Connection establishment for relay terminals in multi-hop relay communication links

Abstract

An intermediate relay terminal sends an intermediate relay terminal (IRT) Radio Resource Control (RRC) Connection Request and a child RRC Connection Request for a child terminal to a network node while in a non-connected RRC state. While in a non-connected RRC state, such as RRC-IDLE or RRC_INACTIVE, the intermediate relay terminal receives a child RRC Connection Request from a child terminal for establishing an RRC Uu connection between a network node and the child terminal. The intermediate relay terminal generates the IRT RRC Connection Request and simultaneously transmits both RRC Connection requests over a PCS link to a last relay terminal (U2N relay UE) connected to the network node where the last relay terminal relays both RRC Connection Requests to the network node. In some situations, the IRT RRC Connection Request and the child RRC Connection Request are transmitted within the same message. In addition, the IRT RRC Connection Request and the child RRC Connection Request may be multiplexed in the message.

Description

TUTL 00406 PC-1 -CONNECTION ESTABLISHMENT FOR RELAY TERMINALS IN MULTI-HOP RELAYCOMMUNICATION LINKSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to Provisional Application No. 63 / 680,980, entitled “Establishment and Re-establishment Procedures under Multihop Relay” and filed August 08, 2024, 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 connection establishment for relay terminals in multi-hop relay communication links.BACKGROUND

[0003] Many wireless communication systems that employ several base stations (network nodes) that provide wireless service to terminals (user equipment (UE) devices) enable sidelink communication between two or more terminals where the terminals can communicate directly with other terminals. In addition, one or more terminal can be used as relay devices to form relay communication links between terminal and a cell of 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 cell of a base station in the network. Accordingly, a remote terminal (remote UE) may be connected to a cell of a network node through one or more intermediate relay terminals (relay UEs) forming the U2N link. The relay terminal directly connected to the cell is typically referred to as the last relay terminal or last relay UE (LRU). In some situations, multiple relay terminals can form a connection from the remote terminal toTUTL 00406 PC-2- the network. Such an arrangement is typically referred to as a multi-hop relay communication link where each relay terminal provides one hop.

[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 llu 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 (network node) with the local Remote UE ID to be used in SRAP headers. In some situations, the U2N communication link may include more than one relay terminal.SUMMARY

[0005] An intermediate relay terminal sends an intermediate relay terminal (IRT) Radio Resource Control (RRC) Connection Request and a child RRC Connection Request for a child terminal to a network node while in a non-connected RRC state. While in a non-connected RRC state, such as RRC-IDLE or RRCJNACTIVE, the intermediate relay terminal receives a child RRC Connection Request from a child terminal for establishing an RRC Uu connection between a network node and the child terminal. The intermediate relay terminal generates the IRT RRC Connection Request and simultaneously transmits both RRC Connection requests over a PC5 link to a last relay terminal (U2N relay UE) connected to the network node where the last relay terminal relays both RRC Connection Requests to the network node. In some situations, the IRT RRC Connection Request and the child RRC Connection Request are transmitted within the same message. In addition, the IRT RRC Connection Request and the child RRC Connection Request may be multiplexed in the message.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 A is a block diagram of an example of a communication system where an intermediate relay terminal sends a combined RRC connection request including aTUTL 00406 PC-3- child RRC connection request for a child terminal and an intermediate relay terminal (IRT) RRC connection request for the intermediate relay terminal.

[0007] FIG. 1 B is a block diagram of an example of a combined RRC connection request message.

[0008] FIG. 1 C is a block diagram of an example of the communication system where the intermediate relay terminal sequentially sends the child RRC connection request for the child terminal and the IRT RRC connection request for the intermediate relay terminal.

[0009] FIG. 2A is a block diagram of an example of a system where a remote terminal in a non-connected RRC state transmits an RRC connection request with a terminal identifier (ID) of the intermediate relay terminal that is connected to the remote terminal by a PC5 link.

[0010] FIG. 2B is a block diagram of an example of a remote terminal RRC connection request message.

[0011] FIG. 3 is a block diagram of an example of a system where a remote terminal in a non-connected RRC state transmits an RRC connection request to be forwarded by an intermediate relay terminal that is connected to the remote terminal by a PC5-RRC link and the intermediate relay terminal transmits a connection information message.

[0012] FIG. 4 is a block diagram of an example of a base station suitable for use as the network node providing the serving cell.

[0013] FIG. 5 is a block diagram of an example of a UE device suitable for use as each of the terminals including remote terminal and relay terminals including the relay terminals.

[0014] FIG. 6A is a message flow diagram for an example where the intermediate relay terminal transmits a combined RRC Setup Request that includes an IRT RRC Setup Request for the intermediate relay terminal and a remote terminal RRC Setup Request for a remote terminal.TUTL 00406 PC-4-

[0015] FIG. 6B is a message flow diagram for an example where the intermediate relay terminal sequentially transmits an IRT RRC Setup Request for the intermediate relay terminal and a remote terminal RRC Setup Request for the remote terminal.

[0016] FIG. 7 is a flow chart of an example of method of forwarding, by an intermediate relay terminal, a child RRC Connection request received from a child terminal while the intermediate relay terminal is in a non-connected RRC state.DETAILED DESCRIPTION

[0017] As discussed above, a relay communication link can be established between a serving cell and a remote terminal (remote user equipment (UE) device) through one or more relay terminals (relay UE devices). The relay communication link, often referred to as a UE-to-Network (U2N) communication link, includes PC5 links between the remote terminal and the relay terminal and between relay terminals when more than one relay terminal forms the U2N communication link. The remote terminal is connected through a first PC5 link to a first relay terminal. The first relay terminal is connected through a second PC5 link to the second relay terminal and the second relay terminal is connected to the serving cell over a Uu link. The relay communication link may include any number of intermediate relay terminals where a PC5 ingress link of each relay terminal is a PC5 egress link of an adjacent relay terminal. Except for the last relay terminal, therefore, each relay terminal in the U2N link has a PC5 ingress link to a terminal and a PC5 egress link to another terminal. The last relay terminal may be referred to as the U2N relay terminal or the last relay UE (LRU). The relay terminals connected within the multi-hop relay communication link between the remote terminal and the last relay terminal may be referred to as intermediate relay terminals and / or intermediate relay UEs (IRUs).

