Method, apparatus and system for relay configuration in wireless network

Abstract

The present disclosure generally relates to methods, devices, and systems for sidelink communications in wireless communications. A method performed by a distributed unit (DU) includes transmitting a first transport message to a centralized unit (CU) of a wireless communication node, where the first transport message is based on a first message associated with a relay UE in a wireless network, and where the first transport message is based on a second message associated with the relay UE in the wireless network. The first transmit message further includes at least one of the following fields: a CU-level remote UE identifier (ID) identifying the remote UE in the CU; identifying a DU-level remote UE ID of the remote UE in the DU; an ID of the remote UE; or a cell radio network temporary identifier (C-RNTI) of the remote UE.

Description

[0001] This application is a divisional application. The application number of the original application is 202180100148.0, and the original application date is October 21, 2021. The entire contents of the original application are incorporated into this application by reference. Technical Field

[0002] The present disclosure relates generally to wireless communications, and more particularly to methods, devices, and systems for sidelink communications. Background Art

[0003] With the development of wireless multimedia services, the demand for high data rate services has increased significantly. Under such conditions, the requirements for system capacity and coverage of wireless communication networks are getting higher and higher. On the other hand, in order to support application scenarios such as public safety, social networks, short-distance data sharing, local advertising, etc., the demand for proximity services that allow one device to communicate with another adjacent device is also increasing. Therefore, device-to-device (D2D) communication technology is proposed to meet such needs. By adopting D2D technology, the burden on wireless communication networks can be reduced, the power consumption of user equipment can be reduced, the data rate can be increased, and the robustness of network infrastructure can be improved. D2D technology can also be referred to as proximity service (Proximity Service, ProSe) or sidelink communication. Summary of the invention

[0004] The present disclosure relates to a method, device and system for sidelink communication in a wireless communication network.

[0005] In some embodiments, a method performed by a distributed unit (DU) of a wireless communication node in a wireless network is disclosed. The method may include: transmitting a first transmission message to a centralized unit (CU) of the wireless communication node, wherein the first transmission message also includes at least one of the following fields: a CU-level remote UE identifier (ID) identifying a remote UE in the CU; a DU-level remote UE ID identifying a remote UE in the DU; an ID of the remote UE; or a cell radio network temporary identifier (C-RNTI) of the remote UE.

[0006] In some embodiments, a method performed by a centralized unit (CU) of a wireless communication node in a wireless network is disclosed. The method may include: transmitting a first F1 Application Protocol (F1AP) signaling to a DU of the wireless communication node to configure a UE context for a relay UE; or transmitting a second F1AP signaling to the DU to configure a UE context for a remote UE, wherein the remote UE is configured with an indirect path to the wireless communication node using the relay UE.

[0007] In some embodiments, a method performed by a CU of a wireless communication node in a wireless network is disclosed. The method may include: sending an ID of a remote UE to a remote UE, wherein the ID of the remote UE is used to relay traffic between the remote UE and the wireless communication node via a relay UE.

[0008] In some embodiments, a method performed by a CU of a wireless communication node in a wireless network is disclosed. The method may include: transmitting a first message to a DU of the wireless communication node to configure a Uu RLC channel between the DU and a relay UE; or sending a second message to the DU to configure a relay UE-side configuration of a PC5 RLC channel between the relay UE and a remote UE, wherein the Uu RLC channel and the PC5 RLC channel are used to transmit services destined for the remote UE, and wherein the relay UE acts as a relay between the remote UE and the wireless communication node.

[0009] In some embodiments, a method performed by a CU of a first wireless communication node in a wireless network is disclosed. The method may include: transmitting a first message to a DU of the first wireless communication node, the first message including sidelink communication authorization information for at least one of a relay UE or a remote UE.

[0010] In some embodiments, a method performed by a wireless device in a wireless network is disclosed. The method may include: receiving an ID of the wireless device from a CU of a wireless communication node in the wireless network, wherein: the ID of the wireless device is used to relay traffic between the wireless device and the wireless communication node via a relay UE.

[0011] In some embodiments, there is a network element or a wireless device comprising a processor and a memory, wherein the processor is configured to read the code from the memory and implement any method described in any of the multiple embodiments.

[0012] In some embodiments, a computer program product includes a computer-readable program medium on which codes are stored. When the codes are executed by a processor, the processor is prompted to implement any method described in any of the embodiments.

[0013] Other aspects and alternatives to the above embodiments and their implementations are described in more detail in the following drawings, description and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 An example wireless communication network is shown.

[0015] Figure 2 An example wireless network node is shown.

[0016] Figure 3 An example user device is shown.

[0017] Figure 4 An exemplary data path for sidelink communications is shown.

[0018] Figure 5 An example protocol stack with an adaptation layer in a wireless communication network is shown.

[0019] Figure 6 An example process for assigning a local ID to a remote UE is shown.

[0020] Figure 7 Another example process for assigning a local ID to a remote UE is shown.

[0021] Figure 8 An example process for sidelink communication initiation is shown.

[0022] Fig. 9 Another example process for sidelink communication initiation is shown.

[0023] Fig.10 An example message flow for a sidelink communication process is shown. DETAILED DESCRIPTION

[0024] Wireless communication network

[0025] Figure 1 An exemplary wireless communication network 100 is shown including a core network 110 and a Radio Access Network (RAN) 120. The core network 110 also includes at least one Mobility Management Entity (MME) 112 and / or at least one Access and Mobility Management Function (AMF) 114. Figure 1Other functions that may be included in the core network 110 are not shown. RAN 120 also includes multiple base stations, for example, base stations 122 and 124. The base station may include at least one evolved NodeB (eNB) for 4G LTE, or a next generation NodeB (gNB) for 5G New Radio (NR), or any other type of signal transmission / reception equipment (such as UMTS NodeB). eNB 122 can communicate with MME 112 via an S1 interface. Both eNB 122 and gNB 124 can be connected to AMF 114 via an Ng interface. Each base station manages and supports at least one cell. For example, base station gNB 124 may be configured to manage and support cell 1, cell 2, and cell 3.

[0026] The gNB 124 may include a centralized unit (CU) and at least one distributed unit (DU). The CU and the at least one DU may be located at the same location, or they may be separately arranged at different locations. The CU and the DU may be connected via an F1 interface. Alternatively, for an eNB capable of connecting to a 5G network, the eNB may also be similarly divided into a CU and at least one DU (referred to as ng-eNB-CU and ng-eNB-DU, respectively). The ng-eNB-CU and the at least one ng-eNB-DU may be connected via a W1 interface.

[0027] The wireless communication network 100 may include a plurality of UEs, for example, UE 130 and UE 132. The UE may be connected to a base station via a Uu interface. Figure 1 As shown in FIG. 1 , UE 130 is connected to gNB 124 via a Uu interface. In addition, sidelink communications may be supported in which UE 132 may be indirectly connected to a base station by using UE 130 as a relay. In a sidelink communication setting, UE 132 may be referred to as a remote UE and UE 130 may be referred to as a relay UE. The remote UE and the relay UE may communicate via a Uu interface. Figure 1 The PC5 interface connections shown in .

[0028] The wireless communication network 100 may be implemented as, for example, a 2G, 3G, 4G / LTE or 5G cellular communication network. Accordingly, the base stations 122 and 124 may be implemented as 2G base stations, 3G NodeBs, LTE eNBs or 5G NR gNBs. The UE 130 may be implemented as a mobile or fixed communication device capable of accessing the wireless communication network 100. The UE 130 may include, but is not limited to, a mobile phone, a laptop computer, a tablet computer, a personal digital assistant, a wearable device, an Internet of Things (IoT) device, an MTC / eMTC (Machine-Type Communication / Enhanced Machine-Type Communication) device, a distributed remote sensor device, a roadside assistance device, an XR device and a desktop computer. The UE 130 may support side link communication to another UE via a PC5 interface.

[0029] Although the following description focuses on Figure 1 The cellular wireless communication system shown in the figure, but the basic principles can be applied to other types of wireless communication systems for paging wireless devices. These other wireless systems can include but are not limited to Wireless Fidelity (Wi-Fi), Bluetooth (Bluetooth), ZigBee (ZigBee) and Worldwide Interoperability for Microwave Access (WiMax) networks.

[0030] Figure 2 An example of an electronic device 200 for implementing a network base station (e.g., a radio access network node), a core network (CN), and / or operation and maintenance (OAM) is shown. In one embodiment, the example electronic device 200 may include a wireless transmission / reception (Tx / Rx) circuit 208 for transmitting / receiving communication information with a UE and / or other base stations. The electronic device 200 may also include a network interface circuit 209 for communicating with other base stations and / or a core network. The network interface circuit 209 may be based on optical interconnection or wired interconnection, Ethernet, and / or other data transmission media / protocols. The electronic device 200 may include an input / output (I / O) interface 206 to communicate with an operator or the like.

