User Equipment and Method for Sidelink Failure Management

Abstract

The present invention provides a user equipment (UE) and a method for sidelink failure management. The method includes: receiving a first message from a source cell, the first message including sidelink radio resource control (RRC) configuration associated with a target cell; determining that a sidelink failure event associated with an associated sidelink destination UE has occurred; and after performing a handover procedure to hand over from the source cell to the target cell, sending a sidelink failure report indicating the sidelink failure event to the target cell.

Description

[0001] Cross - Reference to Related Applications

[0002] This disclosure claims the benefit and priority of U.S. Provisional Patent Application Ser. No. 63 / 008,566, filed Apr. 10, 2020, entitled “Sidelink Access Stratum Configuration Failure Management” (hereinafter referred to as the “’566 provisional application”). The disclosure of the ’566 provisional application is hereby incorporated by reference in its entirety into this disclosure. Technical Field

[0003] This disclosure relates to wireless communication, and in particular, to methods for sidelink failure management in a cellular wireless communication network. Background Art

[0004] Abbreviations used in this disclosure include:

[0005]

[0006]

[0007]

[0008]

[0009] Various efforts have been made to improve different aspects of wireless communication for cellular wireless communication systems such as the Fifth Generation New Radio (5G NR) by improving data rate, latency, reliability, and mobility. The 5G NR system is designed to provide flexibility and configurability to optimize network services and types to accommodate various use cases such as enhanced Mobile Broadband (eMBB), massive Machine - Type Communication (mMTC), and Ultra - Reliable and Low - Latency Communication (URLLC). However, as the demand for radio access continues to increase, further improvements in the art are needed. th This disclosure relates to methods performed by a UE in cellular wireless communication for sidelink failure management. Summary of the Invention

[0010]

[0011] ​According to one aspect of the present disclosure, there is provided a user equipment (UE) for sidelink failure management, the UE including a processor and a memory coupled to the processor, wherein the memory stores a computer-executable program which, when executed by the processor, causes the processor to: receive a first message from a source cell including sidelink RRC configuration associated with a target cell; determine that a sidelink failure event associated with the associated sidelink destination UE has occurred; and after executing a handover procedure to hand over from the source cell to the target cell, send a sidelink failure report indicating the sidelink failure event to the target cell.

[0012] According to another aspect of the present disclosure, there is provided a method for sidelink failure management performed by a UE, the method including: receiving a first message from a source cell including sidelink RRC configuration associated with a target cell; determining that a sidelink failure event associated with the associated sidelink destination UE has occurred; and after executing a handover procedure to hand over from the source cell to the target cell, sending a sidelink failure report indicating the sidelink failure event to the target cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Aspects of the present disclosure may be best understood when read in conjunction with the following drawings. The various features are not drawn to scale. For purposes of discussion, the dimensions of various features may be increased or decreased arbitrarily.

[0014] Figure 1 A sidelink operation scenario within a cell is illustrated according to an embodiment of the present disclosure.

[0015] Figure 2 A V2X queuing scenario is illustrated according to an embodiment of the present disclosure.

[0016] Figure 3 A PC5-RRC connection between a pair of UEs is illustrated according to an embodiment of the present disclosure.

[0017] Figure 4A A procedure for obtaining sidelink AS configuration through PC5-RRC signaling is illustrated according to an embodiment of the present disclosure.

[0018] Figure 4B A procedure for handling a sidelink AS configuration failure event is illustrated according to an embodiment of the present disclosure.

[0019] Figure 5A A signal flow for a full sidelink reset is illustrated according to an embodiment of the present disclosure.

[0020] Figure 5B A signal flow for a full sidelink reset is illustrated according to another embodiment of the present disclosure.

[0021] Figure 5C Another embodiment according to the present disclosure shows the signal flow of a sidelink full reset.

[0022] Figure 6 Another embodiment according to the present disclosure shows the process for handling a sidelink failure event.

[0023] Figure 7 An embodiment according to the present disclosure shows a method for sidelink failure management performed by a UE.

[0024] Figure 8 Another embodiment according to the present disclosure shows a method for sidelink failure management performed by a UE.

[0025] Figure 9A An embodiment according to the present disclosure shows a procedure for initiating an RRC reconstruction procedure to report a sidelink AS configuration failure event.

[0026] Figure 9B An embodiment according to the present disclosure shows a procedure for sending a sidelink AS configuration failure report to the serving RAN.

[0027] Figure 10 is a block diagram showing a node for wireless communication according to an embodiment of the present disclosure. Detailed Description

[0028] The following description includes specific information related to embodiments of the present disclosure. The accompanying drawings and their detailed descriptions are only for embodiments. However, the present disclosure is not limited to these embodiments. Other variations and embodiments of the present disclosure will be apparent to those skilled in the art.

[0029] Unless otherwise indicated, similar or corresponding components in the drawings may be indicated by similar or corresponding reference numerals. In addition, the drawings and diagrams in the present disclosure are generally not drawn to scale and are not intended to correspond to actual relative sizes.

[0030] For the purposes of consistency and ease of understanding, in the drawings, similar features are identified by the same reference numerals (although not shown in some examples). However, the features in different embodiments may differ in other respects and should not be narrowly limited to what is shown in the drawings.

[0031] The phrases "in one embodiment" or "in some embodiments" may refer to one or more of the same or different embodiments. The term "coupled" is defined as connected, whether directly or indirectly through intervening components, and is not necessarily limited to physical connections. The term "comprising" means "including but not necessarily limited to" and specifically indicates an open inclusion relationship or subordination relationship in the disclosed combinations, groups, series, or equivalents. The expression "at least one of A, B, and C" or "at least one of the following: A, B, and C" means "only A, or only B, or only C, or any combination of A, B, and C".

[0032] The terms "system" and "network" may be used interchangeably herein. The term "and / or" is used herein only to describe the association relationship of related objects and indicates that three relationships may exist. For example, A and / or B may indicate: A exists alone, A and B exist simultaneously, or B exists alone. The character " / " generally indicates that the related objects are in an "or" relationship.

[0033] For purposes of explanation and not limitation, specific details (such as functional entities, technologies, protocols, standards, etc.) are set forth to provide an understanding of the disclosed technology. In other instances, detailed descriptions of well-known methods, technologies, systems, architectures, etc. are omitted so as not to obscure the description with unnecessary details.

[0034] Those skilled in the art will immediately recognize that any one or more of the network functions or algorithms described in the present disclosure may be implemented by hardware, software, or a combination of software and hardware. The disclosed functions may correspond to modules, which may be software, hardware, firmware, or any combination thereof.

[0035] Software embodiments may include computer-executable instructions stored on a computer-readable medium such as a memory or other type of storage device. One or more microprocessors or general-purpose computers with communication processing capabilities may be programmed with corresponding executable instructions and execute one or more of the disclosed network functions or algorithms.

[0036] A microprocessor or general-purpose computer may include application specific integrated circuitry (ASIC), programmable logic arrays, and / or use one or more digital signal processors (DSP). Although some of the embodiments of the present disclosure are directed to software installed and executed on computer hardware, alternative exemplary embodiments implemented as firmware or hardware or a combination of hardware and software are well within the scope of the present disclosure. Computer-readable media includes, but is not limited to, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, compact disc read-only memory (CD-ROM), cassette tapes, magnetic tapes, disk storage devices, or any other equivalent medium capable of storing computer-readable instructions.

[0037] A radio communication network architecture (such as: Long Term Evolution (LTE) system, LTE-Advanced (LTE-A) system, LTE Pro system or 5G New Radio (NR) Radio Access Network (RAN)) generally includes at least one base station (BS), at least one user equipment (UE), and one or more optional network components that provide connections within the network. The UE may communicate with a network (such as: Core Network (CN), Evolved Packet Core (EPC) network, Evolved Universal Terrestrial Radio Access Network (E-UTRAN), 5G Core (5GC) or the Internet) through a RAN established by one or more BSs.

[0038] The UE may include, but is not limited to, a mobile station, a mobile terminal or device, a user communication radio terminal. For example, the UE may be a portable radio device, which includes, but is not limited to, a mobile phone with wireless communication capabilities, a tablet computer, a wearable device, a sensor, a vehicle, or a personal digital assistant (PDA). The UE is configured to receive signals via an air interface and transmit signals to one or more cells in the RAN.

[0039] The BS may be configured to provide communication services according to at least one of radio access technologies (RATs) such as: Worldwide Interoperability for Microwave Access (WiMAX), Global System for Mobile communications (GSM, commonly referred to as 2G), GSM Enhanced Data rates for GSM Evolution (EDGE) Radio Access Network (GERAN), General Packet Radio Service (GPRS), Universal Mobile Telecommunication System (UMTS) based on Wideband-Code Division Multiple Access (W-CDMA, commonly referred to as 3G), High-Speed Packet Access (HSPA), LTE, LTE-A, evolved LTE (eLTE) connecting LTE to 5GC, NR (commonly referred to as 5G), and / or LTE-A Pro. However, the scope of the present disclosure should not be limited to the protocols mentioned above.

