Relay selected short id management for u2u sidelink relay adaptation protocol (SRAP)

Abstract

A relay terminal facilitating at least a portion of an end-to-end (E2E) PC5 communication link between a source remote terminal and a destination remote selects a Short ID from a pre-configured set of Short IDs. One or more relay terminals relay communications to form the E2E PC5 communication link where the Short ID is applied to the Sidelink Relay Adaptation Protocol (SRAP) at each relay terminal. The Short ID is included in the headers of E2E transmissions from the source remote terminal and the destination remote terminal. The Short ID is shorter than a ProSe UE ID, such as User Info ID or a L2ID of the remote terminals. Each relay terminal is pre-configured with a set of Short IDs that does not overlap with the sets of Short IDs pre-configured at other relay terminals.

Description

RELAY SELECTED SHORT ID MANAGEMENT FOR U2U SIDELINK RELAY ADAPTATION PROTOCOL (SRAP)CLAIM OF PRIORITY

[0001] The present application claims priority to Provisional Application No. 63 / 533,562, entitled “Short ID For SRAP In U2U Relay”, docket number TPRO 00396 US, filed August 18, 2023, assigned to the assignee hereof and hereby expressly incorporated by reference in its entirety.FIELD

[0002] This invention generally relates to wireless communications and more particularly to relay selected Short ID management for U2U Sidelink Relay Adaptation Protocol (SRAP).BACKGROUND

[0003] Many wireless communication systems that employ several base stations that provide wireless service to user equipment (UE) devices enable sidelink communication between two or more UE devices where the UE devices can communicate directly with other UE devices. In addition, one or more UE devices can be used as relay devices to form relay communication links between a source UE and a base station or between a source UE device and a destination UE device. A relayed connection between a remote UE and the network through a relay device is often referred to as a UE-to-Network (U2N) link. The U2N link includes a PC5 link between the relay device and the remote UE and Uu link between the relay device and a base station in the network.

[0004] In some conventional systems, the U2N communication links use a Sidelink Relay Adaptation Protocol (SRAP) defined by one or more revisions of the 3rdGeneration Partnership Project (3GPP) standards to transmit control and data signals over the PC5 link and the Uu link. The SRAP is used to perform bearer mapping (signaling radio bearers (SRBs) and data radio bearers (DRBs)) between the two links.For U2N relays, a local Remote UE ID is included in both the PC5 SRAP header and the Uu SRAP header. The Layer 2 (L2) U2N Relay UE is configured by the gNB with the local Remote UE ID to be used in SRAP headers.SUMMARY

[0005] A relay terminal facilitating at least a portion of an end-to-end (E2E) PC5 communication link between a source remote terminal and a destination remote selects a Short ID from a pre-configured set of Short IDs. One or more relay terminals relay communications to form the E2E PC5 communication link where the Short ID is applied to the Sidelink Relay Adaptation Protocol (SRAP) at each relay terminal. The Short ID is included in the headers of E2E transmissions from the source remote terminal and the destination remote terminal. The Short ID is shorter than a ProSe UE ID, such as User Info ID or a L2ID of the remote terminals. Each relay terminal is pre-configured with a set of Short IDs that does not overlap with the sets of Short IDs pre-configured at other relay terminals.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 is a block diagram of an example of a U2U control layer protocol stack for a L2 UE-to-UE (U2U) relay terminal.

[0007] FIG. 2A is a block diagram of a system for an example of Short ID (Local ID) selection for PC5 SRAP for an E2E PC5 communication link with multiple hops.

[0008] FIG. 2B is a block diagram of the system for an example of Short ID (Local ID) selection for PC5 SRAP for E2E PC5 communication links for multiple destination terminals.

[0009] FIG. 2C is a block diagram of the system for an example of Short ID (Local ID) selection for PC5 SRAP for E2E PC5 communication links for multiple destination terminals and multiple relay terminals.

[0010] FIG. 3 is a block diagram of an example of a UE device suitable for use as each of the terminal devices.

[0011] FIG. 4 is a message diagram for an example of Short ID (Local ID) selection for PC5 SRAP for the E2E PC5 communication link with multiple hops.

[0012] FIG. 5 is a flow chart of an example of method of managing Short IDs for an E2E PC5 communication link performed at a relay terminal.DETAILED DESCRIPTION

[0013] As discussed above, a relay communication link can be established between a remote source UE device (remote source terminal) and a remote destination UE device (remote destination terminal) through one or more relay devices (relay terminals). The relay communication link, often referred to as a UE-to-UE (U2U) communication link, includes PC5 links between the remote source terminal and the relay terminal, between the relay terminal and the remote destination terminal, and between relay terminals if more than one relay terminal forms the U2U communication link. Each relay terminal in the U2U link has a PC5 ingress link to a terminal and a PC5 egress link to another terminal. For a U2U link with a single relay terminal, therefore, the relay terminal is connected to the remote source terminal over an ingress PC5 link using PC5 Relay radio link control (RLC) channels over a first hop PC5 link and is connected to the remote destination terminal over an egress PC5 link using PC5 Relay RLC channels over a second hop PC5 link. Some conventional systems adopt the SRAP for U2N links for use in the U2U link to map the SRBs and DRBs of the ingress PC5 link and egress PC5 link. As discussed above, a U2N relay is configured by the network (e.g., gNB) with a Local Remote UE ID (Short ID) to be used in both the PC5 SRAP header and the Uu SRAP header. U2U relay terminals, however, cannot rely on the gNB or network to configure the local Remote UE ID since all of the terminals may be out of coverage and unreachable by the gNB. One potential technique for selecting a UE ID for Uu SRAP includes using the Layer 2 UE ID (L2ID). Unfortunately, the L2ID is 24 bits long and is longer than a Short ID which is expected to be 8 bits long or less. Accordingly, conventional systems are limited since a Short ID cannot be used in SRAP headers for a U2U communication link. For the examples herein, however, a Short ID for SRAP is selected by one of the relay terminals facilitating the E2E PC5communication link from a pre-configured set of Short IDs. Each relay terminal is preconfigured with a Short ID set that does not overlap with the Short ID set configured at any other relay terminal. In other words, no Short ID is included in more than one Short ID set.