[0031] The electronic device 200 may also include a system circuit 204. The system circuit 204 may include (one or more) processors 221 and / or a memory 222. The memory 222 may include an operating system 224, instructions 226, and parameters 228. The instructions 226 may be configured to be executed by one or more processors in the plurality of processors 221 to perform the functions of a network node. The parameters 228 may include parameters for supporting the execution of the instructions 226. For example, the parameters may include network protocol settings, bandwidth parameters, radio frequency mapping allocations, and / or other parameters.

[0032] Figure 3 An example of an electronic device for implementing a terminal device 300 (e.g., a user equipment (UE)) is shown. UE 300 may be a mobile device, such as a smartphone or a wireless communication module arranged in any other device. UE 300 may include part or all of the following items: a communication interface 302, a system circuit 304, an input / output interface (I / O) 306, a display circuit 308, and a storage device 309. The display circuit may include a user interface 310. The system circuit 304 may include any combination of hardware, software, firmware, or other logic / circuits. The system circuit 304 may be implemented, for example, using one or more systems on a chip (Systems on a Chip, SoC), application specific integrated circuits (Application Specific Integrated Circuit, ASIC), discrete analog and digital circuits, and other circuits. The system circuit 304 may be part of the implementation of any desired function in UE 300. In this regard, the system circuit 304 may include logic to facilitate operations such as: decoding and playing music and video (e.g., MP3, MP4, MPEG, AVI, FLAC, AC3 or WAV decoding and playback); running applications; accepting user input; saving and retrieving application data; establishing, maintaining and terminating cellular phone calls or data connections for, for example, Internet connections; establishing, maintaining and terminating wireless network connections, Bluetooth connections, or other connections; and displaying relevant information on the user interface 310. The user interface 310 and the input / output (I / O) interface 306 may include a graphical user interface, a touch-sensitive display, tactile feedback or other tactile output, voice or facial recognition input, buttons, switches, speakers, and other user interface elements. Additional examples of the I / O interface 306 may include microphones, video and still image cameras, temperature sensors, vibration sensors, rotation and orientation sensors, headphone and microphone input / output jacks (Jacks), Universal Serial Bus (USB) connectors, memory card slots, radiation sensors (e.g., infrared (IR) sensors), and other types of inputs.

[0033] refer to Figure 3 , the communication interface 302 may include radio frequency (RF) transmission (Tx) and reception (Rx) circuits 316 that handle the transmission and reception of signals through one or more antennas 314. The communication interface 302 may include one or more transceivers. The transceiver may be a wireless transceiver that includes modulation / demodulation circuitry, a digital to analog converter (DAC), a shaping table, an analog to digital converter (ADC), a filter, a waveform shaper, a preamplifier, a power amplifier, and / or other logic for transmission and reception through one or more antennas or (for some devices) through a physical (e.g., wired) medium. The transmitted and received signals may follow any of a variety of formats, protocols, modulations (e.g., QPSK, 16-QAM, 64-QAM, or 256-QAM), frequency channels, bit rates, and encodings. As a specific example, the communication interface 302 may include a transceiver supporting transmission and reception under 2G, 3G, BT, WiFi, Universal Mobile Telecommunications System (UMTS), High Speed ​​Packet Access (HSPA) +, 4G / Long Term Evolution (LTE) and 5G standards. However, the technology described below, whether it is from the 3rd Generation Partnership Project (3GPP), GSM Association, 3GPP2, IEEE, or other partners or standards bodies, can be applied to other wireless communication technologies.

[0034] refer to Figure 3 , the system circuit 304 may include one or more processors 321 and a memory 322. The memory 322 stores, for example, an operating system 324, instructions 326, and parameters 328. The processor 321 may be configured to execute the instructions 326 to perform the desired functions for the UE 300. The parameters 328 may provide and specify configuration and operating options for the instructions 326. The memory 322 may also store any BT, WiFi, 3G, 4G, 5G, or other data that the UE 300 will send or has received through the communication interface 302. In various embodiments, the system power for the UE 300 may be provided by a power storage device (such as a battery or a transformer).

[0035] Sidelink communication

[0036] Sidelink communication aims to expand the coverage of wireless communication networks and improve the power consumption of wireless communication networks. Sidelink-based relay communication can be applied to applications such as indoor relay communication, smart agriculture, smart factories, and public safety services. Figure 1 Two modes for applying sidelink-based relay communication are shown.

[0037] Mode 1: UE to network relay

[0038] In Mode 1, UE 132 may be located in an area with poor coverage or no coverage at all. UE 132 is allowed to communicate with the network (e.g., gNB 124) via nearby UEs 130 covered by the network. As a result, the coverage of the network is extended and the capacity of the network is increased. Note that in this scenario, UE 130 may be referred to as a UE-to-Network relay UE (or, for brevity, a relay UE), and UE 132 may be referred to as a remote UE.

[0039] Mode 2: UE to UE relay

[0040] During an emergency (e.g., an earthquake), the wireless communication network may operate abnormally, or the sidelink communication range of the network may need to be extended. Therefore, relay communication is designed to allow multiple UEs to communicate with each other via a relay UE. Figure 1 As shown in FIG. , UE 134 may be connected to the network via UE 136 (or Figure 1 Multiple relay UEs not shown in the figure communicate with UE 138, wherein UE 136 is called UE-to-UE relay UE (UE-to-UE relay UE) in mode 2.

[0041] Relay Solution

[0042] To support UE service relay, two schemes can be implemented using different layers for relay. One scheme can be based on layer 3 (e.g., Internet Protocol (IP) layer), while the other scheme can be based on layer 2 (e.g., access layer). Layer 3-based relay forwards data according to the UE's IP layer information (e.g., IP address and / or IP port number), while layer 2-based relay routes and forwards user plane (UP) and control plane (CP) data in the access layer. Layer 2 relay can allow network elements (e.g., core network and / or base station) to manage remote UEs and relays more efficiently.

[0043] CU and DU separation architecture

[0044] As described above, the gNB 124 may include a CU and multiple DUs, and the RAN functions of the gNB are allocated to the CU and multiple DUs. For example, the RAN functions may be separated at a point between the Packet Data Convergence Protocol (PDCP) layer and the Radio Link Control (RLC) layer of the 5G protocol stack, where the DU will handle all processes including and below the RLC layer functions, and the CU will handle the PDCP layer and higher layer functions before the core network. By isolating the stack from the PDCP layer and above, the CU will be able to act as a cloud-based aggregation point between multiple heterogeneous technologies in the provisioning network, and will therefore be able to serve multiple heterogeneous DUs.

[0045] Figure 4 An exemplary implementation of sidelink communication under a CU / DU separation architecture is shown. In the present disclosure, from the perspective of data function, data services for UE include control plane (CP) services and user plane (UP) services. From the perspective of data direction, data services include uplink (UL) services and downlink (DL) services. For example, in Figure 4 In the example, UL traffic can be initiated from a remote UE or a relay UE and transmitted to a CU, and the CU can further forward the UL traffic to the core network. DL traffic can be sent from the core network and transmitted to a remote UE or a relay UE. Figure 4 As shown in , since the remote UE does not have direct access to the DU, the DL / UL services destined for the remote UE need to be relayed by the relay UE. In addition, there may be services 410 for the remote UE and services 412 for the relay UE. In a CU / DU separation deployment, it is crucial that relevant network elements (such as CU, DU, and relay UE) are able to identify the source and destination of the service in order to route the service accordingly. For example, for service 410, the DU may use the Uu RLC channel 420 associated with the remote UE. For service 412, the DU may use the Uu RLC channel 422 associated with the relay UE. For another example, the relay UE may identify services destined for itself and services destined for the remote UE. The relay UE may forward (or relay) the service to the remote UE via the PC5 RLC channel.

[0046] In the present disclosure, the identifier (ID) of the UE may be used as a label for routing traffic. The ID of the UE may include, for example, a local UE ID, a layer 2 (L2) source ID of the UE, a cell radio network temporary identifier (Cell Radio Network Temporary Identifier, C-RNTI) of the UE, etc. The local UE ID may include an identifier that can identify a UE within the range of a CU, DU, relay UE, and remote UE. The local UE ID may be allocated by a gNB (or CU).

