Lateral link wireless communication techniques

Abstract

Techniques for performing sidelink wireless communications are described. An example wireless communication method includes receiving, by a first network function of a network device from a second network function of the network device, a request message related to the first communication device, where the request message includes information of a channel to be established or modified, and wherein the information comprises a second communication device identifier indicating a second communication device, the first communication device being configured to establish or modify a channel to the second communication device; and sending, by the first network function, a response message to the second network function in response to receiving the request message.

Description

Technical Field

[0001] This document relates generally to digital wireless communications. Background Art

[0002] Mobile communication technology is pushing the world towards an increasingly connected and networked society. Compared with existing wireless networks, next-generation systems and wireless communication technologies will need to support a wider range of use case features and provide more complex and sophisticated access requirements and flexibility.

[0003] Long Term Evolution (LTE) is a wireless communication standard for mobile devices and data terminals developed by the Third Generation Partnership Project (3GPP). LTE-Advanced (LTE-A) is a wireless communication standard that enhances the LTE standard. The fifth generation wireless system, called 5G, advances the LTE and LTE-A wireless standards and is committed to supporting higher data rates, a large number of connections, ultra-low latency, high reliability, and other emerging business requirements. Summary of the invention

[0004] Techniques for sidelink wireless communications are disclosed.

[0005] A first wireless communication method includes receiving, by a first network function of a network device, a request message related to a first communication device from a second network function of the network device, wherein the request message includes information of a channel to be established or modified, and wherein the information includes a second communication device identifier indicating the second communication device, and the first communication device is configured to establish or modify a channel to the second communication device; and sending, by the first network function, a response message to the second network function in response to receiving the request message.

[0006] A second wireless communication method includes sending a request message by a second network function of a network device to a first network function of the network device, the request message including information of a channel to be established or modified, wherein the information includes a second communication device identifier indicating a second communication device, and the first communication device is configured to establish or modify a channel to the second communication device. Operation 1004 includes receiving a response message from the first network function in response to sending the request message by the second network function.

[0007] In some embodiments, the information includes a control plane service type, which indicates that the type of service transmitted through the channel is a control plane service, wherein the control plane service type includes an identifier of a sidelink (SL) signaling radio bearer or a priority of the SL signaling radio bearer. In some embodiments, the first communication device includes a source communication device, the request message includes a list of sidelink (SL) radio bearers to be established or a list to be modified for establishing or modifying communication between the source communication device, the relay communication device, and the target communication device, the source communication device is configured to communicate with the target communication device via the relay communication device, the list of SL radio bearers to be established or the list to be modified includes any one or more of the following items: an identifier associated with the SL radio bearer between the source communication device and the target communication device, and mapping information indicating a mapping between an identifier of the SL radio bearer and a channel identifier of the channel. In some embodiments, the SL radio bearer includes a SL signaling radio bearer (SRB) or a SL data radio bearer (DRB).

[0008] In some embodiments, the first network function receives path switching related information from the second network function or the second network function sends path switching related information to the first network function, and the path switching related information includes one or more of the following: a path switching indication indicating that the communication device performs a path switching, or a type of path switching, and the type of path switching includes a direct to indirect path switching, an indirect to direct path switching, or an indirect to indirect path switching. In some embodiments, the first communication device includes a source communication device, and the first network function receives path switching related information from the second network function or the second network function sends path switching related information to the first network function, and the path switching related information includes: an identifier of a relay communication device, an identifier of a target communication device, and the identifier of the target communication device indicates that the source communication device is configured to communicate to a destination via the relay communication device. In some embodiments, the first communication device includes a source communication device or a target communication device, and wherein the second communication device includes a relay communication device.

[0009] In some embodiments, the first communication device comprises a relay communication device, and wherein the second communication device comprises a source communication device or a target communication device. In some implementations, the method further comprises receiving, by the second network function, authorization information from an access and mobility management function (AMF) of a core network. In some embodiments, the method further comprises sending, by the second network function, authorization information to the first network function or another base station. In some embodiments, the authorization information comprises any one or more of the following: U2U relay, U2U remote UE, L2 U2U relay, L3 U2U relay, L2 U2U remote UE, or L3 U2U remote UE. In some embodiments, the request message comprises a UE context establishment request or a modification request message, the first network function comprises a distributed unit in a base station, the second network function comprises a centralized unit in a base station, and / or the channel comprises a PC5 radio link control (RLC) channel.

[0010] A third wireless communication method includes sending a switching request message by a first network device to a second network device, the switching request message triggering switching of a remote communication device from the first network device to the second network device, wherein after the switching, the remote communication device is configured to perform communication with the second network device via a relay communication device; and receiving a response message by the first network device from the second network device.

[0011] In some embodiments, the handover request message includes the remote communication device capability of the remote communication device to switch to the relay communication device in an idle state or an inactive state. In some embodiments, the second network device is configured to serve a plurality of candidate relay communication devices including the relay communication device, and for each candidate relay communication device in the plurality of candidate relay communication devices, the handover request message includes any one or more of the following: an identifier of the candidate relay communication device, an identifier of a serving cell of the candidate relay communication device, or a link quality between the candidate relay communication device and the remote communication device. In some embodiments, the second network device is configured to select the relay communication device from the plurality of candidate relay communication devices, and the response message includes the identifier of the relay communication device.

[0012] A fourth wireless communication method includes receiving, by a remote communication device, a radio resource control (RRC) reconfiguration message including path switching related information from a source base station; and performing, by the remote communication device, uplink data transmission to a target base station via a relay communication device, wherein the uplink data transmission is performed by switching communication from the source base station to the relay communication device, and the remote communication device is configured to communicate with the target base station through the relay communication device.