[0014] A network node is any apparatus, equipment, device, or combination of devices, on the network side of the communication system that is connected to the communication network or is part of communication network. Some examples of a network node include a base station, a node B, an E-UTRA Node B, Evolved Node B, eNodeB, eNB, a New Generation eNB (ng-eNB), a gNodeB (also known as a gNB) in new radio (NR) technology, a macro station, pico station, and a femto station. The network node may form, or be a part of, the radio access network (RAN) that provides a connection between the core network and terminal communication devices. A RAN may be organized into three functional blocks including a Radio Unit (RU), a Distributed Unit (DU) and a Centralized Unit (CU). The RU transmits, receives, amplifies, and digitizes radio frequency signals and typically located near, or integrated into, the antenna. The DU and CU perform computations and / or processing to send and receive digitalized radio signals to and from the core network. The DU is typically located at or near the RU and the CU may be closer to the core network. The infrastructure or connection between the RU and the DU is often referred to as fronthaul and the infrastructure or connection between the DU and the CU is often referred to as a midhaul. The communication node, therefore, may perform the functions of one or more of the RU, DU and / or CU depending on the particular implementation.

[0015] A terminal communication device (terminal), such as a remote terminal and a relay terminal, is a communication device on the terminal side of the communication system and is sometimes referred to as user equipment (UE), a UE device, a terminal device, wireless mobile device, wireless communication device and other terms. Some examples of a terminal communication device include a mobile phone, a smart phone, a personal digital assistant (PDA), tablet, and laptop computer. In some situations, the terminal communication device is a machine type communication (MTC) communication device or Internet-of-Things (IOT) device. In addition, the terminal communicationdevice may be, or may be a part of, a wearable device or a vehicle where the vehicle may be terrestrial vehicle, watercraft, or aircraft (including unmanned aerial vehicles). The terminal communication device, therefore, is any fixed, mobile, or portable equipment that performs the functions of the terminal device described herein.

[0016] FIG. 1 is a block diagram of an example of a U2U control layer protocol stack 100 for a L2 UE-to-UE (U2U) relay terminal. The control layer protocol stack 100 includes a Radio Resource Control (RRC) Layer 102, a Packet Data Convergence Protocol (PDCP) layer 104, an adaptation layer 106, a Radio Link Control (RLC) layer 108, a Medium Access Control (MAC) layer 110 and a physical (PHY) layer 112. The PHY layer 112 is typically referred to as Layer 1 (L1 ) 114 and the RLC layer 108 and the MAC layer 110 typically form Layer 2 (L2) 116. SRAP is applied to the adaptation layer 106 for RBs mapping where a SRAP entity is implemented at each device for each link hop. Each SRAP entity has transmitting and receiving portions. For the first hop PC5 interface 118, the transmitting portion of the SRAP entity 120 at the remote source UE (remote source terminal) has a corresponding receiving portion of the SRAP entity 122 at the U2U relay UE (relay terminal), and the transmitting portion of the SRAP entity 122 at the U2U relay UE (relay terminal) has a corresponding receiving portion of the SRAP entity 120 at the source remote UE (remote source terminal).

[0017] For the second hop PC5 interface 124, the transmitting portion of the SRAP entity 126 at the remote destination (target) UE (destination terminal) has a corresponding receiving portion of the SRAP entity 128 at the U2U relay UE (relay terminal), and the transmitting portion of the SRAP entity 128 at the U2U relay UE (relay terminal) has a corresponding receiving portion of the SRAP entity 126 at the remote destination UE (remote destination terminal).

[0018] For the example, the U2U control layer protocol stack 100 is in accordance with at least one revision of the 3GPP communication specification. The identity information in the SRAP entities used for the hop-by-hop mappings of the PC5 RLC channels to RBs between the two remote terminals (UEs) however, is a Local ID (Short ID) for the examples herein. Therefore, each SRAP entity 120, 122, 126, 128 includes the Short ID (Local ID). The Short ID is shorter than the L2IDs and the User Info IDs ofthe remote IDs. In some situations, the Short ID is 8 bits long but can be shorter in other situations.