[0047] In order to support service transmission between UE and gNB (i.e., CU+DU), various resources need to be configured to relevant network elements. Figure 4 As shown in , these resources may include: a GPRS (General Packet Radio Service) Tunnel Protocol (GPRS Tunnel Protocol, GTP) tunnel between CU and DU, a Uu interface (including a Uu radio link control (RLC) channel between DU and relay UE), and a PC5 interface (including a PC5 RLC channel between relay UE and remote UE). Each type of resource may include multiple instances. For example, some resource instances may be allocated to support services for the relay UE itself, while some source instances may be allocated to support services for remote UEs. In addition, for a specific type of resource instance (such as a Uu RLC channel), each resource instance may be configured with different characteristics. The characteristics may include: Quality of Service (QoS), data service type (e.g., user plane data or control plane data), bearer mapping, etc. For example, a PC5 RLC channel supports higher QoS requirements, and another PC5 RLC channel supports lower QoS requirements. For another example, a Uu RLC channel is mapped to a signaling radio bearer (SRB) 1, and another RLC channel is mapped to SRB2. For another example, a GTP tunnel is configured for remote UE traffic transmission, and another GTP tunnel is configured for relay UE traffic transmission. It should be noted that the GTP tunnel, Uu RLC channel, and PC5 RLC channel are only exemplary protocols / links to be used, and other types of protocols / links may be adapted to implement data / signal transmission.

[0048] In the present disclosure, various embodiments are disclosed to provide at least solutions for the following operations: identifying a remote UE at a relevant network element; configuring various resources for relaying services for the remote UE; authorizing and transmitting system information to support service relay to the remote UE. In these embodiments, various types of signaling may be used between network elements such as CU, DU, relay UE, and remote UE. Signaling may include UE-specific (or UE-associated) signaling and non-UE-specific (or non-UE-associated) signaling. More details will be described in the following sections.

[0049] Sidelink communication using L2 adaptation layer

[0050] In the present disclosure, the adaptation layer may be used to carry sidelink communication related information (such as the ID of the remote UE), which includes the local ID of the remote UE as described above, the L2 source ID of the remote UE, or another form of UE ID.

[0051] Figure 5 An example protocol stack for L2 UE to network relay is shown. The basic principles apply to both the user plane (UP) and the control plane (CP). Adaptation layers 514 and 516 are located above the RLC sublayer at the Uu interface between the relay UE and the gNB. Similarly, adaptation layers 510 and 512 are located above the RLC sublayer at the PC5 interface between the remote UE and the relay UE.

[0052] In the present disclosure, at the adaptation layer, a subheader may be added to the relay service between the remote UE and the relay UE, and / or between the relay UE and the DU. Remote UE related information (such as the remote UE ID and / or the Radio Bearer (RB) ID) may be encapsulated in the subheader. Therefore, at the layer 2 level, the relevant network element may resolve the source or destination of the service. Figure 5 A detailed diagram of an adaptation layer 520 with a subheader 522 is shown. The subheader 522 is encapsulated with the ID of the remote UE and / or the RB ID. In other words, the ID of the remote UE and / or the RB ID may be carried in the subheader 522. In one embodiment, the RB may include a signaling RB (SRB) or a data RB (DRB). In the present disclosure, when a data packet associated with a remote UE is transmitted between the remote UE, the relay UE, and the DU, the adaptation layer subheader may be used to carry identification information. The data packet may carry signaling as well as user data.

[0053] like Figure 5As shown in , on the Uu interface, the SDAP (Service Data Adaptation Protocol) layer and the PDCP layer are terminated between the remote UE and the gNB, while the RLC layer, the MAC layer, and the PHY layer are terminated between the remote UE and the relay UE or between the relay UE and the gNB. In this way, in order to support service relay for the remote UE, the PC5 RLC layer may need to be configured on the remote UE and the relay UE, and the Uu RLC layer may need to be configured on the relay UE and the gNB (or the DU of the gNB). Figure 5 Not shown in the figure, the Radio Resource Control (RRC) layer may also be terminated between the remote UE and the gNB.

[0054] like Figure 5 As shown in , in the CU / DU separation scenario, the adaptation layer terminates at the DU level. From the perspective of the remote UE, an F1-U tunnel corresponding to the Uu data radio bearer (DRB) of the remote UE can be established between the DU and the CU. Similarly, an F1-C connection corresponding to the remote UE is maintained between the DU and the CU.

[0055] Example 1

[0056] As described in the previous section, in order to support service relay for remote UEs, the adaptation layer is supported (or implemented) on both the Uu interface and the PC5 interface. The adaptation layer subheader may include the ID of the remote UE and the RB ID of the relayed service. The relay UE may need to parse the ID of the remote UE from the adaptation layer subheader. At the same time, the remote UE may need to encapsulate the same ID when initiating a service to be relayed by the relay UE. The ID of the remote UE may include a local ID that can identify the remote UE within the range of the CU, DU, and relay UE. In this embodiment, the local ID of the remote UE may be allocated by the gNB.

[0057] In this embodiment, various implementations on how to request and allocate a local ID of a remote UE are described.

[0058] refer to Figure 6 , the remote UE and the relay UE may obtain the local ID of the remote UE using the following steps. In the present disclosure, the steps used for each embodiment are for exemplary purposes only, and other alternatives may be applicable. For example, only some of the steps may need to be performed. For another example, the order of the steps may be adjusted. For another example, multiple steps may be combined (for example, multiple messages may be combined in one message). For another example, a single step may be split (for example, one message may be sent via two sub-messages).

[0059] Step 1

[0060] The remote UE initiates sidelink communication by sending an RRC message (eg, an RRCSetupRequest message) to the relay UE via the PC5 RLC channel.

[0061] Alternatively, the remote UE may also send a layer 2 link setup message (eg, direct communication request) or a first Uu RRC message in step 1 to trigger the local ID acquisition procedure (for the remote UE). More details are described below.

[0062] Step 2

[0063] The relay UE does not yet know the local ID of the remote UE. Upon receiving the RRCSetupRequest message, the relay UE may request the local ID of the remote UE from the gNB. For example, the relay UE may send SidelinkUEInformation or other RRC signaling to the gNB to request the local ID of the remote UE. The SidelinkUEInformation or other RRC signaling may include at least one of the following: the destination L2 ID of the remote UE, an indication (or identifier) ​​of the remote UE, or an indication for requesting the local ID of the remote UE.

[0064] Alternatively, when receiving the layer 2 link setup message from the remote UE, if the relay UE is in the connected state, the relay UE may request the local ID of the remote UE via SidelinkUEInformation or other RRC signaling.

[0065] As another alternative, when receiving the first Uu RRC message from the remote UE, if the relay UE is in an idle state or an inactive state, the relay UE may request the local ID of the remote UE via SidelinkUEInformation or other RRC signaling.

[0066] Step 3

[0067] Upon receiving the request for the local ID, the gNB (e.g., CU) may respond to the relay UE with the local ID of the remote UE via an RRCReconfiguration message.

[0068] In one embodiment, the subheader of the adaptation layer on the PC5 interface may not be applicable to the SRB0 message. That is, when the remote UE sends an SRB0 message to the relay UE, the remote UE does not encapsulate the subheader with its local ID. This may be because the remote UE has not yet received the local ID assigned to it when the sidelink communication session is initiated. Therefore, when the relay UE receives the SRB0 message from the remote UE, the relay UE needs to encapsulate the subheader of the adaptation layer by itself to ensure the correct routing of SRB0. It should be noted that only after the relay UE receives the local remote UE ID assigned by the gNB (for example, via step 3 above), the relay UE can encapsulate the local ID of the remote UE in the adaptation layer subheader and forward the SRB0RRC message to the gNB.

[0069] In one embodiment, after the gNB sends the local ID of the remote UE to the relay UE, the relay UE may forward the local ID to the remote UE, for example, via PC5 RRC signaling. The remote UE can then encapsulate subsequent messages (e.g., SRB1, SRB2, etc.) and data packets to be relayed to the gNB.

[0070] In one embodiment, the relay UE may support multiple remote UEs. To improve efficiency, the relay UE may request multiple local IDs from the gNB at one time. For example, the relay UE may send the requested multiple remote local IDs to the gNB. The gNB may respond to the relay UE with a list of local IDs of multiple remote UEs in turn. When the remote UE later attempts to connect to the relay UE via the PC5 interface, or when the remote UE sends a first RRC message to the relay UE, the relay UE may select a local ID from the list of local IDs and assign it to the remote UE. The relay UE may also notify the remote UE of the assigned local ID. The relay UE may also choose to send the remote UE's L2 source ID and its corresponding local ID to the gNB, so that the gNB can establish a mapping between the remote UE's local ID and its corresponding L2 source ID. In one embodiment, the UE's L2 destination ID may also be used to identify a specific UE.

[0071] In one embodiment, instead of being notified by the relay UE, the gNB directly configures the local ID of the remote UE to the remote UE via an RRC signaling message. Figure 7 As shown in , upon receiving the RRCSetupRequest message from the remote UE in step 1, the gNB may send a message carrying the local UE ID in step 2. The message may include an RRC Setup message, an RRC Resume message, an RRC Reestablishment message, or an RRC Reconfiguration message, etc.

