Method executed by user equipment and user equipment

Abstract

The invention provides a method executed by user equipment and the user equipment, and the method comprises the following steps: the user equipment sends side communication control information SCI on an unauthorized frequency spectrum; and the user equipment attempts to receive a physical sidewalk communication feedback channel (PSFCH) associated with the SCI. Therefore, the communication reliability of sidewalk communication on the unlicensed spectrum can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communications, and in particular to a method executed by a user equipment and corresponding user equipment. Background Art

[0002] In traditional cellular networks, all communications must go through base stations. In contrast, D2D communication (Device-to-Device communication) refers to the direct communication between two user devices without forwarding through a base station or core network. At the RAN#63 plenary meeting of the 3rd Generation Partnership Project (3GPP) in March 2014, a research project on using LTE devices to implement proximity D2D communication services was approved (see non-patent document 1). The functions introduced by LTE Release 12 D2D include:

[0003] 1) Discovery function between nearby devices in LTE network coverage scenarios;

[0004] 2) Direct broadcast communication (Broadcast) function between adjacent devices;

[0005] 3) The upper layer supports unicast and multicast communication functions.

[0006] At the 3GPP RAN#66 plenary meeting in December 2014, the research project of enhanced LTE eD2D was approved (see non-patent document 2). The main functions introduced by LTE Release 13eD2D include:

[0007] 1) D2D discovery in scenarios with no network coverage and partial network coverage;

[0008] 2) Priority handling mechanism for D2D communication.

[0009] Based on the design of D2D communication mechanism, the feasibility study of V2X based on D2D communication was approved at the RAN#68 plenary meeting of 3GPP in June 2015. V2X stands for Vehicle to Everything, which hopes to achieve information exchange between vehicles and all entities that may affect vehicles, with the aim of reducing accidents, easing traffic congestion, reducing environmental pollution and providing other information services. The application scenarios of V2X mainly include four aspects:

[0010] 1) V2V, Vehicle to Vehicle, i.e. vehicle-to-vehicle communication;

[0011] 2) V2P, Vehicle to Pedestrian, that is, the vehicle sends warnings to pedestrians or non-motor vehicles;

[0012] 3) V2N, Vehicle to Network, that is, vehicles connected to mobile networks;

[0013] 4) V2I, Vehicle to Infrastructure, refers to the communication between vehicles and road infrastructure.

[0014] 3GPP divides the research and standardization of V2X into three stages. The first stage was completed in September 2016, focusing mainly on V2V, based on LTE Release 12 and Release 13D2D (also known as sidelink communication), that is, proximity communication technology (see non-patent document 3). V2X stage 1 introduced a new D2D communication interface, called the PC5 interface. The PC5 interface is mainly used to solve the communication problems of cellular vehicle networks in high-speed (up to 250 km / h) and high-node density environments. Vehicles can exchange information such as location, speed and direction through the PC5 interface, that is, vehicles can communicate directly through the PC5 interface. Compared with the proximity communication between D2D devices, the functions introduced by LTE Release 14V2X mainly include:

[0015] 1) Higher density DMRS to support high-speed scenarios;

[0016] 2) Introducing sub-channels to enhance resource allocation;

[0017] 3) Introduce a user equipment sensing mechanism with semi-persistent scheduling.

[0018] The second phase of the V2X research project falls within the scope of LTE Release 15 research (see non-patent document 4). The main features introduced include high-order 64QAM modulation, V2X carrier aggregation, short TTI transmission, and feasibility study of transmit diversity.

[0019] At the 3GPP RAN#80 plenary meeting in June 2018, the corresponding third phase V2X feasibility study project based on 5G NR network technology (see non-patent document 5) was approved.

[0020] In the 5G NR V2X topic, a resource allocation mode 2 based on user equipment sensing is supported, or transmission mode 2. For resource allocation mode 2 based on user equipment sensing, the physical layer of the user equipment senses the transmission resources in the resource pool, indicating that the user equipment determines whether to exclude resources in the candidate resource set that overlap with the resources indicated by the above indication information based on the indication information in the SCI received from other user equipments. The resources in the candidate resource set that are not excluded are reported to the upper layer, and the upper layer randomly selects resources for PSSCH / PSCCH transmission from the reported resource set.