[0018] In order to access the network, a child terminal, such as remote terminal, performs relay selection to select an intermediate relay terminal for facilitating the relay link to the network. After evaluating discovery messages transmitted by candidate relay terminals, the child terminal selects an intermediate relay terminal and PC5 links are established between the child, the intermediate relay terminal, and any other relayTUTL 00406 PC-5- terminals in the relay communication link. In addition, a Uu link is established between the last relay terminal and the serving cell provided by the network node (gNB). The child terminals sends a child RRC Connection Request to the intermediate relay terminal which may be in a non-connected RRC state, such as RRC_IDLE or RRCJNACTIVE. In conventional systems, the intermediate relay terminal that is in a non-connected RRC state establishes the RRC_CONNECTED state for itself before it can forward the child RRC Connection Request through the relay link to the network. Accordingly, the intermediate relay terminal first establishes RRC-CONNECTED by transmitting and receiving messages over the relay link to the cell that typically includes sending an RRC Setup Request message to the cell, receiving an RRC Setup message from the cell, applying the parameters provided in the RRC Setup and transmitting an RRC Setup Complete message to the cell. Therefore, the child RRC Setup Request is not forwarded by the intermediate relay terminal until the above steps are completed introducing delays in the establishment procedure for the child terminal.

[0019] For at least some of examples herein, however, latency is reduced by transmitting the RRC Reestablishment Request for the child terminal at the same time (or nearly the same time) the intermediate relay terminal transmits is own RRC Reestablishment Request. The two requests may be sent in a single message or sequentially in separate messages. In one example, the two request messages are multiplexed and sent in the same message. By sending both reestablishment requests at the same time, the reestablishment for the child terminal is initiated sooner and completed earlier compared to conventional techniques.

[0020] 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 RANTUTL 00406 PC-6- 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.

[0021] 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 communication device 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.

[0022] A parent terminal is a terminal that is connected to a child terminal where the parent terminal is typically closer within the multi-hop communication link to the cell of the network node. The parent terminal, therefore, has one less hop to the network than the child terminal. For example, an intermediate relay terminal is a child terminal of a U2N relay terminal that is Uu connected to the cell of the network node and the U2N relay terminal is parent terminal of the intermediate relay terminal. Similarly, a remote terminal is a child terminal of an intermediate relay terminal and the intermediate relay terminal is parent terminal of the remote terminal.TUTL 00406 PC-7-

[0023] An access node is a terminal or a cell that provides access to the network. Accordingly, a cell may be an access node for a terminal. A U2N relay terminal may be an access node as well as an intermediate relay terminal that is connected (or can connect) to the cell via a U2N relay terminal or via one or more intermediate relay terminals and a U2N relay terminal.

[0024] FIG. 1 A is a block diagram of an example of a communication system 100 where an intermediate relay terminal 102 sends a combined RRC connection request 104 including a child RRC connection request 106 for a child terminal 108 and an intermediate relay terminal (IRT) RRC connection request 110 for the intermediate relay terminal 102. The child terminal 108 is connected to the intermediate relay terminal 102 through PC5 link 112 and is in an RRC connection state other than RRC_CONNECTED. Accordingly, the child terminal 108 is initially in RRCJDLE or RRCJNACTIVE. For the example, the child terminal 108 is a remote terminal that is out-of-coverage of the serving cell. However, the child terminal 108 may be in coverage and / or may perform the functions of relay terminal in some situations. The intermediate relay terminal 102 is connected to a last relay terminal 114 through PC5 link 116 and is in an RRC connection state other than RRC_CONNECTED. The last relay terminal 114 is a U2N relay terminal that is in the RRC_CONNECTED state with a network node 118 and connected to the network node 118 through a llu link 120 in the example.

[0025] While in the RRCJDLE state of RRCJNACTIVE state, the intermediate relay terminal 102 receives a child RRC connection request 106 from a remote terminal (child terminal) 108. For the example, the child RRC connection request 106 is an RRC Setup Request directed to the network node and transmitted over a Signal Radio Bearer 0 (SRB0) using the preconfigured SL-RLC0. In response, intermediate relay terminal 102 generates an RRC connection request for itself and transmits both requests at the same time to the last relay terminal 114. The RRC connection request for the intermediate relay terminal is referred to herein as an intermediate relay terminal (IRT) RRC connection request 110 and is an RRC Setup Request in the example. For the example of FIG. 1A, the intermediate relay terminal 102 multiplexes the IRT RRC connection request 110 and the child RRC connection request 106 and transmits the multiplexed result in the combined connection request 104. In some situations, multiplexing the twoTUTL 00406 PC-8- requests can be omitted. The combined connection request 104 is transmitted over the PC5 link 116 to the last relay terminal 114 in a preconfigured Side Link Radio Link Control (SL-RLC) message. The last relay terminal 114 relays (i.e. , forwards) the combined connection request 104 to the network node 118 over the Uu link 120. For the example, the last relay terminal 114 is in RRC_CONNECTED when it received the combined connection request 104. In situations where the last relay terminal 114 receives the combined connection request 102 while in a non-connected RRC state (e.g., RRCJDLE or RRCJNACTIVE), the last relay terminal 114 transitions to RRC_CONNECTED before relaying the combined connection request 104 to the network node 118. Accordingly, the last relay terminal 114 sends its own RRC Connection Request (RRC Setup Request) to the network node, receives the RRC connection acknowledgement (RRC Setup), and responds with complete message (RRC Setup complete) to transmission to RRC_CONNECTED where it was not in RRC_CONNECTED when it receives the combined connection request 104. When the last relay terminal 114 is RRC_CONNECTED, it sends an RRC message including the information for the two RRC Connection Requests. For the example, the remote terminal sends a SUI (SidelinkUEInformation) message 123 including the two RRC Setup Requests from the two child terminals to the network node. Accordingly, a combined RRC connection request message 123 is sent to the network node 118 where the combined RRC connection request message 123 includes the child RRC Setup Request and the IRT Setup Request in the example.