[0072] In one embodiment, the local ID of the remote UE may be transmitted to the remote UE via an adaptation layer subheader. For example, when the RRCResume / RRCRestablishment message is transmitted to the remote UE via a PC5 RLC channel, the RRCResume / RRCRestablishment message may carry an adaptation layer subheader, which may include the local UE ID and / or RB ID information of the remote UE. The remote UE may decapsulate the local ID and / or RB ID from the adaptation layer subheader. Subsequently, the remote UE may encapsulate the adaptation layer subheader for uplink traffic.

[0073] In one embodiment, the UE may switch from a direct connection to an indirect connection with the gNB. For example, if it is determined that the signal coverage condition of the remote UE is below a threshold, this is referred to as a direct to indirect path handover scenario. In this scenario, the UE to be handed over is a candidate remote UE. The gNB may assign a local ID to the candidate remote UE and find a suitable relay UE to support the handover. The gNB may then send the local ID of the candidate remote UE to the relay UE or the candidate remote UE via, for example, an RRCReconfiguration message.

[0074] Example 2

[0075] In order to correctly route traffic for a remote UE, the DU needs to know the local ID of the remote UE. In addition, the CU and DU should also be able to associate the relay UE with the remote UE, for example by using the ID of each UE.

[0076] For the CU / DU separation scenario, the CU and DU can communicate via the F1 interface. The F1 Application Protocol (F1AP) provides the signaling services between the DU and the CU that are required to meet the F1AP function. F1AP services are divided into two groups: non-UE associated (or non-UE specific) and UE associated (or UE specific). When an F1AP message is associated with a UE, a logical F1 connection associated with the UE is used to facilitate identification of the UE in the DU and the CU. The UE-associated logical F1 connection can be identified by IDs such as GNB-CU UE F1AP ID and GNB-DU UE F1AP ID. For example, for a received UE-associated F1AP message, the CU identifies the associated UE based on the GNB-CU UE F1AP ID information element (InformationElement, IE). Similarly, the DU identifies the associated UE based on the GNB-DU UE F1AP ID IE.

[0077] In one embodiment, before the F1 UE context is established in the gNB-DU, there may be a logical F1 connection associated with the UE. When the UE initiates the RRC link establishment, the UE sends an RRCSetupRequest message to the DU. The DU may transmit this initial RRC message to the CU. The transmission may be performed via an INITIAL UL RRC MESSAGETRANSFER message. The message may contain the gNB-DU UE F1AP ID of the UE and the C-RNTI of the UE allocated by the DU.

[0078] In one embodiment, for DL ​​RRC message transmission, the transmission message may include the gNB-DU UE F1AP ID assigned to the UE by the DU and the gNB-CU UE F1AP ID assigned to the UE by the CU. For subsequent UE-specific F1AP signaling, the gNB-DU UE F1AP ID and gNB-CU UE F1AP ID are included so that the DU and / or CU can identify a specific UE.

[0079] In sidelink communication using a layer 2 relay scheme, when the DU receives a relayed uplink control plane (UL CP) packet of a remote UE, the DU should be able to associate the local UE ID of the remote UE contained in the adaptation layer subheader with the corresponding gNB-DU UE F1AP ID and / or gNB-CU UE F1AP ID of the remote UE. The DU can then forward the UL CP packet of the remote UE (which can carry RRC signaling) via the logical F1 connection of the remote UE. Similarly, for the downlink control plane (DL CP) packet of the remote UE, the CU should forward the RRC signaling of the remote UE via the logical F1 connection of the remote UE, and the F1AP signaling associated with the remote UE should include the gNB-DU UE F1AP ID and / or gNB-CU UE F1AP ID of the remote UE, which can be used by the DU to identify the corresponding remote UE. The DU then encapsulates the adaptation layer subheader of the relayed DL CP packet with the local ID and / or RB ID of the remote UE.

[0080] In this embodiment, various implementations are described to facilitate the DU to establish an association between the remote UE's ID and the remote UE's gNB-DUUE F1AP ID (or gNB-CU UE F1AP ID). The remote UE's ID may include a local ID assigned by the gNB (or referred to as a local UE ID).

[0081] Implementation Method 1

[0082] In this embodiment, the relay UE knows the local ID of the remote UE.

[0083] For an exemplary message flow in this embodiment, please refer to Figure 8 .

[0084] Step 1

[0085] The relay UE receives the RRCSetupRequest message from the remote UE. The relay UE may encapsulate the adaptation layer subheader of the RRCSetupRequest message using the local ID and RB ID of the remote UE.

[0086] Step 2

[0087] The relay UE forwards the relayed RRCSetupRequest message to the DU via the Uu RLC channel.

[0088] Step 3

[0089] Upon receiving the RRCSetupRequest message, the DU may detect based on the adaptation layer subheader that it corresponds to an SRB0 message. The DU may record the association between the relay UE and the remote UE.

[0090] DU sends an initial uplink RRC message transfer (INITIAL UL RRC MESSAGE TRANSFER) to CU. INITIAL UL RRC MESSAGE TRANSFER may include at least one of the following fields: gNB-DU UE F1AP ID of remote UE, C-RNTI of remote UE, ID of remote UE, RRC-Container, etc. The ID of remote UE may be a local ID assigned by gNB, or L2 source ID of remote EU. It should be noted that CU knows the local ID because CU assigns the local ID.

[0091] Upon receiving the INITIAL UL RRC MESSAGE TRANSFER, the CU may associate the remote UE with its L2 source ID based on the remote UE's ID. The CU may also associate the remote UE with the relay UE. The CU may also associate the remote UE's L2 source ID or local ID with the relay UE (the relay UE is connected to the remote UE via the PC5 interface) because the given relay UE previously requested the remote UE's local ID, or because the local ID was assigned to the remote UE associated with the relay UE when the CU assigned the local ID. In addition, the CU may know the remote UE's C-RNTI and the remote UE's gNB-DU UE F1AP ID based on the INITIAL UL RRC MESSAGE TRANSFER message.

[0092] Step 4

[0093] The CU sends a DL RRC MESSAGE TRANSFER message to the DU, which may include the gNB-DU UE F1AP ID of the remote UE, the gNB-CU UE F1AP ID of the remote UE, the SRB ID (or RB ID) assigned to the remote UE, and the RRC container. The RRC container may include the RRCSetup message sent from the gNB to the remote UE.

[0094] Step 5

[0095] Upon receiving the DL RRC MESSAGE TRANSFER, the DU is able to identify the remote UE based on the gNB-DU UE F1AP ID (in the message) and the corresponding SRB of the RRC message within the RRC container. The DU may then encapsulate the adaptation layer subheader with the local ID and SRB ID of the remote UE and then transmit the RRC message (e.g., RRCSetup) to the relay UE.

[0096] Step 6

[0097] Upon receiving the RRC message via the Uu RLC channel, the relay UE is able to identify the message destined for the remote UE based on the adaptation layer subheader. The DU removes the adaptation layer subheader and then forwards the RRCSetup message to the remote UE via the PC5 RRC channel.

[0098] Implementation Method 2

[0099] This embodiment is similar to embodiment 1 and also includes 6 steps. For the sake of brevity, only the steps with changes are described below. The other steps can refer back to the corresponding steps in embodiment 1 above.

[0100] Step 3

[0101] Upon receiving the RRCSetupRequest message, the DU may detect based on the adaptation layer subheader that it corresponds to an SRB0 message. The DU may record the association between the relay UE and the remote UE.

[0102] DU sends an INITIAL UL RRC MESSAGE TRANSFER to CU. INITIAL UL RRC MESSAGE TRANSFER may include at least one of the following fields: gNB-DU UE F1AP ID of remote UE, C-RNTI of remote UE, ID of remote UE, RRC container, gNB-DU UE F1AP ID of relay UE, gNB-CU UE F1AP ID of relay UE, etc. The ID of remote UE may be a local ID assigned by gNB or a L2 source ID of remote UE. Note that CU knows the local ID because CU assigns it.

[0103] Upon receiving the INITIAL UL RRC MESSAGE TRANSFER, the CU may associate the remote UE with the relay UE based on the gNB-DU UE F1AP ID of the relay UE and / or the gNB-CU UE F1AP ID of the relay UE. In addition, the CU may know the C-RNTI of the remote UE and the gNB-DU UE F1AP ID of the remote UE based on the INITIAL UL RRC MESSAGE TRANSFER message.

[0104] Implementation 3

[0105] As described above, in a direct to indirect path handover scenario, the UE may be handed over from a direct connection to the gNB to an indirect connection. Prior to the handover, the gNB may configure the UE for the upcoming handover. For an example, refer to Fig. 9 As mentioned above, the gNB includes a CU and a DU.

[0106] Step 1

[0107] The gNB determines that the remote UE needs to be handed over to indirect access via the relay UE. The CU may assign a local ID to the remote UE via an RRCReconfiguration message. The RRCReconfiguration may also include information related to the assigned relay UE.