[0040] The BS may include, but is not limited to, a Node B (NB) in UMTS, an evolved Node B (eNB) in LTE or LTE-A, a Radio Network Controller (RNC) in UMTS, a Base Station Controller (BSC) in GSM / GERAN, a next-generation eNB (ng-eNB) in an E-UTRA BS connected to the 5GC, a next-generation Node B (gNB) in 5G-RAN, and any other device capable of controlling radio communication and managing radio resources within a cell. The BS may serve one or more UEs via one or more radio interfaces.

[0041] The BS is operable to use multiple cells included in the RAN to provide radio coverage to a specific geographical area. The BS may support the operation of the cells. Each cell is operable to serve at least one UE within its radio coverage area.

[0042] Each cell (commonly referred to as a serving cell) provides service to serve one or more UEs within its radio coverage area such that each cell schedules downlink (DL) and optionally uplink (UL) resources to at least one UE within its radio coverage area for DL and optionally UL packet transmission. The BS may communicate with one or more UEs in the radio communication system via multiple cells.

[0043] The cell may allocate sidelink (SL) resources to support Proximity Services (ProSe) (e.g., (ProSe) direct communication service and (ProSe) direct discovery service) or vehicle-to-everything (V2X) services (e.g., E-UTRA V2X sidelink communication service) or sidelink services (e.g., NR sidelink communication service). Each cell may have a coverage area that overlaps with other cells.

[0044] As discussed above, the frame structure of NR is designed to support flexible configuration to meet various next-generation (e.g., 5G) communication requirements, such as enhanced Mobile Broadband (eMBB), massive Machine Type Communication (mMTC), and Ultra-Reliable and Low-Latency Communication (URLLC), while satisfying high reliability, high data rate, and low latency requirements. The Orthogonal Frequency-Division Multiplexing (OFDM) technology agreed upon in the 3rd Generation Partnership Project (3GPP) can be used as a benchmark for the NR waveform. Scalable OFDM parameter sets, such as adaptive subcarrier spacing, channel bandwidth, and Cyclic Prefix (CP), can also be used.

[0045] Two coding schemes are considered for NR: specifically, the Low-Density Parity-Check (LDPC) code and the polar code. The coding scheme adaptation can be configured based on channel conditions and / or service applications.

[0046] At least DL transmission data, guard period, and UL transmission data should be included within the transmission time interval (TTI) of a single NR frame. Each part of the DL transmission data, guard period, and UL transmission data should be configured based on, for example, the NR network dynamics. Sidelink resources can also be provided in the NR frame to support ProSe services or V2X services (e.g., E-UTRA V2X sidelink communication services) or sidelink services (e.g., NR sidelink communication services). Conversely, sidelink resources can also be provided in the E-UTRA frame to support ProSe services or V2X services (e.g., E-UTRA V2X sidelink communication services) or sidelink services (e.g., NR sidelink communication services).

[0047] V2X Services and PC5 Interface

[0048] V2X (Vehicle-to-Everything) services are provided to support information exchange between vehicles. In the LTE protocol, V2X services can be supported over the air interface via the Uu interface and the PC5 interface. The PC5 interface covers the designs in layer 2 and layer 1. The air interface on the PC5 interface is also referred to as the sidelink in the LTE protocol. LTE networks have supported sidelink operations since Release 12.

[0049] Figure 1 According to an embodiment of the present disclosure, a scenario 100 of in-cell sidelink operation is shown. Through sidelink (SL) operation, UEs 106, 108, 110, 112, 114, and 116 within the radio coverage 104 of the BS 102 can directly exchange data and control signaling without the relay of the BS 102. The BS 102 may be an eNB in an LTE network or a gNB in an NR network. For ease of description, all UEs in the present disclosure can and are authorized to access V2X services and the PC5 interface with adjacent UEs and the RAN.

[0050] V2X services can be further classified based on different transfer types in the sidelink, such as:

[0051] Unicast: Only two UEs are in a sidelink group. The formation of the sidelink group can be implemented at the NAS layer.

[0052] Multi-cast / Groupcast: More than two UEs are grouped in a sidelink group to exchange sidelink packets with all other members in the sidelink group.

[0053] In some embodiments, the sidelink group can be formed in NAS layer (e.g., V2X application layer or PC5-S protocol) signaling, AS layer signaling in the PC5 interface (e.g., sidelink RRC layer signaling, PC5-RRC signaling), or AS layer signaling in the Uu interface (e.g., RRC signaling, RRCReconfiguration information).

[0054] Broadcast: There may be no restriction on the sidelink group. A UE can broadcast a message, and adjacent UEs within its sidelink communication range can successfully receive and decode the broadcast message. In some embodiments, the sidelink communication range may depend on transmission (Tx) power, hardware sensitivity, etc.

[0055] To enable sidelink operation within the coverage of a RAN (e.g., E-UTRAN or NR-RAN), an (LTE / NR) cell may provide an SL (radio) configuration and SL (radio) resource allocation to a UE. A UE under the coverage of a cellular network may need to perform sidelink operations based on the (radio) configuration of the serving RAN. To enable sidelink operation within the coverage of a RAN, the serving cell (or the resident cell) may need to provide an SL (AS) configuration and SL resource allocation to the UE. To enable sidelink operation (e.g., E-UTRA V2X sidelink communication service or NR sidelink communication service), a UE may obtain a sidelink (radio) configuration and / or sidelink (radio) resource allocation from the serving / resident cell operating on a sidelink frequency carrier. In some additional embodiments, a UE may obtain a sidelink (radio) configuration and sidelink (radio) resource allocation from a non-serving cell in a sidelink frequency carrier. A sidelink frequency carrier is defined / configured / enabled / allowed by a network operator or service provider for a UE to directly perform sidelink data exchange with neighboring UEs.

[0056] In some embodiments, a UE may obtain the position of a sidelink frequency carrier in the frequency domain (e.g., Absolute Radio-Frequency Channel Number (ARFCN)) based on sidelink pre-configuration (which may be pre-installed in the USIM), broadcast system information from the serving / resident / non-serving cell (e.g., SIB12, SIB13 in the NR protocol), sidelink control signaling exchange between UEs (e.g., PC5-RRC signaling or sidelink master information block), or UE-specific dedicated control signaling from the serving cell.

[0057] There are two basic methods for SL resource allocation in LTE V2X services:

[0058] Scheduled resource allocation, which is characterized by:

[0059] The UE needs to be in the (LTE / NR) RRC_CONNECTED state to transmit data.

[0060] The UE requests SL resources from the eNB (by sending a sidelink buffer status report to the serving cell). The eNB schedules dedicated sidelink resources for the UE to send sidelink control information and sidelink data. To achieve this, the eNB can request the UE to report a sidelink buffer status report (SL-BSR) via the Uu interface. Additionally, when the UE wants to send an SL-BSR to the eNB, the UE can also trigger a scheduling request (SR) or initiate a random access procedure on an uplink physical resource (e.g., PUCCH), but there is no available uplink resource. The SR resource (or configuration) and the SR procedure can be common for both sidelink operations and uplink traffic.

[0061] The UE makes autonomous resource selection from the SL resource pool, characterized by:

[0062] The UE's autonomous resource selection can be applied to both UEs in the RRC connected state (e.g., via dedicated RRC signaling or system information broadcast) and UEs in the RRC inactive / idle state (e.g., via system information broadcast).

[0063] The resource pool is a set of (virtually contiguous) resource blocks, and the UE can autonomously determine which physical (radio) resource blocks the UE wants to access for SL packet transmission.

[0064] The UE itself selects resources from the (sidelink) resource pool and performs transmission format selection to transmit sidelink control information and data.

[0065] The UE can perform (partial) sensing before SL packet delivery for (re)selection of sidelink resources. Based on the (partial) sensing results, the UE (re)selects some specific sidelink resources and reserves multiple sidelink resources. The UE is allowed to perform up to 2 parallel (independent) resource reservation processes. The UE is also allowed to perform a single resource selection for its V2X sidelink transmission.

[0066] When the UE is not within the coverage of the frequency used for V2X sidelink communication and if the eNB does not provide the V2X sidelink configuration for that frequency, the UE can use the preconfigured transmit set and receive resource pool in the UE (e.g., sidelink preconfiguration, which can be pre-installed in the memory module of the UE). The V2X sidelink communication resources may not be shared with other non-V2X data transmitted via the sidelink. In some embodiments, the UE can obtain the preconfiguration through the installed USIM, the stored memory, or the RAN that the UE has previously accessed. In addition, the UE can implement the (LTE / NR) PC5 interface by synchronizing with the Global Navigation Satellite System (GNSS) and applying the preconfiguration. In this case, the PC5 interface can be independent of the RAN and the (LTE / NR) Uu interface.

