Method and apparatus for operation in RLF detection in SL ca

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. A method and apparatus for UE operation when performing RLF detection in SL CA of a wireless communication system are provided. A method of operating a UE includes receiving configuration information related to a plurality of sidelink (SL) carriers for SL carrier aggregation (CA) operation from a base station (BS); releasing the SL carrier for a corresponding destination layer 2 identifier (L2ID) when a hybrid automatic repeat request (HARQ) feedback corresponding to the SL carrier among the plurality of SL carriers is not received N consecutive times and the SL carrier is not the last configured SL carrier; and releasing a PC5-Radio Resource Control (PC5-RRC) connection for the corresponding destination L2ID when the HARQ feedback corresponding to the SL carrier among the plurality of SL carriers is not received M consecutive times and the SL carrier is the last configured SL carrier.

Description

Technical Field

[0001] The present disclosure relates generally to wireless communication systems, and more particularly, to user equipment (UE) operations upon radio link failure (RLF) detection in sidelink (SL) carrier aggregation (CA) in wireless communication systems. Background Art

[0002] 5G mobile communication technology defines a wide frequency band, making high transmission rates and new services possible, and can be implemented not only in "sub-6 GHz" frequency bands such as 3.5 GHz, but also in "above 6 GHz" frequency bands (including 28 GHz and 39 GHz) called millimeter waves. In addition, 6G mobile communication technology (called super 5G system) has been considered to be implemented in terahertz frequency bands (such as 95 GHz to 3 THz bands) in order to achieve a transmission rate fifty times faster than 5G mobile communication technology and ultra-low latency that is one-tenth of 5G mobile communication technology.

[0003] At the beginning of the development of 5G mobile communication technology, in order to support services and meet the performance requirements related to enhanced mobile broadband (eMBB), ultra-reliable and low-latency communication (URLLC) and massive machine type communication (mMTC), standardization on beamforming and massive MIMO has been carried out to reduce radio wave path loss in millimeter waves and increase radio wave transmission distance, thereby supporting parameter sets for dynamic operation of millimeter wave resources and time slot formats for efficient utilization (for example, operating multiple subcarrier spacings), initial access technology for supporting multi-beam transmission and broadband, definition and operation of BWP (bandwidth part), new channel coding methods (such as LDPC (low-density parity check) codes for large-scale data transmission and polarization codes for high-reliability transmission of control information), L2 preprocessing, and network slicing for providing dedicated networks dedicated to specific services.

[0004] Currently, in view of the services supported by 5G mobile communication technology, discussions on the improvement and performance enhancement of initial 5G mobile communication technology are underway, and there is already physical layer standardization on the following technologies, for example, V2X (Vehicle-to-Everything) for assisting driving decisions by autonomous vehicles based on information about the location and status of the vehicle transmitted by the vehicle and for improving user convenience, NR-U (New Radio Unlicensed) for system operation designed to comply with various regulatory requirements in unlicensed bands, NR UE energy saving, and non-terrestrial network (NTN) for UE-satellite direct communication for providing coverage and positioning in areas where terrestrial network communications are not available.

[0005] In addition, the air interface architecture / protocols for the following technologies are being standardized, such as the Industrial Internet of Things (IIoT) for supporting new services through interworking and integration with other industries, IAB (Integrated Access and Backhaul) for providing nodes for network service area extension by supporting wireless backhaul links and access links in an integrated manner, mobility enhancement including conditional switching and DAPS (Dual Active Protocol Stack) switching, and two-step random access (2-step RACH for NR) for simplifying the random access process. The system architecture / services for the following technologies are also being standardized: 5G baseline architecture (e.g., service-based architecture or service-based interface) for combining network function virtualization (NFV) and software defined network (SDN) technologies, and mobile edge computing (MEC) for receiving services based on UE location.

[0006] With the commercialization of 5G mobile communication systems, the number of connected devices, which has been growing exponentially, will be connected to the communication network, and it is therefore expected that there will be a need to enhance the functions and performance of the 5G mobile communication systems and the integrated operations of the connected devices. To this end, new research is planned related to the following technologies: Extended Reality (XR) for effectively supporting AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality), etc., as well as 5G performance improvement and complexity reduction by utilizing artificial intelligence (AI) and machine learning (ML), AI service support, virtual world service support, and drone communication.

[0007] In addition, such developments in 5G mobile communication systems will serve as a foundation for developing new waveforms for providing coverage in the terahertz band for 6G mobile communication technology, multi-antenna transmission technologies such as full-dimensional MIMO (FD-MIMO), array antennas, and large antennas, metamaterial-based lenses and antennas for improving the coverage of terahertz band signals, high-dimensional spatial multiplexing technology using OAM (orbital angular momentum), RIS (reconfigurable smart surface), full-duplex technology for increasing the frequency efficiency of 6G mobile communication technology and improving system networks, AI-based communication technology for achieving system optimization by utilizing satellites and AI (artificial intelligence) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at a complexity level that exceeds the limits of UE operating capabilities by utilizing ultra-high-performance communication and computing resources. Summary of the invention

[0008] Technical issues

[0009] The present invention has solved at least the above problems and / or disadvantages and provides at least the advantages described below.Accordingly, one aspect of the present invention provides a method and apparatus for operation upon RLF detection in SL CA.

[0010] Solution to the problem

[0011] In one embodiment, a UE is provided. The UE includes a transceiver configured to receive configuration information about multiple SL carriers for SL CA operation from a base station (BS). The UE also includes a processor operably connected to the transceiver, the processor being configured to release the SL carrier for the corresponding destination layer 2 identifier (L2 ID) when a hybrid automatic repeat request (HARQ) feedback corresponding to a SL carrier among the multiple SL carriers is not received for N consecutive times and the SL carrier is not the last configured SL carrier; and to release the PC5-radio resource control (PC5-RRC) connection for the corresponding destination L2 ID when a HARQ feedback corresponding to a SL carrier among the multiple SL carriers is not received for M consecutive times and the SL carrier is the last configured SL carrier.

[0012] In another embodiment, a method of a UE is provided. The method includes: receiving configuration information about multiple SL carriers for SL CA operation from a BS; when HARQ feedback corresponding to a SL carrier among the multiple SL carriers is not received for N consecutive times and the SL carrier is not the last configured SL carrier, releasing the SL carrier for the corresponding destination L2 ID; and when HARQ feedback corresponding to a SL carrier among the multiple SL carriers is not received for M consecutive times and the SL carrier is the last configured SL carrier, releasing the PC5-RRC connection for the corresponding destination L2 ID.

[0013] In another embodiment, a BS is provided. The BS includes a processor configured to generate configuration information about multiple SL carriers. The BS also includes a transceiver operably connected to the processor, the transceiver configured to transmit configuration information for SL CA operation to the UE, wherein: when HARQ feedback corresponding to a SL carrier among multiple SL carriers is not received for N consecutive times and the SL carrier is not the last configured SL carrier, the SL carrier for the corresponding destination L2 ID is released; and when HARQ feedback corresponding to a SL carrier among multiple SL carriers is not received for M consecutive times and the SL carrier is the last configured SL carrier, the PC5-RRC connection for the corresponding destination L2 ID is released.

[0014] Other technical features may be apparent to those skilled in the art from the following drawings, descriptions and claims.

[0015] Before the following detailed description, it may be advantageous to set forth the definitions of certain words and phrases used throughout this patent document.The term "connection" and its derivatives refer to any direct or indirect communication between two or more elements, regardless of whether these elements are in physical contact with each other.The terms "transmit", "receive" and "communication" and their derivatives cover both direct and indirect communication.The terms "include" and "include" and their derivatives mean to include but are not limited to.The term "or" is inclusive, meaning and / or.The phrase "associated with ... " and its derivatives mean to include, be included in ..., interconnect with ..., include, be included in ..., be connected to ... or be connected with ..., be connected to ... or be connected with ..., can communicate with ..., collaborate with ..., interlace, parallel, with ..., be adjacent to ..., be combined to ... or be combined with ..., have, have ... characteristic, have a relationship with ... or have a relationship with ... etc.The term "controller" refers to any device, system or part thereof that controls at least one operation.Such a controller can be implemented with hardware or a combination of hardware and software and / or firmware. The functionality associated with any particular controller may be centralized or distributed, whether local or remote. The phrase "at least one of" when used with a list of items means that different combinations of one or more of the listed items may be used, and only one item in the list may be required. For example, "at least one of A, B, and C" includes any of the following combinations: A; B; C; A and B; A and C; B and C; and A and B and C.

[0016] In addition, the various functions described below can be implemented or supported by one or more computer programs, each of which is formed by a computer-readable program code and embedded in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, instruction sets, processes, functions, objects, classes, instances, related data or a part thereof suitable for implementation with a suitable computer-readable program code. The phrase "computer-readable program code" includes any type of computer code, including source code, object code and executable code. The phrase "computer-readable medium" includes any type of medium that can be accessed by a computer, such as a read-only memory (ROM), a random access memory (RAM), a hard drive, a compact disc (CD), a digital video disc (DVD) or any other type of memory. "Non-transitory" computer-readable medium excludes wired, wireless, optical or other communication links that transmit instantaneous electrical signals or other signals. Non-transitory computer-readable media include media that can permanently store data, and media that can store data and rewrite data later, such as rewritable optical discs or erasable memory devices.

[0017] Definitions for certain other words and phrases are provided throughout this patent document. Those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.

