TW202215873A - Methods for signaling transmission in l2 ue via a network relay - Google Patents

Abstract

A method is provided to support a remote UE transmitting SRB0 message for Layer 2 UE-to-Network Sidelink relaying via a relay UE. In one novel aspect, when perform SRB0 transmission over PC5 interface, the relay UE and the remote UE apply default bearer/default RLC channel for SRB0 transmission. In another novel aspect, if the remote UE intends for on-demand system information request, additional signaling is introduced to indicate to the relay UE what system information is forwarded to the remote UE. In another novel aspect, the SRB0 message/response includes a remote UE ID determined by the remote UE/relay UE/gNB during transmitting the SRB0 message/response. In yet another novel aspect, the base station reconfigures per link configuration upon establishment of an end-to-end connection between the remote UE and the network.

Description

Method for signaling transmission by layer 2 user equipment through network relay

Embodiments of the present invention relate generally to wireless network communications, and, more particularly, to enabling signaling between remote user equipment (UE) and a generation Node-B (gNB), To establish a network through Layer 2 (Layer 2, L2) UE-to-Network relaying (UE-to-Network relaying) in the fifth-generation (5G) new radio (New Radio, NR) wireless communication system The end-to-end connection of the road.

New technologies in 5G NR allow cellular devices to connect directly to each other using a technique called sidelink (SL) communication. Sidelink is a new communication paradigm where cellular devices can communicate without relaying their data over the network. The side link interface is also known as the PC5 interface. Various applications may rely on communication over the side link interface, such as vehicle-to-everything (V2X) communication, public safety (PS) communication, and direct file transfer between user devices. To support side-link relaying, there are two UE-to-network relay architectures, namely L2 relay and Layer 3 relay (L3 relay).

In the case of L3 based side link relay, the relay UE acts as a general router in the data communication network to forward the data packet flow of the remote UE as IP traffic. IP-based traffic forwarding is done on a best-effort basis. For L3 UE to network relay, there are sidelink radio bearer (SLRB) and Uu radio bearer on PC5 to carry the quality of service established between remote UE and 5G core (5G core, 5GC) (Quality of Service, QoS) flow. During traffic forwarding, when converting PC5 streams to Uu streams, L3 UE-to-Network Relay can support stream-based mapping at the Service Data Adaptation Protocol (SDAP) layer and vice versa. Note that since the L3-based sidelink relay UE works like an IP router, the remote UE is transparent to the gNB, i.e. the gNB cannot know that the traffic transmitted by the relay UE originates from the relay The UE itself, again originating from the remote UE but forwarded by the relay UE.

In contrast, in the case of L2-based sidelink relays, the control plane (CP) and user plane (UP) between the remote UE and the network are Relays are performed above the radio link control (RLC) sublayer. Uu SDAP/Packet Data Convergence Protocol (PDCP) and Radio Resource Control (RRC) are terminated between the remote UE and gNB, while RLC, Media Access Control (MAC) and A physical (PHY) terminates at each link (ie, the link between the remote UE and the UE to the network relay UE and the link between the UE to the network relay UE and the gNB). The Uu supports the adaptation layer on the RLC layer for bearer mapping, and can also be placed on the PC5 for side link bearer mapping. The adaptation layer between the relay UE and the gNB can distinguish the bearer (signal radio bearer (SRB), data radio bearer (DRB) of a specific remote UE) for a specific remote UE. Within a Uu DRB, different remote The different bearers of the UE and the remote UE can be indicated by additional information included in the adaptation layer header. Unlike the L3 relay, the gNB is aware of each remote UE, so before the relay UE starts to forward normal data traffic, it should First establish the end-to-end connection between the remote UE and the gNB. After establishing the RRC connection through the SL relay, the remote UE can forward the forwarding/router information based on the established bearer data traffic and the adaptation layer bearer.

Currently, an open issue of the L2 connection establishment process is how the remote UE sends its first message to initiate subsequent sidelink transmissions before the end-to-end connection is established. In NR Uu, the message that the UE initiates transmission to the base station is called the SRB0 message. SRB stands for Signaling Radio Bearer, and the SRB0 message is used to carry the necessary signaling before the RRC connection is established. The SRB0 message in the NR Uu includes a message for the UE to establish/restore/re-establish an RRC connection, or request the required system information on demand (only for UEs in RRC_IDLE or RRC_INACTIVE state). In the NR Uu, the UE initiates the transmission of the SRB0 message to the base station to initiate the process of RRC connection management or system information request.

Contrary to NR Uu SRB0 transmission, in L2 SL relay, the remote UE should send SRB0 message to the base station through the relay relay UE. Due to the relay operations involved, additional design is required. For example, the SRB0 of the remote UE should be forwarded to the base station before the relay UE's Uu traffic forwarding bearer (PC5 interface between the remote UE and the relay UE, Uu interface between the relay UE and the base station) is established . Furthermore, the base station should be able to provide a response to the correct remote UE, eg if the remote UE sends an SRB0 message via the SL relay to initiate RRC connection establishment, the gNB should be able to send an RRCSetup message back to the remote UE that initiated the request.

A solution needs to be found.

A method is proposed to support remote UE to send SRB0 for L2 UE to network side link relay through relay UE. In a novel aspect, when SRB0 transmission is performed through the PC5 interface, the relay UE and the remote UE apply the default bearer/default RLC channel for SRB0 transmission. In another novel aspect, if the remote UE intends to make an on-demand system information request, additional signaling is introduced to instruct the relay UE which system information to forward to the remote UE. In another novel aspect, the SRB0 message/response includes a remote UE identity (ID) determined by the remote UE/relay UE/gNB during transmission of the SRB0 message/response. In yet another novel aspect, the base station reconfigures each link configuration when establishing the end-to-end connection between the remote UE and the network.