[0026] The network node 118 generates a child RRC connection acknowledgment in response to the child RRC connection request 106 and generates an IRT RRC connection acknowledgment in response to the IRT RRC connection request 110. For the example, the child RRC connection acknowledgment and the IRT RRC connection acknowledgment are RRC Setup messages. The two acknowledgments are transmitted to the last relay terminal 114 over the Uu link 120. For the example, the two acknowledgments are combined in a single combined acknowledgment message 124 and transmitted in a RRC Reconfiguration message to the last relay terminal 114. The combined acknowledgment message 124 includes an acknowledgement message and Local ID for the intermediate relay terminal and the child terminal as well as SRBTUTL 00406 PC-9- mapping information and the corresponding PC5 relay channel configuration. The RRC Setup messages for the two child terminals is forwarded to the respective child terminal using the dedicated configuration (SL-RLC channel configuration) provided by the network node. The SL-RLC is configured for both egress and ingress for each of the terminals separately associated with the network node assigned Local ID of the terminal. The SRAP header includes the Local ID associated with the child terminal 108, and the last relay terminal 114 applies the information in the SRAP header to transmit the data / control signal towards the intermediate relay terminal 102, and the intermediate relay terminal 102 applies the information to transmit the data / control signal to the child terminal 108. Where the intermediate relay terminal 102 is also a remote terminal a different Local ID is separately transmitted only toward the intermediate relay terminal 102.

[0027] The last relay terminal 114 forwards the combined acknowledgment message 124 to the intermediate relay terminal 102 over the PC5 link 116 using the dedicated SL-RLC channel. The intermediate relay terminal 102 receives and processes the incoming combined acknowledgment message 124 to extract the RT RRC connection acknowledgment and the child RRC connection acknowledgment. The child RRC connection acknowledgment is transmitted to the child terminal 108 over the PC5 link 112 in a child RRC connection acknowledgment message 126. The intermediate relay terminal 102 sends the child RRC connection acknowledgment message 126 using the SL-RLC provided by the network node in the combined acknowledgment message 124. As discussed below, the intermediate relay terminal 102 applies the RRC Setup parameters directed to the intermediate relay terminal 102 and replies to the network node 118 with a RRC Setup complete message (not shown in FIG. 1A) to establish the RRC_CONNECTED state with the network node 118. The child terminal 108 applies the RRC Setup parameters directed to the child terminal 108 and replies to the network node 118 with a RRC Setup complete message to establish the RRC_CONNECTED state with the network node 118.

[0028] The techniques discussed above may be applied to communication paths including additional relay terminals. For example, the child terminal 108 may be anotherTUTL 00406 PC-10- intermediate relay terminal in RRC-IDLE or RRCJNACTIVE when it receives a RRC connection request from its child terminal. In such situations for the examples of FIG. 1A, the child terminal 108 generates a first combined RRC Connection Request that includes its own RRC Connection Request and the RRC Connection Request of its child. The intermediate relay terminals receives the first combined RRC Connection Request, generates its own RRC Connection Request and combines the results IRT RRC Connection Request with the first combined RRC Connection Request to form a second combined RRC Connection Request that is transmitted to the last relay terminal 114. When the last relay terminal 114 is in the RRC-CONNECTED, it transmits a Sidelink UE Information message including the second combined RRC Connection Request. Therefore, the network node 118 receives the three RRC Connection Requests at the same time and generates and transmits a combined RRC Connection Acknowledgment message including information for the intermediate relay terminal 102, the child terminal 108, and the child terminal for the child terminal 108 to establish RRC, as well as the signaling, ID and channel information allowing each relay terminal to direct each acknowledgement to the appropriate terminal.

[0029] FIG. 1 B is a block diagram of an example of a combined RRC connection request message 150. The combined RRC connection request message 150 is an example of the combined RRC connection request message 104 discussed with reference to FIG. 1A. The combined RRC connection request message 150 includes a child RRC connection request 152 and an RT RRC connection request 154 where the two requests 152, 154 are multiplexed. The child RRC connection request 152 is an RRC Setup Request for the child terminal that is generated by the child terminal and received from the child terminal in accordance with known techniques. The RT RRC connection request 154 is an RRC Setup Request for the intermediate relay terminal that is generated by the intermediate relay terminal 102 in accordance with known techniques.

[0030] FIG. 1 C is a block diagram of an example of the communication system 100 where the intermediate relay terminal 102 sequentially sends the child RRC connection request 106 for the child terminal 108 and the IRT RRC connection request 110 for theTUTL 00406 PC-11- intermediate relay terminal 102. As with FIG. 1A, the example begins with the child terminal and the intermediate relay terminal 102 in a non-connected RRC state while the last relay terminal 114 is in RRC_CONNECTED.

[0031] The intermediate relay terminal 102 generates and transmits an IRT RRC Connection Request message 110 for itself in response to receiving a child RRC Connection Request from the child terminal 108. Immediately after transmitting the IRT RRC Connection Request 110, the intermediate relay terminal 102 transmits a child RRC Connection Request message 160. For the example of FIG. 1 C, the child RRC Connection Request message 106 is transmitted over the SL-RLC0 radio bearer to the intermediate relay terminal 102 through the PC5 link 112, the IRT RRC Connection Request message 110 is transmitted over the SL-RLCO radio bearer from the intermediate relay terminal 102 to the last relay terminal 114, and the child RRC Connection Request message 160 is transmitted over a preconfigured sidelink RLC radio bearer (SL-RLCX) to the last relay terminal 114.