[0018] Advantageous Effects of the Invention

[0019] Advantages and salient features of the present invention will be apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the accompanying drawings, discloses exemplary embodiments of the present invention. To further enhance communication systems, a method and apparatus for operation during RLF detection in SL CA is needed. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts:

[0021] Figure 1 An example of a wireless network according to an embodiment of the present disclosure is shown;

[0022] Figure 2 An example of a gNB according to an embodiment of the present disclosure is shown;

[0023] Figure 3 An example of a UE according to an embodiment of the present disclosure is shown;

[0024] Figure 4 shows examples of wireless transmit and receive paths according to the present disclosure;

[0025] Figure 5 shows examples of wireless transmit and receive paths according to the present disclosure;

[0026] Figure 6 An example of V2X communication over SL according to an embodiment of the present invention is shown;

[0027] Fig. 7A An example of SL control and user plane radio protocol stack is shown;

[0028] Figure 7B An example of SL control and user plane radio protocol stack is shown;

[0029] Fig. 8A shows a signaling flow for RLF operation in SL CA according to an embodiment of the present disclosure;

[0030] Figure 8B shows a signaling flow for RLF operation in SL CA according to an embodiment of the present disclosure;

[0031] Fig. 9A flowchart of a method of a UE according to an embodiment of the present disclosure is shown;

[0032] Fig. 10A shows a signaling flow for HARQ-based SL RLF detection in SL CA according to an embodiment of the present disclosure;

[0033] Fig. 10B shows a signaling flow for HARQ-based SL RLF detection in SL CA according to an embodiment of the present disclosure;

[0034] Fig.11A Another signaling flow for HARQ-based SL RLF detection in SL CA according to an embodiment of the present disclosure is shown;

[0035] Fig. 11B Another signaling flow for HARQ-based SL RLF detection in SL CA according to an embodiment of the present disclosure is shown;

[0036] Fig.12 A flowchart showing a method of a UE according to an embodiment of the present disclosure; and

[0037] Fig.13 A flowchart of a method for UE operation upon RLF detection in SL CA according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0038] Before the following detailed description, it may be advantageous to set forth the definitions of certain words and phrases used throughout this patent document.The term "connection" and its derivatives refer to any direct or indirect communication between two or more elements, regardless of whether these elements are in physical contact with each other.The terms "transmit", "receive" and "communication" and their derivatives cover both direct and indirect communication.The terms "include" and "comprising" and their derivatives mean including but not limited to.The term "or" is inclusive, meaning and / or.The phrase "associated with..." and its derivatives mean including, included in, interconnected with, included in, included in, connected to, or connected with, connected to, or connected with, can communicate with, collaborate with, interlace, parallel, adjacent to, coupled to, or coupled with, have, have characteristics, have a relationship with, or have a relationship with, etc.The term "controller" refers to any device, system or part thereof that controls at least one operation.Such a controller can be implemented in hardware or a combination of hardware and software and / or firmware.The function associated with any particular controller can be centralized or distributed, whether local or remote. The phrase "at least one of" when used with a list of items means that different combinations of one or more of the listed items may be used, and only one item in the list may be required. For example, "at least one of A, B, and C" includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C.

[0039] In addition, the various functions described below can be implemented or supported by one or more computer programs, each of which is formed by a computer-readable program code and embodied in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, instruction sets, processes, functions, objects, classes, instances, related data or a part thereof suitable for implementation with a suitable computer-readable program code. The phrase "computer-readable program code" includes any type of computer code, including source code, object code and executable code. The phrase "computer-readable medium" includes any type of medium that can be accessed by a computer, such as a read-only memory (ROM), a random access memory (RAM), a hard drive, a compact disc (CD), a digital video disc (DVD) or any other type of memory. "Non-transitory" computer-readable media excludes wired, wireless, optical or other communication links that transmit instantaneous electrical signals or other signals. Non-transitory computer-readable media include media that can permanently store data, and media that can store data and rewrite data later, such as rewritable optical discs or erasable memory devices.

[0040] Definitions for certain other words and phrases are provided throughout this patent document. Those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.

[0041] Discussed below Figures 1 to 13 The various embodiments used to describe the principles of the present disclosure in this patent document are for illustration only and should not be interpreted in any way as limiting the scope of the present disclosure. Those skilled in the art will appreciate that the principles of the present disclosure can be implemented in any appropriately arranged system or device.

[0042] The following documents are hereby incorporated by reference into the present disclosure as if fully set forth herein: 3GPP TS 38.321 v17.0.0, "NR; Medium Access Control (MAC) Protocol Specification"; 3GPP TS 38.331 v17.0.0, "NR Radio Resource Control (RRC) Protocol Specification"; 3GPP TS 38.300 v17.0.0, "NR and NG-RAN Overall Description Stage 2"; 3GPP TR 38.885 v16.0.0, "NR Vehicle-to-Everything (V2X) Study"; 3GPP TS 23.303 v17.0.0, "Proximity-based Services (ProSe), Stage 2"l and 3GPP TS 23.287 v17.2.0, "Architecture Enhancements for 5G System (5GS) to Support Vehicle-to-Everything (V2X) Services."

[0043] In order to meet the increased demand for wireless data traffic since the deployment of 4G communication systems and to realize various vertical applications, 5G / NR communication systems have been deployed and are currently being deployed. 5G / NR communication systems are considered to be implemented in higher frequency (millimeter wave) bands (e.g., 28 GHz or 60 GHz bands) to achieve higher data rates, or in lower frequency bands (such as 6 GHz) to achieve robust coverage and mobility support. In order to reduce the propagation loss of radio waves and increase the transmission distance, beamforming, massive multiple-input multiple-output (MIMO), omnidirectional MIMO (FD-MIMO), array antennas, analog beamforming, and large antenna technology are discussed in 5G / NR communication systems.

[0044] In addition, in the 5G / NR communication system, development of system network improvements is underway based on advanced small cells, cloud radio access networks (RAN), ultra-dense networks, device-to-device (D2D) communications, wireless backhaul, mobile networks, cooperative communications, coordinated multi-point (CoMP), receiving-end interference cancellation, etc.

[0045] The discussion of 5G systems and frequency bands associated therewith is for reference purposes only, as certain embodiments of the present disclosure may be implemented in 5G systems. However, the present disclosure is not limited to 5G systems or frequency bands associated therewith, and embodiments of the present disclosure may be used in conjunction with any frequency band. For example, aspects of the present disclosure may also be applied to 5G communication systems, 6G, or even higher deployments that may use terahertz (THz) bands.

[0046] the following Figures 1 to 3 Various embodiments are described that are implemented in a wireless communication system and utilizing Orthogonal Frequency Division Multiplexing (OFDM) or Orthogonal Frequency Division Multiple Access (OFDMA) communication techniques. Figures 1 to 3 The description is not intended to imply physical or architectural limitations to the manner in which different embodiments may be implemented. Different embodiments of the present disclosure may be implemented in any suitably arranged communications system.

[0047] Figure 1 An exemplary wireless network according to an embodiment of the present disclosure is shown. Figure 1 The embodiment of the wireless network shown in FIG. 1 is for illustration only. Other embodiments of the wireless network 100 may be used without departing from the scope of the present disclosure.

[0048] like Figure 1 As shown, the wireless network includes gNB 101 (e.g., base station, BS), gNB 102, and gNB 103. gNB 101 communicates with gNB 102 and gNB 103. gNB 101 also communicates with at least one network 130 such as the Internet, a proprietary Internet Protocol (IP) network, or other data network.

[0049] The gNB 102 provides wireless broadband access to a network 130 for a plurality of first user equipments (UEs) located within a coverage area 120 of the gNB 102. The plurality of first UEs include: a UE 111, which may be located in a small business; a UE 112, which may be located in an enterprise; a UE 113, which may be a WiFi hotspot; a UE 114, which may be located in a first residence; a UE 115, which may be located in a second residence; and a UE 116, which may be a mobile device such as a cellular phone, a wireless laptop, or a wireless PDA. The gNB 103 provides wireless broadband access to the network 130 for a plurality of second UEs within a coverage area 125 of the gNB 103. The plurality of second UEs include UE 115 and UE 116. In some embodiments, one or more of the gNBs 101 to 103 may communicate with each other and with the UEs 111 to 116 using 5G / NR, long term evolution (LTE), long term evolution advanced (LTE-A), WiMAX, WiFi, or other wireless communication technologies.

[0050] In another example, UE 116 may be within network coverage and another UE may be outside network coverage (e.g., UEs 111A to 111C). In yet another example, both UEs are outside network coverage. In some embodiments, one or more of gNBs 101 to 103 may communicate with each other and with UEs 111-116 using 5G / NR, LTE, LTE-A, WiMAX, WiFi, or other wireless communication technologies. In some embodiments, UEs 111 to 116 may communicate using a device-to-device (D2D) interface referred to as PC5 (e.g., also referred to as a sidelink at the physical layer).

[0051] Depending on the network type, the term "base station" or "BS" may refer to any component (or set of components) configured to provide wireless access to a network, such as a transmission point (TP), a transmission-reception point (TRP), an enhanced base station (eNodeB or eNB), a 5G / NR base station (gNB), a macro base station, a femto base station, a WiFi access point (AP), or other devices with wireless functions. The base station may provide wireless access according to one or more wireless communication protocols, for example, 5G / NR Third Generation Partnership Project (3GPP) NR, Long Term Evolution (LTE), LTE Advanced (LTE-A), High Speed ​​Packet Access (HSPA), Wi-Fi 802.11a / b / g / n / ac, etc. For convenience, the terms "BS" and "TRP" are used interchangeably in this patent document to refer to network infrastructure components that provide wireless access to remote terminals. In addition, depending on the network type, the term "user equipment" or "UE" may refer to any component such as a "mobile station", "subscriber station", "remote terminal", "wireless terminal", "reception point" or "user device". For convenience, the terms "user equipment" and "UE" are used in this patent document to refer to a remote wireless device that wirelessly accesses a BS, whether the UE is a mobile device (such as a mobile phone or smartphone) or is generally considered a fixed device (such as a desktop computer or vending machine).

[0052] The dashed lines illustrate the approximate extents of coverage areas 120 and 125, which are shown as generally circular for purposes of illustration and explanation only. It should be clearly understood that coverage areas associated with a gNB, such as coverage areas 120 and 125, may have other shapes, including irregular shapes, depending on the configuration of the gNB and variations in the radio environment associated with natural and man-made obstacles.

[0053] As described in more detail below, one or more of the UEs 111 to 116 include circuitry, programming, or a combination thereof for UE operation upon RLF detection in SL CA in a wireless communication system. In certain embodiments, and one or more of the gNBs 101 to 103 include circuitry, programming, or a combination thereof for supporting UE operation upon RLF detection in SL CA in a wireless communication system.

[0054] Although Figure 1 An example of a wireless network is shown, but Figure 1 Various changes may be made. For example, the wireless network may include any number of gNBs and any number of UEs in any suitable arrangement. In addition, gNB 101 may communicate directly with any number of UEs and provide those UEs with wireless broadband access to network 130. Similarly, gNBs 102 to 103 may each communicate directly with network 130 and provide UEs with direct wireless broadband access to network 130. In addition, gNBs 101, 102, and / or 103 may provide access to other or additional external networks, such as an external telephone network or other type of data network.

[0055] As discussed in more detail below, the wireless network 100 may have communications facilitated via one or more devices (e.g., UEs 111A to 111C) that may perform SL communications with UE 111. For example, where UEs 111A to 111C are remotely located or otherwise require the assistance of a network access connection (e.g., BS 102) other than a conventional fronthaul and / or backhaul connection / interface, UE 111 may communicate directly with UEs 111A to 111C via a set of SLs (e.g., SL interfaces) to provide sideline communications. In one example, UE 111 may perform direct communications with UEs 111A to 111C via SL communications with or without BS 102 support. Various UEs (e.g., as depicted by UEs 112 to 116) may be able to communicate one or more times with their other UEs (such as UEs 111A to 111C for UE 111).

[0056] Figure 2 An exemplary gNB 102 according to an embodiment of the present disclosure is shown. Figure 2 The embodiment of gNB 102 shown is for illustration only, and Figure 1 gNBs 101 and 103 may have the same or similar configurations. However, gNBs have a wide variety of configurations, and Figure 2 The scope of this disclosure is not limited to any particular implementation of the gNB.