[0013] In some embodiments, the method further comprises, in response to receiving the RRC reconfiguration message, sending an RRC reconfiguration complete message to the relay communication device, wherein the uplink data transmission is performed in response to the remote communication device receiving a confirmation message, the confirmation message indicating that the RRC reconfiguration complete message is received by the relay communication device. In some embodiments, the uplink data transmission is performed in response to the expiration of a timer configured by the path switch related information, and the timer is started when the remote communication device receives the path switch related information included in the RRC reconfiguration message.

[0014] In another exemplary aspect, the above method is embodied in the form of processor executable code and stored in a non-transitory computer readable storage medium. When executed by a processor, the code included in the computer readable storage medium causes the processor to implement the method described in this patent document.

[0015] In another exemplary embodiment, a device configured or operable to perform the above method is disclosed.

[0016] The above and other aspects and implementations thereof are described in more detail in the drawings, the description and the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 An example scenario of sidelink relay wireless communication is shown.

[0018] Figure 2 An example diagram of a UE-to-UE (U2U) relay communication configuration in a centralized unit (CU)-distributed unit (DU) split architecture is shown.

[0019] FIG. 3A to FIG. 3B An example diagram of a handover procedure for a UE to Network (U2N) path switch is shown.

[0020] Figure 4 An example diagram illustrating data transmission during relay user equipment (UE) handover is shown.

[0021] Figure 5 An example diagram of remote UE Radio Resource Control (RRC) re-establishment is shown.

[0022] Figure 6 An example diagram of inter-gNB indirect to direct path handover with dual-active protocol stack (DAPS) configured for U2N relay is shown.

[0023] Figure 7 An exemplary block diagram of a hardware platform that may be part of a network device or communication device is shown.

[0024] Figure 8An example of wireless communication including a base station (BS) and a user equipment (UE) based on some implementations of the disclosed technology is shown.

[0025] Fig. 9 An exemplary flow diagram for facilitating sidelink wireless communications is shown.

[0026] Fig.10 Another exemplary flow diagram for facilitating sidelink wireless communications is shown.

[0027] Fig.11 Inter-gNB direct to indirect path handover with DAPS configured for U2N relay is shown.

[0028] Fig.12 An exemplary flow chart for facilitating handover is shown.

[0029] Fig.13 An exemplary flow chart for performing uplink transmissions is shown. DETAILED DESCRIPTION

[0030] This patent document describes techniques for New Radio (NR) Sidelink (SL) relay wireless communications. In some embodiments, techniques for addressing SL UE to UE relay support in a split architecture, such as a Centralized Unit (CU) / Distributed Unit (DU) split architecture, are described. For example, techniques for configuring PC5 Radio Link Control (RLC) channels and bearer mapping between end-to-end Sidelink Radio Bearers (SLRBs) (including Sidelink Signaling Radio Bearers (SL SRBs) and Sidelink Data Radio Bearers (SSL DRBs)) and PC5 RLC channels, techniques for enabling UE to UE (U2U) path switching, and / or techniques for supporting authorization of U2U relays are described. In some other embodiments, techniques for providing service continuity for UE to network relays are described, such as techniques for performing inter-gNB direct to indirect path switching, techniques for providing lossless delivery during remote UE RRC reestablishment when a relay UE performs a switch, and / or the impact of a dual active protocol stack (DAPS) on UE to network (U2N) path switching.

[0031] The example titles of the following sections are used to facilitate understanding of the disclosed subject matter and do not limit the scope of the claimed subject matter in any way. Therefore, one or more features of one example section can be combined with one or more features of another example section. In addition, for clarity of explanation, 5G terminology is used, but the technology disclosed in this document is not limited to 5G technology and can be used in wireless systems that implement other protocols.

[0032] Introduction

[0033] With the development of wireless multimedia services, the demand for high data rates and good user experience is increasing, and higher requirements are placed on the system compatibility and coverage of conventional cellular networks. On the other hand, due to application scenarios such as public safety, social networks, near-field data sharing, and local advertising, the demand for proximity services is also increasing. Traditionally, cellular networks using base stations as the center may have obvious limitations in supporting high data rates and proximity services. In order to meet such requirements, device-to-device (D2D) communication technology is proposed. By applying D2D communication technology, the burden on cellular networks can be reduced, the power consumption of user equipment (UE) can be reduced, the data rate can be increased, and the robustness of the network infrastructure can be improved. Therefore, the demand for high data rates and proximity services is greatly met. In this context, D2D communication technology is also called proximity service (ProSe) or sidelink (SL) communication, where the interface between UEs is called PC5 interface.

[0034] In order to support a wider range of applications and services (e.g., indoor relay communication, smart agriculture, smart factories, public safety, etc.), sidelink-based relay communication can be used to extend coverage and improve power consumption. For example, sidelink-based communication can be applied to Figure 1 Two application scenarios are shown:

[0035] 1) UE to Network Relay (Mode 1): This type of relay is used for UEs in weak / no coverage areas. Figure 1 In the example, UE1 in a weak / no coverage area is allowed to communicate with the network (e.g., base station) via UE2 under the coverage of the network. UE-to-network relay can help network operators expand coverage and increase network capacity. Figure 1 In the present invention, UE1 is called a remote UE, and UE2 is called a UE-to-network relay.

[0036] 2) UE-to-UE relay (Mode 2): For emergency situations where the network is not functioning properly (e.g., earthquake) or to extend the sidelink communication range, UEs may be allowed to communicate with each other via (multiple) relay UEs. For example, Figure 1 UE3 and UE4 in the example communicate with each other via UE5 or multiple relay UEs. UE5 may be referred to as a UE-to-UE (U2U) relay.