[0021] At the 3GPP RAN#95e plenary meeting in March 2022, a standardization research topic based on the evolution of the already standardized NR sidelink communication (NR sidelink evolution, referred to as NR SL evo) (see non-patent document 6) was approved. The research objectives of NR SL evo include the following aspects:

[0022] 1) Research and standardize NR sideline communication on unlicensed spectrum, referred to as SL-U. SL-U includes both resource allocation method 1 and resource allocation method 2 for NR sideline communication. The research project specifically includes:

[0023] a. In SL-U, the channel access technology and operation of NR air interface in unlicensed spectrum communication (NR unlicensed, referred to as NR-U) are reused. The channel access technology of NR-U refers to the Listen Before Talk (LBT) technology, which means "listen before talking", which means that the user equipment needs to listen to the channel resources used for transmission before transmission. If the channel is idle, transmission is carried out; otherwise, transmission is abandoned.

[0024] b. Study the design framework of the physical channel in sideline communication: that is, make necessary modifications to the structure of the physical channel in the existing NR sideline communication to enable SL-U.

[0025] At the 3GPP RAN1#113 meeting in May 2023, the following meeting conclusions were reached regarding SL-U (see Non-Patent Document 7):

[0026] 1) For PSFCH in SL-U:

[0027] a) One PSCCH / PSSCH transmission corresponds to N associated candidate PSFCH resources; wherein N is determined by configuration or pre-configuration information, and the value range of N includes {1, 2, 3, 4};

[0028] b) The N associated candidate PSFCH resources are in the same resource block set (RB set) in different time slots.

[0029] The solution of this patent includes a method in which the physical layer of the sideline communication user equipment reports the sideline communication HARQ feedback information to the upper layer in SL-U, and a method in which the upper layer determines the multicast (groupcast) sideline communication HARQ feedback mechanism.

[0030] Prior art literature

[0031] Non-patent literature

[0032] Non-patent literature 1: RP-140518, Work item proposal on LTE Device to DeviceProximity Services

[0033] Non-Patent Literature 2: RP-142311, Work Item Proposal for Enhanced LTE Device to Device Proximity Services

[0034] Non-patent document 3: RP-152293, New WI proposal: Support for V2V services based on LTE sidelink

[0035] Non-patent document 4: RP-170798, New WID on 3GPP V2X Phase 2

[0036] Non-Patent Literature 5: RP-181480, New SID Proposal: Study on NR V2X

[0037] Non-patent document 6: RP-220300, WID revision: NR sidelink evolution

[0038] Non-patent document 7: RAN1#113 Chairman's notes, section 9.4.1.2 Summary of the invention

[0039] In order to solve at least a part of the above problems, the present invention provides a method performed by a user equipment and the user equipment.

[0040] According to a first aspect of the present invention, a method performed by a user equipment is provided, comprising: the user equipment sending sideline communication control information SCI on an unlicensed spectrum; and the user equipment attempting to receive a physical sideline communication feedback channel PSFCH associated with the SCI.

[0041] In the above method, the SCI sent by the user equipment may be a multicast communication.

[0042] In the above method, it may be that, when the high layer provides the size of the group in the multicast communication and / or the identifier of the group members, and the size of the group is not greater than the number of candidate PSFCH resources in a single time slot, the communication type indication field in the SCI is set to a value representing the multicast communication of the hybrid automatic repeat request HARQ feedback mechanism one, or a value representing the multicast communication of the HARQ feedback mechanism two.

[0043] In the above method, when the size of the group is greater than the number of candidate PSFCH resources in a single time slot, the communication type indication field in the SCI is set to a value indicating multicast communication of HARQ feedback mechanism one.