[0057] like Figure 2As shown, the gNB 102 includes multiple antennas 205a to 205n, multiple transceivers 210a to 210n, a controller / processor 225, a memory 230, and a backhaul or network interface 235.

[0058] RF transceivers 210a to 210n receive incoming RF signals from antennas 205a to 205n, such as signals transmitted by UEs in network 100. Transceivers 210a to 210n downconvert incoming RF signals to generate IF or baseband signals. The IF or baseband signals are processed by receive (RX) processing circuitry in transceivers 210a to 210n and / or controller / processor 225, which generates processed baseband signals by filtering, decoding, and / or digitizing the baseband or IF signals. Controller / processor 225 may further process the baseband signals.

[0059] Transmit (TX) processing circuitry in the transceivers 210a-210n and / or the controller / processor 225 receives analog or digital data (such as voice data, network data, email, or interactive video game data) from the controller / processor 225. The TX processing circuitry encodes, multiplexes, and / or digitizes the outgoing baseband data to generate processed baseband or IF signals. The transceivers 210a-210n up-convert the baseband or IF signals into RF signals that are transmitted via the antennas 205a-205n.

[0060] The controller / processor 225 may include one or more processors or other processing devices that control the overall operation of the gNB 102. For example, the controller / processor 225 may control the reception of UL channel signals and the transmission of DL channel signals by the transceivers 210a to 210n in accordance with well-known principles. The controller / processor 225 may also support additional functionality, such as more advanced wireless communication functionality. For example, the controller / processor 225 may support beamforming or directional routing operations, in which outgoing / incoming signals from / to multiple antennas 205a to 205n are weighted differently to effectively direct the outgoing signals in a desired direction. Any of a variety of other functions may be supported in the gNB 102 by the controller / processor 225.

[0061] The controller / processor 225 is also capable of executing programs and other processes, such as an OS, residing in the memory 230. The controller / processor 225 may move data into or out of the memory 230 as required by the executed process. The controller / processor 225 is also capable of executing programs and other processes residing in the memory 230, such as processes for supporting UE operations at the time of RLF detection in SLCA in a wireless communication system.

[0062] The controller / processor 225 is also connected to a backhaul or network interface 235. The backhaul or network interface 235 allows the gNB 102 to communicate with other devices or systems via a backhaul connection or via a network. The interface 235 can support communication via any appropriate wired or wireless connection. For example, when the gNB 102 is implemented as part of a cellular communication system (such as a cellular communication system supporting 5G / NR, LTE, or LTE-A), the interface 235 can allow the gNB 102 to communicate with other gNBs via a wired or wireless backhaul connection. When the gNB 102 is implemented as an access point, the interface 235 can allow the gNB 102 to communicate with a larger network (such as the Internet) via a wired or wireless local area network or via a wired or wireless connection. The interface 235 includes any suitable structure that supports communication via a wired or wireless connection (such as Ethernet or a transceiver).

[0063] Memory 230 is connected to controller / processor 225. A portion of memory 230 may include RAM, and another portion of memory 230 may include flash memory or other ROM.

[0064] Although Figure 2 An example of a gNB 102 is shown, but the Figure 2 For example, gNB 102 may include any number of Figure 2 Each component shown. In addition, Figure 2 The various components in may be combined, further subdivided, or omitted, and additional components may be added according to specific needs.

[0065] Figure 3 An exemplary UE 116 is shown in accordance with an embodiment of the present disclosure. Figure 3 The embodiment of UE 116 shown is for illustration only, and Figure 1 UEs 111 to 115 may have the same or similar configurations. However, UEs have a wide variety of configurations, and Figure 3 The scope of the present disclosure is not limited to any particular implementation of the UE.

[0066] like Figure 3 As shown, UE 116 includes antenna 305, transceiver 310, and microphone 320. UE 116 also includes speaker 330, processor 340, input / output (I / O) interface (IF) 345, input 350, display 355, and memory 360. Memory 360 includes operating system (OS) 361 and one or more applications 362.

[0067] RF transceiver 310 receives an incoming RF signal transmitted by a gNB of network 100 or by another UE (e.g., one or more of UEs 111 to 115) on a SL channel from antenna 305. Transceiver 310 downconverts the incoming RF signal to generate an intermediate frequency (IF) or baseband signal. The IF or baseband signal is processed by RX processing circuitry in transceiver 310 and / or processor 340, which generates a processed baseband signal by filtering, decoding, and / or digitizing the baseband or IF signal. The RX processing circuitry sends the processed baseband signal to speaker 330 (such as for voice data) or is processed by processor 340 (such as for web browsing data).

[0068] The TX processing circuitry in the transceiver 310 and / or processor 340 receives analog or digital voice data from the microphone 320 or other outgoing baseband data (such as web data, email, or interactive video game data) from the processor 340. The TX processing circuitry encodes, multiplexes, and / or digitizes the outgoing baseband data to generate a processed baseband or IF signal. The transceiver 310 up-converts the baseband or IF signal to an RF signal that is transmitted via the antenna 305.

[0069] The processor 340 may include one or more processors or other processing devices and executes the OS 361 stored in the memory 360 to control the overall operation of the UE 116. For example, the processor 340 may control the reception of DL and / or SL channels and / or signals and the transmission of UL and / or SL channels and / or signals by the transceiver 310 according to well-known principles. In some embodiments, the processor 340 includes at least one microprocessor or microcontroller.

[0070] The processor 340 is capable of executing other processes and programs resident in the memory 360, such as processes for UE operation at the time of RLF detection in SL CA in a wireless communication system. The processor 340 can move data into or out of the memory 360 as needed to execute the process. In some embodiments, the processor 340 is configured to execute the application 362 based on the OS 361 or in response to a signal received from the gNB or operator. The processor 340 is also connected to the I / O interface 345, which provides the UE 116 with the ability to connect to other devices such as laptops and handheld computers. The I / O interface 345 is a communication path between these accessories and the processor 340.

[0071] Processor 340 is also connected to input 350 (which includes, for example, a touch screen, a keypad, etc.) and display 355. An operator of UE 116 may use input 350 to enter data into UE 116. Display 355 may be a liquid crystal display, a light emitting diode display, or other display capable of presenting text and / or at least limited graphics (such as from a website).

[0072] The memory 360 is connected to the processor 340. A portion of the memory 360 may include a random access memory (RAM), and another portion of the memory 360 may include a flash memory or other read-only memory (ROM).

[0073] Although Figure 3 An example of UE 116 is shown, but the Figure 3 Make various changes. For example, Figure 3 The various components in may be combined, further subdivided, or omitted, and additional components may be added as required. As a specific example, processor 340 may be divided into multiple processors, such as one or more central processing units (CPUs) and one or more graphics processing units (GPUs). In another example, transceiver 310 may include any number of transceivers and signal processing chains and may be connected to any number of antennas. Additionally, although Figure 3 The UE 116 is shown configured as a mobile phone or smart phone, but the UE may be configured to operate as other types of mobile or stationary devices.

[0074] Figure 4 and Figure 5 Exemplary wireless transmit and receive paths according to the present disclosure are shown. In the following description, the transmit path 400 may be described as being implemented in a gNB (such as, gNB 102), and the receive path 500 may be described as being implemented in a UE (such as, UE 116). However, it is understood that the receive path 500 may be implemented in the gNB and the transmit path 400 may be implemented in the UE. It is also understood that the receive path 500 may be implemented in a first UE and the transmit path 400 may be implemented in a second UE to support SL communications. In some embodiments, the receive path 500 is configured to support operations upon RLF detection in SL CA in a wireless communication system, as described in embodiments of the present disclosure.

[0075] like Figure 4 The transmit path 400 shown includes a channel coding and modulation block 405, a serial to parallel (S to P) block 410, an inverse fast Fourier transform (IFFT) block of size N 415, a parallel to serial (P to S) block 420, an add cyclic prefix block 425, and an upconverter (UC) 430. Figure 5The illustrated receive path 500 includes a downconverter (DC) 555, a remove cyclic prefix block 560, a serial to parallel (S to P) block 565, a size N fast Fourier transform (FFT) block 570, a parallel to serial (P to S) block 575, and a channel decoding and demodulation block 580.

[0076] like Figure 4 As shown, the channel coding and modulation block 405 receives a set of information bits, applies coding (such as, low-density parity check (LDPC) coding) and modulates the input bits (such as, with orthogonal phase shift keying (QPSK) or orthogonal amplitude modulation (QAM)) to generate a sequence of frequency-domain modulation symbols.

[0077] The serial to parallel block 410 converts (such as demultiplexes) the serially modulated symbols into parallel data to generate N parallel symbol streams, where N is the IFFT / FFT size used in the gNB 102 and the UE 116. The size N IFFT block 415 performs an IFFT operation on the N parallel symbol streams to generate a time domain output signal. The parallel to serial block 420 converts (such as multiplexes) the parallel time domain output symbols from the size N IFFT block 415 to generate a serial time domain signal. The add cyclic prefix block 425 inserts a cyclic prefix into the time domain signal. The up-converter 430 modulates (such as up-converts) the output of the add cyclic prefix block 425 to an RF frequency for transmission via a wireless channel. The signal may also be filtered at baseband before conversion to RF frequency.

[0078] The RF signal transmitted from gNB 102 reaches UE 116 after passing through the wireless channel, and an operation opposite to the operation at gNB 102 is performed at UE 116. The RF signal transmitted from the first UE reaches the second UE after passing through the wireless channel, and an operation opposite to the operation at the first UE is performed at the second UE.

[0079] like Figure 5 As shown, the down converter 555 down-converts the received signal to the baseband frequency, and the remove cyclic prefix block 560 removes the cyclic prefix to generate a serial time domain baseband signal. The serial to parallel block 565 converts the time domain baseband signal to a parallel time domain signal. The size N FFT block 570 performs an FFT algorithm to generate N parallel frequency domain signals. The parallel to serial block 575 converts the parallel frequency domain signals into a sequence of modulated data symbols. The channel decoding and demodulation block 580 demodulates and decodes the modulated symbols to recover the original input data stream.

[0080] Each of gNBs 101 to 103 may implement a similar method as that for transmitting in the downlink to UEs 111 to 116. Figure 4The transmission path 400 shown in FIG. 4 and may be implemented similarly to the transmission path 400 received from UEs 111 to 116 in the uplink. Figure 5 Receive path 500 is shown. Similarly, each of UEs 111 to 116 may implement transmit path 400 for transmitting to gNBs 101 to 103 in an uplink and / or to another UE in a sidelink, and may implement receive path 500 for receiving from gNBs 101 to 103 in a downlink and / or from another UE in a sidelink.