[0037] Regarding U2U relay, when the source UE and the target UE are within the SL communication range of each other, the source UE (e.g. Figure 1 UE3 in the example) can directly communicate with the target UE (e.g. Figure 4Due to the movement of the source UE and / or the target UE, the source UE may not be able to communicate directly with the target UE, and needs to find and search for a U2U relay to relay data between the source UE and the target UE. That is, the communication path between the source UE and the target UE can be switched from a direct path to an indirect path (e.g., via a U2U relay). In addition, the communication path between the source UE and the target UE can be switched from an indirect path to a direct path, or from an indirect path to another indirect path (via another U2U relay).

[0038] This patent document relates to methods, systems and devices for sidelink relay communication. It is necessary to study the support of UE-to-UE relay in CU / DU split architecture, such as PC5 RLC channel configuration and bearer mapping between SLRB and PC5 RLC channel, UE-to-UE relay authorization and path switching support. In addition, it is also necessary to study the service continuity of UE-to-network relay, such as support for direct to indirect path switching between gNBs, lossless delivery during remote UE RRC reestablishment, and the impact of DAPS on U2N path switching.

[0039] I. Embodiment 1: Supporting L2 U2U relay in CU-DU split architecture

[0040] It is expected that L2 U2U relay will be supported in gNB CU-DU split architecture. Signaling exchange between CU and DU can be considered to establish / modify / release PC5 RLC channel for U2U relay UE / remote UE. gNB can consist of gNB-CU and one or more gNB-DUs. gNB-CU and gNB-DU are connected via F1 interface. In some embodiments, one gNB-DU can be connected to only one gNB-CU.

[0041] Figure 2An example diagram of U2U relay communication configuration in a CU-DU split architecture is shown. Specifically, after receiving sidenkUEInformation from a U2U remote / relay UE, the gNB-CU may request the DU to provide the PC5 RLC channel configuration. In the UE context establishment / modification request message, the CU may include any one or more of the SL SRB to be established list, the SL DRB to be established list, and the PC5RLC channel to be established list or to be modified list. For the SL SRB to be established list, it may include any one or more of the SL SRB ID, the SL SRB mapping information. The SL SRB mapping information indicates the mapping between the PC5RLC channel (identified by the PC5 RLC channel ID) and the SL SRB ID of the SL SRB to which the PC5 RLC channel is mapped. The SL DRB to be established list may include SL DRB mapping information indicating the mapping between the PC5 RLC channel (identified by the PC5 RLC channel ID) and the SL DRB ID of the SL DRB to which the PC5 RLC channel is mapped. In some embodiments, the PC5 RLC channel ID in the SLSRB mapping information may be the same as the PC5 RLC channel ID in the SL DRB mapping information.

[0042] The SL SRB / DRB is an end-to-end SL SRB / DRB between a UE and a peer / destination UE (e.g., an end-to-end SL SRB / DRB between a source UE and a destination UE). Thus, for example, the SL SRB / DRB is an end-to-end SLSRB / DRB between a source UE and a target UE. The PC5 RLC channel is between a source UE and a relay UE or between a relay UE and a target UE.

[0043] For a PC5 RLC channel to be established list or to be modified list, it may include a peer UE ID indicating a peer UE, a specific PC5 RLC channel to be established between the UE and the peer UE (e.g., a PC5 RLC channel is to be established between the UE and the opposite UE). In some embodiments, the peer UE may refer to a remote UE (e.g., a source remote UE or a destination / target remote UE). In some embodiments, the peer UE may refer to a relay UE. For example, for the configuration of a U2U remote UE, the peer UE is a U2U relay UE. For the configuration of a U2U relay UE, the peer UE is a source remote UE or a destination remote UE. The peer UE ID may be a UE L2 ID or a UE F1AP ID. If the PC5 RLC channel to be established list or to be modified list is used to transmit end-to-end SL control plane traffic (SL SRB), a control plane traffic type indication may be included to indicate the type of SL SRB transmitted via the PC5 RLC channel (e.g., identified by the SL SRB ID or the priority of the SL SRB). Otherwise, if the PC5 RLC channel is used to transmit end-to-end SL data, the PC5 QoS of the PC5 RLC channel may be included, where PC5 QoS refers to the PC5 QoS parameters specified for sidelink data transmission. For the PDB (Packet Delay Budget) in the PC5 QoS parameters associated with the PC5 RLC channel, it defines the upper limit of the time that a packet can be delayed between the L2 U2U remote UE and the L2 U2U relay UE.

[0044] Considering the path switch between a direct path (a direct PC5 link between a source remote UE and a destination remote UE) and an indirect path (between a source remote UE and a destination remote UE via a U2U relay UE), or a path switch between indirect paths (a change from a U2U relay UE to another U2U relay UE), since the path switch configuration is carried in the cellGroupConfig generated by the gNB-DU, the gNB-CU may provide the gNB-DU with path switch related information, wherein the path switch related information includes any one or more of the following: path switch indication (indicating a direct to indirect or indirect to direct or indirect to indirect path switch), target relay UE ID (indicating a selected target U2U relay UE), peer / destination UE ID (indicating a path used by the selected target relay UE to go to the peer UE), path switch timer. In some embodiments, the path switch related information may be sent by the gNB-CU to the gNB-DU via a UE context establishment / modification request. In some embodiments, the path switch related information may be sent by the gNB-CU to the gNB-DU using another message. A path switching indication may be sent by the gNB to the UE, wherein the path switching indication may indicate to the UE a switch from a direct connection to an indirect connection (direct to indirect path switching indication), or from an indirect connection to a direct connection (indirect to direct path switching indication), or from an indirect connection to another indirect connection (indirect to indirect path switching indication). A direct connection indicates that the source remote UE may communicate with the target remote UE without a relay UE between the two UEs, and an indirect connection indicates that the source remote UE may communicate with the target remote UE via a relay UE between the two UEs.