[0032] The last relay terminal 114 generates a combined connection request message 162 that includes the IRT RRC Connection Request and the child RRC Connection Request. For the example, the combined connection request message 162 is a Sidelink LIE Information message.

[0033] The network node 118 generates a child RRC connection acknowledgment in response to the child RRC connection request 106 and generates an IRT RRC connection acknowledgment in response to the IRT RRC connection request 110. For the example, the child RRC connection acknowledgment and the IRT RRC connection acknowledgment are RRC Setup messages. The two acknowledgments are transmitted to the last relay terminal 114 over the Uu link 120. For the example, the two acknowledgments are combined in a single combined acknowledgment message 124 and transmitted in a RRC Reconfiguration message to the last relay terminal 114. As discussed above, the combined acknowledgment message 124 includes an acknowledgement message, signaling information, and channel configurations for the intermediate relay terminal 102 and the child terminal 108.TUTL 00406 PC-12-

[0034] The last relay terminal 114 forwards the combined acknowledgment message 124 to the intermediate relay terminal 102 over the PC5 link 116 using the dedicated SL-RLC channel. The intermediate relay terminal 102 receives and processes the incoming combined acknowledgment message 124 to extract the IRT RRC connection acknowledgment and the child RRC connection acknowledgment. The child RRC connection acknowledgment is transmitted to the child terminal 108 over the PC5 link 112 in a child RRC connection acknowledgment message 126. The intermediate relay terminal 102 sends the child RRC connection acknowledgment message 126 using the SL-RLC provided by the network node in the combined acknowledgment message 124. As discussed below, the intermediate relay terminal 102 applies the RRC Setup parameters directed to the intermediate relay terminal 102 and replies to the network node 118 with a RRC Setup complete message (not shown in FIG. 1A) to establish the RRC_CONNECTED state with the network node 118. The child terminal 108 applies the RRC Setup parameters directed to the child terminal 108 and replies to the network node 118 with a RRC Setup complete message to establish the RRC_CONNECTED state with the network node 118.

[0035] The techniques discussed above with reference to FIG. 1 C may be applied to communication paths including additional relay terminals. For example, the child terminal 108 may be another intermediate relay terminal in RRC-IDLE or RRCJNACTIVE when it receives a RRC connection request from its child terminal. In such situations for the examples of FIG. 1A, the child terminal 108 generates and its own RRC Connection Request to the intermediate relay terminal 102 and transmits the RRC Connection Request of its child. The intermediate relay terminal 102 receives the two RRC Connection Requests and generates and transmits its own RRC Connection Request (IRT RRC Connection Request 110) before forwarding the child RRC Connection Request 160 and forwarding the RRC Connection Request of the child terminal of the child terminal 108. When the last relay terminal 114 is in the RRC- CONNECTED, it transmits a Sidelink UE Information message including the IRT RRC Connection Request 110, the child RRC Connection Request 160, and the RRC Connection Request of the child terminal of the child terminal 108. Therefore, the network node 118 receives the three RRC Connection Requests at the same time andTUTL 00406 PC-13- generates and transmits a combined RRC Connection Acknowledgment message including information for the intermediate relay terminal 102, the child terminal 108, and the child terminal for the child terminal 108 to establish RRC, as well as the signaling, ID and channel information allowing each relay terminal to direct each acknowledgement to the appropriate terminal.

[0036] FIG. 2A is a block diagram of an example of a system 200 where a remote terminal 202 in a non-connected RRC state transmits an RRC connection request 204 with a terminal identifier (ID) of the intermediate relay terminal 206 that is connected to the remote terminal 202 by a PC5 link. For the example, the intermediate relay terminal 206 is facilitating a multi-hop relay communication link 208 between a first remote terminal (remote terminal 1 ) 210 and a network node 212 through a last relay terminal 214 on the network-end. The first remote terminal 210 is connected to another intermediate relay terminal 216 that is connected to the intermediate relay terminal 206. Accordingly, the first remote terminal 210, the intermediate relay terminal 206, the intermediate relay terminal 216, and the last relay terminal 214 are in the RRC_CONNECTED state with the network node 212. The first remote terminal 210 is connected to the intermediate relay terminal 216 over a first PC5 link 218. The intermediate relay terminal 216 is connected to the intermediate relay terminal 206 over a second PC5 link 220. The intermediate relay terminal 206 is connected over a third PC5 link 222 to the last relay terminal 214 and the last relay terminal 214 is connected to the network node 212 over a Uu link 224.

[0037] The second remote terminal 202 is in a non-connected RRC state, such as RRCJDLE or RRCJNACTIVE, and is connected to the intermediate relay terminal 206 over a PC5 link 226. The second remote terminal 202 generates and sends an RRC connection request 204 that includes an identifier of the intermediate relay terminal 206. For the example, the RRC connection request 204 is a RRC Setup Request directed to the network node 212 and the identifier is a Layer 2 Identifier (L2ID). L2IDs identify devices at the data link layer in sidelink communications.

[0038] The intermediate relay terminal 206 forwards the RRC connection request 204 to the last relay terminal 214 which forwards the RRC connection request 204 to the network node 212. In conventional systems, an RRC connection request from aTUTL 00406 PC-14- remote terminal in a non-connected RRC state can be forwarded by relay terminals to the network node 212. The network node 212, however, may not have identification information regarding the relay terminals that form the relay path from the remote terminal to the network note. In other words, the network node 212 may know which relay terminals are involved in the remote terminals RRC Setup Request. For the examples herein, however, the remote terminal 202 identifies, in the RRC Setup Request 204 to the network node 212, the first intermediate relay terminal 206 to which the remote terminal 202 is directly connected through a PC5 link 226. The network node 212 determines the other relay terminals in the relay path 228 based on the identity of the intermediate relay terminal 206.