[0019] Regarding the first hop to the L2 U2U Relay, the N:1 mapping is supported by the first hop PC5 adaptation layer 120, 122 between the remote UE sidelink (SL) RBs and first hop PC5-RLC channels for relaying. The first hop adaptation layer over the first PC5 hop 118 between the source remote UE and the relay UE supports identification of traffic destined to different remote destination UEs. Regarding the second hop of L2 U2U relay 124, the second hop PC5 adaptation layer 126, 128 supports bearer mapping between the ingress RLC channels over the first PC5 hop and egress RLC channels over the second PC5 hop 124 at the L1 U2U relay UE. The PC5 Adaptation layer supports the N:1 bearer mapping between multiple ingress PC5 RLC channels over the first PC5 hop 122 and one egress PC5 RLC channel over the second PC5 hop 124 and supports the Remote UE identification function. The identity information (Short ID) of the remote UE is included in the adaptation layer 106 in the first PC5 hop and the second PC5 hop.

[0020] The adaptation layer 106 is supported over the second PC5 link for the L2 U2U relay. For L2 U2U relay, the adaptation layer 106 is laid over the RLC sublayer for both the control plane and the user plane over the second PC5 link 124. The sidelink Service Data Adaptation Protocol (SDAP)ZPacket Data Convergence Protocol (PDCP) and RRC are terminated between the remote terminals, while the RLC, MAC and PHY are terminated in each PC5 link.

[0021] FIG. 2A is a block diagram of a system 200 for an example of Short ID (Local ID) selection for PC5 SRAP for an E2E PC5 communication link 202 with multiple hops 204, 206, 208. A source remote terminal 210 establishes an E2E PC5 communication link 202 between the source remote terminal 210 and a destination remote terminal 212 through a first relay terminal 214 and a second relay terminal 216. For the example, the remote and relay terminals use ProSe UE IDs to establish the E2E PC5 link 202 in accordance with known techniques. Examples of ProSe UE IDs include Application Layer IDs and L2IDs. A User Info ID is an Application layer ID. The U2E PC5-RRC link 202 includes a PC5 first hop 204 between the source remote terminal 210 and the first relay terminal 214, a PC5 second hop 206 between the first relay terminal 214 and thesecond relay terminal 216, and a PC5 third hop 218 between the second relay terminal 216 and the destination remote terminal 212.

[0022] After the E2E PC5 link (U2U relay communication) is established, one of the relay terminals facilitating the E2E PC5 link selects a Short ID from a Short ID set stored at the Short ID selecting relay terminal. The Short ID (Local ID) is selected for use in the SRAP layer of the protocol stack by both relay terminals 214, 216. Where the E2E PC5 link includes more than one relay terminal, one of the relay terminals is designated as the Short ID-selecting relay terminal that is tasked with selecting the Short ID. Although different techniques may be used to designate the Short ID-selecting relay terminal, an example of suitable technique includes the remote source terminal designating the Short ID-selecting terminal. For the example of FIG. 2A, the remote source terminal 210 selects the first relay terminal 214 as the Short ID-selecting relay terminal. The remote source terminal sends, via the PC5-RRC connection of the PC5 first hop, a relay assignment message 220 to the first relay terminal indicating that the first relay terminal is designated as the Short ID-selecting terminal. For the example, the relay assignment message 220 is a UElnformationRequestSidelink message. The fist relay terminal 214 may respond with a UElnformationResponseSidelink message to acknowledge the message 220. In some situations, the relay assignment message 220 is a RRCReconfigurationSidelink message.

[0023] The first relay terminal 214 selects a Short ID from a pre-configured Short ID set 222 stored at the first relay terminal 214. The first relay terminal 214 selects a Short ID from the set 222 that is not being used by the first relay terminal for other communication. Each relay terminal is preconfigured with a Short ID set comprising Short IDs unique to the Short IDs contained in Short ID sets configured at other relay terminals. For the example of FIG. 2A, therefore, Short IDs in the Short ID set 222 at the first relay terminal are different from the Short IDs in the Short ID set 224 at the second relay terminal 216. As a result, any Short ID being used by the second relay terminal 216 for another communication link will be different from the Short ID selected by the first relay terminal 214.

[0024] In some situations, the Short ID set is preconfigured at the time of deployment of the terminal. In other situations, a network node (e.g., gNB) (not shown in FIG. 2A) may semi-dynamically configure a terminal when it is within coverage of the network node. At least the Short ID sets at terminals within a particular geographical area do not overlap and contain Short IDs that are unique to the other Short ID sets.

[0025] After selecting the Short ID from the Short ID set 222, the first relay terminal 214 transmits a Short ID message 226 to the remote source terminal 210 and a Short ID message 228 to the second relay terminal 216. The Short ID messages 226, 228 identify the selected Short ID. For the example of FIG. 2A, the source remote terminal 210 sends the Short ID over the PC5 first hop 204 to the first relay terminal 214 in an RRCReconfigurationSidelink message 226 using a PC5-RRC link and sends the Short ID over the PC5 second hop 206 to the second relay terminal 216 in an RRCReconfigurationSidelink message 228 using a PC5-RRC link.

[0026] In response to successfully receiving the Short ID message 226, the source remote terminal 210 sends a confirmation message 230 to the first relay terminal 214 confirming receipt of the message 226. For the example, the confirmation message 230 is a RRCReconfigurationCompleteSidelink message in accordance with at least one revision of the 3GPP communication specification.

[0027] In response to successfully receiving the Short ID message 228, the second relay terminal 216 sends a confirmation message 232 to the first relay terminal 214 confirming receipt of the message 228. For the example, the confirmation message 232 is a RRCReconfigurationCompleteSidelink message. The second relay terminal 216 also sends a Short ID message 234 to the remote destination terminal 212 identifying the Short ID. For the example of FIG. 2A, the second relay terminal 216 sends the Short ID over the PC5 third hop 208 to the remote destination terminal 212 in an RRCReconfigurationSidelink message 234 using a PC5-RRC link.