[0045] II. Example 2: L2U2N relay gNB direct to indirect path switching

[0046] Inter-gNB direct to indirect path handover is supported for L2 U2N relay, where a L2 remote UE connected to a source gNB via a direct Uu link is switched to an indirect path via an L2 U2N relay UE whose serving gNB (target gNB) is different from the source gNB. The target L2U2N relay UE can be selected by either the source gNB or the target gNB.

[0047] Figure 3AAn example diagram of a handover process for U2N path handover is shown. After receiving information of one or more candidate relay UEs (candidate relay UE ID, serving cell ID or new radio cell global identity (NCGI) of the serving cell of the candidate relay UE, PC5 link quality of the candidate relay UE) from an L2 remote UE, the source gNB may decide to handover the remote UE to a U2N relay UE served by another gNB. The source gNB may identify the serving gNB of the candidate relay UE through the serving cell information of the candidate relay UE reported by the remote UE. The source gNB sends a handover request message to the serving gNB of the selected relay UE, which may include the remote UE information and the selected target relay UE information. Since the source gNB does not know the RRC state of the candidate relay UE when selecting the target relay UE, it may provide the remote UE capability of handover to the gNB of the target relay UE for the gNB of the target relay UE to decide whether to accept the handover request. Therefore, the remote UE information may include the remote UE capability of handover to the RRC idle / inactive relay UE. Alternatively, the remote UE capabilities for handover to RRC idle / inactive relay UE may be included in the sidelinkUEInformation in the RRC context in the handover request message. After receiving the handover request message, if the gNB of the target relay UE identifies that the target relay UE is in RRC inactive / idle state, and if the remote UE capabilities indicate that handover to RRC idle / inactive relay UE is not supported (or there is no UE capability supporting handover to RRC idle / inactive relay UE in the handover request), the gNB of the target relay UE may reject the handover request.

[0048] Figure 3B Another example diagram of the switching process for U2N path switching is shown. In another case, such as Figure 3B As shown, after receiving the report from the remote UE, if the source gNB identifies the existence of a remote UE that is provided by the same gNB ( Figure 3B If there are multiple candidate relay UEs served by gNB2 (e.g., target gNB) as shown, the source gNB may include information of multiple candidate relay UEs (served by gNB2 (e.g., target gNB)) (e.g., candidate relay UE ID, serving cell ID or NCGI of serving cell of candidate relay UE, PC5 link quality of candidate relay UE) and capability of remote UE in the handover request message sent to gNB2. And gNB2 may select target relay UE from these candidate relay UEs and include target relay UE ID in the handover response message sent to the source gNB.

[0049] Fig.11An inter-gNB direct to indirect path handover with DAPS configured for U2N relay is shown. If the target gNB2 has DAPS configured for the remote UE's DRB(s), the UL / DL transmission can continue in the original path until it is released by an explicit indication from the target node. In tradition, the UE sends UL data to the source gNB until the random access procedure to the target gNB is successfully completed. Afterwards, the UE switches its UL data transmission to the target gNB.

[0050] However, in the case of U2N relay, when the remote UE performs a path switch to an indirect / relay path, there is no random access procedure to the target gNB. Instead, after receiving the RRC reconfiguration with the path switch configuration from the source gNB (step 3), the remote UE initiates a PC5 unicast link establishment with the target relay UE as indicated in the path switch configuration (between steps 3 and 5, which are not drawn in the figure below). The remote UE then issues an RRC reconfiguration complete message to the relay UE via the PC5 RLC channel, and the relay UE forwards the message to gNB2 via the Uu RLC channel. When the relay UE successfully receives the RRC reconfiguration complete message from the remote UE, the relay UE may issue an RLC acknowledgment to the remote UE. After receiving the RLC acknowledgment of the RRC reconfiguration complete message from the relay UE, the remote UE may switch its UL data transmission to the relay / indirect link. Alternatively, if the remote UE determines that the path switch timer T420 (configured in the path switch configuration) has stopped, the remote UE switches its UL data transmission to the relay / indirect link. When the remote UE receives the path switch configuration included in the RRC reconfiguration message, the path switch timer T420 is started.

[0051] When the target gNB2 receives the RRC Reconfiguration Complete message from the remote UE, it sends a HO Success message to the source gNB1 to inform gNB1 that the remote UE has been successfully handed over to gNB2.

[0052] III. Example 3: Remote UE RRC Reestablishment Due to Relay UE Handover

[0053] When a U2N relay UE performs a Uu handover (e.g., receives reconfigurationWithSync in RRC reconfiguration), it may issue a PC5-S release message or a PC5 notification message indicating Uu handover (HO) to its (multiple) connected remote UEs. Upon receiving a PC5 notification message indicating Uu HO, the RRC connected remote UE may choose to maintain the PC5 connection with the current relay UE and initiate RRC reestablishment to the target gNB of the relay UE.

[0054] When the relay UE receives the HO command, it can stop forwarding the remote UE's UL data to gNB1. Then, when the relay UE switches to gNB2, its buffer can store some remote UE packets, 1) which have been confirmed by the remote UE but have not yet been sent to gNB1 (e.g., packet 4), 2) which have been sent to gNB1 but have not yet received RLC confirmation from gNB1 (e.g., packet 2). In the traditional (or current technology), after the remote UE completes the RRC reestablishment with gNB2, the source gNB1 can forward the buffered remote UE data to gNB2 (packets 1, 3), while the buffered remote UE data at the relay UE (packets 2, 4) may be lost from gNB2.