[0044] In the above method, the candidate PSFCH resources may represent all candidate PSFCH resources on N time slots corresponding to a physical sideline communication control channel PSCCH and / or a physical sideline communication shared channel PSSCH transmission, wherein N is a positive integer.

[0045] In the above method, the N may be obtained through configuration or pre-configuration information.

[0046] In the above method, the communication type indication field in the SCI may be set to a value indicating multicast communication of HARQ feedback mechanism one.

[0047] In the above method, the user equipment may report ACK to a higher layer when determining that PSFCH reception is missing on all the candidate PSFCH resources associated with the SCI.

[0048] In the above method, the user equipment may report NACK to a higher layer when determining that PSFCH reception is not missed on all the candidate PSFCH resources.

[0049] According to a second aspect of the present invention, there is provided a user equipment, comprising: a processor; and a memory storing instructions, wherein the instructions, when executed by the processor, execute any one of the methods described in the first aspect.

[0050] Beneficial effects of the present invention

[0051] The solution of the present invention can effectively improve the communication reliability of sidelink communication on unlicensed spectrum. For example, in SL-U, the solution of the present invention ensures that the physical layer reports ACK to the MAC layer when and only when there is no PSFCH reception on the N associated PSFCH resources corresponding to a PSCCH / PSSCH transmission. This solution effectively improves the communication reliability of sidelink communication on unlicensed spectrum; at the same time, the solution of the present invention can be used for the MAC layer to determine the HARQ feedback mechanism of multicast sidelink communication, which can also improve the communication reliability of sidelink communication on unlicensed spectrum. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The above and other features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0053] Figure 1 It is a schematic diagram showing the basic process of the method executed by the user equipment in the first embodiment of the invention.

[0054] Figure 2 is a block diagram illustrating a user equipment according to an embodiment of the present invention. DETAILED DESCRIPTION

[0055] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the present invention should not be limited to the specific embodiments described below. In addition, for the sake of simplicity, detailed descriptions of known technologies that are not directly related to the present invention are omitted to prevent confusion in understanding the present invention.

[0056] The following uses the 5G mobile communication system and its subsequent evolution versions as example application environments to specifically describe multiple embodiments of the present invention. However, it should be noted that the present invention is not limited to the following embodiments, but is applicable to more other wireless communication systems, such as communication systems after 5G and 4G mobile communication systems before 5G.

[0057] The following describes some of the terms involved in the present invention. Unless otherwise specified, the terms involved in the present invention are defined herein. The terms given in the present invention may be named differently in LTE, LTE-Advanced, LTE-Advanced Pro, NR and subsequent communication systems, but unified terms are used in the present invention, and when applied to a specific system, they can be replaced by the terms used in the corresponding system.

[0058] 3GPP: 3rd Generation Partnership Project

[0059] LTE: Long Term Evolution

[0060] NR: New Radio

[0061] PDCCH: Physical Downlink Control Channel, physical downlink control channel

[0062] DCI: Downlink Control Information, downlink control information

[0063] PDSCH: Physical Downlink Shared Channel, physical downlink shared channel

[0064] UE:User Equipment

[0065] eNB: evolved NodeB

[0066] gNB: NR base station

[0067] TTI: Transmission Time Interval, transmission time interval

[0068] OFDM: Orthogonal Frequency Division Multiplexing

[0069] CP-OFDM: Cyclic Prefix Orthogonal Frequency Division Multiplexing, orthogonal frequency division multiplexing with cyclic prefix

[0070] C-RNTI: Cell Radio Network Temporary Identifier, cell radio network temporary identifier

[0071] CSI: Channel State Information

[0072] HARQ: Hybrid Automatic Repeat Request

[0073] CSI-RS: Channel State Information Reference Signal, channel state information reference signal

[0074] CRS: Cell Reference Signal, cell-specific reference signal

[0075] PUCCH: Physical Uplink Control Channel, physical uplink control channel

[0076] PUSCH: Physical Uplink Shared Channel, physical uplink shared channel

[0077] UL-SCH: Uplink Shared Channel, uplink shared channel

[0078] CG: Configured Grant, configuration scheduling permission

[0079] Sidelink: Sidelink communication

[0080] SCI: Sidelink Control Information, sidelink communication control information

