a Session Management Function, SMF, based on Policy and Charging Control, PCC, rules or its local configuration, generates QoS rules and QoS Flow level QoS parameters and signals these to the ProSe UE to Network relay.

4. The method of claim 3 wherein, based upon the QoS rules and QoS Flow level QoS parameters the ProSe UE to Network relay determines end to end PC5 QoS parameters for a corresponding PC5 QoS flow, based on a QoS mapping.

5. The method of claim 4 wherein a number of hops to the Remote UE is taken into account.

6. The method of claim 5 wherein the UE to network relay provides information to a next hop ProSe intermediate relay.

7. The method of claim 6 wherein the information comprises end-to-end PC5 QoS information, a maximum PC5 Packet Delay Budget, PDB, and the generated PC5 QoS Flow parameters.

8. The method of claim 7 wherein a further next hop ProSe intermediate relay determines PC5 Flow QoS parameters for a next hop PC5 link towards the 5G ProSe Layer-3 Remote UE.

9. The method of claim 2, wherein if the QoS flows are initiated by the Remote UE, then the Remote UE provides QoS information to the ProSe UE to network relay via the at least one ProSe intermediate relay.

10. The method of claim 9 wherein the QoS information is interpreted as end-to-end QoS requirements for traffic transmission between Remote UE and the telecommunication network.

11. The method of claim 10 wherein the UE-to-Network Relay determines 5QI for Uu QoS control and PQI for end-to-end PC5 QoS control based on a QoS mapping.

12. The method of any preceding claim wherein the Remote UE is a 5G ProSe Remote UE, the at least one ProSe Intermediate Relay is at least one 5G ProSe intermediate relay and the ProSe UE to network relay is a 5G ProSe UE to network relay.

13. The method of any preceding claim wherein QoS mapping may be pre-configured to provided to the ProSe UE to network relay by a PCF in the telecommunication network.

14. The method of any preceding claim wherein QoS mapping is performed, making use of an adjustment factor, taking to account a number of hops between the remote UE and the telecommunication network.

15. A system arranged to perform the method of any preceding claim, comprising at least one Remote UE, at least one ProSe intermediate relay, at least one ProSe UE to network relay and a telecommunication network.

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