[0039] FIG. 2B is a block diagram of an example of a remote terminal RRC connection request message 250. The remote terminal RRC connection request message 250 is an example of the RRC connection request 204 discussed with reference to FIG. 2A. The remote terminal RRC connection request message 250 includes an ID 252 of the intermediate relay terminal 206 to which the remote terminal 202 is connected via a direct PC5 link 226. The ID is as the L2ID 252 of the intermediate relay terminal 206 in the example. The remote terminal RRC connection request message 250 is an RRC Setup Request for the remote terminal 202 that is generated in accordance with known techniques except that the L2ID of the intermediate relay terminal 206 is included in the RRC Setup Request.

[0040] FIG. 3 is a block diagram of an example of a system 300 where a remote terminal 302 in a non-connected RRC state transmits an RRC connection request 304 to be forwarded by an intermediate relay terminal 306 that is connected to the remote terminal 302 by a PC5-RRC link, and the intermediate relay terminal 306 transmits a connection information message 307. For the example, the intermediate relay terminal 306 is facilitating a multi-hop relay communication link 308 between a first remote terminal (remote terminal 1 ) 310 and a network node 312 through a last relay terminal 314 on the network-end. The first remote terminal 310 is connected to another intermediate relay terminal 316 that is connected to the intermediate relay terminal 306. Accordingly, the first remote terminal 310, the intermediate relay terminal 306, the intermediate relay terminal 316, and the last relay terminal 314 are in theTUTL 00406 PC-15-RRC_CONNECTED state with the network node 312. The first remote terminal 310 is connected to the intermediate relay terminal 316 over a first PC5 link 318. The intermediate relay terminal 316 is connected to the intermediate relay terminal 306 over a second PC5 link 320. The intermediate relay terminal 306 is connected over a third PC5 link 322 to the last relay terminal 214 and the last relay terminal 314 is connected to the network node 312 over a Uu link 224.

[0041] The second remote terminal 302 is in a non-connected RRC state, such as RRCJDLE or RRCJNACTIVE, and is connected to the intermediate relay terminal 306 over a PC5 link 326. The second remote terminal 302 generates and sends an RRC connection request 304 to the intermediate relay terminal 306. For the example, the RRC connection request 304 is RRC Setup Request directed to the network node 312. After forwarding the RRC connection request 304, the intermediate relay terminal 302 sends a connection information message 307 to the network node 312. The connection information message 307 is an RRC message that indicates that the intermediate relay terminal 306 is the first relay terminal to which the remote terminal is connected. For the example, the connection information message 307 is an RRC Sill message including the RRC Setup Requests and the L2ID of the remote terminal.

[0042] The intermediate relay terminal 306 forwards the RRC connection request 304 and transmits the connection information message 307 to the last relay terminal 314 which forwards both messages 304, 307 to the network node 312. In this way, the network node 312 is made aware of the relay terminals forming the relayed link to the remote terminal 302.

[0043] FIG. 4 is a block diagram of an example of a base station 400 suitable for use as each of the network nodes 118, 212, 312. The base station 400 includes a controller 404, transceiver 405 that includes a transmitter 406 and receiver 408, and an antenna 410, as well as other electronics, hardware, and code. The base station 400 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 the network nodes providing cells and base station 400 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 mayTUTL 00406 PC-16- be implemented over several devices. The base station 400 may be a fixed device or apparatus that is installed at a particular location at the time of system deployment. Examples of such equipment include fixed base stations or fixed transceiver stations. Although the base station 400 may be referred to by different terms, the base station 400 is typically referred to as a gNodeB or gNB when operating in accordance with one or more communication specifications of the 3GPP V2X operation. In some situations, the base station 400 may be mobile equipment that is temporarily installed at a particular location. Some examples of such equipment include mobile transceiver stations that may include power generating equipment such as electric generators, solar panels, and / or batteries. Larger and heavier versions of such equipment may be transported by trailer. In still other situations, the base station 400 may be a portable device that is not fixed to any particular location.

[0044] The controller 404 includes any combination of hardware, software, and / or firmware for executing the functions described herein as well as facilitating the overall functionality of the base station 400. An example of a suitable controller 404 includes code running on a microprocessor or processor arrangement connected to memory. The transmitter 406 includes electronics configured to transmit wireless signals. In some situations, the transmitter 406 may include multiple transmitters. The receiver 408 includes electronics configured to receive wireless signals. In some situations, the receiver 408 may include multiple receivers. The receiver 408 may receive signals through multiple antennas or through a selected antenna of a plurality of antennas of the antenna 410. The antenna 410 may include separate transmit and receive antennas or separate arrays in some situations.

[0045] The transmitter 406 and receiver 408 in the example of FIG. 4 perform radio frequency (RF) processing including modulation and demodulation. The receiver 408, therefore, may include components such as low noise amplifiers (LNAs) and filters. The transmitter 406 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 base station functions. The required components may depend on the particular functionality required by the base station.TUTL 00406 PC-17-

[0046] The transmitter 406 includes a modulator (not shown), and the receiver 408 includes a demodulator (not shown). The modulator modulates the signals to be transmitted as part of the downlink signals and can apply any one of a plurality of modulation orders. The demodulator demodulates any uplink signals received at the base station 400 in accordance with one of a plurality of modulation orders.

[0047] The base station 400 includes a communication interface 412 for transmitting and receiving messages with other base stations such as the network nodes providing target cells and / candidate target cells. The communication interface 412 may be connected to a backhaul or network enabling communication with other base stations. In some situations, the link between base stations may include at least some wireless portions. The communication interface 412, therefore, may include wireless communication functionality and may utilize some of the components of the transmitter 406 and / or receiver 408.