The method for signaling transmission from the L2 UE to the network relay proposed by the present invention enables the remote UE to establish an end-to-end connection through the relay UE, thereby improving the communication quality, improving the user experience, and at the same time expanding the existing network. Service coverage.

Other embodiments and advantages are described in the detailed description below. This summary is not intended to define the invention. The present invention is limited by the scope of the invention application patent.

Reference will now be made in detail to some embodiments of the present invention, examples of which are shown in the accompanying drawings.

FIG. 1 illustrates a wireless cellular communication system 100 according to a novel aspect that supports signaling from a remote UE to a network side link relay through an L2 UE of the relay UE. The wireless cellular communication system 100 (5G NR mobile communication network) includes a 5GC 101 , a base station gNB 102 and a plurality of UEs 103 , UE 104 and UE 105 . For UEs within coverage, the base station can schedule data traffic through the Uu link. For out-of-coverage UEs, relay UEs can schedule data traffic through PC5 (or SL). In Figure 1, UE 103 is an RRC-connected UE that acts as a mobile device relay, using PC5 (or SL) to relay data traffic with the terminal's remote UE to extend coverage. The remote UE 104 is out of network coverage. The relay UE 103 helps the remote UE 104 relay all data traffic. The remote UE 105 is connected to the network via a Uu link, but the link quality may be poor. The relay UE 103 helps the remote UE 105 relay some or all of the data traffic. The relay UE 103 performs relay communication between the UE 104/105 and the network, allowing the network to effectively extend its coverage to remote UEs.

In L2 relay, the relay UE only acts as a hop-by-hop RLC-level router, so before data traffic is forwarded, the remote UE should establish an end-to-end connection with the gNB through the SL relay to establish The corresponding end-to-end Uu SDAP/PDCP layer for QoS flow/bearer handling in the user plane, and the RRC/PDCP layer for the control plane. In L2 relay, if the remote UE does not establish an RRC connection through the SL relay, the remote UE cannot directly send its data traffic. Instead, similar to NR Uu, the remote UE is only allowed to send SRB0-like messages before entering the RRC_CONNECTED state. SRB stands for Signaling Radio Bearer, SRB0 message is used to carry basic signaling before establishing an RRC connection.

In NR Uu, SRB0 is used for RRC messages using the common control channel (common control channel, CCCH) logical channel. The UE sends a UL SRB0 message in the following cases: for establishing an RRC connection (RRCSetupRequest), for resuming an RRC connection (RRCResumeRequest), for re-establishing an RRC connection (RRCReestablishmentRequest), or for an on-demand system information request (RRCSystemInfoRequest). In L2 relaying, similar to NR Uu, the remote UE needs to maintain the RRC connection (eg, for setup, for recovery, for re-establishment) and request the required system information. However, since in L2 SL relay, the SRB0 message is transmitted to the base station through the forwarding of the SL relay UE, an additional mechanism should be introduced to ensure successful relay.

According to one novel aspect, a method of SRB0 transmission for a remote UE through a relay UE is presented. For example, mechanisms to ensure that SRB0 messages can be correctly forwarded to the base station, e.g. using appropriate bearers or logical channels on both links (i.e. PC5 link between remote UE and relay UE, and relay UE and gNB Uu link between) to send SRB0 message. For example, a mechanism to ensure that the remote UE can correctly receive the response message from the base station, eg, correct bearer mapping and routing in the downlink direction of the Uu link and the PC5 link. As represented by block 110 of FIG. 1, in one novel aspect, when performing SRB0 transmission over the PC5 interface, the relay UE and the remote UE apply the default bearer/default RLC channel for SRB0 transmission. In another novel aspect, if the remote UE intends to request on-demand system information, additional signaling is introduced to indicate to the relay UE what system information to forward to the remote UE. In another novel aspect, the SRB0 message/response includes the remote UE ID during forwarding of the SRB0 message/response message. In yet another novel aspect, the base station reconfigures each link configuration when establishing an end-to-end connection between the remote UE and the network.

Figure 2 depicts a simplified block diagram 200 of wireless devices 201 and 211 in accordance with an embodiment of the present invention. For wireless device 201 (eg, a relay UE), antennas 207 and 208 transmit and receive radio signals. The RF transceiver 206 is coupled to the antenna, receives RF signals from the antenna, converts them into baseband signals, and sends them to the processor 203 . RF transceiver 206 also converts baseband signals received from the processor, converts them into RF signals, and sends them to antennas 207 and 208 . The processor 203 processes the received baseband signal and invokes different function modules to execute the functions in the wireless device 201 . Memory 202 stores program instructions and data 210 to control the operation of wireless device 201 .

Similarly, for wireless device 211 (eg, a remote UE), antennas 217 and 218 transmit and receive radio signals. The RF transceiver 216 is coupled to the antenna, receives RF signals from the antenna, converts them into baseband signals, and sends them to the processor 213 . RF transceiver 216 also converts baseband signals received from the processor, converts them into RF signals, and sends them to antennas 217 and 218 . The processor 213 processes the received baseband signal and invokes different function modules to execute the functions in the wireless device 211 . Memory 212 stores program instructions and data 220 to control the operation of wireless device 211 .

Wireless devices 201 and 211 also include certain functional modules and circuits that implement embodiments of the present invention. In the example of Figure 2, the wireless device 201 is a relay UE comprising a protocol stack 222, resource management circuitry 205 for allocating and scheduling side link resources, connection processing circuitry 204 for establishing and managing connections, Traffic relay processing controller 209 for relaying all or part of control signaling and/or data traffic for remote UEs, and control and configuration circuitry 221 for providing control and configuration information. The wireless device 211 is a remote UE that includes a protocol stack 232, relay discovery circuitry 214 for discovering relay UEs, connection processing circuitry 219 for establishing and managing connections, and control and configuration circuitry 231. These different functional modules and circuits can be implemented by software, firmware, hardware or a combination thereof. When the functional modules and circuits are executed by processors 203 and 213 (eg, by executing program instructions and data 210 and 220), wireless device 201 and wireless device 211 are allowed to perform embodiments of the present invention accordingly.