[0067] V2X platooning scenario

[0068] Figure 2 A V2X platooning scenario 200 is shown according to an embodiment of the present disclosure. In the platooning scenario, platoon X may include several vehicles (or UEs) 202, 204, 206, and 208, where there may be (at least) one scheduler (e.g., vehicle 202) in platoon X. Additionally, vehicle 210 may be a UE not included in platoon X. In platoon X, the scheduler (e.g., vehicle 202) can configure the SL resources for the members (e.g., vehicles 204, 206, and 208) in the same platoon X by the following methods:

[0069] Method of Mode 1: The scheduler can configure dynamic sidelink grants for the members in the same platoon (e.g., dynamic sidelink grants via sidelink control information). Additionally, the scheduler can also configure semi-periodic sidelink grants (e.g., configured sidelink grants) for the UE via sidelink control signals (e.g., via the physical sidelink broadcast channel or sidelink PC5-RRC signaling). To implement a method similar to Mode 1, the scheduler may require the UE to provide feedback information via the (LTE / NR) PC5 interface.

[0070] Method of Mode 2: The scheduler can configure the sidelink resource pool for the members in the same platoon. The UE can autonomously select the sidelink grant (e.g., sidelink grant selection with or without sensing). The platooning scenario can be applied when the vehicles in the platoon are within the coverage (i.e., all vehicles in the platoon are within the coverage of the cellular radio access network), outside the coverage (i.e., all vehicles in the platoon are not within the coverage of the cellular radio access network), or partially within the coverage (i.e., some UEs in the platoon are within the coverage and some in the platoon are outside the coverage of the cellular radio access network).

[0071] To support the scheduler, in the present disclosure, members in the queue may need to support the following procedures to report their own status to the scheduler via the PC5 interface:

[0072] - Sidelink scheduling request (SL-SR) configuration and reporting

[0073] - Sidelink buffer status report (SL-BSR) configuration and reporting

[0074] - Sidelink power headroom report (SL-PHR) configuration and reporting

[0075] PC5-RRC connection and sidelink radio bearer

[0076] Figure 3 A PC5-RRC connection 300 between a pair of UEs is shown according to an embodiment of the present disclosure. A pair of UEs may establish multiple PC5-RRC connections, where each PC5-RRC connection may support different V2X service sets with different (layer 2 / layer 1) UE IDs and different QoS requirements.

[0077] The concept of a PC5-RRC connection may be different from that of an RRC connection in the Uu interface. In the NR PC5 interface, an SL unicast group (e.g., Figure 3UE#1 and UE#2 in it) may first need to establish (at least) one PC5-S connection, and each PC5-S connection may be independent of a PC5-RRC connection in the AS layer. In other words, the PC5-S connection and the PC5-RRC connection can be a one-to-one mapping. Each PC5-RRC connection is a logical connection between a pair of source and destination (layer 2) UE IDs. At the service level, a PC5-S connection (and the associated PC5-RRC connection) can be established to serve one or more V2X services. For example, the PC5-S connection #1s of UE#1 and UE#2 are constructed to serve V2X service #1 / #2, while the PC5-S connection #2s are constructed to serve V2X service #a / #b. However, there may be multiple active PC5-S connections / PC5-RRC connections in a paired UE to support different groups of V2X services with different QoS requirements. In some embodiments, the UE may report the status of the PC5-RRC connection to the serving cell (e.g., the PCell in the primary cell group or the PSCell in the secondary cell group), and the serving RAN may also know the conditions of the PC5-RRC connection on the UE side. Additionally, the UE may also report a sidelink radio link failure event to the serving RAN (to at least one PC5-RRC connection) (e.g., for sidelink resource management, such as the mode 1 sidelink resource allocation method). In one embodiment, a UE may join multiple SL unicast groups with different target UEs, and thus, a UE may have PC5-RRC connections associated with different UEs.

[0078] Sidelink access stratum configuration via dedicated control signaling over the Uu interface

[0079] In Release 16, for a UE performing (LTE / NR) sidelink operations, the sidelink AS configuration (e.g., SL-ConfigDedicatedNR / SL-ConfigDedicatedEUTRA in the NR protocol or sl-ConfigDedicatedForNR / sl-V2X-ConfigDedicated in the E-UTRA protocol) can be based on dedicated control signaling received via the serving cell (e.g., the RRC (Connection) Reconfiguration message in the LTE / NR RRC protocol). Additionally, the NR cell can configure the sidelink AS configuration for the LTE / NR PC5 interface in the RRC (Connection) Reconfiguration message (e.g., sl-ConfigDedicatedNR / sl-ConfigDedicatedEUTRA for the AS configuration of the NR PC5 interface / LTE PC5 interface, respectively). Similarly, an E-UTRA cell can also configure the sidelink AS configuration for the LTE / NR PC5 interface via the RRC (Connection) Reconfiguration message (e.g., by sending sl-ConfigDedicatedForNR / sl-V2X-ConfigDedicated in the E-UTRA protocol to the UE). For the UE, the sidelink AS configuration includes the AS layer configuration for the LTE PC5 interface and / or the NR PC5 interface. In the present disclosure, the sidelink AS configuration sent via RRC signaling can also be referred to as the sidelink RRC configuration.

[0080] Table 1 lists an exemplary RRC (Connection) Reconfiguration message including the sidelink AS configuration.

[0081] Table 1

[0082]

[0083] The UE can receive the sidelink AS configuration for the (LTE / NR) PC5 interface via the RRC (Connection) Reconfiguration message. After receiving the (LTE / NR) sidelink AS configuration from the serving cell, the UE can configure the AS layer of the (LTE / NR) PC5 interface accordingly.

[0084] Sidelink AS configuration broadcast via system information

[0085] In some embodiments, the UE can obtain the sidelink AS configuration for the (LTE / NR) PC5 interface by receiving broadcast control signaling from the serving cell (or from a non-serving cell when the cell is operating on a sidelink component carrier in which the UE is interested in operating sidelink data exchange). In some embodiments, the UE can obtain the sidelink AS configuration via the SI on-demand procedure.

[0086] Sidelink AS configuration via PC5-RRC signaling

[0087] In contrast, in a sidelink unicast service, a UE can obtain a sidelink AS configuration from a paired UE. Figure 4A A procedure 400A for obtaining a sidelink AS configuration via PC5-RRC signaling is shown according to an embodiment of the present disclosure. {UE#1410, UE#2 420} are designated as a sidelink unicast group (e.g., via a V2X application layer). Additionally, UE#1 410 and UE#2 420 can exchange PC5-RRC signaling. In operation 432, UE#1 410 can provide a sidelink AS configuration to UE#2 420 by sending an RRCReconfigurationSidelink message to UE#2 420. Then, UE#2 420 can configure its sidelink AS configuration (associated with UE#1 410) based on the received RRCReconfigurationSidelink message. UE#2 420 can reply by sending an RRCReconfigurationCompleteSidelink message to UE#1 410 in operation 434.

[0088] When UE#2 420 cannot configure according to the (partial) configuration included in the RRCReconfigurationSidelink message, a sidelink AS configuration failure event (or a sidelink RRC configuration failure event) may occur. Figure 4B A procedure 400B for handling a sidelink AS configuration failure event is shown according to an embodiment of the present disclosure. In operation 442, UE#1 410 can provide a sidelink AS configuration to UE#2 420 by sending an RRCReconfigurationSidelink message to UE#2 420. UE#2420 can perform at least one of the following actions when a sidelink AS configuration failure event occurs: continue to use the stored (associated with UE#1 410) sidelink AS configuration used before receiving the RRCReconfigurationSidelink message; and send an RRCReconfigurationFailureSidelink message to UE#1 410 in operation 444.

[0089] The sidelink AS configuration can cover the following settings:

[0090] - Sidelink radio bearer configuration (e.g., for adding / modifying or releasing one (or more than one) sidelink radio bearer). In some embodiments, the sidelink radio bearer configuration may include / cover the sidelink AS configuration of (at least) one radio bearer in the SDAP layer and the PDCP layer. In addition, the 'transmission range of the SLRB' associated with a sidelink radio bearer may also be included in the sidelink radio bearer configuration. Each sidelink radio bearer may be associated with a sidelink radio bearer index. In some embodiments, the sidelink radio bearers and the normal radio bearers may share the same index pool. In some embodiments, each bearer index may have two index pools, e.g., one index pool for sidelink radio bearers and another index pool for normal radio bearers.