[0048] FIG. 5 is a block diagram of an example of a UE device 500 suitable for use as each of the terminals including child terminals, parent terminals, last relay terminals, remote terminals, and relay terminals, such as the intermediate relay terminals 106, 206, 306 the child terminals 108, 202, 220, 302, 310, the last relay terminal 118, 214, 314 and any other intermediate relay terminals. In some examples, the UE device 500 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 500 is a machine type communication (MTC) communication device or Internet- of-Things (IOT) device. The UE device 500, 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 500 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.

[0049] The UE device 500 includes at least a controller 502 and a transceiver 503 that includes a transmitter 504 and a receiver 506. The controller 502 includes any combination of hardware, software, and / or firmware for executing the functionsTUTL 00406 PC-18- described herein as well as facilitating the overall functionality of a communication device. An example of a suitable controller 502 includes code running on a microprocessor or processor arrangement connected to memory 510. The transmitter 504 includes electronics configured to transmit wireless signals. In some situations, the transmitter 504 may include multiple transmitters. The receiver 506 includes electronics configured to receive wireless signals. In some situations, the receiver 506 may include multiple receivers. The receiver 506 and transmitter 504 receive and transmit signals, respectively, through the antenna 508. The antenna 508 may include separate transmit and receive antennas. In some circumstances, the antenna 508 may include multiple transmit and receive antennas.

[0050] The transmitter 504 and receiver 506 in the example of FIG. 5 perform radio frequency (RF) processing including modulation and demodulation. The receiver 506, therefore, may include components such as low noise amplifiers (LNAs) and filters. The transmitter 504 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.

[0051] The transmitter 504 includes a modulator (not shown), and the receiver 506 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.

[0052] The UE device 500 is capable of transmitting and receiving sidelink signals to and from other UE devices as well as communicating with a base station. The controller 502, in conjunction with the receiver 506, measures signals, such as discovery signals, transmitted by nearby UE devices to generate the neighbor list that includes neighbor UE devices within the maximum distance. The neighbor list is stored in the memory 510 and transmitted to a base station 200 when the UE device 500 is a reporting UE device.TUTL 00406 PC-19-

[0053] FIG. 6A is a message flow diagram 600 for an example where the intermediate relay terminal 102 transmits a combined RRC Setup Request that includes an IRT RRC Setup Request for the intermediate relay terminal 102 and a remote terminal RRC Setup Request for a remote terminal 602. The transmissions and events related to FIG. 6A are an example of the procedure discussed with reference to FIG. 1A above. Accordingly, the RRC Connection Requests are RRC Setup Requests for the example of FIG. 6A. The example begins with the remote terminal 602 and intermediate relay terminal 102 in a non-connected RRC state, such as RRCJDLE or RRCJNACTIVE, and the last relay terminal 118 in the RRC_CONNECTED state.

[0054] At transmission 604, the remote terminal 602 transmits a remote terminal RRC Setup Request. For the example, the RRC Setup Request is transmitted via SL- RLC over the PC5 link to the intermediate relay terminal 102.

[0055] At event 606, the intermediate relay terminal 102 generates an RRC Setup request. Since the intermediate relay terminal 102 is in RRC-IDLE or RRCJNACTIVE, it determines that it must establish an RRC link with the network node in order to forward the remote terminal RRC Setup Request message.

[0056] At event 608, the intermediate relay terminal 102 combines the remote terminal RRC Setup Request and the IRT RRC Setup Request to form the combined RRC Setup Request. For the example, the remote terminal RRC Setup Request and the IRT RRC Setup Request are multiplexed.

[0057] At transmission 610, the combined RRC Setup Request message is sent to the network node 118 via the relay communication link through the last relay terminal 116. For the example, the combined RRC Setup Request message is transmitted via a preconfigured SL-RLC radio bearer to the last relay terminal 114.

[0058] At transmission 611 , the last relay terminal 114 sends the combined RRC Setup message to the network node 118 over the Uu link 120 via an Sill (RRC message). Accordingly, the combined RRC Setup Request message is transmitted to the last relay terminal 114 and is forwarded to the network node 118 by the last relay terminal 114.

[0059] At transmission 612, the network node 118 sends a combined RRC Setup message that includes a remote terminal RRC Setup for the remote terminal and anTUTL 00406 PC-20- intermediate relay terminal (IRT) RRC Setup for the intermediate relay terminal 102. For the example, the network node 118 generates an RRC Reconfiguration message that includes the two RRC Setup messages to form the combined RRC Setup message. For the example, the RRC Reconfiguration message includes, for each child terminal (intermediate relay terminal 102 and child terminal 108), an RRC Setup message, the local ID, corresponding SRAP mappings for SRBs, and the corresponding PC5 relay RLC channel configuration. The RRC Setup messages for the two child terminals is forwarded to the respective child terminal using the dedicated configuration (SL-RLC channel configuration) provided by the network node. The SL-RLC is configured for both egress and ingress for each of the terminals separately associated with the network node 118 assigned Local ID of the terminal. The SRAP header includes the Local ID associated with the child terminal 108 and the last relay terminal 114 applies the information in the SRAP header to transmit the data / control signal towards the intermediate relay terminal 102. Other techniques may be used to send the remote terminal RRC Setup message and the IRT RRC Setup message. For example, the network node 118 may send a separate RRC Reconfiguration for each RRC Setup message.

[0060] At event 614, the intermediate relay terminal 102 deciphers, decodes, and / or otherwise processes the combined RRC Setup message to extract the remote terminal RRC Setup and the IRT RRC Setup.

[0061] At event 616, the intermediate relay terminal 102 applies the parameters received in the IRT RRC Setup. In accordance with known techniques, the intermediate relay terminal 102 establishes the RRC link using the parameters and transmits an RRC Setup Complete message at transmission 618.