Figure 3 illustrates an implementation of sending and receiving SRB0 using a designated/fixed/preset configuration in accordance with a novel aspect. In step 311 , the remote UE 301 sends an SRB0 message to the relay UE 302 . In step 312, the relay UE 302 forwards the SRB0 message of the remote UE 301 to the base station gNB 303. In step 313, the gNB 303 provides a response to the SRB0 message and sends the response to the relay UE 302. Finally, in step 314, the relay UE 302 forwards the response from the gNB 303 to the SRB0 to the remote UE 301. There are different ways of SRB0 message transmission from remote UE to gNB. In one embodiment, the SRB0 message (eg, RRCSetupRequest) may pass through the adaptation layer (at Uu and PC5, or only at Uu), and in this case the adaptation layer header is added to the encapsulation by the remote UE In the data packet of the SRB0 message. When the gNB responds to the SRB0 message, if it is a unicast-based response, the response message can also pass through the adaptation layer (at Uu and PC5, or only at Uu). In another embodiment, the SRB0 message does not pass through the adaptation layer (at Uu and PC5, or only at Uu) because no RRC connection is established between the remote UE and the gNB. However, the message may be carried by the DCCH (Dedicated Control Channel) on the Uu between the relay UE and the gNB, instead of the CCCH (Common Control Channel). This means that a designated Uu logical channel needs to be configured for this type of common SRB0 message transmission from remote UEs. When the gNB responds to the SRB0 message, if it is a unicast-based response, the response message does not pass through the adaptation layer (at Uu and PC5, or only at Uu).

In step 311 , the SRB0 message may be transmitted from the remote UE 301 to the relay UE 302 through the PC5 interface based on a preset sidelink radio bearer (SL-SRB) and/or a preset PC5 RLC channel. The preset SL bearer/PC5 RLC channel may be established after confirming that SL relay between the remote UE and the relay UE is allowed, eg, when the relay UE is authorized to relay, the PC5 RLC channel may be established. In other words, after confirming the relay permission, a preset or designated/fixed PC5 RLC channel for relaying SRB0 can be established. Specifying and Presetting the SL RLC/MAC layer configuration is a configuration specifying detailed information in the 3GPP standard, including logical channel ID, logical channel configuration, and the like. Note that the specified configuration is fixed, while the preset configuration can be modified using dedicated signaling. For specified configuration, specifies parameters for unicast of NR sidelink communication for transporting sidelink signaling radio bearers, such as PC5-RRC messages over PC5-RLC channel. The SL-SRB carrying the Uu SRB0 message of the remote UE may be SL-SRB3. The Uu SRB0 message can be carried by the SCCH (Side Link Common Control Channel) through the PC5-RLC channel.

There are several possible ways to establish an RLC channel for SRB0 transmission. In one embodiment, the relay UE and the remote UE can configure the RLC channel according to a preset or specified configuration without additional signaling exchange between the remote UE and the relay UE. For example, on the remote UE side, (1) when the relay is authorized, or (2) when sending SRB0 to the relay UE, a preset/designated RLC channel for SRB0 transmission is established. Similarly, on the relay UE side, a preset/designated RLC channel for SRB0 reception is established (1) when the relay is authorized, or (2) when SRB0 is received from the remote UE. In another embodiment, the remote UE configures the SL radio bearer/SL RLC channel for SRB0 transmission according to one of the configurations from pre-configured, specified (fixed) configuration or from network (NW) configuration. The NW configuration can come from a system information block (SIB) or dedicated signaling, where the SIB includes system information broadcast by the base station. For example, a remote UE may be in coverage to obtain a sidelink configuration that may be used to transmit Uu SRB0 messages via SIB or via dedicated NW signaling before or after SRB0 transmission. For example, the remote UE may obtain the configuration for SRB0 transmission from the relay UE before sending the SRB0. Specifically, the relay UE can provide the configuration (system information) required for Uu SRB0 transmission to the remote UE. When an explicit request is received from the remote UE, or when PC5-RRC is established between the remote UE and the relay UE, the relay UE can provide the required configuration via (periodic) broadcast.

Through the PC5 interface, the remote UE can use the PC5-RRC message (eg, RRCReconfigurationSidelink) as a container to transmit the SRB0 message to the relay UE. After the relay UE receives the PC5-RRC message, the relay UE replies an acknowledgement message (eg, RRCReconfigurationCompleteSidelink) to the remote UE, and then forwards the included SRB0 message to the base station. In one embodiment, the remote UE sends the SRB0 message via an existing or new sidelink radio bearer. For example, SRB0 messages may be carried by existing SL-SRB3 (ie, for PC5-RRC messages), or may be carried by a new SL-SRB dedicated to processing/forwarding Uu SRBs or dedicated to processing Uu SRB0. In one embodiment, the SRB0 message is carried by the SCCH (Sidelink Common Control Channel) via PC5.

In step 312, the forwarded SRB0 may be transmitted in several ways. In one embodiment, the SRB0 message is included in the RRC message on the UL-DCCH of the relay UE. That is, the relay UE uses the RRC message as a container to include the SRB0 message of the remote UE. The RRC message can be an extension of SUI (sidelink UEInformation) or UAI (UEAssistanceInformation), or can be a new UL RRC message for reporting relay-related information. The Uu UL RLC channel used for the relay UE to send/forward SRB0 messages from the remote UE may apply a preset configuration, a specific/fixed configuration, or an NW configuration from SIB or dedicated signaling. When the relay UE is authorized to provide relay services, when an RLC channel/logical channel establishment request is received from a remote UE, when an SRB0 message is received from a remote UE, or when forwarding of an SRB0 message is initiated, it can be established for remote The Uu RLC channel forwarded by the UE's Uu SRB0.