[0091] - Sidelink RLC bearer configuration (e.g., for adding / modifying or releasing one (or more than one) sidelink RLC radio bearer associated with a corresponding sidelink radio bearer index). In some embodiments, the sidelink RLC radio bearer configuration may include / cover the sidelink AS configuration of (at least) one radio bearer in the RLC (e.g., ARQ mode) layer and / or the MAC layer (e.g., the logical channel configuration associated with the RLC bearer).

[0092] - Sidelink measurement configuration (e.g., the targets of sidelink measurements, such as the configuration of SL-RSRP measurement and reporting events). In some embodiments, both the layer 1 SL measurement configuration and the layer 3 SL measurement configuration may be included in the sidelink measurement configuration.

[0093] - Sidelink resource configuration (which may include / cover mode 1 and / or mode 2 sidelink resource configuration and / or the authorization configuration of type 1 / type 2 sidelink configuration).

[0094] - Radio resources on the Uu interface for supporting sidelink operations (e.g., the PUCCH resource configuration for transmitting sidelink HARQ responses or the PDCCH search space for receiving DL control signaling for sidelink operations).

[0095] - Sidelink frequency configuration (e.g., for adding or releasing one or (more than one) sidelink frequency component carriers).

[0096] - Sidelink synchronization configuration (e.g., whether to allow the UE to become a sidelink synchronization source and the corresponding configuration or the related configuration for a UE to transmit sidelink synchronization signal burst sets and / or SL-MIB).

[0097] - Sidelink partial bandwidth (SL-BWP) configuration.

[0098] - A sidelink QoS profile is used to provide / set QoS parameters for sidelink QoS flows.

[0099] - Whether the UE is configured to report semi-persistent-scheduling (SPS) information for V2X sidelink communication (e.g., sl-AssistanceConfigEUTRA, which can be included in OtherConfig in the RRC (connection) reset message).

[0100] - Whether the UE is configured to report authorization assistance information for the NR sidelink configuration for NR sidelink communication (e.g., sl-AssistanceConfigNR, which can be included in OtherConfig in the RRC (connection) reset message).

[0101] sl-AssistanceConfigEUTRA and sl-AssistanceConfigNR can be sent by the serving (NR / LTE) cell via the RRC (connection) reset message.

[0102] In some embodiments, a sidelink AS configuration can be associated with a specific destination identifier (layer 2) UE ID in the AS layer of the (LTE / NR) PC5 interface. In some other embodiments, a sidelink AS configuration can be associated with more than one specific destination identifier ID in the AS layer. In some embodiments, a sidelink AS configuration can be associated with all associated destination (UE) IDs on the UE side. For example, a common sidelink AS configuration can be sent via broadcast system information. Then, the UE can apply the common sidelink AS configuration to all associated destination IDs.

[0103] In some embodiments, the combination of sidelink AS configurations associated with a destination (UE) ID can depend on the type of situation associated with the destination ID (e.g., broadcast, multicast, and unicast). For example: A sidelink AS configuration can be associated with all associated destination IDs for the broadcast type. Under some other conditions (e.g., for the sidelink unicast type), each destination ID can be associated with a corresponding sidelink AS configuration.

[0104] The UE can derive the destination (layer 2) ID through an upper layer input. For example: When the UE is establishing a PC5-RRC connection with a target UE, the V2X layer on the UE side can generate a service-level destination (UE) ID associated with the target UE. Then, the service-level destination ID can be sent to the AS layer of the UE, and a destination (layer 2) ID is generated in the AS layer to identify the target UE in the AS layer on the UE side.

[0105] This disclosure is based on V2X services. However, the proposals and the proposed implementations can also be applied to other services implemented on (LTE / NR) sidelink services implemented on the (LTE / NR) PC5 interface and (LTE / NR) sidelink operations.

[0106] Problem statement

[0107] As Figure 4B shown, when UE#2 420 receives a sidelink AS configuration via PC5-RRC signaling, a sidelink AS configuration failure event may occur. In the NR PC5 interface, if a sidelink AS configuration failure event occurs after receiving an RRC reconfiguration sidelink message from UE#1 410 (or UE#2 420 can only release the 'failed' sidelink radio bearer indicated in the RRCReconfigurationSidelink message), then UE#2 420 can release the PC5-RRC connection with UE#1 410.

[0108] Observation #1: However, more UE behavior may be needed to resolve the sidelink RRC reconfiguration failure event between the Tx UE and the Rx UE of the RRCReconfigurationFailureSidelink message.

[0109] Table 2 shows exemplary UE behavior in the event of a sidelink RRC reconfiguration failure.

[0110] Table 2

[0111]

[0112] Observation #2: In addition, in the latest specification, there is still no signaling content, and further signaling is needed to resolve the reconfiguration failure event.

[0113] Table 3 shows an exemplary RRCReconfigurationFailureSidelink message.

[0114] Table 3

[0115]

[0116]

[0117] In the present disclosure, embodiments are disclosed that further enhance the side-link AS configuration failure event and signaling design in the PC5 interface. In addition, when a UE receives a side-link AS configuration via dedicated control signaling (e.g., RRC(connection)Reconfiguration message) through the Uu interface, a side-link AS configuration failure event may also occur. This event can be considered a sub-case of a reset failure in the associated Uu interface (e.g., LTE Uu interface and NR Uu interface). In addition, when a reset failure event occurs in the Uu interface, the UE can be instructed to perform at least one of the following actions:

[0118] - Continue to use the configuration used before receiving the RRCReconfiguration message;

[0119] - Move to the RRC idle state (e.g., if AS security has not been activated); and

[0120] - Initiate an RRC reestablishment procedure (e.g., if AS security has been activated).

[0121] Table 4 shows exemplary UE behavior in the event of an RRC reset failure.

[0122] Table 4

[0123]

[0124]

[0125]

[0126] Observation #3: Different UE behaviors can be applied to the side-link AS configuration failure event. The specific UE behavior to be applied can depend on whether the side-link AS configuration is from the serving cell (through the Uu interface) or the paired UE (through the PC5 interface via one or more PC5-RRC signaling).

[0127] In addition, since a UE with an RRC connection (e.g., Figure 4B UE#1 410 in Figure 4B can report a'side-link RRC configuration failure event' (associated with Figure 4B UE#2 420 in

[0128] In some embodiments, the term 'SideLink AS configuration' may be equivalent to 'SideLink RRC configuration' (since the RRC layer manages all AS layer SideLink configurations) or may be equivalent to 'SideLink radio configuration'. Under this condition, 'SideLink AS configuration failure report' and 'SideLink RRC configuration failure report' may be the same for a UE and a serving RAN for SideLink unicast / multicast / broadcast services. However, in some other embodiments, the SideLink RRC configuration may be restricted by the PC5-RRC connection, which only supports 'SideLink unicast service' in the Release 16 (Rel-16) specification. Under this condition, a 'PC5-RRC configuration failure report' may be supported only in the SideLink unicast service. In contrast, when an AS configuration failure event occurs for the SideLink multicast / broadcast service, the UE may send a 'SideLink AS configuration failure report' to the serving cell.

[0129] Observation #4: For a UE, when obtaining a failed SideLink AS configuration via the (LTE / NR) Uu interface, the same SideLink AS configuration failure report caused by the failed SideLink AS configuration in the PC5 interface may also be applied.

[0130] In addition, the conventional reset failure method in the Uu interface may increase the vulnerability of the RRC connection.

[0131] Observation #5: An RRCReconfiguration message may contain SideLink AS configurations for up to 32 destination IDs. A failed SideLink AS configuration to any destination ID may cause the UE to initiate an RRC reconstruction procedure or move to the RRC idle state. In addition, the RRC reconstruction procedure or the RRC state transition may also affect the SideLink packet exchange for other destination IDs, and the associated SideLink AS configurations in the RRCReconfiguration message are not changed / modified.

[0132] Therefore, in order to prevent the (unnecessary) impact from the PC5 interface to the Uu interface and the unnecessary impact on other destination IDs, embodiments are disclosed for enhancing the SideLink AS configuration failure report when only a partial SideLink AS configuration fails on the UE side. Embodiments of the partial failure design are disclosed to reduce the impact of the PC5 interface on the Uu interface. Then, the management of the SideLink AS configuration can also be simplified.

[0133] Observation #6: When the failure cause is a SideLink RRC configuration failure event, the partial failure design may be applied to the (Uu) RRC reset failure event.

[0134] In addition, SideLink RRC configuration failure reports are also disclosed in the present disclosure when the SideLink AS configuration is derived via a broadcast control message (e.g., system information).