[0081] PSCCH: Physical Sidelink Control Channel, physical sidelink communication control channel

[0082] MCS: Modulation and Coding Scheme, modulation and coding scheme

[0083] RB: Resource Block

[0084] RE:Resource Element

[0085] CRB: Common Resource Block

[0086] CP: Cyclic Prefix

[0087] PRB: Physical Resource Block, physical resource block

[0088] PSSCH: Physical Sidelink Shared Channel, physical sidelink communication shared channel

[0089] FDM: Frequency Division Multiplexing

[0090] RRC: Radi0 Resource Control, radio resource control

[0091] RSRP: Reference Signal Receiving Power, reference signal receiving power

[0092] SRS: Sounding Reference Signal, detection reference signal

[0093] DMRS: Demodulation Reference Signal

[0094] CRC: Cyclic Redundancy Check

[0095] PSDCH: Physical Sidelink Discovery Channel, physical sidelink communication discovery channel PSBCH: Physical Sidelink Broadcast Channel, physical sidelink communication broadcast channel SFI: Slot Format Indication, time slot format indication

[0096] TDD: Time Division Duplexing

[0097] FDD: Frequency Division Duplexing

[0098] SIB: System Information Block

[0099] SIB1: System Information Block Type 1, system information block type 1

[0100] SLSS: Sidelink synchronization Signal, sidelink communication synchronization signal

[0101] PS SS:Primary Sidelink Synchronization Signal,sideline communication primary synchronization signal SSSS:Secondary Sidelink Synchronization Signal,sideline communication auxiliary synchronization signal

[0102] PCI: Physical Cell ID, physical cell identifier

[0103] PSS: Primary Synchronization Signal

[0104] SSS: Secondary Synchronization Signal, auxiliary synchronization signal

[0105] BWP: BandWidth Part, bandwidth fragment / part

[0106] GNSS: Global Navigation Satellite System

[0107] SFN: System Frame Number, system (wireless) frame number

[0108] DFN: Direct Frame Number, direct frame number

[0109] IE: Information Element

[0110] SSB: Synchronization Signal Block, synchronization system information block

[0111] EN-DC: EUTRA-NR Dual Connection, LTE-NR dual connection

[0112] MCG: Master Cell Group

[0113] SCG: Secondary Cell Group

[0114] PCell: Primary Cell

[0115] SCell: Secondary Cell

[0116] PSFCH: Physical Sidelink Feedback Channel, physical sidelink communication feedback channel

[0117] SPS: Semi-Persistant Scheduling

[0118] TA: Timing Advance, uplink timing advance

[0119] PT-RS: Phase-Tracking Reference Signals, phase tracking reference signal

[0120] TB: Transport Block

[0121] CB: Code Block, coding block / code block

[0122] QPSK: Quadrature Phase Shift Keying, orthogonal phase shift keying

[0123] 16 / 64 / 256QAM: 16 / 64 / 256Quadrature Amplitude Modulation, quadrature amplitude modulation

[0124] AGC: Auto Gain Control, automatic gain control

[0125] TDRA (field): Time Domain Resource Assignment, time domain resource allocation indication (field)

[0126] FDRA(field): Frequency Domain Resource Assignment, frequency domain resource allocation indication (field)

[0127] ARFCN: Absolute Radi0 Frequency Channel Number, absolute wireless frequency channel number

[0128] SC-FDMA: Single Carrier-Frequency Division Multiple Access

[0129] MAC: Medium Access Control

[0130] PDU: Protocol Data Unit

[0131] DRX: Discontinuous Reception

[0132] SL-U: Sidelink unlicensed, sidelink communication on unlicensed spectrum

[0133] NR-U: NR unlicensed, NR communication on unlicensed spectrum

[0134] LBT: Listen Before Talk

[0135] TBS: Transport Block Size, transport block size

[0136] CQI: Channel Quality Information

[0137] CPE: Cyclic Prefix extension

[0138] The following is a description of the prior art associated with the solution of the present invention. Unless otherwise specified, the meanings of the same terms in the specific embodiments and the prior art are the same.