In step 313, gNB 303 determines how to provide a response to the SRB0 message. How the base station responds depends on the intent of the RRC procedure that triggers the SRB0 transmission via the SL relay (eg, RRC setup in response to an RRCSetupRequest). The response to SRB0 can be transmitted in a number of ways. In one embodiment, the base station sends an SRB0 response to the relay UE through the RRC message on the DL-DCCH of the Uu. For example, the response can be put into an RRC message container such as an RRCReconfiguration message.

In one embodiment, there is a Uu DL logical channel suitable for the relay UE to receive the response to SRB0 from the base station. Messages as SRB0 responses can be transmitted through relay-specific/SRB0-specific Uu DL logical channels. The Uu DL logical channel used to receive the SRB0 response can be configured by the network (eg, through pre-configuration, SIB or dedicated signaling) through a default configuration or a specified/fixed configuration. A Uu RLC logical channel may be established when authorized to provide relay services, when an SRB0 message is received, when a forwarded SRB0 message is sent, or when an SBR0 response from a base station is received.

In step 314, the relay UE 302 forwards the SRB0 response from the gNB 303 to the remote UE 301. For the transmission of SRB1 RRC messages (eg, RRCReestablishment and RRCResume messages) of the remote UE, the default configuration is used for the configuration of the PC5 RLC channel. During the SRB0 transmission in step 311, a preset/designated RLC channel may have been established for the transmission of SRB0. The RLC channel can be established bidirectionally, so when the remote UE sends the SRB0, the RLC channel for the remote UE to receive the corresponding SRB0 is ready, and then the RLC channel can be reused in step 314 to send messages. In one embodiment, the RLC/MAC/PHY configuration on the PC5 for the relay UE to send the SRB0 response to the remote UE is the same as the configuration for the remote UE to send the SRB0 in step 311 .

In one embodiment, the SRB0 response forwarded by the relay UE to the remote UE is carried by the PC5-RRC message, eg, the message of the Uu SRB0 is included using the PC5-RRC message as a container. In one embodiment, the SRB0 response forwarded by the relay UE to the remote UE is carried by an existing SL-SRB (eg, SL-SRB3), or by a new SL-SRB dedicated to relay Uu-SRB or Uu-SRB0. In one embodiment, the SRB0 response forwarded by the relay UE to the remote UE is either dedicated to relay Uu traffic or dedicated to relay Uu control signaling (eg, for Uu SRB only or for both Uu SRB0 and SRB1) sidelink logical channel bearer. In one embodiment, the SRB0 response forwarded by the relay UE to the remote UE is carried by the SCCH (Sidelink Common Control Channel) via PC5.

In another embodiment, the RLC/MAC/PHY configuration for the relay UE to send the SRB0 response to the remote UE through the PC5 in step 314 is different from the configuration for the remote UE to send the SRB0 in step 311 . For example, the base station may provide a reconfiguration message (eg, RRC reconfiguration sidelink message) to the relay UE to reconfigure the PC5 link between the remote UE and the relay UE. If the base station sends the PC5 reconfiguration message before or at the same time as the SRB0 response, the SRB0 response may be sent using the new configuration and/or bearer mapping. Otherwise, if the PC5 link reconfiguration message is sent after the SRB0 response, the SRB0 response sent to the remote UE may apply a method/configuration similar to the way the remote UE sent the SRB0 in step 311 .

Figure 4 illustrates an embodiment in which a remote UE in connected mode requests SRB0 transmission of system information (SI) in accordance with a novel aspect. For a remote UE in RRC_Connected state, a dedicated SIB request procedure is used for the remote UE to request SI through the relay UE. In step 411 , the remote UE 401 sends an SRB0 message (eg, RRCSystemInfoReq) to the relay UE 402 . In step 412 , the relay UE 402 forwards the SRB0 message (eg, RRCSystemInfoReq) of the remote UE 401 to the base station gNB 403 . In step 413, gNB 403 provides a response to the SRB0 message (eg, the requested system information) and sends the response to relay UE 402. Finally, in step 414, the relay UE 402 forwards the response to the SRB0 message (eg, the requested system information) from the gNB 403 to the remote UE 401.

In another optional embodiment, if the remote UE is in the RRC_CONNECTED state through the L2 relay of the relay UE, the remote UE can obtain various system information via end-to-end RRC messages (eg, DedicatedSIBRequest SRB1 message) on the DCCH to request the designation of the SIB (step 411). In one embodiment, the SRB1 message is forwarded along with the remote UE ID (step 412) and, in response, the base station always provides system information in a unicast manner (eg, the base station sends the The relay UE sends the requested system information (step 413), and the relay UE forwards it to the remote UE (step 414)). In addition to system information, in the same MAC Protocol data unit (PDU) or RRC message, the base station also indicates the remote UE ID, which is the same as the remote UE ID included in the SRB1 message forwarded to the base station. The UE ID is the same. After receiving the response, the relay UE forwards the response to the remote UE matching the remote UE ID. Note that the remote UE ID may be an ID recognizable by the NW (eg, cell Radio Network Tempory Identity (C-RNTI)), or may simply be meaningless to the NW but can be used by the relay UE to identify the remote UE's local ID.