[0028] In response to successfully receiving the Short ID message 234, the remote destination terminal 212 sends a confirmation message 236 to the second relay terminal 216 confirming receipt of the message 234. For the example, the confirmation message 236 is an RRCReconfigurationCompleteSidelink message. After the messageconfirmations are received, the Short ID is applied to the SRAP layer and each remote terminal includes the Short ID in the SRAP header for E2E transmissions.

[0029] For the example, the source remote terminal 210 does not initiate any other Short ID negotiations until the current the Short ID is applied to the SRAP for the E2E PC5 link 202. Such a technique avoids confusion regarding multiple Short IDs in other messages for another E2E link.

[0030] Although the example of FIG. 2A includes two relay terminals supporting the E2E link 202, the principles described above can be applied to E2E links including any number of relay terminals. In some situations, the SRAP Short ID management technique may be applied to an E2E link including only a single relay terminal.

[0031] FIG. 2B is a block diagram of the system 200 for an example of Short ID (Local ID) selection for PC5 SRAP for E2E PC5 communication links 202, 240 for multiple destination terminals 212, 242. A source remote terminal 210 establishes a first E2E PC5 communication link 202 between the source remote terminal 210 and a first destination remote terminal 212 through a relay terminal 214 and establishes a second E2E PC5 communication link 240 between the source remote terminal 210 and a second destination remote terminal 242 through the relay terminal 214. For the example, the remote and relay terminals use the ProSe UE IDs, such as the User Info IDs to establish the E2E PC5 links 202, 240 in accordance with known techniques. In some situations, the L2IDs may be used. The first E2E PC5 link 202 includes a PC5 first hop 244 between the source remote terminal 210 and the relay terminal 214, and a PC5 second hop 246 between the relay terminal 214 and the first destination remote terminal 212. The second U2E PC5-RRC link 242 includes a PC5 first hop 248 between the source remote terminal 210 and the relay terminal 214, and a PC5 second hop 250 between the relay terminal 214 and the second destination remote terminal 242.

[0032] After the first E2E PC5 link 202 is established, the source remote terminal 210 sends a first relay assignment message 252 to the relay terminal 214 indicating the relay terminal 214 is to select a first Short ID for the first E2E PC5 link 202. The relay terminal 214 selects a Short ID from its Short ID set 222 for the first E2E link 202. The relay terminal identifies a Sort ID in the set 222 that is not in use.

[0033] The relay terminal 214 sends a Short ID message 254 to the first remote destination terminal 212 identifying the selected Short ID for the first E2E link 202. The Short ID message 254 is sent over the PC5 second hop 246 of the first E2E link 202. The relay terminal 214 also sends a Short ID message 256 to the remote source terminal 210 identifying the selected Short ID for the first E2E link 202. The Short ID message 256 is sent over the PC5 first hop 244 of the first E2E link 202.

[0034] The remote source terminal 210 sends a message confirmation 258 to the relay terminal 214 confirming successful receipt of the Short ID message 256. The first remote destination terminal 212 sends a message confirmation 259 to the relay terminal 214 confirming successful receipt of the Short ID message 254. The message confirmation 258 is sent via the PC5 first hop 244 of the first E2E link 202 and the message confirmation 259 is sent via the PC5 second hop 246 of the first E2E link 202. For the example, the Short ID messages 254, 256 are RRCReconfigurationSidelink messages and the message confirmations 258, 259 are RRCReconfigurationCompleteSidelink messages.

[0035] For the example, the source remote terminal 210 does not initiate any other Short ID negotiations until the current the Short ID is applied to the SRAP for the E2E PC5 RRC link 202. Such a technique avoids confusion regarding multiple Short IDs and confirmation messages with other messages for another E2E link. For the example, therefore, the relay terminal 214 does not send a second Short ID message 264 until the remote source terminal receives a message confirmation from the relay terminal 214.

[0036] After the second E2E PC5 link 240 is established, the source remote terminal 210 sends a second relay assignment message 262 to the relay terminal 214 indicating the relay terminal 214 is to select a second Short ID for the second E2E PC5 link 240. The relay terminal 214 selects a Short ID from its Short ID set 222 for the second E2E link 202. The relay terminal identifies a Sort ID in the set 222 that is not in use. Accordingly, the Short ID for the second E2E link 240 is different from the Short ID for the first E2E link 202.

[0037] The relay terminal 214 sends a Short ID message 264 to the remote source terminal 210 identifying the selected Short ID for the second E2E link 240. The Short ID message 264 is sent over the PC5 first hop 248 of the second E2E link 240. The relay terminal 214 also sends a Short ID message 266 to the second remote destination terminal 212 identifying the selected Short ID for the second E2E link 240. The Short ID message 266 is sent over the PC5 second hop 250 of the second E2E link 240.