[0055] To ensure lossless delivery of the remote UE’s UL data, after the remote UE completes RRC re-establishment with gNB2 via the relay UE, the relay UE may continue to forward the buffered remote UE UL data to gNB2.

[0056] Figure 4 An example diagram showing data transmission during relay UE handover.

[0057] Specifically, after the relay UE completes the RAN handover (e.g., sends an RRC reconfiguration complete message to the target gNB2), the relay UE may forward the RRC reestablishment request message of the remote UE to the target gNB2. When gNB2 sends an RRC reestablishment message to the remote UE or receives an RRC reestablishment complete message from the remote UE, gNB2 may send an RRC reconfiguration to the relay UE using the Uu RLC channel configuration so that the relay UE forwards the data of the remote UE. Specifically, the RRC reconfiguration message may include any one or more of the following: remote UE L2 ID, remote UE local ID, Uu RLC channel configuration, PC5 RLC channel configuration, bearer mapping (between remote UE Uu SRB / DRB and relay UE Uu / PC5 RLC channel), data forwarding indication (instructing the relay UE to forward the buffered remote UE data to gNB2 via the configured UuRLC channel).

[0058] Figure 5 An example diagram showing remote UE RRC re-establishment.

[0059] After receiving the configuration from gNB2, the relay UE may retransmit / send the first packet in the original link that was not successfully acknowledged by the lower layer / RLC (e.g., from packet 2) to gNB2 via the configured Uu RLC channel and exclude packets that have been successfully acknowledged by the lower layer (e.g., exclude packet 3). In addition, when such buffered data is sent to gNB2 and / or before new data is received from the remote UE, the relay UE may issue an end marker to gNB2. (For example, the end marker is issued after packet 4 and before packet 5.)

[0060] If the local ID of the remote UE is updated in the RRC reconfiguration that the relay UE receives from gNB2, for example, gNB2 assigns a new local ID to the remote UE that is different from the local ID assigned by gNB1 (for example, after gNB2 obtains the context information of the remote UE from gNB1, it finds that the local ID of the remote UE assigned by gNB1 conflicts with the local ID of another remote UE assigned to gNB2. As a result, gNB2 reallocates the local ID of the remote UE), there may be a gap regarding the local ID of the remote UE when forwarding the data of the remote UE. There are two ways to solve this problem.

[0061] -Option 1: The relay UE repacks the packets with a SRAP header containing a new local ID before forwarding the packets. Specifically, the SRAP header of the buffered remote UE's packet contains the original local ID assigned by gNB1. If the local ID is updated, the relay UE can remove the original SRAP header and rebuild the SRAP header with the new local ID and the corresponding bearer ID.

[0062] -Option 2: gNB2-based implementation. The relay UE forwards the buffered remote UE’s packets with the original local ID in the SRAP header. After receiving them, the gNB2 identifies the data belonging to the remote UE based on the mapping of the original local ID and the new local ID.

[0063] In order for gNB2 to correctly parse the data forwarded by the relay UE, gNB1 may send its security keys (e.g., gNB1's gNB keys, keys for user data) to gNB2. And, gNB2 uses the keys from gNB1 to parse the data forwarded by the relay UE. Alternatively, gNB2 may send the data forwarded by the relay UE to gNB1, and gNB1 parses the data and sends the parsed PDCP PDU to gNB2.

[0064] IV. Example 4: Impact of DAPS on U2N Path Switching

[0065] During the L2 U2N relay path switching process, DAPS can be configured for the remote UE and the impact of DAPS can be considered.

[0066] In legacy HO, for DRBs configured with DAPS, UL / DL transmission may continue in the original path until it is released by an explicit indication from the target node. The source gNB issues an EARLY STATUS TRANSFER message to the target gNB. The DL COUNT value transmitted in the EARLY STATUS TRANSFER message indicates the PDCP SN and HFN of the first PDCP SDU forwarded by the source gNB to the target gNB. The source gNB may additionally issue (multiple) EARLY STATUS TRANSFER messages including a DISCARD DL COUNT value to notify the discarding of the forwarded PDCP SDUs. The target gNB does not send the forwarded downlink PDCP SDUs to UEs whose COUNT is less than the transferred DL COUNT value, and discards them.

[0067] Figure 6 An example diagram of inter-gNB indirect to direct path handover with DAPS configured for U2N relay is shown.

[0068] When it comes to L2 U2N inter-relay gNB indirect to direct path handover, if DAPS is configured for the remote UE (in step 3), in order for the original indirect link (remote UE <-> relay UE <-> gNB1) to continue to serve the remote UE, the indirect / relay link can be maintained at least until the remote UE successfully accesses the target gNB. That is, after receiving the handover success message from the target gNB (step 8), the RRC reconfiguration of the relay UE (step 10) can be performed to release the remote UE related configuration.

[0069] In the traditional, the source gNB determines the discarded DL count value in the early state transfer message based on the lower layer / RLC acknowledgment. However, in the case of U2N relay path handover, in the original indirect link, the RLC acknowledgment from the relay UE is not equal to the reception status of the remote UE, for example, there may be some DL packets of the remote UE buffered at the relay UE and may be lost. To ensure service continuity and lossless delivery:

[0070] - Option 1: The source gNB determines the discard DL count value based on the reception status of the remote UE (e.g., indicated by a PDCP status report or a relay UE). The reception status of the remote UE may be indicated by the relay UE, e.g., the relay UE issues a PDCP SN that is successfully acknowledged by the remote UE (based on a PC5 RLC acknowledgement from the remote UE).