[0135] In addition, all configuration methods similar to those of the Uu interface can also be implemented on the PC5 - RRC connection. In one embodiment, if a new configuration for SL cannot be performed by delta configuration (e.g., RRC state transition, change of SIB for NR / E - UTRA SL, and fullconfig present in dedicated signaling), the UE uses all configuration operations as in the Uu interface to handle the new NR SL configuration.

[0136] However, the details of all configurations on the sidelink are still not available. Therefore, how to implement all sidelink configurations is also in this disclosure.

[0137] Embodiment #1: RRCReconfigurationFailureSidelink Signaling Design

[0138] Table 5 summarizes the embodiments of the RRCReconfigurationFailureSidelink message sent from the Rx UE to the Tx UE.

[0139] Table 5

[0140]

[0141]

[0142]

[0143]

[0144]

[0145]

[0146]

[0147]

[0148]

[0149] Embodiment #1 - 1

[0150] Figure 5AAccording to an embodiment of the present disclosure, a signal flow 500A for a sidelink full reset is shown. In some embodiments, the Tx UE 510 may further indicate whether the'sidelink full configuration for the corresponding sidelink RRC reset' is configured (e.g., provide a specific information element 'SL-fullconfig = true' to the Rx UE 520 in the RRCReconfigurationSidelink message). If a sidelink re-failure event occurs, the Rx UE 520 may accordingly execute the sidelink full configuration procedure (when SL-fullconfig = true). The Tx UE 510 may also implement the sidelink full configuration after receiving the RRCReconfigurationFailureSidelink message from the Rx UE 520. Table 6 shows exemplary UE behavior in the event of a sidelink RRC reset failure.

[0151] Table 6

[0152]

[0153]

[0154] Figure 5B According to another embodiment of the present disclosure, a signal flow 500B for a sidelink full reset is shown. In some embodiments, when a sidelink reset failure event occurs, the Rx UE 520 may start the sidelink full configuration procedure by itself (the TxUE 510 may not provide the SL-fullconfig IE in the RRCReconfigurationSidelink message to the Rx UE520). In action 542, the Rx UE 520 may provide the information element 'SL-fullconfig = true' to the Tx UE 510 in the RRCReconfigurationFailureSidelink message. After receiving the RRCReconfigurationFailureSidelink message, the Tx UE 510 may also implement the sidelink full configuration for the corresponding PC5-RRC connection. Table 7 shows exemplary UE behavior in the event of a sidelink RRC reset failure.

[0155] Table 7

[0156]

[0157] In some embodiments, if the Rx UE 520 fails to reset after receiving the RRCReconfigurationSidelink message, the Rx UE 520 may implicitly implement the sidelink full configuration. Then, after implementing the sidelink full configuration, the Rx UE 520 may also reply to the Tx UE 510 with an RRCReconfigurationFailureSidelink message.

[0158] In some embodiments, the Tx UE 510 may implicitly initiate the sidelink full configuration after receiving an RRCReconfigurationFailureSidelink message from the Rx UE 520 (e.g., no sidelink configuration information about the failure or further information with SL-fullconfig = true).

[0159] In some embodiments, a UE (e.g., the Rx UE 520) may obtain the SL-fullconfig information element from a cell in the RAN via the relay of another UE (e.g., the Tx UE 510). Thus, the Tx UE 510 may receive the SL-fullconfig (e.g., associated with one or more (layer 2) destination IDs having a PC5-RRC connection with the Tx UE 510) from its serving cell via dedicated control signaling or broadcast system information.

[0160] The sidelink full configuration may include all or some of the UE implementations proposed below.

[0161] Sidelink full configuration for sidelink RRC connection

[0162] Table 8 shows an exemplary method for sidelink full configuration.

[0163] Table 8

[0164]

[0165]

[0166] In some embodiments, the Tx UE 510 may also instruct the Rx UE 520 to directly implement the sidelink full configuration procedure (e.g., the RRCReconfigurationSidelink message contains another IE 'SL-fullconfig_direct = true' 『to trigger the Rx UE to directly implement the sidelink full configuration procedure, as Figure 5AAs shown). In operation 532, the Tx UE 510 may send SL-fullconfigdirect or SL-fullconfig_direct via an RRCReconfigurationSidelink message. In some embodiments, in the same signaling (e.g., the RRCReconfigurationSidelink message), it may not be possible to provide the Rx UE 520 with other sidelink RRC reset IEs (which convey the sidelink (radio) configuration of the Rx UE 520). Thus, the Rx UE 520 may directly initiate the sidelink full configuration procedure after receiving the RRCReconfigurationSidelink message. Then, after successfully completing the sidelink full configuration message procedure at the Rx UE 520, the Rx UE 520 may also reply to the Tx UE 510 with an RRCReconfigurationCompleteSidelink message. In some other embodiments, other sidelink RRC reset IEs (which convey the sidelink RRC configuration for the Rx UE 520) may be provided to the Rx UE 520 by the Tx UE 510 in the same signaling (e.g., the RRCReconfigurationSidelink message in operation 532). Thus, the Rx UE 520 may directly initiate the sidelink full configuration procedure after receiving the RRCReconfigurationSidelink message with 'SL-fullconfig_direct = true'. Then, after successfully completing the sidelink full configuration message procedure at the Rx UE 520, the Rx UE 520 may reset the sidelink AS layer configuration associated with the Tx UE 510 based on the sidelink radio configuration received in the same RRCReconfigurationSidelink message in operation 532. After resetting the sidelink radio configuration with the Tx UE 510, the Rx UE 520 may also reply to the Tx UE 510 with an RRCReconfigurationCompleteSidelink message. Note that during sidelink full configuration, the Rx UE 520 may release or clear all current sidelink radio configurations associated with the Tx UE 510. In some embodiments, the Rx UE 520 may also release the sidelink radio bearer (SL-DRB) associated with the Tx UE 510. In some additional embodiments, the UE may also apply the default MAC configuration for the sidelink specific MAC function (or MAC entity) associated with the Tx UE 510.For the sidelink-specific MAC associated with the Tx UE 510, in some embodiments, the original sidelink-specific MAC associated with the Tx UE 510 (before the Rx UE 520 receives the RRCReconfigurationSidelink message from the Tx UE 510 in operation 532) may be configured as part of a MAC entity, which may share with the sidelink-specific MAC (function) associated with other layer 2 destination IDs in the (LTE / NR) PC5 interface and / or the (non-sidelink-specific) MAC (function) associated with the serving RAN in the (LTE / NR) Uu interface. However, in some other embodiments, the sidelink-specific MAC (function) associated with the Tx UE 510 may be configured as an independent MAC entity on the Rx UE 520 side. Additionally, for the default MAC application, when the Rx UE 520 is implementing the full sidelink configuration (based on instructions from the Tx UE 510), the original sidelink-specific MAC associated with the Tx UE 510 may be reset first. Also note that the sidelink radio configuration may not be limited to the sidelink radio resource configuration (e.g., sidelink Tx / Rx resource pool configuration or exceptional resource pool configuration), but may also include other configurations regarding the (LTE / NR) PC5 interface, such as: sidelink measurement configuration and / or sidelink CSI-RS configuration.

[0167] Figure 5CAccording to yet another embodiment of the present disclosure, a signal flow 500C for a side link full reset is shown. In some embodiments, a base station 550 (e.g., an E-UTRA eNB or an NR gNB) may configure a UE 560 (which has a PC5-RRC connection with one or more Rx UEs) to perform a side link full configuration procedure (e.g., by configuring SL-fullconfig = true). In some embodiments, SL-fullconfig = true may be associated with all (active) PC5-RRC connections of a corresponding UE 560 (thus, the UE 560 may apply the side link full configuration to all associated Rx UEs). In some other embodiments, SL-fullconfig = true may be associated with a subset of (active) PC5-RRC connections. For example, the (layer 2) destination IDs of some Rx UEs may be configured by the base station together with the 'SL-fullconfig = true' IE in the RRCReconfiguration message. After receiving the RRCReconfiguration message, the UE 560 may perform a side link full configuration on the PC5-RRC connections associated with those indicated (layer 2) destination IDs. Conversely, the PC5-RRC connections of other UEs (whose (layer 2) destination IDs are not indicated in the RRCReconfiguration message) may not be affected by the 'SL-fullconfig = true' IE. In some embodiments, the SL-fullconfig IE may be applied to all destinations associated with an (Rx) UE, which may also include targets associated with side link unicast / multicast / broadcast services.