[0038] The remote source terminal 210 sends a message confirmation 268 to the relay terminal 214 confirming successful receipt of the Short ID message 264. The second remote destination terminal 242 sends a message confirmation 270 to the relay terminal 214 confirming successful receipt of the Short ID message 266. The message confirmation 268 is sent via the PC5 first hop 248 of the second E2E link 240 and the message confirmation 270 is sent via the PC5 second hop 250 of the second E2E link 240. For the example, the Short ID messages 264, 266 are RRCReconfigurationSidelink messages and the message confirmations 268, 270 are RRCReconfigurationCompleteSidelink messages. After each remote terminal 210, 242 confirm the Short ID messages 264, 266, the second Short ID is applied to the SRAP layer for the second E2E link 240 and each remote terminal 210, 242 includes the Short ID in the SRAP header for E2E transmissions. For the examples, the E2E PC5-RRC messages are encapsulated within an SL-RLC channel of the hop-by-hop PC5-RRC connections, whereby each of the hop-by-hop PC5-RRC connections will utilize SRAP with the Short ID.

[0039] FIG. 2C is a block diagram of the system 200 for an example of Short ID (Local ID) selection for PC5 SRAP for E2E PC5 communication links 202, 240 for multiple destination terminals 212, 242 and multiple relay terminals 214, 216. A source remote terminal 210 establishes a first E2E PC5 communication link 202 between the source remote terminal 210 and a first destination remote terminal 212 through a first relay terminal 214 and a second relay terminal 216. The source remote terminal 210 also establishes a second E2E PC5 communication link 240 between the source remote terminal 210 and a second destination remote terminal 242 through the relay terminal 214. For the example, the remote and relay terminals use the PreoSe UE IDs such asthe L2IDs or User Info IDs to establish the E2E PC5 links 202, 240 in accordance with known techniques. The first E2E PC5 link 202 includes a PC5 first hop 204 between the source remote terminal 210 and the relay terminal 214, a PC5 second hop (2) 206 between the first relay terminal 214 and the second relay terminal 216 and a PC5 third hop 208 between the second relay terminal 216 and the first destination remote terminal 212. The second E2E PC5 link 240 includes a PC5 first hop 248 between the source remote terminal 210 and the relay terminal 214, and a PC5 second hop 250 between the relay terminal 214 and the second destination remote terminal 242.

[0040] After the first E2E PC5 link 202 is established, the source remote terminal 210 sends a first relay assignment message 252 to the first relay terminal 214 indicating the first relay terminal 214 is to select a first Short ID for the first E2E PC5 link 202. The first relay terminal 214 selects a Short ID from its Short ID set 222 for the first E2E link 202. The first relay terminal identifies a Short ID in the set 222 that is not in use.

[0041] The first relay terminal 214 sends a Short ID message 272 to the second relay terminal 216 identifying the selected Short ID for the first E2E link 202. The Short ID message 272 is sent over the PC5 second hop 206 of the first E2E link 202. The first relay terminal 214 also sends a Short ID message 256 to the remote source terminal 210 identifying the selected Short ID for the first E2E link 202. The Short ID message 256 is sent over the PC5 first hop 244 of the first E2E link 202.

[0042] The remote source terminal 210 sends a message confirmation 258 to the first relay terminal 214 confirming successful receipt of the Short ID message 256. The second relay terminal 216 sends a message confirmation 274 to the first relay terminal 214 confirming successful receipt of the Short ID message 272. The message confirmation 258 is sent via the PC5 first hop 244 of the first E2E link 202 and the message confirmation 274 is sent via the PC5 second hop 206 of the first E2E link 202. For the example, the Short ID messages 256, 272 are RRCReconfigurationSidelink messages and the message confirmations 258, 274 are RRCReconfigurationCompleteSidelink messages.

[0043] The second relay terminal 216 sends a Short ID message 276 to the first remote destination terminal 212 identifying the selected Short ID for the first E2E link202. The Short ID message 276 is sent over the PC5 third hop 208 of the first E2E link 202. The first remote destination terminal 212 sends a message confirmation 278 to the second relay terminal 216 confirming successful receipt of the Short ID message 276. The message confirmation 278 is sent via the PC5 third hop 208 of the first E2E link 202. For the example, the Short ID message 276 is an RRCReconfigurationSidelink message and the message confirmation 278 is an RRCReconfigurationCompleteSidelink message.

[0044] After the second E2E PC5 link 240 is established, the source remote terminal 210 sends a second relay assignment message 262 to the first relay terminal 214 indicating the first relay terminal 214 is to select a second Short ID for the second E2E PC5 link 240. The relay terminal 214 selects a Short ID from its Short ID set 222 for the second E2E link 202. The relay terminal identifies a Short ID in the set 222 that is not in use. Accordingly, the Short ID for the second E2E link 240 is different from the Short ID for the first E2E link 202.

[0045] The first relay terminal 214 sends a Short ID message 264 to the remote source terminal 210 identifying the selected Short ID for the second E2E link 240. The Short ID message 264 is sent over the PC5 first hop 248 of the second E2E link 240. The relay terminal 214 also sends a Short ID message 266 to the second remote destination terminal 212 identifying the selected Short ID for the second E2E link 240. The Short ID message 266 is sent over the PC5 second hop 250 of the second E2E link 240.

[0046] The remote source terminal 210 sends a message confirmation 268 to the relay terminal 214 confirming successful receipt of the Short ID message 264. The second remote destination terminal 242 sends a message confirmation 270 to the relay terminal 214 confirming successful receipt of the Short ID message 266. The message confirmation 268 is sent via the PC5 first hop 248 of the second E2E link 240 and the message confirmation 270 is sent via the PC5 second hop 250 of the second E2E link 240. For the example, the Short ID messages 264, 266 are RRCReconfigurationSidelink messages and the message confirmations 268, 270 are RRCReconfigurationCompleteSidelink messages. After each remote terminal 210, 242confirm the Short ID messages 264, 266, the second Short ID is applied to the SRAP layer for the second E2E link 240 and each remote terminal 210, 242 includes the Short ID in the SRAP header for E2E transmissions.