[0062] At transmission 620, the intermediate relay terminal 102 transmits a remote terminal RRC Setup message to the remote terminal 602. For the example, the intermediate relay terminal 102 forwards the remote terminal RRC Setup message extracted from the combined RRC message.

[0063] At event 622, the remote terminal 602 applies the parameters from the remote terminal RRC Setup message and establishes the RRC link to the network node with the transmission of the Setup Complete message to the network node 118 atTUTL 00406 PC-21- transmission 624. The message is forwarded to network node 118 through the intermediate relay terminal 102 and the last relay terminal 116.

[0064] FIG. 6B is a message flow diagram 650 for an example where the intermediate relay terminal 102 sequentially transmits an IRT RRC Setup Request for the intermediate relay terminal 102 and a remote terminal RRC Setup Request for the remote terminal 602. The transmissions and events related to FIG. 6B are an example of the procedure discussed with reference to FIG. 1 C above. Accordingly, the RRC Connection Requests are RRC Setup Requests for the example of FIG. 6B. The example begins with the remote terminal 602 and intermediate relay terminal 102 in a non-connected RRC state, such as RRCJDLE or RRCJNACTIVE, and the last relay terminal 118 in the RRC_CONNECTED state. The messages for the example of FIG. 6B are similar to the messaging discussed with reference to FIG. 6A except that transmission 610 and transmission 611 are replaced with transmissions 652, 654, 656. In the interest of clarity and brevity, only transmissions 652, 654, 656 are discussed below in detail. The operation of the other events and transmissions of the example of FIG. 6B are discussed above with reference to FIG. 6A and apply to the example of FIG. 6B.

[0065] At transmission 652, the intermediate relay terminal 102 sends the IRT RRC Setup Request to the last relay terminal 114. For the example, the message is transmitted over the PC5 link 116 using the SL-RLC0 signal bearer. Therefore, in response to receiving the child RRC Setup Request from the child terminal 108, the intermediate relay terminal 102 initiates a transition to RRC_CONNECTED.

[0066] At transmission 654, the intermediate relay terminal 102 sends the child RRC Setup Request to the last relay terminal 114. For the example, the message is transmitted over the PC5 link 116 using a preconfigured SL-RLC signal bearer. Therefore, in response to receiving the child RRC Setup Request from the child terminal 108, the intermediate relay terminal 102 initiates a transition to RRC_CONNECTED and forwards the child RRC Setup Request. The messages are sent sequentially before the intermediate relay terminal 102 established RRC_CONNECTED. Both messages are sent to the last relay terminal 114.TUTL 00406 PC-22-

[0067] At transmission 656, the last relay terminal 114 sends a combined RRC Setup Request that includes the IRT RRC Setup Request and the child RRC Setup Request. For the example, the transmission 656 is an RRC message using Sidelink UE Information over eh Uu link 120.

[0068] Transmissions 612, 618, 620, 624 and events 614, 616, 422 are performed as discussed above with reference to FIG. 6A. Accordingly, the network node 118 sends a combined RRC Setup message that is forwarded to the intermediate relay terminal 102, the intermediate relay terminal 102 sends an RRC Setup Complete message to the network node 118 and forwards the child RRC Setup Request to the child terminal using he designated SBRs and SRAP mapping. The child terminal 108 sends an RRS Setup complete message over the relay link to the network node 118 to establish RRC-CONNECTED.

[0069] FIG. 7 is a flow chart of an example of method of forwarding, by an intermediate relay terminal, a child RRC Connection request received from a child terminal while the intermediate relay terminal is in a non-connected RRC state. The method may be performed in a system such as the system 100 discussed herein. For the example, the method is performed by a terminal that may be selected to perform the functions of an intermediate relay terminal, such as the intermediate relay terminal 102. 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 terminal may facilitate the generation, formatting, reception and transmission of signals and messages. 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. 7. In still further examples, additional steps may be added that are not explicitly described in connection with the example discussed with reference to FIG. 7.

[0070] At step 702, the intermediate relay terminal 102 is operating in a nonconnected RRC state. For example, the intermediate relay terminal 102 may be in RRC- IDLE or RRCJNACTIVE.TUTL 00406 PC-23-

[0071] At step 704, a child RRC connection request message is received from the child terminal. While the intermediate relay terminal is in a non-connected RRC state, it receives a child RRC Setup Request message from the child terminal.

[0072] At step 706, an IRT RRC connection request is generated. The intermediate relay terminal generates an IRT RRC Setup Request message for establishing the RRC-CONNECTED state for the intermediate relay terminal.

[0073] At step 708, the IRT RRC connection request and the child RRC connection request are transmitted to the network node via a last relay terminal (parent terminal). In one example, the IRT RRC connection request and the child RRC connection request are combined in single message that is transmitted using a preconfigured SL-RLC bearer to the last relay terminal. The IRT RRC connection request and the child RRC connection request may be multiplexed in some cases. In another example, the IRT RRC connection request and the child RRC connection are transmitted sequentially in separate messages. For such an example, the IRT RRC connection request message may be an IRT Setup Request transmitted using the SL-RLCO bearer and the child RRC connection request message may be a child Setup Request transmitted using a preconfigured SL-RLC bearer.

[0074] At step 710, a combined RRC connection acknowledgment message is received from the last relay terminal where the combined RRC connection acknowledgment message includes a child RRC connection acknowledgment message and an IRT RRC connection acknowledgment message. The child RRC connection acknowledgment message includes RRC connection parameters for the child terminal to establish RRC_CONNECTED and the IRT RRC connection acknowledgment message includes RRC connection parameters for the intermediate relay terminal to establish RRC_CONNECTED. For the example, the combined RRC connection acknowledgment message includes a child RRC Setup message, an IRT RRC Setup message, Local IDs for the intermediate relay terminal and the child terminal, as well as SRB mapping information and the corresponding PC5 relay channel configuration. In some situations, the information may be sent by the network node in two separate acknowledgment messages.TUTL 00406 PC-24-

[0075] At step 712, the combined RRC connection acknowledgment message is processed to extract the child RRC connection acknowledgment message, the IRT RRC connection parameters, and the SRAP and SRB information.