[0071] - Option 2: After receiving the discard DL count value from gNB1, gNB2 does not discard packets immediately. Instead, after receiving the PDCP status report from the remote UE, gNB2 determines whether to discard packets without resending them.

[0072] In option 1, the source gNB may not be able to obtain the remote UE’s reception status as fast as the relay UE’s RLC ACK update, which may result in repeated transmission of some unnecessary resend packets at gNB2.

[0073] V. Example 5: U2U Authorization

[0074] To support L2 / L3 UE to UE relay communication, the gNB may provide SL configuration for RRC connected U2U relay / remote UE. Before providing SL configuration, the gNB may check whether the UE is authorized to act as an L2 / L3 U2U relay UE or a remote UE, or whether the UE is authorized to use L2 / L3 U2U relay services / communications. For UE authorization check at the gNB, the core network (e.g., access and mobility management function (AMF)) may provide UE authorization information to the gNB. In addition, during handover, the source gNB may provide UE authorization information to the target gNB, or the AMF may provide UE authorization to the target gNB. In the gNB-CU / DU split architecture, since the SL resources are configured as gNB-DU, the gNB-CU may provide UE authorization information to the gNB-DU. UE authorization may include any one or more of the following: U2U relay (indicating whether the UE is authorized to be used for / act as a U2U relay), U2U remote UE (indicating whether the UE is authorized to be used for / act as a U2U remote UE), L2 U2U relay (indicating whether the UE is authorized to be used for / act as a L2 U2U relay), L3U2U relay (indicating whether the UE is authorized to be used for / act as a L3 U2U relay), L2 U2U remote UE (indicating whether the UE is authorized to be used for / act as a L2 U2U remote UE), L3 U2U remote UE (indicating whether the UE is authorized to be used for / act as a L3 U2U remote UE).

[0075] Figure 7 1 shows an exemplary block diagram of a hardware platform 700, which may be part of a network device (e.g., a base station) or a communication device (e.g., a user equipment (UE)). The hardware platform 700 includes at least one processor 710 and a memory 705 on which instructions are stored. The instructions, when executed by the processor 710, configure the hardware platform 700 to perform Figures 1 to 6 and Figures 8 to 13 The operations described in the various embodiments described in and throughout this patent document. Transmitter 715 sends or issues information or data to another device. For example, a network device transmitter can issue a message to a user device. Receiver 720 receives information or data sent or issued by another device. For example, a user device can receive a message from a network device.

[0076] The implementation described above will be applied to wireless communications. Figure 8An example of a wireless communication system (e.g., a 5G or NR cellular network) including a base station 820 and one or more user equipments (UEs) 811, 812, and 813 is shown. In some embodiments, the UE uses a communication link to the network (sometimes referred to as an uplink direction, as shown by dashed arrows 831, 832, 833) to access the BS (e.g., the network), which then enables subsequent communication from the BS to the UE (e.g., shown in the direction from the network to the UE, sometimes referred to as a downlink direction, as shown by arrows 841, 842, 843). In some embodiments, the BS sends information to the UE (sometimes referred to as a downlink direction, as shown by arrows 841, 842, 843), which then enables subsequent communication from the UE to the BS (e.g., the direction from the UE to the BS, sometimes referred to as an uplink direction, as shown by dashed arrows 831, 832, 833). The UE can be, for example, a smart phone, a tablet computer, a mobile computer, a machine-to-machine (M2M) device, an Internet of Things (IoT) device, etc.

[0077] Fig. 9 An exemplary flow chart for facilitating sidelink wireless communications is shown. Operation 902 includes receiving, by a first network function of a network device, a request message associated with a first communication device from a second network function of the network device, wherein the request message includes information of a channel to be established or modified, and wherein the information includes a second communication device identifier indicating the second communication device, the first communication device being configured to establish or modify a channel to the second communication device. Operation 904 includes sending, by the first network function, a response message to the second network function in response to receiving the request message.

[0078] Fig.10 Another exemplary flow chart for facilitating sidelink wireless communications is shown. Operation 1002 includes sending, by a second network function of a network device, a request message to a first network function of the network device, the request message including information of a channel to be established or modified, wherein the information includes a second communication device identifier indicating a second communication device, the first communication device being configured to establish or modify a channel to the second communication device. Operation 1004 includes receiving, by the second network function, a response message from the first network function in response to sending the request message.

[0079] In some embodiments, the information includes a control plane service type, which indicates that the type of service transmitted through the channel is a control plane service, wherein the control plane service type includes an identifier of a sidelink (SL) signaling radio bearer or a priority of the SL signaling radio bearer. In some embodiments, the first communication device includes a source communication device, the request message includes a list of sidelink (SL) radio bearers to be established or a list to be modified for establishing or modifying communication between the source communication device, the relay communication device, and the target communication device, the source communication device is configured to communicate with the target communication device via the relay communication device, the list of SL radio bearers to be established or the list to be modified includes any one or more of the following items: an identifier associated with the SL radio bearer between the source communication device and the target communication device, and mapping information indicating a mapping between an identifier of the SL radio bearer and a channel identifier of the channel. In some embodiments, the SL radio bearer includes a SL signaling radio bearer (SRB) or a SL data radio bearer (DRB).