[0047] FIG. 3 is a block diagram of an example of a UE device 300 suitable for use as each of the terminal devices 210, 212, 214, 216, 242. In some examples, the UE device 300 is any wireless communication device such as a mobile phone, a transceiver modem, a personal digital assistant (PDA), a tablet, or a smartphone. In other examples, the UE device 300 is a machine type communication (MTC) communication device or Internet-of-Things (IOT) device. The UE device 300, therefore is any fixed, mobile, or portable equipment that performs the functions described herein. The various functions and operations of the blocks described with reference to UE device 300 may be implemented in any number of devices, circuits, or elements. Two or more of the functional blocks may be integrated in a single device, and the functions described as performed in any single device may be implemented over several devices.

[0048] The UE device 300 includes at least electronics 302, a transmitter 304 and a receiver 306. The electronics 302 include any combination of hardware, software, and / or firmware for communicating with and controlling other UE device components to execute the functions described herein as well as facilitating the overall functionality of a communication device. The electronics 302, therefore, cooperatively operate with other UE device components to initiate tasks and perform the operations and functions of the UE device 300. An example of suitable electronics 302 includes code running on a microprocessor or processor arrangement connected to memory 310. The transmitter 304 includes electronics configured to transmit wireless signals. In some situations, the transmitter 304 may include multiple transmitters. The receiver 306 includes electronics configured to receive wireless signals. In some situations, the receiver 306 may include multiple receivers. The receiver 306 and transmitter 304 receive and transmit signals, respectively, through antenna 308. The antenna 308 may include separate transmit and receive antennas. In some circumstances, the antenna 308 may include multiple transmit and receive antennas.

[0049] The transmitter 304 and receiver 306 in the example of FIG. 3 perform radio frequency (RF) processing including modulation and demodulation. The receiver 306, therefore, may include components such as low noise amplifiers (LNAs) and filters. The transmitter 304 may include filters and amplifiers. Other components may include isolators, matching circuits, and other RF components. These components in combination or cooperation with other components perform the communication device functions. The required components may depend on the particular functionality required by the communication device.

[0050] The transmitter 304 includes a modulator (not shown), and the receiver 306 includes a demodulator (not shown). The modulator can apply any one of a plurality of modulation orders to modulate the signals to be transmitted as part of the uplink signals. The demodulator demodulates the downlink signals in accordance with one of a plurality of modulation orders.

[0051] The UE device 300 is capable of transmitting and receiving sidelink signals to and from other UE devices as well as communicating with base stations. The electronics 302, in conjunction with the receiver 306, measure an evaluate signals transmitted by other devices, such as base stations and UE devices. The electronics 302 and the receiver 306, therefore, can receive, measure, and evaluate downlink reference signals transmitted by a base station. Signal measurements and evaluations can be stored in the memory 310. The electronics 302 and receiver 306 can also receive, measure and evaluate discovery signals transmitted by nearby UE devices to generate a neighbor list that includes neighbor UE devices within the maximum distance. The neighbor list is stored in the memory 310 and may be transmitted to a base station.

[0052] FIG. 4 is a message diagram for an example of Short ID (Local ID) selection for PC5 SRAP for the E2E PC5 communication link 202 with multiple hops 204, 206, 208.

[0053] At event 402, an E2E communication link is established between the source remote terminal 210 and the remote destination terminal 212. In accordance with knowntechniques and using the ProSe UE IDs, the E2E PC5 communication link is established.

[0054] At event 404, the source remote terminal 210 sends a relay assignment message to the first relay terminal 214 indicating that the first relay terminal should select a Short ID. In some situations, the Short ID-selecting relay terminal may be identified using other techniques.

[0055] At event 406, the first relay terminal selects the Short ID for the SRAP of the E2E PC5 link 202. The first relay terminal 214 evaluates the Short ID set and selects a Short ID that is not in use.

[0056] At transmission 408, a Short ID notification message is sent to the source remote terminal 210 from the first relay terminal 214. For the example, a RRCReconfigurationSidelink message is sent over the PC5 first hop to the remote source terminal 210 where the message identifies the Short ID selected by the first relay terminal 214.

[0057] At transmission 410, a Short ID notification message is sent to the second relay terminal 216 from the first relay terminal 214. For the example, a RRCReconfigurationSidelink message is sent over the PC5 second hop to the second relay terminal 216 where the message identifies the Short ID selected by the first relay terminal 214.

[0058] At transmission 412, the remote source terminal 210 sends a message confirmation to the first relay terminal 214 in response to successfully receiving the Short ID message in the transmission 408. The remote source terminal 210 transmits a RRCReconfigurationCompleteSidelink message over the PC5 first hop.

[0059] At transmission 414, second relay terminal 216 transmits a Short ID notification message to the remote destination terminal 212. The second relay terminal 216 transmits a RRCReconfigurationSidelink message over the PC5 third hop to the remote destination terminal 212 where the message identifies the Short ID selected by the first relay terminal 214.