[0081] Can be implemented using hardware only or a combination of hardware and software / firmware Figure 4 and Figure 5 As a specific example, Figure 4 and Figure 5 At least some of the components in can be implemented with software, while other components can be implemented by configurable hardware or a mixture of software and configurable hardware. For example, FFT block 570 and IFFT block 515 can be implemented as a configurable software algorithm, wherein the value of size N can be modified according to the implementation.

[0082] In addition, although described as using FFT and IFFT, this is only by way of illustration and should not be construed as limiting the scope of the present disclosure. Other types of transforms may be used, such as discrete Fourier transform (DFT) and inverse discrete Fourier transform (IDFT) functions. It will be appreciated that the value of the variable N may be any integer (such as 1, 2, 3, 4, etc.) for the DFT and IDFT functions, while the value of the variable N may be any integer (such as 1, 2, 4, 8, 16, etc.) as a power of two for the FFT and IFFT functions.

[0083] although Figure 4 and Figure 5 Examples of wireless transmit and receive paths are shown, but Figure 4 and Figure 5 Make various changes. For example, Figure 4 and Figure 5 The various components in the can be combined, further subdivided or omitted, and additional components can be added according to specific needs. Figure 4 and Figure 5 It is intended to illustrate examples of the types of transmit and receive paths that may be used in a wireless network. Any other suitable architecture may be used to support wireless communications in a wireless network.

[0084] In the 3GPP wireless standards, New Radio Access Technology (NR) has been specified as 5G wireless communications. One of the NR features is Vehicle-to-Everything (V2X).

[0085] Figure 6An example of V2X communication on the SL 600 according to an embodiment of the present invention is shown. Figure 6 The embodiment of V2X communication on the SL600 shown in FIG. 1 is for illustration only.

[0086] Figure 6 Describes an exemplary scenario of vehicle-to-vehicle communication. Two or more vehicles can transmit and receive data / control via a direct link / interface between vehicles. The direct link / interface between vehicles or between vehicles and other objects is named SL in 3GPP, so "SL communication" is often used instead of "V2X communication".

[0087] It should be noted that Figure 6 Describes a scenario where the vehicle can still communicate with the gNB in ​​order to obtain SL resources, SL radio bearer configuration, etc., however, even without interacting with the gNB, the vehicles can still communicate with each other via SL. In this case, the SL resources, SL radio bearer configuration, etc. are pre-configured (e.g., via a V2X server or any other core network entity).

[0088] One of the main differences compared to the uplink (UL) from the UE to the gNB is the resource allocation mechanism for transmission. In UL, the resources for transmission are allocated by the gNB, whereas in SL, if multiple SL resource pools are configured, based on the UE's channel sensing results and the amount of resources required for data / control transmission, the UE itself selects resources within the SL resource pool, which is configured by the gNB and selected by the UE.

[0089] For SL communication, the radio interface L1 / L2 / L3 (Layer 1 / Layer 2 / Layer 3) protocol consists of the physical protocol (PHY), specified in 3GPP standards TS 38.211, 38.212, 38.213, 38.214 and 38.215), the medium access control (MAC), specified in 3GPP standard TS 38.321), the radio link control (RLC), specified in 3GPP standard TS 38.322), the packet data convergence protocol (PDCP), specified in 3GPP standard TS 38.323), the radio resource control (RRC), specified in 3GPP standard TS38.331), and the service data adaptation protocol (SDAP), specified in 3GPP standard TS 37.324).

[0090] Fig. 7A and Figure 7B An example of SL control and user plane radio protocol stack according to an embodiment of the present disclosure is shown. Fig. 7A An embodiment of the SL control and user plane radio protocol stack shown in (700A) and Figure 7BThe embodiment of the SL control and user plane radio protocol stack shown in (700B) is for illustration only.

[0091] Fig. 7A An example of a SL control plane radio protocol stack (for SL-RRC) is shown and Figure 7B An example of an SL user plane data radio protocol stack for NR SL communications is shown.

[0092] The physical protocol layer processes physical layer signals / channels and physical layer processes (e.g., physical layer channel structure, physical layer signal encoding / decoding, SL power control process, SL channel state information (CSI) related process).

[0093] The main physical SL channels and signals are defined as follows: (1) The physical sidelink control channel (PSCCH) indicates the resources and other transmission parameters used by the UE for PSSCH; (2) The physical sidelink shared channel (PSSCH) transmits the TB of the data itself and CSI feedback information, etc.; (3) The physical sidelink feedback channel (PSFCH) transmits HARQ feedback from the UE that is the intended recipient of the PSSCH transmission to the UE that performs the transmission via the sidelink; (4) The sidelink synchronization signal includes the sidelink primary synchronization signal and the sidelink secondary synchronization signal (S-PSS, S-SSS); and (5) The physical sidelink broadcast channel (PSBCH) indicates the basic system information required for SL operation.

[0094] The MAC protocol layer performs packet filtering (e.g., determining whether a received packet is actually destined for the UE (based on the L2 source and destination ids in the MAC header), SL carrier / resource pool / resource (re)selection within a resource pool, priority handling between SL and UL for a given UE, SL logical channel priority, corresponding packet multiplexing (e.g., multiplexing multiple MAC SDUs into a given MAC PDU), and SL HARQ retransmission / reception. The RLC protocol layer performs RLC SDU segmentation / SDU reassembly, re-segmentation of RLC SDU segments, and error correction through ARQ (for AM data transmission only).

[0095] The PDCP protocol layer performs header compression / decompression, encryption and / or integrity protection, duplicate detection, reordering and in-sequence packet delivery to upper layers and out-of-sequence packet delivery to upper layers. The RRC protocol layer performs the transmission of SL-RRC messages between peer UEs, also known as PC5-RRC (PC5 indicates a reference point for SL communication between UEs), maintenance and release of the SL-RRC connection between two UEs, and detection of SL radio link failure of the SL-RRC connection. The SDAP protocol layer performs mapping between QoS (Quality of Service) processes and SL data radio bearers. It should be noted that the terms SL-RRC or PC5-RRC are used in the present disclosure.

[0096] In 3GPP Rel-18, more features are planned to be introduced into SL communication, and one of the candidate features is to enable carrier aggregation (CA) in SL communication. CA is a mechanism to transmit and / or receive control / data through multiple carriers. In Release-17 SL communication, for SL unicast (UC), a PC5-RRC connection is established between two UEs. The PC5-RRC connection is a logical connection between two UEs for a pair of source and destination layer-2 IDs, which is considered to be established after the corresponding PC5 unicast link is established as specified in the 3GPP standard specification.

[0097] For each PC5-RRC connection for unicast, one sidelink SRB (i.e., SL-SRB0) is used to transmit PC5-S messages before PC5-S security has been established. One sidelink SRB (i.e., SL-SRB1) is used to transmit PC5-S messages to establish PC5-S security. One sidelink SRB (i.e., SL-SRB2) is used to transmit protected PC5-S messages after PC5-S security has been established. One sidelink SRB (i.e., SL-SRB3) is used to transmit protected PC5-RRC signaling that is sent only after PC5-S security has been established. There is a one-to-one correspondence between PC5-RRC connections and PC5 unicast links. A UE can have multiple PC5-RRC connections with one or more UEs for different pairs of source and destination layer-2 IDs. Separate PC5-RRC procedures and messages are used for UEs to transmit UE capabilities and sidelink configurations to peer UEs, as specified in the 3GPP standard specifications.

[0098] Two peer UEs may exchange their own UE capabilities and sidelink configurations in both sidelink directions using separate bidirectional procedures. If SL RLF on the PC5-RRC connection is declared, the UE releases the PC5-RRC connection. SL RLF may be detected in the MAC based on HARQ feedback as specified in the 3GPP standard specification.

[0099] The HARQ-based sidelink RLF detection procedure is used to detect the sidelink RLF based on the number of consecutive DTX on PSFCH reception occasions for the PC5-RRC connection.

[0100] RRC configures the following parameters to control HARQ-based sidelink RLF detection: (1) sl-maxNumConsecutiveDTX.

[0101] The following UE variables are used for HARQ-based sidelink RLF detection: (1) numConsecutiveDTX, which is maintained for each PC5-RRC connection.

[0102] For each PC5-RRC connection (if any) that has been established by upper layers, the sidelink HARQ entity shall (re)initialize numConsecutiveDTX to zero when establishing the PC5-RRC connection or (re)configuring sl-maxNumConsecutiveDTX.

[0103] Table 1 shows the HARQ-based side link RLF detection specified in the 3GPP standard specification.

[0104] Table 1. HARQ-based sidelink RLF detection

[0105]

[0106] In addition, if the following conditions specified in the 3GPP standard specification (as shown in Table 2) are met, SL RLF can be detected in RRC.

[0107] Table 2. Conditions used for SL RLF

[0108]

[0109]

[0110] Once RRC detects SL RLF or RRC receives HARQ-based sidelink RLF detection from MAC, RRC performs the following operations specified in the 3GPP standard specification, as shown in Table 3.

[0111] Table 3. RRC operations

[0112]

[0113] It should be noted that the SL specific MAC reset is defined as shown in Table 4.

[0114] Table 4. SL specific MAC resets

[0115]

[0116] Fig. 8A and Figure 8B 1400 shows signaling flows 800 and 850 for RLF operation in SL CA according to an embodiment of the present disclosure. Figure 1 111 to 116) and BS (e.g., as shown Figure 1 101 to 103) shown in the figure are executed. Fig. 8A and Figure 8B The illustrated embodiments of signaling flows 800 and 850 are for illustration only. Fig. 8A and Figure 8B One or more of the components shown may be implemented in dedicated circuitry configured to perform the functions described, or one or more of the components may be implemented by one or more processors executing instructions to perform the functions described. Figure 8B Connect to Fig. 8A .

[0117] In one embodiment, RLF operation in SL CA is provided. Fig. 8A and Figure 8B An example of an embodiment of RLF operation in SL CA is described. The SL UE (801) is configured for transmission. The SL UE (803) is configured for reception, and the serving gNB (805) and core network (CN, 807) entities of the UE (801) are responsible for SL pre-configuration. The CN 807 configures the SL UE (801) with a carrier list (or L2 destination id / a pair of source and destination) for a given service type via SL pre-configuration (811). If the SL UE (801) is interested in SL unicast (UC) communication with the SL UE (803), a PC5-RRC connection establishment procedure is performed between the SL UE (801) and the SL UE (803) in 821.

[0118] Once the PC5-RRC connection is established, the SL UE (801) may send an RRCReconfigurationSidelink PC5-RRC message to the SL UE (803) to configure the SL CA carrier (833) for a specific destination (or a specific source and destination pair, or a specific PC5-RRC connection). It includes information of the SL carrier (e.g., frequency information of SL carriers #1, #2, and #3) and a corresponding L2 destination id / index for a pair of source and destination id / index for the PC5-RRC connection. When the SL CA carrier in 833 is configured as successful (835), the SL UE (803) sends an RRCReconfigurationCompleteSidelink PC5-RRC message to the SL UE (801).