[0108] Step 2

[0109] In response, the remote UE sends an RRCReconfigurationComplete message to the relay UE. The adaptation layer at the PC5 interface is encapsulated for the RRCReconfigurationComplete message. The adaptation layer has a subheader. The remote UE can encapsulate the adaptation layer subheader with the remote UE ID and the RB ID. The remote UE ID can include one of the UE's local ID or the remote UE's L2 source ID.

[0110] Step 3

[0111] The relay UE may be in an inactive state or an idle state and may not have an RRC connection with the gNB. The relay UE may initiate an RRC connection establishment with the gNB and send its own L2 source ID to the gNB. The gNB may identify the relay UE as the relay UE that the gNB previously assigned to the remote UE to perform path switching.

[0112] Step 4

[0113] The CU configures the UE context of the relay UE to support sidelink communication. The CU may send F1AP signaling (e.g., UE context establishment or UE context modification request message) to the DU for the relay UE (i.e., the signaling is targeted at the relay UE), and the F1AP signaling may include at least one of the following fields:

[0114] CU-level relay ID that identifies the relay UE in the CU;

[0115] DU-level relay ID that identifies the relay UE in the DU;

[0116] ID of the remote UE;

[0117] A request to configure a PC5 RLC channel between the relay UE and the remote UE; or

[0118] Request for configuration of Uu RLC channels between relay UE and gNB.

[0119] Step 5

[0120] The DU may configure the corresponding resources according to the request of the CU in step 4. Then, the DU may send F1AP signaling (e.g., a UE context establishment response message or a UE context modification response message) to the CU, and the F1AP signaling may include PC5 RLC channel and Uu RLC channel configuration information. Details about the PC5 RLC channel and Uu RLC channel configuration information will be described in another embodiment, which will be found in a later section.

[0121] Step 6

[0122] The CU configures the UE context of the remote UE to support sidelink communication. The CU may send F1AP signaling (e.g., UE context establishment request message) to the DU for the remote UE (i.e., the signaling is targeted at the remote UE), and the F1AP signaling may include at least one of the following fields:

[0123] CU-level remote ID identifying the remote UE in the CU;

[0124] ID of the remote UE;

[0125] A request to configure a PC5 RLC channel between the relay UE and the remote UE; or

[0126] Bearer mapping configuration.

[0127] The remote UE’s ID may include a local ID assigned by the gNB or the remote UE’s L2 source ID.

[0128] Step 7

[0129] The DU may configure corresponding resources according to the request of the CU in step 6. Then, the DU may send F1AP signaling (eg, a UE context establishment response message or a UE context modification response message) to the CU, and the F1AP signaling may include PC5 RLC channel configuration information.

[0130] Step 8

[0131] The CU may send an RRCReconfiguration message to the relay UE to configure the Uu RLC channel and / or PC5 RLC channel for service relay of the remote UE.

[0132] Step 9

[0133] Now that the relay UE has established an RRC connection with the gNB and the UuRLC channels for supporting remote UE service relay have been configured, the relay UE may forward the RRCReconfigurationComplete message received from the remote UE in step 2 to the gNB.

[0134] Step 10

[0135] If the DU has served a remote UE before the path switch, the DU may identify the remote UE via the remote UE's ID encapsulated in the adaptation layer subheader, and then the DU may send an uplink RRC message transfer (UL RRC MESSAGE TRANSFER) message to the CU. The UL RRC MESSAGE TRANSFER may include at least one of the following fields: the gNB-DU UE F1AP ID of the remote UE, or the gNB-CU UE F1AP ID of the remote UE. Upon receiving the UL RRC MESSAGE TRANSFER, the CU may associate the remote UE with the relay UE. For example, based on the gNB-CU UE F1AP ID of the remote UE or the gNB-DU UE F1AP ID of the remote UE. It should be noted that the CU may identify the corresponding relay UE based on the association between the remote UE ID and the relay UE ID.

[0136] Implementation 4

[0137] In this embodiment, base station switching conditions are considered.

[0138] If the UE performs a direct path to indirect path handover and switches to a relay UE served by a different gNB, the source gNB needs to perform a handover preparation procedure. During this procedure, the target gNB can assign a local ID to the UE to be handed over and send the local ID to the source gNB. The source gNB then sends the local ID to the UE to be handed over via a message such as RRC signaling.

[0139] Alternatively, the CU of the target gNB may send the local ID of the remote UE together with other remote UE contexts to the DU of the target gNB.

[0140] Example 3

[0141] To support sidelink communications, various resources need to be configured, and this configuration applies to multiple network elements and interfaces. Figure 4 Along the data path between the remote UE and the CU, these interfaces need to be configured: the interface between the remote UE and the relay UE (ie, the PC5 interface); the interface between the relay UE and the DU (ie, the Uu interface).

[0142] Specifically, it is necessary to configure the Uu RLC channel connecting the DU and the relay UE and the PC5 RLC channel connecting the relay UE and the remote UE.

[0143] In order to correctly route uplink user plane traffic, the DU should be able to determine the GTP User Plane (GTP-U) tunnel associated with the remote UE's DRB based on the remote UE's ID and / or Radio Bearer (RB) information in the adaptation layer subheader. The RB information may include the RB ID. The DU can then transmit the remote UE's uplink user plane traffic via the GTP-U tunnel associated with or allocated to the remote UE.

[0144] Similarly, the CU can transmit the downlink user plane service of the remote UE via the GTP-U tunnel of the remote UE. On the DU side, upon receiving the downlink user plane service of the remote UE, based on the GTP-U tunnel used, the DU identifies the remote UE and its associated RB information (e.g., RB ID or DRB ID). The DU can also establish an association between the ID / RB ID of the remote UE and the GTP-U tunnel of the remote UE. The DU can then encapsulate the relayed downlink user plane data packet using an adaptation layer subheader, which can include the ID and RB ID of the remote UE. After encapsulation, the DU can map the data packet to the Uu RLC channel assigned to the remote UE and transmit the data packet to the corresponding Uu RLC channel.

[0145] refer to Figure 4 , the DU is able to distinguish data packets destined for a remote UE from data packets destined for a relay UE. The DU essentially connects (or maps) the GTP-U tunnel of the remote UE to the corresponding Uu RLC channel associated with the remote UE. It should also be noted that there may be multiple Uu RLC channels, each of which may be mapped to a QoS flow, and each of which may also be mapped to an RB.

[0146] In this embodiment, in order to support side link communication, the Uu RLC channel, PC5 RLC channel, and the bearer mapping rules between the RB / GTP-U tunnel of the remote UE and the Uu RLC channel can be configured. This configuration can be performed by using signaling between the CU and the DU. More details are described below.

[0147] Uu RLC channel configuration

[0148] The Uu RLC channel configuration may include the following parameters:

[0149] Channel ID of the Uu RLC channel;

[0150] QoS configuration of Uu RLC channels;

[0151] Mapping between QoS flows and Uu RLC channels;

[0152] QoS flow-level QoS profile;

[0153] Control plane service type;

[0154] · RLC mode of the Uu RLC channel; or

[0155] Bearer mapping configuration.

[0156] In the above list, the mapping between the QoS flow and the Uu RLC channel can be based on at least one of the following: the ID of the remote UE, the QoS flow identifier (QoS Flow Identifier, QFI) or the channel ID of the Uu RLC channel. For example, the QFI can be mapped to the channel ID, or the combination of the remote UE ID and the QFI can be mapped to the channel ID.

[0157] In one embodiment, a QoS flow may also be referred to as a profile QoS flow.

[0158] The QoS profile of the Uu RLC channel may include at least one of the following: Packet Delay Budget (PDB) information, or a QoS flow-level QoS profile. The PDB indicates a packet delay budget between the relay UE and the remote UE.

[0159] As mentioned above, the ID of the remote UE may include the local UE ID assigned by the gNB (or CU), the L2 source ID of the remote UE, or the C-RNTI of the remote UE.

[0160] The control plane service type may include one of the following items: SRB0, SRB1, SRB2, SRB3, etc. The control plane service type may also be represented by a priority.

[0161] The CU can send various types of configuration messages to the DU to configure the Uu RLC channel.

[0162] In one embodiment, the CU may configure the Uu RLC channel via the F1AP signaling associated with the relay UE, which may include one of the following items: PC5 RLC channel establishment request, Uu RLC channel modification request, or PC5 RLC channel release request. Each request may include a list of Uu RLC channels that need to be established (or modified) together with the corresponding Uu RLC channel configuration. The Uu RLC channel configuration may include the Uu RLC channel configuration parameters listed above in any combination.

[0163] In one embodiment, the CU may configure the Uu RLC channel via non-UE associated F1AP signaling. In this case, in addition to the Uu RLC channel list that needs to be established (or modified) and the corresponding Uu RLC channel configuration, the message may also include the ID of the relay UE, so that the relay UE can be identified by the DU.