[0060] At transmission 416, second relay terminal 216 sends a message confirmation to the first relay terminal 214 in response to successfully receiving the Short ID message in the transmission 410. The second relay terminal 216 transmits a RRCReconfigurationCompleteSidelink message over the PC5 second hop.

[0061] At event 418, the remote destination terminal 212 sends a message confirmation in response to successfully receiving the short ID message at transmission 414. The remote destination terminal 212 transmits a RRCReconfigurationCompleteSidelink message over the PC5 third hop to the second relay terminal 216.

[0062] At event 420, the terminals 210, 212, 214, 216 apply the Short ID to the E2E PC5 communication link 202. The relay terminals 214, 216 apply the short ID to their respective adaption layer entities to perform RB mapping for the E2E PC5 link 202. The headers of E2E transmissions from the remote terminals 210, 212 include the Short ID. For the examples, the E2E PC5-RRC messages are encapsulated within an SL-RLC channel of the hop-by-hop PC5-RRC connections, whereby each of the hop-by-hop PC5-RRC connections will utilize SRAP with the Short ID.

[0063] FIG. 5 is a flow chart of an example of method of managing Short IDs for an E2E PC5 communication link performed at a relay terminal. The method may be performed in a system such the system 100 discussed herein. For the example, the method is performed by a relay terminal such as the relay terminal 214 or the relay terminal 216. The method may be performed using any of several techniques involving any combination of software, hardware, and firmware. For example, software code running on electronics including a processor, computer or other processor arrangement within the remote terminal device may facilitate the reception of signals, measurements, and transmissions. One or more of the steps may be omitted, combined, performed in parallel, or performed in a different order than that described herein or shown in FIG. 5. In still further examples, additional steps may be added that are not explicitly described in connection with the example discussed with reference to FIG. 5.

[0064] At step 502, the relay terminal provides relay service to the establish and maintain an E2E PC5 communication link between the remote source terminal and the remote destination terminal.

[0065] Ats step 504, the relay terminal receives a relay assignment message indicating that the relay terminal should select a Short ID for the E2E PC5 link.

[0066] At step 506, the relay terminal selects the Short ID for the SRAP of the E2E PC5 link 202. The relay terminal evaluates the Short ID set and selects a Short ID that is not in use.

[0067] At step 508, the relay terminal determines whether the egress hop is to the remote destination terminal. Therefore, the relay terminal determines if the relay terminal is the last relay to the remote destination terminal in the link 202 or if the egress hop is to another relay terminal. If the egress hop is directly to the remote destination terminal, the method proceeds to step 510. Otherwise, the method continues at step 512.

[0068] At step 510, a Short ID notification message is sent to the remote destination terminal 212 from the relay terminal. For the example, an RRCReconfigurationSidelink message is sent over the PC5 second hop to the remote destination terminal 212 where the message identifies the Short ID selected by the relay terminal.

[0069] At step 512, a Short ID notification message is sent to the next relay terminal facilitating the E2E PC5 link from the relay terminal. For the example, an RRCReconfigurationSidelink message is sent over the PC5 egress hop to the next relay terminal where the message identifies the Short ID selected by the relay terminal.

[0070] At step 514, a Short ID notification message is sent to the source remote terminal 210 from the first relay terminal 214. For the example, an RRCReconfigurationSidelink message is sent over the PC5 first hop to the remote source terminal 210 where the message identifies the Short ID selected by the first relay terminal 214.

[0071] At step 516, it is determined whether all Short ID messages for E2E PC5 link have been confirmed. The relay terminal determines if a message confirmationmessage as been received for each Short ID message transmitted from the relay terminal. If all messages have been confirmed, the method continues at step 518 where the relay terminal applies the Short ID to the SRAP for the radio bearer mapping for the E2E PC5 link. Otherwise, the method returns to step 508. For the examples, the E2E PC5-RRC messages are encapsulated within an SL-RLC channel of the hop-by-hop PC5-RRC connections, whereby each of the hop-by-hop PC5-RRC connections will utilize SRAP with the Short ID.

[0072] To clearly illustrate this interchangeability of hardware, firmware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware or software, or a combination of these techniques, depends upon the particular application and design constraints imposed on the overall system. The described functionality may be implemented in various ways for each particular application, but such implementation decisions do not cause a departure from the scope of the present disclosure. In accordance with various embodiments, a processor, device, component, circuit, structure, machine, module, etc. can be configured to perform one or more of the functions described herein. The term "configured to" or "configured for" as used herein with respect to a specified operation or function refers to processors, devices, components, circuits, electronics, and equipment that are physically constructed, programmed, instructed and / or arranged to perform the specified operation or function. Furthermore, the various illustrative logical blocks, modules, devices, components and circuits described herein can be implemented within or performed by an integrated circuit (IC) that can include a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), other electronics or combinations thereof. (ASIC), a field programmable gate array (FPGA) or other programmable logic device, or any combination thereof. The logical blocks, electronics, and circuits can further include antennas and / or transceivers to communicate with various components within the network or within the device. A general-purpose processor can be a microprocessor, but in the alternative, the processor can be any conventional processor, controller, or state machine. A processor can also be implemented as a combination of computing devices, e.g., a combination ofa DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other suitable configuration to perform the functions described herein.

[0073] When implemented in software, the functions can be stored as one or more instructions or code on a computer-readable medium. Thus, the steps of a method or algorithm disclosed herein can be implemented as software stored on a computer- readable medium. Computer readable media includes both computer storage media and communication media including any medium that can be enabled to transfer a computer program or code from one place to another. A storage media can be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, 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.