[0119] It should be noted that if the SL UE (801) is in the RRC connected state and / or the SL UE (801) is in mode 1 operation / resource allocation for SL transmission, the gNB (805) may configure the SL CA carrier for a specific destination (or a specific source and destination pair, or a specific PC5-RRC connection) before the 833 and 835 processes in 831. In this case, the configuration of the SL CA carrier in 833 may be the same as that in 831.

[0120] Once processes 833 and 835 are successfully completed, the SL UE (801) may transmit data and / or control information through multiple SL carriers configured from 833 (in 841). The SL UE (803) may also monitor only the reception of data and / or control information on multiple SL carriers configured from 833. It should be noted that the list of SL carriers used for a specific destination (or a specific source and destination pair, or a specific PC5-RRC connection) in 811 and 833 may not be exactly the same. For example, the list of SL carriers in 833 may be a subset of the list of SL carriers in 811. In this case, for transmission and reception in SL CA, the SL UE (801) and the SL UE (803) may only be able to consider the SL carriers configured in 833.

[0121] It can be assumed that SL carriers #1, #2 and #3 are configured in 833. If the SL UE (801) detects RLF on SL carrier #1, the SL UE excludes SL carrier #1 from (further) resource allocation, regards the allocated resources in SL carrier #1 as invalid resources, flushes the soft buffers of all SL processes of all TBs associated with the destination (or source and destination pair, or PC5-RRC connection) and SL carrier #1 (the resources used for TB transmission are in SL carrier #1), regards all SL processes of all TBs associated with the destination (or source and destination pair, or PC5-RRC connection) and SL carrier #1 (the resources used for TB transmission are in SL carrier #1) as unoccupied, and cancels the triggered SL CSI reporting process (if any) associated with the destination (or source and destination pair, or PC5-RRC connection) and SL carrier #1 (851).

[0122] The SL UE (801) then sends an RRCReconfigurationSidelink PC5-RRC message to the SL UE (803) to release SL carrier #1 (865) from the SL CA carrier. The RRCReconfigurationSidelink PC5-RRC message includes the SL carrier information to be released (e.g., frequency information of the SL carrier), possibly with an SL RLF cause indication / value and an associated destination id (or an index of a pair of source and destination ids, or an index of a PC5-RRC connection). The SL UE (803) responds with an RRCReconfigurationCompleteSidelink PC5-RRC message to the SL UE (801) in 867.

[0123] The SL UE (801) and the SL UE (803) release SL carrier #1 from SL CA and transmit / receive data and / or control information (869) only in the remaining SL carriers (e.g., SL carriers #2 and #3). It should be noted that if the SL UE (801) is in an RRC connected state and / or the SL UE (803) is in mode 1 operation / resource allocation for SL transmission, the UE notifies the gNB (805) via a SidelinkUEInformationNR UL-RRC message that a SL RLF state (861) of a specific destination (or a specific source and destination pair or a specific PC5-RRC connection) is detected in SL carrier #1, and the gNB may release SL carrier #1 (863) from the SL CA carrier via an RRCReconfiguration DL-RRC message before the 865 and 867 processes. 861 includes an indication of SL RLF, SL carrier information where SL RLF occurs (eg, frequency information of SL carrier #1), and an associated destination id (or an index of a pair of source and destination ids, or an index for a PC5-RRC connection).

[0124] After releasing SL carrier #1, if the SL UE (801) detects RLF (871) on SL carrier #2, the SL UE excludes SL carrier #2 from (further) resource allocation, regards the allocated resources in SL carrier #2 as invalid resources, flushes the soft buffers of all SL processes of all TBs associated with the destination (or source and destination pair, or PC5-RRC connection) and SL carrier #2 (the resources used for TB transmission are in SL carrier #2), regards all SL processes of all TBs associated with the destination (or source and destination pair, or PC5-RRC connection) and SL carrier #2 (the resources used for TB transmission are in SL carrier #2) as unoccupied, and cancels the triggered SL CSI reporting process (if any) associated with the destination (or source and destination pair, or PC5-RRC connection) and SL carrier #2 (871).

[0125] It should be noted that although the following process is omitted in the figure, the SL UE (801) and the SL UE (803) can perform similar processes described in 861, 863, 865 and 867 to release SL carrier #2 from the SL CA carrier. With the release of SL carrier #2, the SL UE (801) and the SL UE (803) transmit and receive data and / or control information (881) only in a single SL carrier (e.g., SL carrier #3). If the SL UE (801) detects RLF in SL carrier #3, the UE applies the traditional SL RLF operation (891) specified in the 3GPP standard specification explained above.

[0126] It should be noted that in the accompanying drawings, it is assumed that the SL TX UE (801) detects the SL RLF. As another example, if the SL RX UE (803) detects the SL RLF, the SL RX UE (803) may use the associated destination information (L2 destination id, an index of a pair of L2 source and destination ids, or an index of a PC5-RRC connection) and SL carrier information (frequency information of the SL carrier where the SL RLF is detected) to notify the SL TX UE (801) of the SL RLF detection. This information may be sent via a UEAssistanceInformationSidelink PC5-RRC message.

[0127] It should be noted that in the accompanying drawings, it is assumed that a specific SL carrier in SL CA is not defined. The UE applies different SL RLF operations depending on whether the SL carrier in which the SL RLF is detected is the last carrier configured for SL transmission. If it is not the last one, the UE applies the operations described in 851 and 871. If it is the last one, the UE applies the traditional operations described in 891. As another example, a specific SL carrier may be introduced. Then, if the SL carrier in which the SL RLF is detected is not a specific SL carrier, the UE applies the same or similar operations described in 851 and 871. If the SL carrier in which the SL RLF is detected is a specific SL carrier, the UE applies the traditional operations described in 891. In order to support specific SL carriers, when the SL CA carrier is configured in 831 or 833, information indicating which SL carrier is the specific SL carrier needs to be added in 831 or 833.

[0128] It should be noted that in the accompanying drawings, it is assumed that the SL CA carrier is configured between the UEs (801 and 803) using the PC5-RRC message. As another example, the SL CA carrier information may be configured through a system information block. For example, candidate SL CA carrier information associated with QoS (Quality of Service) may be broadcast through a system information block. The UEs (801 and 803) select SL CA carriers based on the QoS they intend to transmit and / or receive. For example, SL carriers #1 and #3 are configured for QoS #A, and SL carriers #2 and #4 are configured for QoS #B. If the QoS mapped to the SL logical channel (or SL service type) to which the UE intends to transmit and / or receive data is QoS #A, the UE applies SL carriers #1 and #3 to SL CA operation.

[0129] Fig. 9 900 according to an embodiment of the present disclosure. The method 900 may be performed by a UE (eg, Figure 1 111 to 116) as shown. Fig. 9 The illustrated embodiment of method 900 is for illustration only. Fig. 9 One or more of the components shown may be implemented in dedicated circuits configured to perform the functions mentioned, or one or more of the components may be implemented by one or more processors executing instructions to perform the functions mentioned.

[0130] Fig. 9An example of a flowchart of SL UE behavior according to the embodiment in Figure 8 is described. Assume that the UE is in SL transmission and / or reception (901). If SL RLF is declared in the SL carrier based on a specific SL RLF condition (hereinafter referred to as SL RLF condition #1) in 911, the UE checks in 941 whether the SL carrier where SL RLF condition #1 occurs is the only SL carrier used for transmission and / or reception of the corresponding destination id (or an index of a pair of source and destination ids, or an index of a PC5-RRC connection).

[0131] As an example of SL RLF condition #1, SL RLF is detected in a specific SL carrier after an indication from the MAC entity that the maximum number of consecutive HARQ DTXs for a specific destination has been reached. If the SL carrier is the only SL carrier used for transmission and / or reception of the corresponding destination id (or an index of a pair of source and destination ids, or an index of a PC5-RRC connection), the UE performs conventional SL RLF operations specified in the 3GPP standard specification in 931.

[0132] If the SL carrier is not only the SL carrier for transmission and / or reception of the corresponding destination id (or an index of a pair of source and destination ids, or an index of a PC5-RRC connection) in 941, which means that the UE is configured with multiple SL carriers for SL CA, the UE excludes the SL carrier in (further) resource allocation, regards the allocated resources in the SL carrier as invalid resources, refreshes the soft buffers of all SL processes of all TBs associated with the destination (or source and destination pair, or PC5-RRC connection) and the SL carrier (resources for TB transmission are in the SL carrier), regards all SL processes of all TBs associated with the destination (or source and destination pair, or PC5-RRC connection) and the SL carrier (resources for TB transmission are in the SL carrier) as unoccupied, and cancels the triggered SL CSI reporting process (if any) associated with the destination (or source and destination pair, or PC5-RRC connection) and the SL carrier in 951.

[0133] The UE also releases the SL carrier, possibly with SL RLF cause / indication, to the peer UE via RRCReconfigurationSidelink in 951. It should be noted that if the UE is in RRC connected state and / or the UE is in mode 1 operation / resource allocation for SL transmission, the UE notifies the serving gNB of SL RLF detection in 951 through the SL carrier information and the corresponding destination id (or the index of the source and destination id pair, or the index of the PC5-RRC connection). If SL RLF is declared based on other conditions other than SL RLF condition #1 in 921, the UE performs the traditional SL RLF actions specified in the 3GPP standard specification in 931.

[0134] As examples of conditions other than SL RLF condition #1, SL RL is detected when there is an indication from the SL RLC entity that the maximum number of retransmissions for a specific destination has been reached, or when T400 for a specific destination expires, or when there is an indication from the SL PDCP entity that an integrity check of SL-SRB2 or SL-SRB3 for a specific destination has failed.

[0135] Fig. 10A and Fig. 10B 1000 and 1050 are shown for HARQ-based SL RLF detection in SL CA according to an embodiment of the present disclosure. The signaling flows 1000 and 1050 may be performed by a UE (e.g., Figure 1 111 to 116) and a base station (e.g., Figure 1 101 to 103) shown in the figure are executed. Fig. 10A and Fig. 10B The illustrated embodiments of signaling flows 1000 and 1050 are for illustration only. Fig. 10A and Fig. 10B One or more of the components shown may be implemented in dedicated circuitry configured to perform the functions described, or one or more of the components may be implemented by one or more processors executing instructions to perform the functions described. Fig. 10A and Fig. 10B Connected together.

[0136] In one embodiment, HARQ-based SL RLF detection in SL CA is provided. Fig. 10A and Fig. 10B An example of an embodiment of HARQ-based SL RLF detection in SLCA is described. A SL UE (1001) is configured for SL transmission, a peer SL UE (1003) is configured for SL reception, and the serving gNB (1005) of the UE (1001) and the core network (CN, 1007) entities are responsible for SL pre-configuration. The CN (1007) pre-configures the SL UE (1001) in 1011 a list of SL carriers of a given service type (or L2 destination id / a pair of source and destination ids), the maximum number of consecutive DTXs of SL CA carriers in a PC5-RRC connection (hereinafter referred to as maximum number #1), and the maximum number of consecutive DTXs for a PC5-RRC connection (hereinafter referred to as maximum number #2).