[0139] It is worth pointing out that V2X and sidelink mentioned in the specification of the present invention have the same meaning. V2X in the text can also represent sidelink; similarly, sidelink in the text can also represent V2X, and no specific distinction or limitation will be made in the following text.

[0140] The resource allocation method of V2X (sidelink) communication in the specification of the present invention can be equivalently replaced with the transmission mode of V2X (sidelink) communication. The resource allocation method involved in the specification can represent the transmission mode, and the transmission mode involved can represent the resource allocation method. In NR side communication, transmission mode 1 represents a transmission mode (resource allocation method) based on base station scheduling; transmission mode 2 represents a transmission mode (resource allocation method) based on user equipment sensing and resource selection.

[0141] The PSCCH in the specification of the present invention is used to carry SCI. The PSCCH corresponding to, or corresponding to, or related to, or scheduled PSSCH involved in the specification of the present invention have the same meaning, all representing associated PSSCH or corresponding PSSCH. Similarly, the SCI (including first-level SCI and second-level SCI) corresponding to, or corresponding to, or related to PSSCH involved in the specification have the same meaning, all representing associated SCI or corresponding SCI. It is worth noting that the first-level SCI is called 1st stage SCI or SCI format 1-A, which is transmitted in PSCCH; the second-level SCI is called 2nd stage SCI or SCI format 2-A (or, SCI format 2-B), which is transmitted in the corresponding PSSCH resources.

[0142] The NR side communication (SL-U for short) on the unlicensed spectrum in the specification of the present invention may also be referred to as shared spectrum channel access, that is, on the unlicensed spectrum, there may be user devices that access the channel through Wifi technology (wireless LAN technology based on IEEE 802.11 standard), and there may also be NR side communication user devices that access the channel through the PC5 interface.

[0143] Parameter set (numerology) in NR (including NR sidelink) and NR (including NR sidelink Slot

[0144] The parameter set numerology includes two meanings: subcarrier spacing and cyclic prefix CP length. Among them, NR supports 5 subcarrier spacings, namely 15k, 30k, 60k, 120k, and 240kHz (corresponding to μ=0, 1, 2, 3, and 4). Table 4.2-1 shows the supported transmission parameter sets, as shown below.

[0145] Table 4.2-1 Subcarrier spacing supported by NR

[0146] μ <![CDATA[Δf=2 μ ·15[kHz]]]> CP (Cyclic Prefix) 0 15 normal 1 30 normal 2 60 Normal, Extended 3 120 normal 4 240 normal

[0147] Only when μ=2, that is, when the subcarrier spacing is 60kHz, the Extended CP is supported. For other subcarrier spacings, only the Normal CP is supported. For the Normal CP, each slot contains 14 OFDM symbols; for the Extended CP, each slot contains 12 OFDM symbols. For μ=0, that is, 15kHz subcarrier spacing, 1 slot = 1ms; μ=1, that is, 30kHz subcarrier spacing, 1 slot = 0.5ms; μ=2, that is, 60kHz subcarrier spacing, 1 slot = 0.25ms, and so on.

[0148] NR and LTE have the same definition of subframe, which means 1ms. For the subcarrier spacing configuration μ, the slot number within 1 subframe (1ms) can be expressed as The range is 0 to The slot number within a system frame (frame, duration 10ms) can be expressed as The range is 0 to in, and The definitions of different subcarrier spacings μ are shown in the following table.