[0076] At step 714, a RRC connection complete message is sent to the network node via the last relay terminal. The intermediate relay terminal 102 applies the IRT connection parameters and sends an IRT Setup Complete message to establish RRC-CONNECTED.

[0077] At step 716, the child RRC connection acknowledgement message is sent to the child terminal. Using the SRAP mapping and the corresponding PC5 relay channel configuration, the intermediate relay terminal transmits the child RRC connection acknowledgement message to the child terminal.

[0078] At step 718, a child RRC connection complete message is received from the child terminal and forwarded to the network node via the parent terminal (last relay terminal). The intermediate relay terminal receives the child RRC connection complete message transmitted using the RRC connection parameters and transmits the child RRC connection complete message to the last relay terminal. For the example, the child RRC connection message is child RRC Setup Complete message.

[0079] 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,TUTL 00406 PC-25- 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 of a 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.

[0080] 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.

[0081] 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 fiberTUTL 00406 PC-26- 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.

[0082] 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 functionality between 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.

[0083] 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

TUTL 00406 PC-27-CLAIMS1 . A method comprising: receiving, from a child terminal by an intermediate relay terminal in a Radio Resource Control (RRC) non-connected state, a child RRC connection request message requesting a child llu RRC connection for the child terminal; generating an intermediate relay terminal (IRT) RRC connection request message for a IRT Uu RRC connection for the intermediate relay terminal; transmitting, while in the RRC non-connected state to a parent terminal, the child RRC connection request message and the IRT RRC connection request message.

2. The method of claim 1 , wherein the transmitting the child RRC connection request message and the IRT RRC connection request message comprises sequentially transmitting the IRT RRC connection request message and the child RRC connection request message.

3. The method of claim 2, wherein the IRT RRC connection request message is transmitted using a Sidelink Radio Link Control (SL-RLC) 0 radio bearer and the child RRC connection request message is transmitted using a preconfigured SL-RLC radio bearer.

4. The method of claim 1 , wherein the transmitting the child RRC connection request message and the IRT RRC connection request message comprises transmitting a combined RRC connection request message comprising child RRC connection request message and the IRT RRC connection request message.

5. The method of claim 4, further comprising multiplexing the child RRC connection request message with the IRT RRC connection request message to generate the combined RRC connection request message.TUTL 00406 PC-28-6. The method of claim 1 , further comprising: receiving, from the parent relay terminal, a combined RRC connection acknowledgement message comprising an IRT RRC connection acknowledgement and a child RRC connection acknowledgement, the IRT RRC connection acknowledgement comprising IRT RRC connection parameters, the child RRC connection acknowledgement comprising child RRC connection parameters; processing the combined RRC connection acknowledgement message to extract the IRT RRC connection parameters and the child RRC connection acknowledgement; transmitting, to the network node via the parent relay terminal, an IRT RRC connection complete message using the IRT RRC connection parameters to establish RRC .CONNECTED; transmitting, to the child terminal, the child RRC connection acknowledgement; receiving, from the child terminal, a child RRC connection complete message transmitted using the child RRC connection parameters; and forwarding, to the network node via the parent relay terminal, the child RRC connection complete message.

7. The method of claim 6, wherein: the child RRC connection request message is a child RRC Setup Request message for the child terminal; the IRT RRC connection request message is an IRT RRC Setup Request message for the intermediate relay terminal; the IRT RRC connection acknowledgement is an IRT RRC Setup message comprising IRT RRC Setup parameters, the child RRC connection acknowledgement is a child RRC Setup message comprising child RRC Setup parameters; the IRT RRC connection complete message is an IRT Setup Complete message; and the child RRC connection complete message is a child Setup Complete message.TUTL 00406 PC-29-8. The method of claim 7, wherein the combined RRC connection request comprises a Sidelink Relay Adaptation Protocol (SRAP) bearer mapping and wherein the SRAP bearer mapping is used to transmit the child RRC connection acknowledgement.

9. The method of claim 1 , the child RRC connection request message comprises a terminal identifier (ID) of the intermediate relay terminal.

10. An intermediate relay terminal comprising: a receiver configured to receive, from a child terminal and while the intermediate relay terminal is in a Radio Resource Control (RRC) non-connected state, a child RRC connection request message requesting a child llu RRC connection for the child terminal; and a transmitter configured to transmit, while in the RRC non-connected state to a parent relay terminal an intermediate relay terminal (IRT) RRC connection request message for an IRT Uu RRC connection for the intermediate relay terminal and to transmit, while in the RRC non-connected state to the parent relay terminal, the child RRC connection request message.

11. A method comprising: determining, at a child terminal, a layer 2 identifier (L2ID) of an intermediate relay terminal connected to the child terminal through a PC5 link; and transmitting, from the child terminal to a network node via the intermediate relay terminal, a child Radio Resource Control (RRC) Setup Request message requesting a child Uu RRC connection for the child terminal, the RRC Setup Request message comprising a the L2ID of the intermediate relay terminal.

12. A method comprising: receiving, at an intermediate relay terminal from a child terminal, a child Radio Resource Control (RRC) Setup Request message requesting a child Uu RRCTUTL 00406 PC-30- connection for the child terminal, the intermediate relay terminal connected to the child terminal via a PC5 link, forwarding, the child RRC Setup Request message to a network node via a parent relay terminal; and transmitting, to network node via a parent relay terminal, an RRC message indicating the intermediate relay terminal is connected to the child terminal through a PC5 link.

Images