[0137] The gNB (1005) configures the list of available SL CA carriers in the serving cell (or the list of SL CA carriers for each QoS in the serving cell), the maximum number of continuous DTX for SL CA carriers in the PC5-RRC connection (hereinafter referred to as maximum number #1), and the maximum number of continuous DTX for the PC5-RRC connection (hereinafter referred to as maximum number #2) for the SL UE (1001) in 1013. For maximum number #1 and maximum number #2, if the SL UE (1001) is outside the coverage of the gNB, the UE applies the pre-configuration from 1011, otherwise, if the UE is in the serving cell of the gNB, the UE applies the configuration from 1013. For the candidate SL CA carriers, if the SL UE (1001) is outside the coverage of the gNB, the UE applies the pre-configuration from 1011 according to the service type (or L2 destination id / a pair of source and destination id) that the UE is interested in and the possible UE location; otherwise, if the UE is located in the serving cell of the gNB, the UE applies the SL CA carriers that can be supported according to the service type (or L2 destination id / a pair of source and destination id) that the UE is interested in from both 1011 and 1013. 1013 can be signaled through a system information block or a UE-specific RRC message.

[0138] An example of a UE-specific RRC message is the RRCReconfiguration message defined in the 3GPP standard specification. It can be assumed that in 1011 / 1013, the maximum number #1 is pre-configured or configured to 2, and the maximum number #2 is pre-configured or configured to 3. If the SL UE (1001) is interested in SL unicast (UC) communication with the SL UE (1003), a PC5-RRC connection establishment process is performed between the SL UE (1001) and the SL UE (1003) in 1021. During the PC5-RRC connection establishment, the SL CA carrier actually used for SL transmission and / or reception between the two UEs can also be configured. It can be assumed that SL carriers #1 and #2 are configured as SL CA carriers. It should be noted that after the PC5-RRC connection is established, the SL CA carriers can also be configured through a separate SL RRC reconfiguration process.

[0139] Once SL CA is configured / activated, the SL UE (1001) initializes UE variables (1023). The UE maintains three variables for the number of consecutive DTXs. The first is the number of consecutive DTXs applied to SL carrier #1 (for the associated PC5-RRC connection), the second is the number of consecutive DTXs applied to SL carrier #2 (for the associated PC5-RRC connection), and the third is the number of consecutive DTXs applied to the PC5-RRC connection. It should be noted that it can be assumed that there is one PC5-RRC connection between the UEs (1001 and 1003). If there are multiple PC5-RRC connections between the UEs (1001 and 1003), the UE may need to maintain a number of {3*number of PC5-RRC connections} of consecutive DTXs. The UE sets all three numbers of consecutive DTXs to 0. The SL UEs (1001 and 1003) can send and / or receive SL control information and / or data (1025) via SL carrier #1 and SL carrier #2.

[0140] For example, a SL UE (1001) sends SL control information and / or data (1031) in PSCCH and / or PSSCH via SL carrier #1, and if the UE does not receive / detect HARQ Ack / Nack (A / N) (also indicated as detected DTX) (1033) from the PSFCH resources associated with 1031 PSCCH and / or PSSCH, the UE increases the number of consecutive DTX #1s for the scheduled SL carrier (in this case SL carrier #1) and the number of consecutive DTX #3s for the scheduled PC5-RRC connection by 1, while the UE does not change the number of consecutive DTX #2s for another SL carrier (in this case SL carrier #2) (1035).

[0141] Therefore, the number of consecutive DTX #1 for SL carrier #1 and the number of consecutive DTX #3 for PC5 connection increases to 1, and the number of consecutive DTX #2 for SL carrier #2 remains 0. Then, the UE sends SL control information and / or data in PSCCH and / or PSSCH through SL carrier #1 (1041), and if the UE receives / detects HARQ A / N (1043) from PSFCH resources associated with 1041PSCCH and / or PSSCH, the UE reinitializes the number of consecutive DTX #1 for the scheduled SL carrier (in this case, SL carrier #1) and the number of consecutive DTX #3 for the scheduled PC5-RRC connection to 0 (1045).

[0142] Therefore, the number of consecutive DTX#1 for SL carrier #1, the number of consecutive DTX#2 for SL carrier #2, and the number of consecutive DTX#3 for the PC5-RRC connection are all 0. Then, the UE sends SL control information and / or data in PSCCH and / or PSSCH through SL carrier #2 (1051), and if the UE does not receive / detect HARQ Ack / Nack (A / N) (also indicated as detected DTX) (1053) from the PSFCH resources associated with 1051PSCCH and / or PSSCH, the UE increases the number of consecutive DTX#2 for the scheduled SL carrier (in this case, SL carrier #2) and the number of consecutive DTX#3 for the scheduled PC5-RRC connection by 1, while the UE does not change the number of consecutive DTX#1 for another SL carrier (in this case, SL carrier #1) (1055).

[0143] Therefore, the number of consecutive DTX#2 for SL carrier #2 and the number of consecutive DTX#3 for PC5 connection are increased to 1, and the number of consecutive DTX#1 for SL carrier #1 remains 0. Then, the UE sends SL control information and / or data in PSCCH and / or PSSCH through SL carrier #2 (1061), and if the UE does not receive / detect HARQ Ack / Nack (A / N) (also indicated as detected DTX) (1063) from the PSFCH resources associated with 1061PSCCH and / or PSSCH, the UE increases the number of consecutive DTX#2 for the scheduled SL carrier (in this case, SL carrier #2) and the number of consecutive DTX#3 for the scheduled PC5-RRC connection by 1, while the UE does not change the number of consecutive DTX#1 for another SL carrier (in this case, SL carrier #1) (1065).

[0144] Therefore, the number of consecutive DTX #2 for SL carrier #2 and the number of consecutive DTX #3 for the PC5 connection increase to 2, and the number of consecutive DTX #1 for SL carrier #1 remains 0. It should be noted that it can be assumed that in 1011 / 1013, the maximum number #1 is preconfigured or configured to 2, and the maximum number #2 is preconfigured or configured to 3. Since the number of consecutive DTX #2 (2) reaches the preconfigured / configured maximum number #1 (2), the UE considers that the SL RLF (1071) for SL carrier #2 associated with the PC5-RRC connection is detected.

[0145] It should be noted that since the number of consecutive DTX #1 (0) does not reach the pre-configured / configured maximum number #1 (2), the UE does not consider the SL RLF for the SL carrier #1 associated with the PC5-RRC connection, that is, the UE still uses the SL carrier #1 to transmit SL control information and / or data in the PSCCH and / or PSSCH. It should also be noted that since the number of consecutive DTX #3 (2) does not reach the pre-configured / configured maximum number #2 (3), the UE does not consider the SL RLF for the PC5-RRC connection, that is, the PC5-RRC connection is maintained.

[0146] Once the SL RLF for SL carrier 2 associated with the PC5-RRC connection is detected, the UE's MAC performs the following operations only for SL carrier #2: 1) release all reserved / configured resources associated with the PC5-RRC connection; 2) stop resource allocation associated with the PC5 connection; 3) flush the soft buffers of all SL processes of all TBs associated with the PC5-RRC connection; 4) consider all sidelink processes of all TBs associated with the PC5-RRC connection as unoccupied; 5) cancel the triggered sidelink CSI reporting process associated with the PC5-RRC connection (if any and it is for SL carrier #2); 6) stop all SL CA carrier-specific timers associated with the PC5-RRC connection (if running); and 7) reset all SL CA carrier-specific variables associated with the PC5-RRC connection (if any) (e.g., the number of consecutive DTX#2).

[0147] Fig.11A and Fig. 11B 1100 and 1150 are another signaling flows for HARQ-based SL RLF detection in SL CA according to an embodiment of the present disclosure. The signaling flows 1100 and 1150 may be received by a UE (e.g., Figure 1 111 to 116) and a base station (e.g., Figure 1 101 to 103) shown in the figure are executed. Fig.11A and Fig. 11B The illustrated embodiments of signaling flows 1100 and 1150 are for illustration only. Fig.11A and Fig. 11B One or more of the components shown may be implemented in dedicated circuitry configured to perform the functions described, or one or more of the components may be implemented by one or more processors executing instructions to perform the functions described. Fig.11A and Fig. 11B Connected together.

[0148] Fig.11A and Fig. 11BAnother example of HARQ-based SL RLF detection in SL CA is described. A SL UE (1101) is configured for SL transmission, a peer SL UE (1103) is configured for SL reception, and the serving gNB (1105) and CN (1107) entities of the UE (1101) are responsible for SL pre-configuration. CN 1107 pre-configures a list of SL carriers of a given service type (or L2 destination id / a pair of source and destination ids), the maximum number of consecutive DTXs of SL CA carriers in a PC5-RRC connection (hereinafter referred to as maximum number #1), and the maximum number of consecutive DTXs for a PC5-RRC connection (hereinafter referred to as maximum number #2) for the SL UE 1101 in 1111. The gNB (1105) configures in 1113 for the SL UE 1101 a list of available SL CA carriers in the serving cell (or a list of SL CA carriers for each QoS in the serving cell), the maximum number of consecutive DTXs for SL CA carriers in a PC5-RRC connection (hereinafter referred to as maximum number #1), and the maximum number of consecutive DTXs for a PC5-RRC connection (hereinafter referred to as maximum number #2).

[0149] For maximum number #1 and maximum number #2, if the SL UE (1101) is outside the coverage of the gNB, the UE applies the pre-configuration from 1111, otherwise, if the UE is in the serving cell of the gNB, the UE applies the configuration from 1113. For the candidate SL CA carriers, if the SL UE (1101) is outside the coverage of the gNB, the UE applies the pre-configuration from 1111 according to the service type (or L2 destination id / a pair of source and destination id) of interest to the UE and the possible UE location; otherwise, if the UE is in the serving cell of the gNB, the UE applies the supported SL CA carriers from both 1111 and 1113 according to the service type (or L2 destination id / a pair of source and destination id) of interest to the UE. 1113 may be signaled via a system information block or a UE-specific RRC message.

[0150] An example of a UE-specific RRC message is the RRCReconfiguration message defined in the 3GPP standard specification. It can be assumed that in 1111 / 1113, the maximum number #1 is preconfigured or configured to 3, and the maximum number #2 is preconfigured or configured to 4. If the SL UE (1101) is interested in SL unicast (UC) communication with the SL UE (1103), a PC5-RRC connection establishment process is performed between the SL UE (1101) and the SL UE (1103) in 1121. During the PC5-RRC connection establishment, the SL CA carrier actually used for SL transmission and / or reception between the two UEs can also be configured. It can be assumed that SL carriers #1 and #2 are configured as SL CA carriers. It should be noted that after the PC5-RRC connection is established, the SL CA carriers can also be configured through a separate SL RRC reconfiguration process.