[0074] Therefore, the methods and apparatus of this invention may take the form, at least partially, of program logic or program code (i.e., instructions) embodied in tangible media, such as a machine-readable storage medium. When the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the invention. The methods and apparatus of the present invention may also be embodied in the form of program code that is transmitted over some transmission medium, such as over electrical wiring or cabling, through fiber optics, or via any other form of transmission. When the program code is received and loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the invention. When implemented on a general-purpose processor, the program code combines with the processor to provide a unique apparatus that operates analogously to specific logic circuits.

[0075] Additionally, memory or other storage, as well as communication components, may be employed in embodiments of the present disclosure. It will be appreciated that, for clarity purposes, the above description has described embodiments of the present disclosure with reference to different functional units and processors. However, it will be apparent that any suitable distribution of functionalitybetween different functional units, processing logic elements or domains may be used without detracting from the present disclosure. For example, functionality illustrated to be performed by separate processing logic elements, or controllers, may be performed by the same processing logic element, or controller. Therefore, references to specific functional units are only references to a suitable means for providing the described functionality, rather than indicative of a strict logical or physical structure or organization.

[0076] Clearly, other embodiments and modifications of this invention will occur readily to those of ordinary skill in the art in view of these teachings. The above description is illustrative and not restrictive. This invention is to be limited only by the following claims, which include all such embodiments and modifications when viewed in conjunction with the above specification and accompanying drawings. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.

Claims

CLAIMS1 . A method comprising: providing, by a relay terminal, at least a portion of an end-to-end (E2E) PC5 communication link between a remote source terminal and a remote destination terminal; selecting a Short ID, from a Short ID set, for a Sidelink Relay Adaptation Protocol (SRAP) for communication over the E2E PC5 communication link, the Short ID being shorter than a ProSe UE ID of the remote source terminal and a ProSe UE ID of the remote destination terminal, the Short ID set including one or more Short IDs that are different from Short IDs included in Short ID sets of other relay terminals; transmitting a Short ID notification message identifying the Short ID to the remote source terminal; and applying the Short ID to the SRAP for communication over the E2E PC5 communication link.

2. The method of claim 1 , further comprising: transmitting another Short ID notification message to the remote destination terminal identifying the selected Short ID.

3. The method of claim 2, wherein the Short ID notification message is a RRCReconfigurationSidelink message and the another Short ID notification message is another RRCReconfigurationSidelink message.

4. The method of claim 1 , further comprising: transmitting another Short ID notification message to another relay terminal facilitating the E2E PC5 communication link.

5. The method of claim 4, wherein the Short ID notification message is a RRCReconfigurationSidelink message and the another Short ID notification message is another RRCReconfigurationSidelink message.

6. The method of claim 1 , further comprising: receiving an E2E PC5-RRC message from the transmitting terminal, the E2E RRC-PC5 message comprising a header including the Short ID; and forwarding the E2E RRC-PC5 message to the remote destination terminal.

7. The method of claim 6, wherein the E2E PC5-RRC message is encapsulated within a hop-by-hop SL-RLC channel.

8. The method of claim 1 , further comprising: receiving a relay assignment message from the remote source terminal, wherein the selecting the Short ID is at least partially in response to receiving the relay assignment message.

9. A relay terminal comprising: a transceiver comprising a transmitter and a receiver, the transceiver configured to provide at least a portion of an end-to-end PC5 communication link between a remote terminal and a remote destination terminal; and a processor configured to select a Short ID, from a Short ID set, for a Sidelink Relay Adaptation Protocol (SRAP) for communication over the E2E PC5 communication link, the Short ID being shorter than a ProSe UE ID of the remote source terminal and a ProSe UE ID of the remote destination terminal, the Short ID set including one or more Short IDs that are different from Short IDs included in Short ID sets of other relay terminals; the transmitter configured to transmit a Short ID notification message identifying the Short ID to the remote source terminal, processor configured to apply the Short ID to the SRAP for communication over the E2E PC5 communication link.

10. The relay terminal of claim 9, wherein the transmitter is further configured to transmit another Short ID notification message to the remote destination terminal identifying the selected Short ID.

11. The relay terminal of claim 10, wherein the Short ID notification message is a RRCReconfigurationSidelink message and the another Short ID notification message is another RRCReconfigurationSidelink message.

12. The relay terminal of claim 9, wherein the transmitter is further configured to transmit another Short ID notification message to another relay terminal facilitating the E2E PC5 communication link.

13. The relay terminal of claim 12, wherein the Short ID notification message is a RRCReconfigurationSidelink message and the another Short ID notification message is another RRCReconfigurationSidelink message.1 . The relay terminal of claim 9, wherein: the receiver is configured to receive an E2E PC5-RRC message from the remote source terminal, the E2E RRC-PC5 message comprising a header including the Short ID; and the transmitter is configured to forward the E2E RRC-PC5 message to the remote destination terminal.

15. The relay terminal of claim 14, wherein the E2E PC5-RRC message is encapsulated within a hop-by-hop SL-RLC channel.

16. The relay terminal of claim 9, wherein: the receiver is configured top receive a relay assignment message from the remote source terminal; and the processor is configured to select the Short ID at least partially in response to receiving the relay assignment message.

Images