Figure 5 illustrates an implementation of an SRB0 transmission of system information requested by a remote UE in idle mode in accordance with a novel aspect. For the remote UE in the RRC idle/inactive (RRC_Idle/INACTIVE) state, the remote UE informs the relay UE of the requested SIB or SI message type through PC5 signaling (eg, PC5-RRC message). After receiving the SI request, the relay UE triggers the traditional SI acquisition procedure according to its RRC status (if needed), and sends the acquired SIB and/or SI information to the remote UE. PC5-RRC messages can be used to forward requested system information through PC5. In step 511, the remote UE 501 sends an SRB0 message (eg, RRCSystemInfoReq) or a message with the same purpose to the relay UE 502 via a new or existing PC5-RRC message/SL SRB for on-demand system information request. Please note that, unlike the conventional behavior, after the relay UE receives the system information request message from the UE in the RRC_Idle/INACTIVE state, the relay UE does not directly forward the message to the base station. In step 512, if the relay UE 502 has a valid stored version of the requested system information, the relay UE 502 sends the requested system information to the relay UE 501.

In step 513, if the relay UE 502 does not have a valid stored version of the requested system information, the relay UE 502 triggers a conventional SI acquisition procedure. For example, 1) If the requested system information is broadcast by the base station of the relay UE, the relay UE applies the R15 procedure to obtain it, i.e., monitors a specific Physical Downlink Control Channel (PDCCH) opportunity to use System Information Radio Network Tempory Identity (SI-RNTI) receives the requested SIB/SI message; 2) if the requested system information is provided by the base station of the relay UE on demand, and if the relay The UE is in the RRC connected (RRC_CONNECTED) state, and the relay UE applies the R16 process to obtain information, that is, the relay UE in the RRC connected state indicates the required SIB by sending a DedicatedSIBRequest message to perform the on-demand system information request process; 3) If The requested system information is provided on demand by the base station of the relay UE, and if the relay UE is in the RRC_Idle/INACTIVE state, the relay UE applies the R15 procedure to request the system information requested by the remote UE, i.e., in the RRC_Idle/INACTIVE state. Next, the UE triggers a random access channel (RACH) process to notify the base station of the requested system information. Finally, in step 514 , the relay UE 502 forwards the response to the SRB0 message (eg, a message requesting system information) from the gNB 503 to the remote UE 501 . Responses to system information requests, including the requested system information, may be transmitted through PC5-RRC messages (eg, RRCReconfigurationSidelink).

Figure 6 shows an embodiment of SRB0 transmission by a remote UE with a remote UE ID, where the remote UE ID is determined by the remote UE, relay UE or gNB. In step 611 , the remote UE 601 sends an SRB0 message to the relay UE 602 . In one embodiment, the remote UE explicitly indicates its remote UE ID along with the SRB0 message sent to the relay UE. In one embodiment, the remote UE ID may be included in the MAC layer of the SL MAC PDU carrying the SRB0 message, eg, in the MAC subheader of the SL MAC sub-PDU (subPDU) including the SRB0 message, or in In the MAC header (header) of the SL MAC PDU including the SRB0 message, or in the MAC Control Element (MAC CE) of the SL MAC PDU carrying the SRB0 message. In one embodiment, the remote UE ID may be included in the adaptation layer header associated with the MAC sub-PDU that includes the SRB0 message. In one embodiment, the remote UE ID may be included in the RLC layer header or subheader.

In step 612, the relay UE 602 forwards the SRB0 message of the remote UE 601 to the base station gNB 603. In order to forward the SRB0 message, the relay UE determines what information should be carried with the forwarded message. In one embodiment, the relay UE indicates the remote UE ID associated with the forwarded SRB0 message. In one embodiment, the remote UE ID sent to the gNB is the same as the remote UE ID of the SRB0 message forwarded from the remote UE to the relay UE. In one embodiment, there is a one-to-one mapping between the remote UE ID sent to the gNB and the remote UE ID of the SRB0 message forwarded from the remote UE to the relay UE. For example, the remote UE 601 may have a local ID for the relay, eg, assigned by the relay UE 602 . After receiving the SRB0 message from the remote UE, the relay UE sends the remote UE's ID to the base station along with the forwarded SRB0, where the remote UE ID is converted from the local ID and can be identified by the base station. For example, the NW-identifiable ID may be a destination ID, which is used in sidelink communications to indicate a peer UE.

In one embodiment, the remote UE ID sent to gNB 603 is temporarily determined by relay UE 602. For example, the temporary remote UE ID is only used to identify whether the response received later from the NW is for the remote UE that initiated the transmission of the SRB0 message. The relay UE maintains the mapping between the remote UE and the temporary remote UE ID. After the relay UE receives the response associated with the temporary remote UE ID, the relay UE forwards the response to the correct remote UE mapped to the temporary remote UE ID. After the relay UE forwards the response to the SRB0 message to the remote UE, the temporary remote UE ID may or may not be used to transmit subsequent traffic of the remote UE. For example, after the SRB0 transmission, the remote UE may have been configured with a new ID (eg, the same as or different from the C-RNTI). For example, when the SRB0 message is an RRCSetup, RRCResume or RRCReestablishment message, the gNB may provide the C-RNTI in the response to the SRB0 message in step 613 . In this way, after SRB0 transmission, the relay UE can discard the temporary remote UE ID and store the new ID of the remote UE for routing, e.g. update the connection between the remote UE ID and the destination UE ID of the remote UE in the PC5 interface map.

The remote UE ID forwarded by the relay UE 602 to the gNB 603 may be located in a plurality of candidate locations. In one embodiment, the relay UE adds an adaptation layer header to the forwarded SRB0 message. The adaptation layer header may include the remote UE ID and/or the Uu radio bearer ID (or equivalent information indicating the RB type). In one embodiment, the remote UE ID is included in the MAC subheader associated with the RLC Service Data Unit (SDU) that includes the forwarded SRB0 message. In one embodiment, the remote UE ID is included in the MAC header of the UL MAC PDU that includes the forwarded SRB0 message. In one embodiment, the remote UE ID is carried as a MAC CE in the same MAC PDU together with the RLC SDU carrying the SRB0 message. In one embodiment, the relay UE does not multiplex SRB0 from the remote UE and material from the relay UE itself or from other remote UEs into the same MAC PDU. In one embodiment, the relay UE does not multiplex data from the remote UE and data from the relay UE itself or from other remote UEs into the same MAC PDU.