[0164] In response, the DU may send a response message (e.g., a response F1AP message) to the CU, which may include a list of Uu RLC channels that have been established. Each Uu RLC channel in the list may include a Uu RLC channel ID and / or a Uu logical channel ID corresponding to the Uu RLC channel. In one embodiment, the detailed Uu RLC channel configuration of each Uu RLC channel may be carried in the RRC information from the DU to the CU. In the event that some Uu RLC channels cannot be established, the response message may also include a list of Uu RLC channels that failed to be established. Each Uu RLC channel in the list may include the Uu RLC channel ID and the cause of the failure of the corresponding Uu RLC channel. In addition, if the configuration message from the CU includes a list of Uu RLC channels that need to be modified, the DU may send a response message to the CU, which may include a list of Uu RLC channels that have been modified. Each Uu RLC channel in the list may include a Uu RLC channel ID. Similarly, error conditions may also be reported back to the CU.

[0165] PC5 RLC channel configuration

[0166] PC5 RLC channel configuration may include:

[0167] Channel ID of PC5 RLC channel;

[0168] QoS configuration of PC5 RLC channel;

[0169] Mapping between QoS flows and PC5 RLC channels;

[0170] QoS flow level QoS;

[0171] Control plane service type;

[0172] · RLC mode for PC5 RLC channel; or

[0173] Carrying mapping information.

[0174] It should be noted that the PC5 RLC channel configuration may be applied to a relay UE or a remote UE. When the PC5 RLC channel configuration is applied to a relay UE, the PC5 RLC channel configuration may also include the ID of the remote UE. When the PC5 RLC channel configuration is applied to a remote UE, the PC5 RLC channel configuration may also include the ID of the relay UE. The ID of the relay UE may include one of the following: the gNB-DU UE F1AP ID of the relay UE, the gNB-CU UE F1AP ID of the relay UE, a local ID assigned by the CU to the relay UE, or the C-RNTI of the relay UE.

[0175] In the above list, the mapping between the QoS flow and the PC5 RLC channel can be based on at least one of the following: the remote UE's ID, the QFI flow identifier (QFI), or the channel ID of the PC5 RLC channel. For example, the QFI can be mapped to the channel ID, or a combination of the remote UE's ID and the QFI can be mapped to the channel ID.

[0176] In one embodiment, a QoS flow may also be referred to as a profile QoS flow.

[0177] The QoS profile of the PC5 RLC channel may include at least one of the following: Packet Delay Budget (PDB) information, or QoS flow-level QoS profile. The PDB indicates the packet delay budget between the gNB and the relay UE or between the DU and the relay UE.

[0178] The control plane service type may include one of the following items: SRB0, SRB1, SRB2, SRB3, etc. The control plane service type may also be represented by a priority.

[0179] The CU can send various types of messages to the DU to configure the PC5 RLC channel.

[0180] In one embodiment, the CU may configure the PC5 RLC channel via F1AP signaling associated with the relay UE, which may include one of the following items: a PC5 RLC channel establishment request, a PC5 RLC channel modification request, or a PC5 RLC channel release request. Each request may include a list of PC5 RLC channels that need to be established (or modified) together with the corresponding PC5 RLC channel configuration. The PC5 RLC channel configuration may include the PC5 RLC channel configuration parameters listed above in any combination.

[0181] In one embodiment, the CU may configure the PC5 RLC channel via F1AP signaling associated with the remote UE, which may include one of the following items: PC5 RLC channel establishment request, PC5 RLC channel modification request, PC5RLC channel release request, Uu DRB establishment request, Uu DRB modification request, Uu DRB release request, GTP-U establishment request, GTP-U modification request, or GTP-U release request. Each request may include a list of PC5 RLC channels that need to be established (or modified) together with the corresponding PC5RLC channel configuration. The PC5 RLC channel configuration may include the PC5RLC channel configuration parameters listed above in any combination.

[0182] In one embodiment, the CU may configure the PC5 RLC channel via non-UE associated F1AP signaling. In this case, in addition to the PC5 RLC channel list and the corresponding PC5 RLC channel configuration that need to be established (or modified), the message may also include the ID of the relay UE and / or the ID of the remote UE.

[0183] In response, the DU may send a response message (e.g., a response F1AP message) to the CU, which may include a list of established PC5 RLC channels. Each Uu RLC channel in the list may include a PC5 RLC channel ID and / or a PC5 logical channel ID corresponding to the PC5 RLC channel. In one embodiment, the detailed UuRLC channel configuration of each PC5 RLC channel may be carried in the RRC information from the DU to the CU. In the event that some PC5 RLC channels cannot be established, the response message may also include a list of PC5 RLC channels that failed to be established. Each PC5 RLC channel in the list may include the PC5 RLC channel ID and the cause of the failure of the corresponding PC5 RLC channel. If the configuration message from the CU includes a list of PC5 RLC channels that need to be modified, the DU may send a response message to the CU, which may include a list of PC5 RLC channels that have been modified. Each PC5 RLC channel in the list may include a PC5 RLC channel ID. Similarly, error conditions may also be reported back to the CU.

[0184] Downlink User Plane (DL UP) bearer mapping configuration

[0185] The CU can send various types of messages to the DU to configure DL UP bearer mapping.

[0186] In one embodiment, the CU may send the bearer mapping configuration to the DU via signaling associated with the relay UE. The bearer mapping configuration may include a mapping between a GTP-U tunnel of the remote UE and a Uu RLC channel of the relay UE. As an example, the GTP-U tunnel may be identified by a combination of an IP address of the tunnel and a tunnel endpoint identifier (TEID) of the tunnel, and the Uu RLC channel may be identified by a channel ID.

[0187] In one embodiment, the CU may send the bearer mapping configuration to the DU via remote UE associated signaling. The bearer mapping configuration may include a mapping between a GTP-U tunnel of the remote UE and a Uu RLC channel of the relay UE. As an example, the GTP-U tunnel may be identified by a combination of an IP address of the tunnel and a TEID of the tunnel. The Uu RLC channel may be identified by a combination of a channel ID and an ID of the relay UE. The ID of the relay UE may include a gNB-DU UE F1AP ID and a gNB-CU UE F1AP ID of the relay UE.

[0188] In one embodiment, the CU may send the bearer mapping configuration to the DU via non-UE associated F1AP signaling. The bearer mapping configuration may include a mapping between a GTP-U tunnel of a remote UE and a Uu RLC channel of a relay UE. As an example, the GTP-U tunnel may be identified by a combination of an IP address of the tunnel and a TEID of the tunnel, and the Uu RLC channel may be identified by a combination of a channel ID and an ID of the relay UE.

[0189] Downlink Control Plane (DL CP) Bearer Mapping Configuration

[0190] The CU can send various types of messages to the DU to configure DL CP bearer mapping.

[0191] In one embodiment, the CU may send the bearer mapping configuration to the DU via signaling associated with the relay UE. The bearer mapping configuration may include a mapping between the SRB of the remote UE and the Uu RLC channel of the relay UE. As an example, the SRB may be identified by a combination of the ID of the SRB and the ID of the remote UE. The ID of the remote UE may include one of the following items: the gNB-DU UE F1AP ID of the remote UE, the gNB-CU UE F1AP ID of the remote UE, or the local ID of the remote UE. The local ID may be assigned by the CU / gNB. The Uu RLC channel of the relay UE may be identified by the ID of the Uu RLC channel.

[0192] In one embodiment, the CU may send the bearer mapping configuration to the DU via remote UE associated signaling. The bearer mapping configuration may include a mapping between the SRB of the remote UE and the Uu RLC channel of the relay UE. As an example, the SRB may be identified by an ID of the SRB. The Uu RLC channel of the relay UE may be identified by a combination of the ID of the relay UE and the ID of the Uu RLC channel. The ID of the relay UE may include one of the following: the gNB-DU UE F1AP ID of the relay UE or the gNB-CU UE F1AP ID of the relay UE.

[0193] In one embodiment, the CU may send the bearer mapping configuration to the DU via non-UE associated F1AP signaling. The bearer mapping configuration may include a mapping between the SRB of the remote UE and the Uu RLC channel of the relay UE. As an example, the SRB may be identified by a combination of the ID of the SRB and the ID of the remote UE. The Uu RLC channel of the relay UE may be identified by a combination of the ID of the relay UE and the ID of the Uu RLC channel.

[0194] Example 4

[0195] The AMF may provide indications to the Radio Access Network (RAN) regarding the UE authorization status on ProSe Direct Discovery and ProSe Direct Communication (i.e., as a 5G ProSe UE for ProSe Direct Discovery or as a 5G ProSe UE for ProSe Direct Communication), and the UE authorization status on UE to network relay discovery and communication (i.e., as a 5G ProSe Layer-2 Remote UE, as a 5G ProSe Layer-2 UE to Network Relay, or as a Layer-3 UE to Network Relay).