[0080] In some embodiments, the first network function receives path switching related information from the second network function or the second network function sends path switching related information to the first network function, and the path switching related information includes one or more of the following: a path switching indication indicating that the communication device performs a path switching, or a type of path switching, and the type of path switching includes a direct to indirect path switching, an indirect to direct path switching, or an indirect to indirect path switching. In some embodiments, the first communication device includes a source communication device, and the first network function receives path switching related information from the second network function or the second network function sends path switching related information to the first network function, and the path switching related information includes: an identifier of a relay communication device, an identifier of a target communication device, and the identifier of the target communication device indicates that the source communication device is configured to communicate to a destination via the relay communication device. In some embodiments, the first communication device includes a source communication device or a target communication device, and wherein the second communication device includes a relay communication device.

[0081] In some embodiments, the first communication device comprises a relay communication device, and wherein the second communication device comprises a source communication device or a target communication device. In some implementations, the method further comprises receiving, by the second network function, authorization information from an access and mobility management function (AMF) of a core network. In some embodiments, the method further comprises sending, by the second network function, authorization information to the first network function or another base station. In some embodiments, the authorization information comprises any one or more of the following: U2U relay, U2U remote UE, L2 U2U relay, L3 U2U relay, L2 U2U remote UE, or L3 U2U remote UE. In some embodiments, the request message comprises a UE context establishment request or a modification request message, the first network function comprises a distributed unit in a base station, the second network function comprises a centralized unit in a base station, and / or the channel comprises a PC5 radio link control (RLC) channel.

[0082] Fig.12 An exemplary flow chart for facilitating handover is shown. Operation 1202 includes sending, by a first network device, a handover request message to a second network device, the handover request message triggering handover of a remote communication device from the first network device to the second network device, wherein after the handover, the remote communication device is configured to perform communication with the second network device via a relay communication device. Operation 1204 includes receiving, by the first network device, a response message from the second network device.

[0083] In some embodiments, the handover request message includes the remote communication device capability of the remote communication device to switch to the relay communication device in an idle state or an inactive state. In some embodiments, the second network device is configured to serve a plurality of candidate relay communication devices including the relay communication device, and for each candidate relay communication device in the plurality of candidate relay communication devices, the handover request message includes any one or more of the following: an identifier of the candidate relay communication device, an identifier of a serving cell of the candidate relay communication device, or a link quality between the candidate relay communication device and the remote communication device. In some embodiments, the second network device is configured to select the relay communication device from the plurality of candidate relay communication devices, and the response message includes the identifier of the relay communication device.

[0084] Fig.13 An exemplary flow chart for performing uplink transmission is shown. Operation 1302 includes receiving, by a remote communication device, a radio resource control (RRC) reconfiguration message including path switch related information from a source base station. Operation 1304 includes performing, by the remote communication device, uplink data transmission to a target base station via a relay communication device, wherein the uplink data transmission is performed by switching communication from the source base station to the relay communication device, the remote communication device being configured to communicate with the target base station via the relay communication device.

[0085] In some embodiments, the method further comprises, in response to receiving the RRC reconfiguration message, sending an RRC reconfiguration complete message to the relay communication device, wherein the uplink data transmission is performed in response to the remote communication device receiving a confirmation message, the confirmation message indicating that the RRC reconfiguration complete message is received by the relay communication device. In some embodiments, the uplink data transmission is performed in response to the expiration of a timer configured by the path switch related information, and the timer is started when the remote communication device receives the path switch related information included in the RRC reconfiguration message.

[0086] In this document, the term "exemplary" is used to mean "an example of," and not to indicate an ideal or preferred embodiment unless otherwise stated.

[0087] Some of the embodiments described herein are described in the general context of methods or processes, which in one embodiment can be implemented by a computer program product embodied in a computer-readable medium, which includes computer-executable instructions, such as program code, executed by a computer in a networked environment. Computer-readable media may include removable and non-removable storage devices, including but not limited to read-only memory (ROM), random access memory (RAM), compact disk (CD), digital versatile disk (DVD), etc. Therefore, computer-readable media may include non-transitory storage media. Typically, program modules may include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. Computer or processor executable instructions, associated data structures, and program modules represent examples of program codes for executing the steps of the methods disclosed herein. A specific sequence of such executable instructions or associated data structures represents an example of corresponding actions for implementing the functions described in such steps or processes.

[0088] Some of the disclosed embodiments may be implemented as devices or modules using hardware circuits, software, or a combination thereof. For example, a hardware circuit implementation may include discrete analog and / or digital components that are, for example, integrated as parts of a printed circuit board. Alternatively or additionally, the disclosed components or modules may be implemented as application specific integrated circuits (ASICs) and / or field programmable gate arrays (FPGAs) devices. Some implementations may additionally or alternatively include a digital signal processor (DSP), which is a dedicated microprocessor with an architecture optimized for the operational requirements of digital signal processing associated with the disclosed functions of the present application. Similarly, various components or subcomponents within each module may be implemented with software, hardware, or firmware. The connection between the modules and / or components within the modules may be provided using any of the connection methods and media known in the art, including but not limited to communications using appropriate protocols over the Internet, wired, or wireless networks.

[0089] Although this document contains a lot of details, these details should not be interpreted as limitations on the scope of the claimed invention or the content that can be claimed, but rather as descriptions of the features of a particular embodiment. Certain features described in this document in the context of a separate embodiment may also be implemented in combination in a single embodiment. On the contrary, the various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments. In addition, although features may be described above as working in certain combinations, and even initially claimed as such, in some cases, one or more features from the claimed combination may be deleted from the combination, and the claimed combination may involve a sub-combination or a variation of a sub-combination. Similarly, although operations are described in a particular order in the accompanying drawings, this should not be understood as requiring such operations to be performed in the particular order shown or in sequence or requiring all the operations shown to be performed to obtain the desired result.