In step 613, gNB 603 provides a response to the SRB0 message and sends to relay UE 602. In one embodiment, the remote UE ID may be included in the adaptation layer header. In one embodiment, the remote UE ID may be included in the MAC subheader of the RLC SDU, which includes the response to the forwarded SRB0 message. In one embodiment, the remote UE ID may be included in the MAC header of the DL-MAC PDU, which includes the response to the forwarded SRB0 message. In one embodiment, the remote UE ID included in the response to the SRB0 message is the same as the remote UE ID included in the SRB0 message forwarded from the relay to the base station. Finally, in step 614, the relay UE 602 forwards the response to SRB0 from the gNB 603 to the remote UE 601.

Figure 7 shows an embodiment of the PC5 RLC channel configuration and DRB configuration of the remote UE after connection establishment. The procedure for the base station to reconfigure the PC5 RLC/MAC/PHY configuration is described below. In step 711, the relay UE 702 receives the RRCReconfiguration message from the gNB 703. In step 712, the relay UE 702 applies the ADAPT/RLC/MAC/PHY Uu configuration provided by the gNB 703. In step 713, the relay UE 702 sends an RRCReconfigurationSidelink message to the remote UE 701, the RRCReconfigurationSidelink message including the SL RLC/MAC/PHY configuration provided in the RRCReconfiguration message. The remote UE applies the SL RLC/MAC/PHY configuration provided by the relay UE in step 714 and replies with a RRCReconfigurationCompleteSidelink message in step 715 . In step 716, after receiving the RRCReconfigurationCompleteSidelink message, the relay UE updates its SL RLC/MAC/PHY configuration for the link between the relay UE and the remote UE. After updating the PC5 link configuration, in step 717 , the relay UE sends a message (eg, RRCReconfigurationComplete message) to the gNB 703 in response to the RRCReconfiguration of the gNB in step 711 .

The RRCReconfiguration message for each link configuration (ie, the Uu link between the relay UE and the gNB, and the PC5 link between the remote UE and the relay UE) can consist of two parts: the first part is the Uu ADAPT/ RLC/MAC/PHY configuration, the second part is the SL (ADAPT)/RLC/MAC/PHY configuration connected to the PC5 interface of the remote UE. After receiving the RRC reconfiguration message, the relay UE reconfigures its Uu link based on the received Uu configuration, and in response, the relay UE replies to the base station with a response message (eg, rrcreconfigurationcomplete). Furthermore, based on the PC5 configuration included in the RRCReconfiguration received on the Uu, the relay UE is triggered to send the RRCReconfigurationSidelink message to the remote UE. After receiving the RRCReconfigurationSidelink message, the remote UE reconfigures the SL(ADAPT)/RLC/MAC/PHY configuration of its PC5 link with the relay UE according to the configuration included in the RRCReconfigurationSidelink message, and then uses the confirmation message (for example, via RRCReconfigurationCompleteSidelink) ) to reply. When the confirmation message is received, the relay UE then applies the (ADAPT)/RLC/MAC/PHY configuration of the PC5 link with the remote UE. In this way, the bidirectional PC5 link reconfiguration is completed.

In addition to bidirectional PC5 link (re)configuration, unidirectional PC5 link configuration is also possible. For example, when the relay UE receives the RRCReconfiguration message from the gNB, if the included SL(ADAPT)/RLC/MAC/PHY configuration is only for the relay UE and not for the remote UE, the relay UE may only apply the PC5 configuration, and The sending of the RRCReconfigurationSidelink message is not triggered to transfer the PC5 configuration to the remote UE. In another example, when the relay UE receives the RRCReconfiguration message from the gNB, if the included SL(ADAPT)/RLC/MAC/PHY configuration is only for the remote UE and not for the relay UE, the relay UE may only send The RRCReconfigurationSidelink message is used to transfer the PC5 configuration to the remote UE, but the relay UE does not apply the PC5 configuration forwarded to the remote UE.

Please note that in FIG. 7 , after the relay UE applies the Uu and PC5 configurations included in the RRCREConfiguration message in step 711 , the relay UE sends the RRCREConfigurationComplete message in step 717 . In another embodiment, the relay UE may send the RRCREConfigurationComplete message immediately after applying the Uu configuration included in the RRCREConfiguration in step 711 .

The RRCReconfiguration message for end-to-end connection (ie between remote UE and gNB) may include Uu SDAP/PDCP configuration. Note that the mentioned RRCReconfiguration message does not include the Uu RLC/MAC/PHY configuration of the Uu-DRB configuration because there is no direct Uu communication between the remote UE and the base station.

In one embodiment, the base station reconfigures the per-link configuration after establishing the end-to-end connection. For example, after the remote UE receives the response of SRB0 from the base station, the remote UE enters RRC_CONNECTED and considers that the end-to-end connection has been successfully established. And, after providing a response to the SRB0 message, the base station sends a reconfiguration message to one or more relay UEs to reconfigure one or more links for relay. In order to update the configuration of the end-to-end connection, in step 721, the base station sends an RRC message (eg, RRC reconfiguration message) for reconfiguring the link. In step 722, the remote UE sends RRCReconfigurationComplete to the gNB.

In one embodiment, the base station may reconfigure the end-to-end for relay when receiving SRB0 (for RRC setup request, for RRC recovery request or for RRC re-establishment request) or when Uu DRBs are added or modified end configuration.