[0168] As Figure 5CAs shown, in some embodiments, a subset of (active) PC5-RRC connections associated with SL-fullconfig = true may have been signaled (e.g., the base station 550 has configured the sidelink radio configuration associated with a subset of (active) PC5-RRC connections in the (at least one) previous RRCReconfiguration message) via the serving base station 550 prior to action 552. Then, in action 552, the base station 550 may directly configure 'SL-fullconfig = true' in the RRCReconfiguration message without re-indicating the (Layer 2) destination (UE) ID of the subset of (active) PC5-RRC connections in the RRCReconfiguration message. After receiving 'SL-fullconfig = true' in action 552, if the serving base station 550 configures the sidelink RRC configuration associated with the (Layer 2) destination (UE) ID via the (at least one) previous RRCReconfiguration message, the UE 560 may implement the sidelink full configuration for the subset of (active) PC5-RRC connections associated with these (Layer 2) destination (UE) IDs. Conversely, after action 552, if the base station 550 does not configure the sidelink RRC configuration associated with the same (Layer 2) destination ID via the (at least one) previous RRCReconfiguration message, the UE 560 may not implement the sidelink RRC configuration for the (active) PC5-RRC connection associated with one (Layer 2) destination ID.

[0169] In some embodiments, the SL-fullconfig IE may not be present in the RRCReconfiguration message. Instead, the fullconfig IE may be configured in the control signaling dedicated to NR sidelink operations (e.g., in the sl-ConfigDedicatedNR message) such that the UE knows that the sidelink full configuration will be initiated instead of the regular full configuration procedure in the Uu interface.

[0170] In some embodiments, an original fullconfig IE, which initially defines all configurations of an RRC connection in the Uu interface (such that the fullconfig IE is configured outside the sl-ConfigDedicatedNR IE), may be configured to have the functionality of the SL-fullconfig in the present disclosure. If the fullconfig is configured for the UE via an RRCReconfiguration message, the UE may initiate a sidelink full configuration procedure on one (or more than one) active PC5-RRC connection and on the active RRC connection (in the Uu interface).

[0171] The disclosed RRC signaling (and the disclosed information elements) may not be limited to the NR RRC signaling protocol (they may be implemented in the LTE RRC protocol to implement sidelink full configuration on the LTE / NR PC5 interface).

[0172] In one embodiment, if the UE resets its own sidelink AS configuration based on the received sidelink configuration, the UE may also initiate a sidelink full configuration, where the sidelink configuration reset is received from the serving cell (e.g., via dedicated control signaling or broadcast system information, which may or may not be via a system information on demand procedure). The serving cell may or may not convey the SL-fullconfig to the in-coverage UE via dedicated control signaling (e.g., RRC signaling) or system information (e.g., system information specified for NR sidelink or V2X services).

[0173] All or some of the information elements related to the Uu interface in the present disclosure may be conveyed via RRC signaling, such as: RRC establishment message, RRC reset message, RRC release message with / without suspension configuration, RRCReconfiguration message with a reconfigurationwithsync IE (e.g., for inter-RAT / intra-RAT handover procedures or special cell change) or RRCReconfiguration message without a reconfigurationwithsync IE, or RRC resume message. In the uplink direction, parts of the disclosed embodiments may be sent via an RRC establishment request message, an RRC re-establishment message, or an RRC resume request message. Additionally, the disclosed embodiments may not be limited to the NR sidelink protocol. For example: the disclosed embodiments may also be applicable to LTE (ProSe) sidelink operations or LTE V2X sidelink communication services.

[0174] Embodiment #2

[0175] Table 9 lists the implementation methods of UE behavior when reconfiguring a failure event. In Table 9, if the failed RRC configuration is not provided for the (LTE / NR) Uu interface (e.g., cases #1 / #2 in Table 9), the UE may initiate a regular (RRC) reset failure event.

[0176] Table 9

[0177]

[0178] In contrast, if a failed configuration is provided for the (LTE / NR) PC5 interface for one or more destination IDs (e.g., case #3), the UE may not initiate a regular (RRC) reset failure event. Instead, the UE may only implement a 'partial failure design'. For example, only a sidelink radio link failure may be implemented, or only the 'failed' sidelink radio bearers (for those corresponding destination IDs) may be released / cleared. In addition, the UE may also report the'sidelink RRC configuration failure' event to the serving cell. Further, in some implementations, the UE may not initiate a reset failure event (or part of the UE implementation in the reset failure event). In other words, the RRC connection in the Uu interface may not be affected, or the impact on the RRC connection may be limited. The details of the implementation in Table 9 are disclosed in Implementation #2-1.

[0179] Implementation #2-2 addresses the case of obtaining a failure event indication for sidelink AS configuration through broadcast system information.

[0180] Implementation #2-1 Dedicated control signaling from the serving cell causes a sidelink RRC configuration failure event

[0181] Implementation #2-1 addresses sidelink RRC configuration failure when the UE receives sidelink RRC configuration through dedicated control signaling (e.g., RRC signaling) in the Uu interface. Table 10 lists the detailed implementations of Implementation #2-1, which may correspond to case #3 in Table 9.

[0182] Table 10

[0183]

[0184]

[0185]

[0186]

[0187]

[0188]

[0189] Figure 6 Another embodiment according to the present disclosure illustrates a process 600 for handling a sidelink failure event. In operation 612, the UE 606 receives a first message from the source cell 604, the first message including sidelink RRC configuration associated with the target cell 602. The source cell 604 may be the current serving cell of the UE 606. In operation 614, the UE 606 may determine that a sidelink failure event associated with the associated sidelink destination UE 608 has occurred. In operation 616, the UE 606 may execute a handover procedure to handover from the source cell 604 to the target cell 602. In operation 618, the UE 606 may send a sidelink failure report indicating the sidelink failure event to the target cell 602.

[0190] In one embodiment, during a handover procedure, the source cell 604 may communicate with the target cell 602. For example, the source cell 604 may provide information of the UE 606 to the target cell 602. The target cell 602 may send configuration parameters (e.g., parameters related to sidelink radio configuration) to the source cell 604, and the source cell 604 may send the configuration parameters to the UE 606 via a first message. Note that the SL RRC configuration message in action 612 may be sent via a UE-specific DL RRC signaling (e.g., an RRC reconfiguration message with the'sync' IE provided for UE mobility events of the connected UE). Also note that in some embodiments, the UE 606 may also provide information / configuration related to the sidelink destination UE 608 (e.g., (layer 2) destination ID, cast type, QoS information, or other AS layer configurations associated with the sidelink destination UE 608) to the source cell 604 before action 612 (e.g., via sidelinkUEInformationNR or sidelinkUEInformationEUTRA sent from the UE 606 to the source cell 604 in UL UE-specific RRC signaling). Additionally, after receiving sidelinkUEInformationNR / sidelinkUEInformationEUTRA from the UE 606, the source cell 604 may forward sidelinkUEInformationNR / sidelinkUEInformationEUTRA to the target cell 602 via a backhaul connection (e.g., via a handoverpreparationInformation message transfer procedure before action 612). Thus, the target cell 602 may provide the sidelink radio configuration (e.g., the sidelink radio configuration associated with the sidelink destination UE 608) to the UE 606 by forwarding the source cell 604. Furthermore, after the handover procedure in action 616, the target cell 602 may also identify an SL failure report sent by the UE 606 in action 618.

[0191] During process 600, in some embodiments, UE 606 may act as a relay UE, and the sidelink destination UE 608 may act as a remote UE. A base station (e.g., the base station configuring source cell 604) may control the sidelink radio configuration and sidelink resource allocation of the remote UE (sidelink destination UE 608) via the relay UE (UE 606). In one embodiment, after receiving the first message in operation 612, UE 606 may send a second message to the sidelink destination UE 608 that includes the sidelink RRC configuration associated with target cell 602. The second message may be sent via the PC5-RRC connection between UE 606 and the sidelink destination UE 608.

[0192] There may be a sidelink failure event regarding the transmission of the second message from UE 606 to the sidelink destination UE 608. The sidelink failure event may be a sidelink RRC reset failure event of the PC5-RRC connection between UE 606 and the associated sidelink destination UE 608. For example, the sidelink destination UE 608 may successfully receive the sidelink RRC configuration but fail to apply the sidelink RRC reset. In one embodiment, the sidelink destination UE 608 may send a sidelink failure indication to UE 606 to indicate the sidelink RRC reset failure. UE 606 may determine that a sidelink failure event associated with the sidelink destination UE 608 has occurred in operation 614 based on the sidelink failure indication received from the sidelink destination UE 608. Then, UE 606 may report the sidelink failure event to target cell 602 in operation 618 via an SL failure report (e.g., by attaching the (layer 2) destination ID of UE 608 and the failure cause of '(sidelink) reset failure' in the SL failure report in operation 618).