[0196] In order for the DU to allocate resources for the relay UE, the CU may transmit an authorization information element (IE), such as a 5G ProSe Layer-2 UE-to-Network Relay IE, or a Layer-3UE-to-Network Relay authorization IE, to the DU via a message, such as a UE Context Setup Request message or a UE Context Modification Request message. For example, if the relay UE is authorized to perform layer-2UE to network relay, the DU may forward the first RRC message of the remote UE, i.e., allocate a gNB-DU UE F1AP ID to the remote UE and transmit the initial UL RRC message transmission for the remote UE. Otherwise, if the relay UE is not authorized to perform layer-2UE to network relay, the DU may discard the first RRC message. In addition, the DU may use the authorization IE to check whether sidelink discovery and / or communication resources should be configured for the relay UE. If the relay UE is authorized for layer-3UE to network relay, the DU may allocate sidelink discovery and sidelink communication resources to the relay UE.

[0197] The DU may also need to check whether the remote UE can be allocated sidelink discovery and / or communication resources, so the CU also needs to send a 5G ProSe layer-2 remote UE authorization IE to the DU.

[0198] In one embodiment, to support ProSe discovery, the CU may receive a ProSe direct discovery IE from an access and mobility management function (AMF). The CU may then send a ProSe direct discovery authorization IE to the DU.

[0199] During a handover procedure for a relay UE, a remote UE, or a UE capable of ProSe discovery, the source gNB may send UE authorization information to the target gNB in ​​a handover request message, and the UE authorization information may include a 5G ProSe Layer-2 UE-to-Network Relay IE, a Layer-3 UE-to-Network Relay authorization IE, a 5G ProSe Layer-2Remote UE authorization IE, or a ProSe Direct Discovery authorization IE.

[0200] Example 5

[0201] In this example, using Fig.10 An example signaling procedure for initial access of a remote UE is described as a reference.

[0202] Step 1

[0203] The remote UE sends an RRCSetupRequest message to the relay UE via the PC5 RLC channel.

[0204] Steps 2-5

[0205] The relay UE is unaware of the local ID of the remote UE. The relay UE may request the local ID from the gNB by sending SidelinkUEInformation or other RRC signaling to the gNB. The SidelinkUEInformation or other RRC signaling may include at least one of the following: the destination L2 ID of the remote UE, an indication (or identifier) ​​of the remote UE, or an indication for requesting the local ID of the remote UE.

[0206] Upon receiving SidelinkUEInformation, the gNB (e.g., CU) may allocate a local ID for the remote UE and send it to the relay UE via an RRCReconfiguration message. If the adaptation layer via the PC5 interface is supported, the remote UE may also need to know the local ID so that the remote UE can encapsulate SRB messages (e.g., SRB1, SRB2, etc.) and data packets to be relayed to the gNB. In this case, the relay UE may send the local remote UE ID to the remote UE via PC5 RRC signaling, as shown in step 5'.

[0207] Step 6

[0208] Once the relay UE has acquired the local ID of the remote UE, the relay UE may encapsulate the local ID of the remote UE in the adaptation layer subheader and then forward the RRCSetupRequest message to the gNB-DU via the Uu RLC channel. In one embodiment, the Uu RLC channel includes a predetermined RLC channel for SRB0 messaging of the remote UE.

[0209] Step 7

[0210] Upon receiving the RRCSetupRequest message from the relay UE via the Uu RLC channel, the DU may determine that it corresponds to an SRB0 message based on the adaptation layer subheader. The DU may identify that it is the first RRC message from the remote UE. The DU may allocate a C-RNTI for the remote UE and record the association between the relay UE and the remote UE. The DU then allocates a gNB-DU UE F1APID for the remote UE and sends an INITIAL UL RRC MESSAGE TRANSFER to the CU. The INITIAL UL RRC MESSAGE TRANSFER may include at least one of the following fields: gNB-DU UE F1AP ID of the remote UE, C-RNTI of the remote UE, ID of the remote UE, RRC container, etc. The ID of the remote UE may be a local ID assigned by the gNB, or an L2 source ID of the remote UE.

[0211] Step 8

[0212] Upon receiving the INITIAL UL RRC MESSAGE TRANSFER, the CU may associate the remote UE with its L2 source ID based on the remote UE's ID. The CU may also associate the remote UE with the relay UE. The CU may also associate the remote UE's L2 source ID or local ID with the relay UE (the relay UE is connected to the remote UE via the PC5 interface) because the given relay UE previously requested the remote UE's local ID, or because the local ID was assigned to the remote UE associated with the relay UE when the CU assigned the local ID. In addition, the CU may know the remote UE's C-RNTI and the remote UE's gNB-DU UE F1AP ID based on the INITIAL UL RRC MESSAGE TRANSFER message.

[0213] Upon receiving the INITIAL UL RRC MESSAGE TRANSFER, the CU may associate to the remote UE based on the remote UE's ID. For example, the CU may associate the remote UE's L2 source ID with the relay UE connected to PC5 because the relay UE requested the remote UE's local ID. In addition, the CU may know the remote UE's C-RNTI and the remote UE's gNB-DU UE F1AP ID. The CU assigns a gNB-CU UE F1AP ID to the remote UE and generates an RRCSetup message to the remote UE. The CU then sends a DL RRC MESSAGE TRANSFER to the DU, which may include the remote UE's gNB-DU UE F1AP ID, the remote UE's gNB-CU UE F1AP ID, the SRB ID assigned to the remote UE, and an RRC container. The RRC container may include the RRCSetup message sent from the gNB to the remote UE.

[0214] Step 9

[0215] Upon receiving the DL RRC MESSAGE TRANSFER, the DU is able to identify the remote UE based on the gNB-DU UEF1AP ID (in the message) and the corresponding SRB of the RRC message within the RRC container. The DU may then encapsulate the adaptation layer subheader with the local ID and RB ID of the remote UE and then transmit the RRC message (e.g., RRCSetup) to the relay UE via the Uu RLC channel.

[0216] Step 10

[0217] The relay UE removes the adaptation layer subheader and then transmits the RRCSetup message to the remote UE via the PC5 RRC channel.

[0218] Steps 11-13

[0219] The remote UE sends an RRCSetupComplete message to the DU, which is forwarded by the relay UE. At this time, the adaptation layer subheader can be encapsulated by the remote UE. The relay UE can check the adaptation layer subheader to map the RRCSetupComplete message to the corresponding Uu RLC channel and then send the packet to the DU.

[0220] The DU removes the adaptation layer subheader, encapsulates the RRCSetupComplete message in a UL RRCMESSAGE TRANSFER message for the remote UE, and sends it to the CU.

[0221] Step 14

[0222] CU sends an initial UE message (INITIAL UE MESSAGE) to AMF.

[0223] Step 15

[0224] The AMF sends an initial context establishment request (INITIAL CONTEXT SETUP REQUEST) message to the CU.

[0225] Step 16

[0226] The CU sends a UE CONTEXT SETUP REQUEST message to establish a remote UE context in the DU. In this message, a Security Mode Command message may also be encapsulated.

[0227] Steps 17-18

[0228] The DU sends a SecurityModeCommand message to the remote UE, and the SecurityModeCommand message is forwarded by the relay UE.

[0229] Step 19

[0230] The gNB DU sends a UE CONTEXT SETUP RESPONSE message for the remote UE to the CU.

[0231] Steps 20-21

[0232] The remote UE responds with a SecurityModeComplete message and sends it to the DU via the relay UE.

[0233] Step 22

[0234] The DU encapsulates the RRC message in an uplink RRC message transfer (UL RRC MESSAGE TRANSFER) message and sends it to the CU.

[0235] Step 23

[0236] The CU generates an RRCReconfiguration message for the remote UE and encapsulates it in a DL RRC MESSAGETRANSFER message.

[0237] Steps 24-25

[0238] The DU sends an RRCReconfiguration message to the remote UE.

[0239] Steps 26-27

[0240] The remote UE sends an RRCReconfigurationComplete message to the DU.

[0241] Step 28

[0242] The DU encapsulates the RRC message in a UL RRC MESSAGE TRANSFER message and sends it to the gNB-CU.

[0243] Step 29

[0244] CU sends an initial context setup response (INITIAL CONTEXT SETUP RESPONSE) message to AMF.

[0245] At this stage, the RRC connection establishment has been completed for the CU / DU separation scenario. During this process, the CU can send RRCReconfiguration messages to the relay UE and / or remote UE to perform Uu RLC channel configuration and / or PC5 RLC channel configuration and bearer mapping configuration. Once these configurations are completed, the remote UE can initiate more service requests to establish data radio bearers (DRBs). Both the relay UE and the remote UE can be reconfigured by the gNB for Uu RLC channel configuration and / or PC5 RLC channel configuration and bearer mapping configuration.