[0151] Once SL CA is configured / activated, the SL UE (1101) initializes UE variables (1123). The UE maintains three variables for the number of consecutive DTXs. The first is the number of consecutive DTXs applied to SL carrier #1 (for the associated PC5-RRC connection), the second is the number of consecutive DTXs applied to SL carrier #2 (for the associated PC5-RRC connection), and the third is the number of consecutive DTXs applied to the PC5-RRC connection. It should be noted that it can be assumed that there is one PC5-RRC connection between the UEs (1101 and 1103). If there are multiple PC5-RRC connections between the UEs (1101 and 1103), the UE may need to maintain a number of {3*number of PC5-RRC connections} of consecutive DTXs. The UE sets all three numbers of consecutive DTXs to 0. The SL UEs (1101 and 1103) can send and / or receive SL control information and / or data (1125) via SL carrier #1 and SL carrier #2.

[0152] For example, a SL UE (1101) sends SL control information and / or data (1131) in PSCCH and / or PSSCH via SL carrier #1, and if the UE does not receive / detect HARQ Ack / Nack (A / N) (also indicated as detected DTX) (1133) from the PSFCH resources associated with the 1131 PSCCH and / or PSSCH, the UE increases the number of consecutive DTX #1s for the scheduled SL carrier (in this case, SL carrier #1) and the number of consecutive DTX #3s for the scheduled PC5-RRC connection by 1, while the UE does not change the number of consecutive DTX #2s for another SL carrier (in this case, SL carrier #2) (1135).

[0153] Therefore, the number of consecutive DTX #1 for SL carrier #1 and the number of consecutive DTX #3 for PC5 connection increases to 1, and the number of consecutive DTX #2 for SL carrier #2 remains 0. Then, the UE sends SL control information and / or data in PSCCH and / or PSSCH through SL carrier #1 (1141), and if the UE receives / detects HARQ A / N (1143) from PSFCH resources associated with 1141PSCCH and / or PSSCH, the UE reinitializes the number of consecutive DTX #1 for the scheduled SL carrier (in this case, SL carrier #1) and the number of consecutive DTX #3 for the scheduled PC5-RRC connection to 0 (1145).

[0154] Therefore, the number of consecutive DTX#1 for SL carrier #1, the number of consecutive DTX#2 for SL carrier #2, and the number of consecutive DTX#3 for the PC5-RRC connection are all 0. Then, the UE sends SL control information and / or data in PSCCH and / or PSSCH through SL carrier #2 (1151), and if the UE does not receive / detect HARQ Ack / Nack (A / N) (also indicated as detected DTX) (1153) from the PSFCH resources associated with 1151 PSCCH and / or PSSCH, the UE increases the number of consecutive DTX#2 for the scheduled SL carrier (in this case, SL carrier #2) and the number of consecutive DTX#3 for the scheduled PC5-RRC connection by 1, while the UE does not change the number of consecutive DTX#1 for another SL carrier (in this case, SL carrier #1) (1155).

[0155] Therefore, the number of consecutive DTX#2 for SL carrier #2 and the number of consecutive DTX#3 for PC5 connection are increased to 1, and the number of consecutive DTX#1 for SL carrier #1 remains 0. Then, the UE sends SL control information and / or data in PSCCH and / or PSSCH through SL carrier #2 (1161), and if the UE does not receive / detect HARQ Ack / Nack (A / N) (also indicated as detected DTX) (1163) from the PSFCH resources associated with 1161PSCCH and / or PSSCH, the UE increases the number of consecutive DTX#2 for the scheduled SL carrier (in this case, SL carrier #2) and the number of consecutive DTX#3 for the scheduled PC5-RRC connection by 1, while the UE does not change the number of consecutive DTX#1 for another SL carrier (in this case, SL carrier #1) (1165).

[0156] Therefore, the number of consecutive DTX#2 for SL carrier #2 and the number of consecutive DTX#3 for PC5 connection increases to 2, and the number of consecutive DTX#1 for SL carrier #1 remains 0. Then, the UE sends SL control information and / or data in PSCCH and / or PSSCH through SL carrier #1 (1171), and if the UE does not receive / detect HARQ Ack / Nack (A / N) (also indicated as detected DTX) (1173) from the PSFCH resources associated with 1171PSCCH and / or PSSCH, the UE increases the number of consecutive DTX#1 for the scheduled SL carrier (in this case, SL carrier #1) and the number of consecutive DTX#3 for the scheduled PC5-RRC connection by 1, while the UE does not change the number of consecutive DTX#2 for another SL carrier (in this case, SL carrier #2) (1175).

[0157] Therefore, the number of consecutive DTX#1 for SL carrier #1 increases to 1, the number of consecutive DTX#3 for PC5-RRC connection increases to 3, and the number of consecutive DTX#2 for SL carrier #2 remains 2. Then, the UE sends SL control information and / or data in PSCCH and / or PSSCH through SL carrier #1 (1181), and if the UE does not receive / detect HARQ Ack / Nack (A / N) (also indicated as detected DTX) (1183) from the PSFCH resources associated with 1181PSCCH and / or PSSCH, the UE increases the number of consecutive DTX#1 for the scheduled SL carrier (in this case, SL carrier #1) and the number of consecutive DTX#3 for the scheduled PC5-RRC connection by 1, while the UE does not change the number of consecutive DTX#2 for another SL carrier (in this case, SL carrier #2) (1185).

[0158] Therefore, the number of consecutive DTX #2 for SL carrier #1 increases to 1, the number of consecutive DTX #3 for the PC5-RRC connection increases to 4, and the number of consecutive DTX #2 for SL carrier #2 remains at 2. It should be noted that it can be assumed that in 1111 / 1113, the maximum number #1 is preconfigured / configured to 3, and the maximum number #2 is preconfigured / configured to 4. Since the number of consecutive DTX #3 (4) reaches the preconfigured / configured maximum number #2 (4), the UE considers that the SL RLF for the associated PC5-RRC connection is detected (1191).

[0159] Once the SL RLF for the PC5-RRC connection is detected, the MAC sublayer of the UE will indicate the SL RLF detection for the PC5-RRC connection to the RRC sublayer (with information of the PC5-RRC connection, such as the index of the PC5-RRC connection, or information of the corresponding destination, such as the L2 destination id). The MAC then performs the following operations on both SL carrier #1 and SL carrier #2: 1) release all reserved / configured resources associated with the PC5-RRC connection, 2) stop resource allocation associated with the PC5 connection, 3) flush soft buffers of all SL processes for all TBs associated with the PC5-RRC connection, 4) consider all sidelink processes for all TBs associated with the PC5-RRC connection as unoccupied, 5) cancel the triggered SL CSI reporting process associated with the PC5-RRC connection (if any), 6) stop all timers associated with the PC5-RRC connection (if running) (including SL CA carrier-specific timers associated with the PC5-RRC connection), and 7) reset all UE variables associated with the PC5-RRC connection (if any) (including SL CA carrier-specific UE variables associated with the PC5-RRC connection, e.g., the number of consecutive DTX#1s and the number of consecutive DTX#2s).

[0160] MAC also cancels the triggered scheduling request procedure associated only with the PC5-RRC connection (if any), and cancels the triggered sidelink buffer status reporting procedure associated only with the PC5-RRC connection (if any). Once RRC receives SL RLF detection for a PC5-RRC connection from MAC, RRC performs the following operations: 1) releases the DRB (data radio bearer) for this destination (if configured); 2) releases the SRB for this destination; 3) releases the PC5 relay RLC channel for this destination (if configured); 4) discards the NR sidelink communication related configuration for this destination; 5) considers the PC5-RRC connection to be released for the destination; 6) indicates to the upper layers of this destination that the PC5-RRC connection is released (i.e., PC5 is not available); and 7) if the UE is in RRC connected state, indicates this SL RLF detection to the serving gNB via the SidelinkUEInformationRRC message.

[0161] exist Fig. 10A and Fig. 10B as well as Fig.11A and Fig. 11B As another example, the pre-configured / configured maximum number #1 and maximum number #2 in 1011 / 1013 and 1111 / 1113 may be the same value, and in this case, only a single maximum number may be signaled.

[0162] As another example, for the pre-configured / configured maximum number #1 and maximum number #2 in 1011 / 1013 and 1111 / 1113, an integer value and a relative correlation information may be signaled instead of two separate integer values. For example, the maximum number #2 is signaled as 4, and the scaling factor 1 / 2 is signaled, then the maximum number #1 derived by the UE is {4*1 / 2}=2. Or for example, the maximum number #2 is signaled as 4, and the relative offset -2 is signaled, then the maximum number #1 derived by the UE is {4-2}=2.

[0163] As another example, for the pre-configured / configured maximum number #1 in 1011 / 1013 and 1111 / 1113, a separate maximum number may be signaled for each SL CA carrier, rather than a common single value for all SL CA carriers (e.g., maximum number #1 is applied to both SL carrier #1 and SL carrier #2). For example, a list of maximum numbers #1 may be signaled, for example, a list of two maximum numbers #1 may be signaled, and in this case, the UE uses the first maximum number #1 for SL detection in SL carrier #1 and the second maximum number #1 for SL detection in SL carrier #2. To this end, some mapping information between the SL carriers and the corresponding maximum number #1 may be further configured in 1011 / 1013 and 1111 / 1113.

[0164] Fig.12 1 is a flowchart of a method 1200 of a UE according to an embodiment of the present disclosure. The method 1200 may be performed by a UE (eg, Figure 1 111 to 116) as shown. Fig.12 The illustrated embodiment of method 1200 is for illustration only. Fig.12 One or more of the components shown may be implemented in dedicated circuits configured to perform the functions mentioned, or one or more of the components may be implemented by one or more processors executing instructions to perform the functions mentioned.

[0165] Fig.12 Describes the Fig. 10A and Fig. 10B as well as Fig.11A and Fig. 11BAn example of UE behavior of the embodiments described in 1201. 1201 shows that the UE receives the configuration of maximum number #1 and maximum number #2, and starts SL transmission and / or reception in multiple SL CA carriers. The UE then initializes the relevant UE variables (i.e., the number of consecutive DTXs for each SL CA carrier associated with the PC5-RRC connection and the number of consecutive DTXs for the PC5-RRC connection) to 0 (1211). The UE transmits SL control information and / or data in PSCCH and / or PSSCH via SL carrier #M, which carrier #M has associated PSFCH resources for HARQ A / N information (1213). The UE checks whether there is no PSFCH reception on the PSFCH resources associated with the transmission in 1213 (i.e., no HARQ A / N is detected / received or HARQ DTX is detected) (1221). If there is no PSFCH reception (i.e., HARQ A / N is detected / received), the UE reinitializes the number of consecutive DTXs for the SL CA scheduled carrier (carrier #M) associated with the scheduled PC5-RRC connection and the number of consecutive DTXs for the PC5-RRC connection to 0 (1231). If there is no PSFCH reception, the UE increases the number of consecutive DTXs for the SL CA scheduled carrier (carrier #M) associated with the scheduled PC5-RRC connection and the number of consecutive DTXs for the PC5-RRC connection by 1 (1241).