[0090] Only a few implementations and examples are described, and other implementations, enhancements, and variations may be made based on what is described and illustrated in this disclosure.

Claims

1. A wireless communication method, comprising: receiving, by a first network function of a network device, a request message related to a first communication device from a second network function of the network device, wherein the request message includes information of the channel to be established or modified, and wherein the information includes a second communication device identifier indicating a second communication device, the first communication device being configured to establish or modify the channel to the second communication device; as well as A response message is sent by the first network function to the second network function in response to receiving the request message.

2. A wireless communication method, comprising: A second network function of a network device sends a request message to a first network function of the network device, wherein the request message includes information of a channel to be established or modified. wherein the information includes a second communication device identifier indicating a second communication device, and the first communication device is configured to establish or modify the channel to the second communication device; as well as A response message is received by the second network function from the first network function in response to sending the request message.

3. A method according to any one of claims 1 or 2, wherein the information includes a control plane service type, the control plane service type indicating that the type of service transmitted through the channel is a control plane service, wherein the control plane service type includes an identifier of a sidelink (SL) signaling radio bearer or a priority of the SL signaling radio bearer.

4. The method according to any one of claims 1 or 2, wherein the first communication device comprises a source communication device, The request message includes: a list of sidelink (SL) radio bearers to be established or modified for establishing or modifying communication between the source communication device, the relay communication device and the target communication device, wherein the source communication device is configured to communicate with the target communication device via the relay communication device, The SL radio bearer to be established list or to be modified list includes any one or more of the following items: an identifier associated with a SL radio bearer between the source communication device and the target communication device, and Mapping information indicating the mapping between the identifier of the SL radio bearer and the channel identifier of the channel.

5. The method according to claim 4, wherein the SL radio bearer comprises a SL signaling radio bearer (SRB) or a SL data radio bearer (DRB).

6. The method according to any one of claims 1 or 2, wherein the first network function receives path switching related information from the second network function, or the second network function sends path switching related information to the first network function, and the path switching related information includes one or more of the following: A path switching instruction instructs the communication device to perform a path switching, or The type of path switching includes direct to indirect path switching, indirect to direct path switching, or indirect to indirect path switching.

7. The method according to any one of claims 1 or 2, wherein the first communication device comprises a source communication device, The first network function receives path switching related information from the second network function, or the second network function sends path switching related information to the first network function, and the path switching related information includes: An identifier of a relay communication device, an identifier of a target communication device, the identifier of the target communication device indicating a destination to which the source communication device is configured to communicate via the relay communication device.

8. The method according to any one of claims 1 or 2, wherein the first communication device comprises a source communication device or a target communication device, and wherein the second communication device comprises a relay communication device.

9. The method according to any one of claims 1 or 2, wherein the first communication device comprises a relay communication device, and wherein the second communication device comprises a source communication device or a target communication device.

10. The method according to claim 2, further comprising: The second network function receives authorization information from an access and mobility management function (AMF) of the core network.

11. The method according to claim 10, further comprising: The authorization information is sent by the second network function to the first network function or to another base station.

12. The method according to any one of claims 10 or 11, wherein the authorization information comprises any one or more of the following: U2U relay, U2U remote UE, L2 U2U relay, L3 U2U relay, L2 U2U remote UE, or L3 U2U remote UE.

13. The method according to any one of claims 1 to 12, The request message includes a UE context establishment request or a modification request message, wherein the first network function comprises a distributed unit in a base station, wherein the second network function comprises a centralized unit in the base station, and / or The channels include PC5 Radio Link Control (RLC) channels.

14. A wireless communication method, comprising: A first network device sends a switching request message to a second network device, wherein the switching request message triggers a switching of a remote communication device from the first network device to the second network device. wherein after the switching, the remote communication device is configured to perform communication with the second network device via a relay communication device; as well as A response message is received by the first network device from the second network device.

15. The method according to claim 14, wherein the handover request message comprises: The remote communication device switches to the remote communication device capability of the relay communication device in an idle state or an inactive state.

16. The method according to claim 14, wherein the second network device is configured to serve a plurality of candidate relay communication devices including the relay communication device, and For each candidate relay communication device among the multiple candidate relay communication devices, the handover request message includes any one or more of the following items: an identifier of a candidate relay communication device, an identifier of a serving cell of the candidate relay communication device, or The link quality between the candidate relay communication device and the remote communication device.

17. The method according to any one of claims 14 or 16, wherein the second network device is configured to select the relay communication device from the plurality of candidate relay communication devices, and The response message includes an identifier of the relay communication device.

18. A wireless communication method, comprising: receiving, by the remote communication device from the source base station, a radio resource control (RRC) reconfiguration message including path switch related information; as well as performing, by the remote communication device, uplink data transmission to a target base station via a relay communication device, Wherein the uplink data transmission is performed by switching the communication from the source base station to the relay communication device, and the remote communication device is configured to communicate with the target base station through the relay communication device.

19. The method according to claim 18, further comprising: In response to receiving the RRC reconfiguration message, sending an RRC reconfiguration complete message to the relay communication device, The uplink data transmission is performed in response to the remote communication device receiving a confirmation message, the confirmation message indicating that the RRC reconfiguration complete message is received by the relay communication device.

20. The method according to claim 18, wherein the uplink data transmission is performed in response to expiration of a timer configured by the path switch related information, and the timer is started when the remote communication device receives the path switch related information included in an RRC reconfiguration message.

21. An apparatus for wireless communication, comprising a processor configured to implement the method according to one or more of claims 1 to 20.

22. A non-transitory computer-readable program storage medium having codes stored thereon, which, when executed by a processor, cause the processor to implement the method according to one or more of claims 1 to 20.

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