[0246] The above description and accompanying drawings provide specific example embodiments and implementations. However, the described subject matter can be implemented in various different forms, and therefore, the subject matter covered or claimed is intended to be interpreted as not being limited to any example embodiment set forth herein. It is intended to give the claimed or covered subject matter a suitable wide range. Among other things, for example, the subject matter can be implemented as a method, device, component, system or non-transient computer-readable medium for storing computer code. Therefore, the embodiment can, for example, take the form of hardware, software, firmware, storage medium or any combination thereof. For example, the above method embodiment can be implemented by a component, device or system including a memory and a processor that executes the computer code stored in the memory.

[0247] Throughout the specification and claims, terms may have nuanced meanings that are suggested or implied in the context beyond their explicitly stated meanings. Likewise, the phrase "in one embodiment / implementation" as used herein does not necessarily refer to the same embodiment, and the phrase "in another embodiment / implementation" as used herein does not necessarily refer to a different embodiment. For example, it is intended that the claimed subject matter includes, in whole or in part, a combination of the example embodiments.

[0248] In the present disclosure, various embodiments may be combined to cover more scenarios and / or provide more solutions. A single embodiment may be split to cover partial functions. The steps in the embodiments are for exemplary purposes only and may be adjusted.

[0249] In general, terms may be understood, at least in part, from usage in context. For example, terms used herein (such as "and," "or," or "and / or") may include a variety of meanings (which may depend, at least in part, on the context in which the terms are used). Typically, "or," if used to associate a list (such as A, B, or C), is intended to represent A, B, and C (used here as an inclusive sense), as well as A, B, or C (used here as an exclusive sense). In addition, depending, at least in part, on the context, the term "one or more" as used herein may be used to describe any feature, structure, or characteristic in a singular sense, or may be used to describe a combination of features, structures, or characteristics in a plural sense. Similarly, depending, at least in part, on the context, terms such as "one," "an," or "the" may be understood to convey singular usage or to convey plural usage. In addition, the term "based on" may be understood to not necessarily be intended to convey an exclusive set of factors, but, again, depending, at least in part, on the context, to allow for the presence of additional factors that may not be explicitly described.

[0250] References throughout this specification to features, advantages, or similar language do not mean that all features and advantages that can be achieved using the present solution should be included or included in any single embodiment thereof. Rather, language referencing features and advantages is understood to mean that a particular feature, advantage, or characteristic described in conjunction with an embodiment is included in at least one embodiment of the present solution. Thus, discussion of features and advantages and similar language throughout the specification may (but does not necessarily) refer to the same embodiment.

[0251] Furthermore, in one or more embodiments, the features, advantages, and characteristics of the present solution may be combined in any suitable manner. Based on the description herein, one of ordinary skill in the relevant art will recognize that the present solution may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the present solution.

Claims

1. A method performed by a distributed unit DU of a wireless communication node in a wireless network, the method comprising: A first transmission message is transmitted to a centralized unit CU of the wireless communication node, wherein the first transmission message includes an identifier ID of a remote user equipment UE and triggers the CU to associate the remote UE with a relay UE, and wherein the relay UE serves as a relay between the remote UE and the wireless communication node.

2. The method according to claim 1, wherein: The remote UE ID includes a local UE ID that identifies the remote UE within range of a relay UE in the wireless network.

3. The method according to claim 1, wherein: The first transmission message also includes a DU-level relay UE ID identifying the relay UE in the DU.

4. The method according to claim 3, wherein: The DU-level relay UE ID includes the gNB-DU UEF1AP ID of the relay UE.

5. The method according to claim 1, further comprising: receiving a first message of the CU from the wireless communication node, where the first message is used to configure a Uu radio link control RLC channel between the DU and the relay UE; or receiving a second message from the CU, the second message being used to configure a relay UE side configuration of a PC5 RLC channel between the relay UE and the remote UE, The Uu RLC channel or the PC5 RLC channel is used to transmit the service whose destination is the remote UE.

6. The method according to claim 5, further comprising: receiving a third message from the CU, where the third message is used to configure a bearer mapping for supporting a downlink DL user plane UP service of the remote UE; as well as A fourth message is received from the CU, where the fourth message is used to configure bearer mapping for supporting a DL control plane CP service of the remote UE.

7. The method according to claim 6, wherein: The fourth message is transmitted via UE-specific F1AP signaling associated with the remote UE, and wherein the fourth message includes a mapping between a signaling radio bearer SRB of the remote UE and the Uu RLC channel of the relay UE, wherein the Uu RLC channel is identified by a combination of an ID of the Uu RLC channel and an ID of the relay UE.

8. A method performed by a centralized unit CU of a wireless communication node in a wireless network, the method comprising: Transmitting a first F1 application protocol F1AP signaling to a distributed unit DU of the wireless communication node to configure a UE context for a relay user equipment UE; or A second F1AP signaling is transmitted to the DU to configure a UE context for a remote UE, wherein the remote UE is configured with an indirect path to the wireless communication node using the relay UE.

9. The method according to claim 8, wherein: The first F1AP signaling includes at least one of the following: The identifier ID of the remote UE; A request for configuring a PC5 radio link control RLC channel between the relay UE and the remote UE; or A request for configuring a Uu RLC channel between the relay UE and the wireless communication node.

10. The method according to claim 9, wherein: The request for configuring a PC5 RLC channel between the relay UE and the remote UE includes a list of PC5 RLC channels to be configured; Each PC5 RLC channel in the list of PC5 RLC channels to be configured includes at least one of the following: The PC5 RLC channel ID, The PC5 RLC channel Quality of Service QoS profile, Control plane service type, or the ID of the remote UE; and The PC5 RLC channel list to be configured includes at least one of the following: List of PC5 RLC channels to be established, List of PC5 RLC channels to be modified, or List of PC5 RLC channels to be released.

11. The method according to claim 10, wherein: The QoS profile of the PC5 RLC channel includes packet delay budget PDB information, and wherein the PDB information indicates a packet delay budget between the relay UE and the remote UE.

12. The method according to claim 9, wherein: The request for configuring a Uu RLC channel between the relay UE and the wireless communication node includes a list of Uu RLC channels to be configured, and each Uu RLC channel in the list of Uu RLC channels to be configured includes at least one of the following: The ID of the Uu RLC channel; a QoS profile of the Uu RLC channel; or Control plane service type.

13. The method according to claim 12, wherein: The QoS profile of the Uu RLC channel includes packet delay budget PDB information, and wherein the PDB information indicates a packet delay budget between the DU and the relay UE.

14. The method according to claim 8, wherein: After transmitting the first F1AP signaling to the DU, the method further includes: receiving a first response message to the first F1AP signaling from the DU, the first response message including at least one of the following: PC5 RLC channel configuration; or Uu RLC channel configuration.

15. The method of claim 8, wherein: The first F1AP signaling triggers configuration of a Uu RLC channel between the DU and the relay UE; The second F1AP signaling triggers configuration of a PC5 RLC channel between the relay UE and the remote UE; and The Uu RLC channel and the PC5 RLC channel are used to transmit traffic destined for the remote UE, and wherein the relay UE serves as a relay between the remote UE and the wireless communication node.

16. The method according to claim 8, further comprising: Transmitting a third message to the DU, wherein the third message is used to configure a bearer mapping for supporting a downlink DL user plane UP service of the remote UE; as well as A fourth message is transmitted to the DU, where the fourth message is used to configure a bearer mapping for supporting a downlink DL control plane CP service of the remote UE.

17. The method according to claim 16, wherein: The fourth message is transmitted via UE-specific F1AP signaling associated with the remote UE, and wherein the fourth message includes a mapping between a signaling radio bearer SRB of the remote UE and a Uu RLC channel of the relay UE, wherein the Uu RLC channel is identified by a combination of an ID of the Uu RLC channel and an ID of the relay UE.

18. The method according to claim 8, further comprising: transmitting a sixth message to the DU, the sixth message comprising sidelink communication grant information for at least one of the relay UE or the remote UE, wherein the sidelink communication grant information comprises at least one of: 5G Proximity Services ProSe layer-2UE to network relay grant for the relay UE; a layer-3 UE-to-network relay grant for the relay UE; 5G ProSe Layer-2 Remote UE Authorization; or ProSe direct discovery authorization.

19. A distributed unit DU of a wireless communication node, the DU comprising a memory for storing computer instructions and a processor in communication with the memory, wherein: When the processor executes the computer instructions, the processor is configured to cause the DU to implement the method according to any one of claims 1 to 7.

20. A centralized unit CU of a wireless communication node, the CU comprising a memory for storing computer instructions and a processor communicating with the memory, wherein: When the processor executes the computer instructions, the processor is configured to cause the CU to implement the method according to any one of claims 8 to 18.

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