Figure 8 illustrates an embodiment of an L2 SL relay architecture for UE-to-network relay in accordance with a novel aspect. In the case of L2-based SL relaying, the relaying UE performs relaying on the RLC sublayer through the control plane (CP) and user plane (UP) between the remote UE and the network. Uu SDAP/PDCP and RRC are terminated between remote UE and gNB, RLC, MAC and PHY are terminated in each link (i.e. link between remote UE and UE to network relay UE and UE to network relay the link between the UE and the gNB). The adaptation layer on the RLC layer is supported in Uu to perform bearer mapping, and it can also be placed on PC5 to perform bearer mapping on the side link. The adaptation layer between the relay UE and the gNB is able to distinguish bearers (SRB, DRB) for a specific remote UE. Within Uu-DRB, different remote UEs and different bearers for remote UEs can be indicated by additional information included in the adaptation layer header. Unlike in L3 relay, the gNB is aware of each remote UE, so the end-to-end connection between the remote UE and the gNB should be established first before the relay UE starts to forward regular data traffic. After establishing the RRC connection via the SL relay, the remote UE can then forward the data traffic based on the established bearer and the forwarding/router information carried in the adaptation layer.

9 is a flowchart of a method of SRB0 transmission and reception in L2 UE-to-Network Relay in accordance with a novel aspect. In step 901, the relay UE receives the SRB0 message from the remote UE. Send SRB0 through the first RLC channel on the PC5 interface. The first RLC channel applies the specified configuration. In step 902, the relay UE forwards the SRB0 message to the base station. In step 903, the relay UE receives a response message from the base station. In step 904, the relay UE forwards the response message to the remote UE, wherein the response message is sent through the second RLC channel of the PC5 interface. The second RLC channel applies the preset configuration. In step 905, the relay UE receives the RRCReconfiguration message from the base station. In step 906, the relay UE forwards the RRCReconfigurationSidelink message to transmit the sidelink RLC channel configuration to the remote UE through the PC5 interface.

10 is a flowchart of a method for a remote UE to obtain system information in an L2 UE to network relay in accordance with a novel aspect. In step 1001, the relay UE receives a system information request message from the remote UE, wherein the request message is sent through the first RLC channel of the PC5 interface. In step 1002, the relay UE sends the requested system information to the remote UE. In one embodiment, the remote UE is in an RRC connected state, and the request message is a DedicatedSIBRequest message. The process of processing the request message by the relay UE further includes: forwarding the request message to the base station; receiving the response message from the base station; and forwarding the response message to the remote UE, wherein the response message is sent through the second RLC channel on the PC5 interface. In another embodiment, the remote UE is in RRC idle state or RRC inactive state, and the request message is an RRCSystemInfoReq message. The process of the relay UE sending the requested system information to the remote UE further includes: when the relay UE has a valid stored version of the requested system information, sending the requested system information to the remote UE; otherwise, when the relay UE does not have the requested system information When a valid stored version of the requested system information is available, the system information acquisition process is triggered to obtain the requested system information.

FIG. 11 is a flowchart of a method for PC5 RLC channel configuration and DRB configuration of a remote UE after the connection is established. In step 1101, the relay UE receives the RRC layer RRCReconfiguration message from the base station. In step 1102, when the RRCReconfiguration message is used for the relay UE, as indicated in the received RRCReconfiguration message, the relay UE is triggered to send the RRCReconfigurationSidelink message to transmit the SL configuration to the remote UE through the PC5 interface. In step 1103, when the RRCReconfiguration message is used for the relay UE, the relay UE forwards the received RRCReconfiguration message to transmit the Uu SDAP/PDCP configuration of the Uu DRB configuration to the remote UE through the PC5 interface.

Although the present invention has been described in connection with certain specific embodiments for instructional purposes, the present invention is not limited thereto. Accordingly, various modifications, adaptations, and combinations of the various features of the described embodiments may be made without departing from the scope of the invention as set forth in the claims.

100: Wireless Cellular Communication System 101:5GC 102,303,403,503,603,703:gNB 103, 104, 105: UE 110: Box 200: Block Diagram 201, 211: Wireless Devices 202, 212: Memory 203,213~Processor 204, 219: Connection Processing Circuits 205: Resource Management Circuits 206, 216: RF Transceivers 207,208,217,218~Antenna 209: Communication relay processing controller 210, 220: Program Instructions and Information 214: Relay discovery circuit 221, 231: Control and Configuration Circuits 222,232: Protocol stacking 301, 401, 501, 601, 701: Remote UE 302, 402, 502, 602, 702: Relay UE 311,312,313,314,411,412,413,414,511,512,513,514,611,612,613,614,711,712,713,714,715716,717,721,722,901,902,903,904,905,906,1001,1002,1101,1102,1103:步驟

FIG. 1 illustrates a wireless cellular communication system according to a novel aspect that supports signaling from a remote UE to a network side link relay through an L2 UE of the relay UE. Figure 2 depicts a simplified block diagram of a wireless device in accordance with an embodiment of the present invention. Figure 3 illustrates an implementation of sending and receiving SRB0 using a designated/fixed/preset configuration in accordance with a novel aspect. Figure 4 illustrates an implementation of an SRB0 transmission of system information requested by a remote UE in connected mode in accordance with a novel aspect. Figure 5 illustrates an implementation of an SRB0 transmission of system information requested by a remote UE in idle mode in accordance with a novel aspect. Figure 6 illustrates an embodiment of SRBO transmission by a remote UE with a remote UE ID, where the remote UE ID is determined by the remote UE or relay UE or gNB, in accordance with a novel aspect. Figure 7 shows an embodiment of the PC5 RLC channel configuration and DRB configuration of the remote UE after connection establishment. Figure 8 illustrates an embodiment of an L2 SL relay architecture for UE-to-network relay in accordance with a novel aspect. 9 is a flowchart of a method of SRB0 transmission and reception in L2 UE-to-Network Relay in accordance with a novel aspect. 10 is a flowchart of a method for a remote UE to obtain system information in an L2 UE to network relay in accordance with a novel aspect. FIG. 11 is a flowchart of a method for PC5 RLC channel configuration and DRB configuration of a remote UE after the connection is established.