[0166] Then, the UE checks whether the number of consecutive DTXs for the PC5-RRC connection reaches the maximum number #2 (1251). If the number of consecutive DTXs for the PC5-RRC connection reaches the maximum number #2, the UE detects the SLRLF for the PC5-RRC connection and performs the SL RLF operation #2 defined for each PC5-RRC connection (1261).

[0167] An example of SL RLF operation #2 is described as Fig.11A and Fig. 11B If the number of consecutive DTXs for the PC5-RRC connection does not reach the maximum number #2, the UE further checks whether the number of consecutive DTXs for the SL CA carrier #M associated with the PC5-RRC connection reaches the maximum number #1 (1271). If the number of consecutive DTXs for the SL CA carrier #M associated with the PC5-RRC connection reaches the maximum number #1, the UE detects the SL RLF for the SL CA carrier #M associated with the PC5 RRC connection and performs SL RLF operation #1, which is defined for each SL CA carrier for each PC5-RRC connection (1281). An example of SL RLF operation #1 is described as Fig. 10A and Fig. 10B The content of part 1071.

[0168] Fig.13 1 is a flowchart of a method 1300 for UE operation during RLF detection in SL CA according to an embodiment of the present disclosure. The method 1300 may be performed by a UE (eg, Figure 1 111 to 116) as shown. Fig.13 The illustrated embodiment of method 1300 is for illustration only. Fig.13 One or more of the components shown may be implemented in dedicated circuits configured to perform the functions mentioned, or one or more of the components may be implemented by one or more processors executing instructions to perform the functions mentioned.

[0169] like Fig.13 As shown, the method 1300 starts at step 1302. In step 1302, the UE receives configuration information of multiple SL carriers for SL CA operation from the BS.

[0170] In step 1304, when HARQ feedback corresponding to a SL carrier among the multiple SL carriers is not received for N consecutive times and the SL carrier is not the last configured SL carrier, the UE releases the SL carrier for the corresponding destination L2 ID.

[0171] In step 1306, when HARQ feedback corresponding to a SL carrier among the multiple SL carriers is not received for M consecutive times and the SL carrier is the last configured SL carrier, the UE releases the PC5-RRC connection for the corresponding destination L2 ID.

[0172] In one embodiment, the UE receives the value N and information for multiple SL carriers via a UE-dedicated RRC message or system information.

[0173] In one embodiment, the UE receives a value M via a UE-dedicated RRC message or system information; and releases the SL carrier based on a first counter, and releases the PC5-RRC connection based on a second counter, wherein: the first counter is compared with a value N, and the first counter is configured for each SL carrier; and the second counter is compared with a value M, and the second counter corresponds to all SL carriers among multiple SL carriers.

[0174] In one embodiment, the UE starts a counter to count the number of HARQ feedbacks that have not been received; and resets the counter when HARQ feedback is received before the counter reaches a value N, where: the value N is the same as the value M; and the counter corresponds to each SL carrier of the multiple SL carriers.

[0175] In one embodiment, when the SL carrier is released, the UE flushes the soft buffer for the corresponding destination L2 ID corresponding to the TB associated with the SL carrier; and cancels the SL CS reporting operation associated with the SL carrier.

[0176] In one embodiment, the UE transmits information indicating that the SL carrier is released to the base station via an RRC message or a MAC CE; or transmits information indicating that the SL carrier is released to a peer UE via a PC5-RRC connection or a SL MAC CE.

[0177] In one embodiment, when any SL carrier does not receive HARQ feedback, the UE increases the second counter by 1; and when HARQ feedback is received by any SL carrier before the second counter reaches the value M, the second counter is reset.

[0178] In one embodiment, the UE determines the value of the second counter based on the sum of the values ​​of the first counters corresponding to all SL carriers.

[0179] The above flow charts illustrate exemplary methods that can be implemented according to the principles of the present disclosure, and various changes can be made to the methods shown in the flow charts herein. For example, although shown as a series of steps, the individual steps in each figure can overlap, occur in parallel, occur in different orders, or occur multiple times. In another example, a step can be omitted or replaced by another step.

[0180] Although the present disclosure has been described with exemplary embodiments, various changes and modifications may be proposed to those skilled in the art. The present disclosure is intended to include such changes and modifications that fall within the scope of the appended claims. Any description in this application should not be construed as implying that any particular element, step or function is an essential element that must be included within the scope of the claims. The scope of the patent subject matter is defined by the claims.

Claims

1. A user equipment UE, comprising: A transceiver configured to receive configuration information about a plurality of SL carriers for sidelink SL carrier aggregation CA operation from a base station BS; as well as A processor operably connected to the transceiver, the processor being configured to: When no hybrid automatic repeat request HARQ feedback corresponding to a SL carrier among the plurality of SL carriers is received for N consecutive times and the SL carrier is not the last configured SL carrier, releasing the SL carrier for the corresponding destination layer 2 identifier L2 ID, and When the HARQ feedback corresponding to a SL carrier among the multiple SL carriers is not received for M consecutive times and the SL carrier is the last configured SL carrier, the PC5-Radio Resource Control PC5-RRC connection for the corresponding destination L2 ID is released.

2. The UE according to claim 1, The transceiver is further configured to: receive the value of N and the information of the multiple SL carriers via a UE-specific RRC message or system information, wherein the value of N is the same as the value of M, and The processor is further configured to: starting a counter to count the number of said HARQ feedbacks that have not been received, and When the HARQ feedback is received before the counter reaches the value of N, the counter is reset, the counter corresponding to each SL carrier of the plurality of SL carriers.

3. The UE according to claim 2, wherein: The transceiver is further configured to: receive a value of M via a UE-specific RRC message or system information, and The processor is further configured to: Determine to release the SL carrier based on a comparison between a first counter and a value of N, wherein the first counter is configured for each SL carrier, and Based on the comparison between a second counter and the value of M, it is determined to release the PC5-RRC connection, wherein the second counter corresponds to all SL carriers among the multiple SL carriers.

4. The UE of claim 3, wherein the processor is further configured to: When the HARQ feedback is not received on any SL carrier among the plurality of SL carriers, increasing the second counter by 1, and When the HARQ feedback is received by any SL carrier of the plurality of SL carriers before the second counter reaches the value of M, the second counter is reset. 5 . The UE of claim 3 , wherein the processor is further configured to determine the value of the second counter based on a sum of values ​​of the first counter corresponding to all SL carriers among the plurality of SL carriers.

6. The UE according to claim 1, wherein when the SL carrier is released, the processor is further configured to: flushing a soft buffer for the corresponding destination L2 ID corresponding to a transport block TB associated with the SL carrier, and cancelling the SL channel state information (CSI) reporting operation associated with the SL carrier, and The transceiver is further configured to: Transmitting information indicating that the SL carrier is released to the base station via an RRC message or a medium access control element MAC CE, or Information indicating that the SL carrier is released is transmitted to the peer UE via the PC5-RRC connection or the SL MAC CE.

7. A method performed by a user equipment UE, the method comprising: receiving, from a base station BS, configuration information about a plurality of SL carriers for sidelink SL carrier aggregation CA operation; When no hybrid automatic repeat request HARQ feedback corresponding to a SL carrier among the plurality of SL carriers is received N times in succession and the SL carrier is not the last configured SL carrier, releasing the SL carrier for the corresponding destination layer 2 identifier L2 ID; and When the HARQ feedback corresponding to a SL carrier among the multiple SL carriers is not received for M consecutive times and the SL carrier is the last configured SL carrier, the PC5-Radio Resource Control PC5-RRC connection for the corresponding destination L2 ID is released.

8. The method of claim 7, further comprising: receiving a value of N and information of the plurality of SL carriers via a UE-specific RRC message or system information, and Wherein the value of N is the same as the value of M, the method further comprises: Starting a counter to count the number of the HARQ feedbacks that have not been received; and When the HARQ feedback is received before the counter reaches the value of N, the counter is reset, wherein the counter corresponds to each SL carrier of the plurality of SL carriers.

9. The method of claim 8, further comprising: Receiving a value of M via a UE-specific RRC message or system information; Determine to release the SL carrier based on a comparison between a first counter and a value of N, wherein the first counter is configured for each SL carrier; as well as Based on the comparison between a second counter and the value of M, it is determined to release the PC5-RRC connection, wherein the second counter corresponds to all SL carriers among the multiple SL carriers.

10. The method of claim 9, further comprising: When the HARQ feedback is not received on any SL carrier of the plurality of SL carriers, increasing the second counter by 1; as well as When the HARQ feedback is received by any SL carrier of the plurality of SL carriers before the second counter reaches the value of M, the second counter is reset.

11. The method of claim 9, further comprising: The value of the second counter is determined based on the sum of the values ​​of the first counter corresponding to all of the plurality of SL carriers.

12. The method according to claim 7, wherein when the SL carrier is released, the method further comprises: flushing a soft buffer for the corresponding destination L2 ID corresponding to a transport block TB associated with the SL carrier; Canceling the SL channel state information CSI reporting operation associated with the SL carrier; as well as The method further comprises: Transmitting information indicating that the SL carrier is released to the base station via an RRC message or a medium access control-control element MAC CE; or Information indicating that the SL carrier is released is transmitted to the peer UE via the PC5-RRC connection or the SL MAC CE.

13. A base station BS, comprising: a processor configured to generate configuration information for a plurality of sidelink SL carriers; as well as A transceiver, operably connected to the processor, the transceiver being configured to: transmit the configuration information for SL carrier aggregation CA operation to a user equipment UE, in: When no hybrid automatic repeat request HARQ feedback corresponding to a SL carrier among the plurality of SL carriers is received for N consecutive times and the SL carrier is not the last configured SL carrier, the SL carrier for the corresponding destination layer 2 identifier L2 ID is released, and When the HARQ feedback corresponding to a SL carrier among the multiple SL carriers is not received for M consecutive times and the SL carrier is the last configured SL carrier, the PC5-Radio Resource Control PC5-RRC connection for the corresponding destination L2 ID is released.

14. The BS of claim 13, wherein the transceiver is further configured to: Transmitting the value of N and the information of the plurality of SL carriers via a UE-specific RRC message or system information, and The value of M is transmitted to the UE via a UE-specific RRC message or system information.

15. The BS of claim 14, wherein the transceiver is further configured to: receive information indicating that the SL carrier is released from the UE via an RRC message or a Medium Access Control-Control Element MAC CE, and wherein the value of N is the same as the value of M.

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