[0193] The sidelink failure event may be a sidelink radio link failure event of the PC5-RRC connection between UE 606 and the associated sidelink destination UE 608. For example, when at least one of the following events occurs, UE 606 may consider that a sidelink radio link failure event with the sidelink destination UE 608 will be detected:

[0194] (a) UE 606 may be unable to send sidelink RRC signaling to the sidelink destination UE 608. For example, in some embodiments, a sidelink RLC entity (configured on a sidelink radio bearer in UE 606 for sidelink packet exchange with the sidelink destination UE 608) may provide an indication to the RRC entity of UE 606 that the maximum number of (ARQ) retransmissions to the sidelink destination UE 608 has been reached (reaching a predefined upper threshold). Then, UE 606 (e.g., the RRC entity in UE 606) may consider that a sidelink radio link failure event for the sidelink destination UE 608 has been detected.

[0195] (b) Sidelink radio link failure may occur due to channel quality problems on the air interface between UE 606 and the sidelink destination UE 608. For example, in some embodiments, the sidelink-specific MAC (function / entity) in UE 606 may be notified (by a lower layer) that the maximum number of consecutive hybrid automatic repeat request (HARQ) discontinuous transmissions (DTX) for sidelink packet (re)transmission to the sidelink destination UE 608 has been reached. This event may occur due to unstable channel quality between UE 606 and the sidelink destination UE 608.

[0196] (c) In one embodiment, UE 606 may determine sidelink radio link failure based on predefined conditions / parameters (such as the expiration of a timer related to the transmission of a second message). For example, when UE 606 sends a second message (e.g., an RRCReconfigurationsidelink message that conveys sidelink radio configuration to the sidelink destination UE 608 for (re)configuring the PC5-RRC connection between UE 606 and the sidelink destination UE 608) to the sidelink destination UE 608, UE 606 may start counting the sidelink timer T400 as zero. Also note that the initial value of T400 may be determined based on sidelink presets / broadcast sidelink SIBs of service RAN / UE-specific control signaling from the serving cell. Then, when UE 606 receives an ACK / NACK message (e.g., an RRCReconfigurationCompleteSidelink / RRCReconfigurationFailureSidelink message) from UE 608, UE 606 may stop T400. Conversely, when T400 expires but UE 606 does not receive any response message from UE 608, the UE may consider that a sidelink radio link failure event for UE 608 has been detected.

[0197] (d) In one embodiment, the UE 606 may determine a sidelink radio link failure upon receiving an integrity check failure indication from a sidelink PDCP entity configured on a sidelink radio bearer in the UE 606 for sidelink packet exchange with a sidelink destination UE 608.

[0198] Based on the above trigger event, the UE 606 may determine that a sidelink failure event associated with the sidelink destination UE 608 occurs at the UE 606 itself in operation 614.

[0199] Note that: in some scenarios, when the UE 606 believes that a sidelink radio link failure event for the sidelink destination UE 608 has been detected, the UE 606 may release the PC5-RRC connection with the sidelink destination UE 608 (and release / discard / remove the sidelink radio configuration associated with the sidelink destination UE 608). However, also note that: the UE 606 may also receive (sidelink) full configuration instructions (e.g., the first message in operation 612) from the serving cell (before or after) the occurrence of the sidelink radio link failure event. Under such conditions, in some embodiments, the UE 606 may only release the PC5-RRC connection with the sidelink destination UE 608, without being affected by the (sidelink) full configuration (and thus the UE 606 may still provide an SL failure report to the target cell 602 in operation 618). Additionally, even if any new sidelink radio configuration (associated with the sidelink destination UE 608) is provided in the first message in operation 612, the UE 606 may still ignore all (sidelink) configuration instructions in the first message.

[0200] In one embodiment, the handover procedure in operation 616 may be an intra-RAT handover procedure. Both the source cell 604 and the target cell 602 may belong to E-UTRAN or NR-RAN.

[0201] In one embodiment, the handover procedure in operation 616 may be an inter-RAT handover procedure. One of the source cell 604 and the target cell 602 may belong to E-UTRAN, while the other of the source cell 604 and the target cell 602 may belong to NR-RAN. For example: the target cell 602 may belong to E-UTRAN, and the signaling for the target cell 602 may comply with the E-UTRAN protocol. On the other hand, the sidelink failure report in operation 618 may comply with the NR protocol. An inter-RAT transceiver or an inter-RAT (signaling) container may be provided such that the target cell 602 can accommodate the sidelink failure report.

[0202] In one embodiment, the sidelink failure report in action 618 may include the cause of failure and the ID of the sidelink destination UE 608 (also referred to as the destination UE ID). The cause of failure may indicate one of 'Sidelink RRC reset failure' and 'Sidelink radio link failure'. For example, when the sidelink failure event is a sidelink RRC reset failure event, the cause of failure indicates 'Sidelink (RRC) reset failure', and when the sidelink failure event is a sidelink radio link failure event, the cause of failure indicates 'Sidelink radio link failure'.

[0203] In one embodiment, the sidelink failure report in action 618 may be sent via an RRC reset complete message, which may be the last step of the handover procedure in action 616. In some other embodiments, the sidelink failure report in action 618 may be sent to the target cell 602 after the transmission of the RRC reset complete message.

[0204] In one embodiment, in the case where the target cell 602 is an NR cell, the sidelink failure report in action 618 may be sent to the target cell 602 via NR RRC signaling, and in the case where the target cell 602 is an E-UTRA cell, the sidelink failure report in action 618 may be sent via E-UTRA RRC signaling.

[0205] In one embodiment, in operation 612, the UE 606 may receive all configuration indicators in the first message (e.g., all configurations indicated by the target cell 602). In the case where the dedicated sidelink radio configuration is configured by the serving RAN (which may be the source cell 604) via UE-specific dedicated control signaling before receiving the first message, the UE 606 may decide to release the dedicated sidelink radio configuration associated with the sidelink destination UE 608. In the case where the dedicated sidelink radio configuration is not configured by the serving RAN (e.g., via UE-specific dedicated control signaling and / or broadcast system information) before receiving the first message, the UE 606 may decide not to release the dedicated sidelink radio configuration associated with the sidelink destination UE 608. The dedicated sidelink radio configuration includes a sidelink radio configuration for the UE 606 to implement at least one of the NR sidelink communication service and the LTE V2X sidelink communication service. However, in some embodiments, regardless of whether the target cell 602 indicates all configurations in operation 612 and regardless of whether the target cell 602 provides any new sidelink radio configuration (associated with the sidelink destination UE 608), the UE 606 may still send an SL failure report associated with the sidelink destination UE 608. In other words, when the UE 606 is implementing all configurations (on the Uu interface / PC5 interface), the UE 606 may not release the SL failure report. Conversely, in some additional embodiments, if the PC5-RRC connection associated with the sidelink destination UE 608 is to be released by the (sidelink) all configuration instruction in the first message in operation 612 (e.g., when the (sidelink) all configuration is indicated by the target cell 602 in operation 612) and the new sidelink radio configuration associated with the sidelink destination UE 608 may or may not be jointly sent in the first message in operation 612, the UE 606 may not implement an SL failure report associated with the sidelink destination UE 608 to the target cell 602.

[0206] Figure 7Method 700 for sidelink failure management performed by a UE is shown according to an embodiment of the present disclosure. In operation 712, the UE receives a first message from a source cell that includes sidelink RRC configuration associated with a target cell (e.g., SIB12 / SIB13 of the target cell or SL-ConfigDedicatedNR / SL-ConfigDedicatedEUTRA configured for the UE by the target cell). In operation 714, the UE determines that a sidelink failure event associated with the associated sidelink destination UE has occurred. In operation 718, after performing a handover procedure to switch from the source cell to the target cell, the UE sends a sidelink failure report indicating the sidelink failure event to the target cell. Operations 712, 714, and 718 may correspond to Figure 6 operations 612, 614, and 618 shown in

[0207] Figure 8 Method 800 for sidelink failure management performed by a UE is shown according to another embodiment of the present disclosure. Operations 812, 814, and 818 may correspond to Figure 7 operations 712, 714, and 718 shown in

[0208] Embodiment #2-2 Sidelink AS configuration failure event caused by broadcast control signaling

[0209] Embodiment #2-2 solves the side-link AS configuration failure when the UE receives the side-link AS configuration through broadcast control signaling (e.g., system information specific to LTE or NR V2X services). Table 11 lists the specific embodiments of Embodiment #2-2, which are related to the side-link AS configuration failure when the side-link AS configuration is obtained by reading system information from the corresponding cell.

[0210] Table 11

[0211]

[0212]

[0213]

[0214]

[0215]

[0216]

[0217]

[0218] Figure 10 is a block diagram 1000 showing a node for wireless communication according to an embodiment of the present disclosure. As Figure 10 illustrated, the node 1000 may include a transceiver 1020, a processor 1028, a memory 1034, one or more presentation components 1038, and at least one antenna 1036. The node 1000 may also include a radio frequency (RF) spectrum band module, a BS communication module, a network communication module, and a system communication management module, input / output (I / O) ports, I / O components, and a power supply ( Figure 10 not shown in the figure).