100: Wireless Cellular Communication System

101:5GC

102: gNB

103, 104, 105: UE

110: Box

Claims (16)

A method for signaling transmission by a layer 2 user equipment through a network relay, the method is performed by a relay user equipment, and the method includes: (a) Receive a Signal Radio Bearer 0 message from a remote user equipment, wherein the Signal Radio Bearer 0 message is sent through a first RLC channel on the PC5 interface, and the first RLC channel Apply a specified configuration; (b) forwarding the signal radio bearer 0 message to a base station; (c) receiving a response message from the base station; and (d) forwarding the response message to the remote user equipment, wherein the response message is sent through a second radio link control channel on the PC5 interface, and the second radio link control channel applies a pre- set configuration. The method for signaling transmission by a layer 2 user equipment through a network relay as claimed in claim 1, wherein step (b) comprises forwarding the signaling radio bearer through a preset radio link control channel on the Uu interface 0 message for signal radio bearer 0 message transmission. The method for signaling transmission by a layer 2 user equipment through a network relay as claimed in claim 1, wherein the signal radio bearer 0 message in step (b) includes an uplink dedicated message on the Uu interface in a radio resource control message on the control channel. The method for signaling transmission by a layer 2 user equipment through a network relay as described in claim 1, wherein the response message in step (c) includes a downlink dedicated control channel on the Uu interface. in radio resource control messages. The method for signaling transmission by layer 2 user equipment through a network relay as claimed in claim 1, wherein the response message in step (d) includes a radio on a side link control channel on the PC5 interface resource control message. The method for signaling transmission by a layer 2 user equipment through a network relay as claimed in claim 1, wherein the SRBR 0 message is sent together with an identifier of the remote user equipment. The method for signaling transmission by a layer 2 user equipment through a network relay according to claim 6, wherein the identifier of the remote user equipment is determined by the remote user equipment, the relay user The device or the base station is determined to identify the remote user equipment associated with the SIGNAL Radio Bearer 0 message. The method for signaling transmission by a layer 2 user equipment through a network relay as claimed in claim 6, wherein the identifier of the remote user equipment includes an adaptation of a medium access control protocol data unit one of a layer header, a radio link control layer header, a medium access control element, a medium access control layer header. A method for signaling transmission by a layer 2 user equipment through a network relay, the method is performed by a relay user equipment, and the method includes: receiving a system information request message from a remote user equipment, wherein the system information request message is sent over a first radio link control channel on the PC5 interface; and Send the requested system information to the remote user device. The method for signaling transmission by a layer 2 user equipment through a network relay according to claim 9, wherein the remote user equipment is in a RRC connection state, and the system information request message is a DedicatedSIBRequest message, And the process of processing the system information request message by the relay user equipment further includes: forwarding the system information request message to a base station; receiving a response message from the base station; and The response message is forwarded to the remote user equipment, wherein the response message is sent over a second radio link control channel on the PC5 interface. The method for signaling transmission by a layer 2 user equipment through a network relay according to claim 9, wherein the remote user equipment is in a RRC idle state or in a RRC inactive state, so A first radio link control channel used by the remote user equipment to send the system information request message applies a designation or a default configuration, and the relay user equipment sends the request to the remote user equipment The system information process also includes: sending the requested system information to the remote user equipment when the relay user equipment has a valid stored version of the requested system information; Otherwise, when the relay UE does not have a valid stored version of the requested system information, a system information acquisition process is triggered to acquire the requested system information. The method for signaling transmission by a layer 2 user equipment through a network relay according to claim 11, wherein the relay user equipment is in a radio resource control connection state, and the system information acquisition process further comprises: sending a DedicatedSIBRequest message indicating the system information requested by the remote user equipment to a base station; receiving from the base station one or more response messages including the requested system information; and forwarding the requested system information to the remote user equipment, wherein the requested system information is sent over a second radio link control channel on the PC5 interface, and the second radio link control channel applies a default or a specific configuration. The method for signaling transmission by a layer 2 user equipment through a network relay according to claim 11, wherein the relay user equipment is in a RRC idle state or in a RRC inactive state, The system information acquisition process includes: when the requested system information is provided by a base station on demand, the relay user equipment performs a random access channel process. A method for signaling transmission from a layer 2 user equipment to a network relay, the method is performed by a relay user equipment, and the method includes: receiving a radio resource control layer RRCReconfiguration message from a base station; When the RRCReconfiguration message is used for the relay UE, as indicated in the received RRCReconfiguration message, triggers the sending of an RRCReconfigurationSidelink message to transmit the side link configuration to a remote UE via the PC5 interface ;as well as When the RRCReconfiguration message is used for the relay UE, forward the received RRCReconfiguration message to transmit the Uu packet data aggregation protocol/service data suitable for the Uu data radio bearer configuration to the remote UE through the PC5 interface With the agreement configuration. The method for layer 2 user equipment signaling through a network relay as claimed in claim 14, wherein the RRCReconfigurationSidelink message includes a PC5 radio link control channel configuration provided to the remote user equipment. Side link radio link control/logical channel configuration. The method for signaling by a layer 2 user equipment over a network relay as claimed in claim 14, wherein the RRCReconfiguration message provided to the relay user equipment includes a Uu radio link control channel configuration The Uu Radio Link Control/Logical Channel Configuration, or the Sidelink Radio Link Control Logical Channel Configuration for the Sidelink Radio Link Control Logical Channel Configuration on the link directed to the remote user equipment.

Images