[0219] Each of these components may communicate with each other directly or indirectly through one or more buses 1040. The node 1000 may be a UE or a BS that performs various functions disclosed with reference to Figures 1 to 9B the present disclosure.

[0220] The transceiver 1020 has a transmitter 1022 (e.g., a transmitting / transmission circuit) and a receiver 1024 (e.g., a receiving / reception circuit) and can be configured to transmit and / or receive time and / or frequency resource partitioning information. The transceiver 1020 can be configured to transmit in different types of subframes and time slots, which include (but are not limited to) available, unavailable, and flexibly usable subframe and time slot formats. The transceiver 1020 can be configured to receive data and control channels.

[0221] The node 1000 may include a variety of computer-readable media. The computer-readable media can be any available media accessible by the node 1000 and includes both volatile and non-volatile media, as well as removable and non-removable media.

[0222] Computer-readable media includes computer storage media and communication media. Computer storage media can include both volatile and non-volatile, removable and non-removable media implemented according to any method or technology for storing information such as computer-readable instructions, data structures, program modules, or data.

[0223] Computer storage media can include RAM, ROM, EPROM, EEPROM, flash memory, or other storage technologies, CD-ROM, digital versatile disk (DVD), or other optical disk storage, cassette tapes, magnetic tapes, magnetic disk storage, or other magnetic storage devices, etc. Computer storage media does not include propagated data signals. Communication media typically embodies computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transmission mechanism and includes any information delivery medium.

[0224] The term "modulated data signal" can refer to a signal in which one or more of its characteristics are set or changed in some manner to encode information in the signal. Communication media can include wired media (such as a wired network or a direct wired connection), and wireless media (such as acoustic, RF, infrared, and other wireless media). Combinations of any of the previously listed components should also be included within the scope of computer-readable media.

[0225] The memory 1034 can include computer storage media in the form of volatile and / or non-volatile memory. The memory 1034 can be removable, non-removable, or a combination thereof. Exemplary memories can include solid-state memory, hard disk drives, optical disk drives, etc. As Figure 10As shown, the memory 1034 may store computer-readable and / or computer-executable instructions 1032 (e.g., software code), and these programs are configured to cause the processor 1028 to perform various disclosed functions, such as: reference Figures 1 to 9B . Alternatively, the instructions 1032 may not be directly executed by the processor 1028, but may be configured to cause the node 1000 (e.g., when compiled and executed) to perform various disclosed functions.

[0226] The processor 1028 (e.g., having processing circuitry) may include intelligent hardware devices such as: a Central Processing Unit (CPU), a microcontroller, an ASIC, etc. The processor 1028 may include a memory. The processor 1028 may process the data 1030 and instructions 1032 received from the memory 1034, as well as the information received and sent via the transceiver 1020, the baseband communication module, and / or the network communication module. The processor 1028 may also process the information to be sent to the transceiver 1020 for transmission via the antenna 1036, and the information to be transmitted to the network communication module for sending to the core network.

[0227] One or more presentation components 1038 may present data indications to a person or other device. Examples of the presentation component 1038 may include a display device, a speaker, a printing component, a vibrating component, etc.

[0228] It can be seen from the present disclosure that various techniques can be used to implement the concepts described in the present disclosure without departing from the scope of these concepts. In addition, although these concepts have been specifically described with reference to certain implementations, those of ordinary skill in the art can recognize that changes can be made in form and detail without departing from the scope of these concepts. Therefore, the disclosed embodiments will be considered illustrative rather than restrictive in all respects. It should also be understood that the present disclosure is not limited to the above specific embodiments, and many rearrangements, modifications, and substitutions are possible without departing from the scope of the present disclosure.

Claims

1. A user equipment (UE) for sidelink failure management, the UE comprising: a processor and a memory coupled to the processor, wherein the memory stores a computer-executable program which, when executed via the memory, causes the processor to: receive a first message from a source cell that includes sidelink radio resource control (RRC) configuration associated with a target cell; determine that a sidelink failure event associated with an associated sidelink destination UE has occurred; and after performing a handover procedure to hand over from the source cell to the target cell, send a sidelink failure report indicating the sidelink failure event to the target cell; wherein, in the case where the target cell is a new radio (NR) cell, the sidelink failure report is sent to the target cell via NR RRC signaling, in the case where the target cell is an evolved universal terrestrial radio access (E-UTRA) cell, the sidelink failure report is sent via E-UTRA RRC signaling, and the sidelink failure event includes a sidelink RRC reset failure event for a PC5-RRC connection between the UE and the associated sidelink destination UE or a sidelink radio link failure event for a PC5-RRC connection between the UE and the associated sidelink destination UE.

2. The UE according to claim 1, wherein the handover procedure is a radio access technology (RAT) handover procedure within radio, and both the source cell and the target cell belong to an evolved universal terrestrial radio access network (E-UTRAN) or a new radio radio access network (NR-RAN).

3. The UE according to claim 1, wherein the handover procedure is a radio access technology (RAT) inter-system handover procedure, one of the source cell and the target cell belongs to E-UTRAN, and the other of the source cell and the target cell belongs to NR-RAN.

4. The UE according to claim 1, wherein the sidelink failure report includes a failure cause indicating one of'sidelink RRC reset failure' and'sidelink radio link failure' and an identifier (ID) of the sidelink destination UE.

5. The UE according to claim 1, characterized in that, The computer-executable program, when executed via the memory, further causes the processor to: receive all configuration indicators in the first message; and determine to release the dedicated sidelink radio configuration associated with the sidelink destination UE in the case where the dedicated sidelink radio configuration was configured by the serving radio access network (RAN) via one or more UE-specific dedicated control signaling before receiving the first message.

6. The UE according to claim 5, wherein The computer-executable program, when executed via the memory, further causes the processor to: In the case where the dedicated sidelink radio configuration is not configured by the serving RAN via the one or more UE-specific dedicated control signaling before receiving the first message, determine not to release the dedicated sidelink radio configuration associated with the sidelink destination UE.

7. The UE according to claim 5, wherein the dedicated sidelink radio configuration includes a sidelink radio configuration for the UE to implement at least one of NR sidelink communication service and long-term evolution LTE vehicle-to-everything V2X sidelink communication service.

8. A method for sidelink failure management performed by a user equipment UE, the method comprising: receiving, from a source cell, a first message including sidelink radio resource control RRC configuration associated with a target cell; determining that a sidelink failure event associated with an associated sidelink destination UE has occurred; and after performing a handover procedure to hand over from the source cell to the target cell, sending a sidelink failure report indicating the sidelink failure event to the target cell; wherein, in the case where the target cell is a new radio NR cell, the sidelink failure report is sent to the target cell via NR RRC signaling, in the case where the target cell is an evolved universal terrestrial radio access E-UTRA cell, the sidelink failure report is sent via E-UTRA RRC signaling, and the sidelink failure event includes a sidelink RRC reset failure event for a PC5-RRC connection between the UE and the associated sidelink destination UE or a sidelink radio link failure event for a PC5-RRC connection between the UE and the associated sidelink destination UE.

9. The method according to claim 8, wherein the handover procedure is an intra-radio access technology RAT handover procedure, and both the source cell and the target cell belong to an evolved universal terrestrial radio access network E-UTRAN or a new radio radio access network NR-RAN.

10. The method according to claim 8, wherein the handover procedure is an inter-radio access technology RAT handover procedure, one of the source cell and the target cell belongs to E-UTRAN, and the other of the source cell and the target cell belongs to NR-RAN.

11. The method according to claim 8, wherein the sidelink failure report includes a failure cause indicating one of'sidelink RRC reset failure' and'sidelink radio link failure' and an identifier ID of the sidelink destination UE.

12. The method according to claim 8, characterized in that The method further includes: receiving all configuration indicators in the first message; and in the case where the dedicated sidelink radio configuration is configured by the serving radio access network RAN via one or more UE-specific dedicated control signaling before receiving the first message, determining to release the dedicated sidelink radio configuration associated with the sidelink destination UE.

13. The method according to claim 12, characterized in that, The method further includes: In the case where the dedicated sidelink radio configuration is not configured by the serving RAN via the one or more UE-specific dedicated control signaling before receiving the first message, it is determined not to release the dedicated sidelink radio configuration associated with the sidelink destination UE.

14. The method according to claim 12, wherein the dedicated sidelink radio configuration includes a sidelink radio configuration for the UE to implement at least one of NR sidelink communication service and long-term evolution (LTE) vehicle-to-everything (V2X) sidelink communication service.

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