[0149] Table 4.3.2-1: Number of symbols in each slot, number of slots in each system frame, number of slots in each subframe under normal CP

[0150]

[0151] Table 4.3.2-2: Number of symbols in each slot, number of slots in each system frame, number of slots in each subframe when using extended CP (60kHz)

[0152]

[0153] On the NR carrier, the system frame (or, simply referred to as frame) number SFN ranges from 0 to 1023. The concept of direct system frame number DFN is introduced in sidelink communication, and the number range is also 0 to 1023. The above description of the relationship between system frames and numerology can also be applied to direct system frames. For example, the duration of a direct system frame is also equal to 10ms. For a subcarrier spacing of 15kHz, a direct system frame includes 10 time slots, and so on. DFN is applied to timing on the sidelink carrier.

[0154] Resource Block RB and Resource Unit RE

[0155] Resource blocks RB are defined in the frequency domain as For example, for a subcarrier spacing of 15kHz, the RB is 180kHz in the frequency domain. μ , the resource unit RE represents 1 subcarrier in the frequency domain and 1 OFDM symbol in the time domain.

[0156] Sidelink communication scenarios

[0157] 1) Out-of-Coverage sidelink communication: Both UEs performing sidelink communication have no network coverage (for example, the UE cannot detect any cell that meets the "cell selection criteria" on the frequency required for sidelink communication, indicating that the UE has no network coverage).

[0158] 2) Sidelink communication with network coverage (In-Coverage): Both UEs performing sidelink communication have network coverage (for example, the UE detects at least one cell that meets the "cell selection criteria" on the frequency required for sidelink communication, indicating that the UE has network coverage).

[0159] 3) Partial-Coverage sidelink communication: One of the UEs performing sidelink communication has no network coverage, while the other UE has network coverage.

[0160] From the UE side, the UE has only two scenarios: no network coverage and network coverage. Partial network coverage is described from the perspective of sidelink communication.

[0161] Sidelink resource pool

[0162] In sidelink communication, the resources sent and received by the UE belong to the resource pool. For example, for a transmission mode based on base station scheduling in sidelink communication, the base station schedules transmission resources for the sidelink UE in the resource pool, or, for a transmission mode based on UE perception in sidelink communication, the UE determines the transmission resources in the resource pool.

[0163] For NR sideline communications, the frequency domain supports resource allocation based on sub-channels as the minimum granularity, that is, for PSSCH transmission, the resources occupied in the frequency domain are an integer number of sub-channels. A sub-channel can represent several consecutive resource blocks RBs in the frequency domain.

[0164] Resource allocation based on perception

[0165] For the perception-based resource allocation method (resource allocation method 2), the sidelink communication user equipment selects candidate resources within a time window (optionally, resource selection window [n+T1, n+T2]), and determines the candidate resources that overlap with the reserved resources based on the reserved resources indicated by the PSCCH sent by other user equipment in the monitoring time slot, and excludes these overlapping candidate resources. The physical layer reports the set of candidate resources that are not excluded to the MAC layer, and the MAC layer selects transmission resources for the PSSCH / PSCCH. The set of transmission resources selected by the MAC layer is called a selected sidelink grant. The sidelink communication resources contained in a selected sidelink grant can be used for the initial transmission and all retransmissions of a MAC PDU (corresponding to a transmission block TB), or can be used for the initial transmission and all retransmissions of multiple MAC PDUs (corresponding to multiple transmission blocks TB). The present invention does not impose any restrictions on this.

[0166] LBT (Listen Before Talk) mechanism

[0167] For wireless communications on unlicensed spectrum, some countries or regions (for example, Europe) stipulate that user equipment must perform LBT operation before transmitting wireless communications, which is a "listen before talk" mechanism, also known as channel access operation, which means a mechanism to determine channel availability by sensing the channel. Specifically, during a period of time before communication transmission, the user equipment will only transmit when it detects that the channel is idle; otherwise, the user equipment will not transmit.

[0168] Specifically, for NR communication over unlicensed spectrum (NR-U) (or, for SL-U), the basic time unit for sensing the channel can be T sl =9μs. In this time unit, if the energy detected by the base station or user equipment on the channel is lower than the energy threshold value X ThreshWhen the duration is equal to or greater than 4μs, the base station or user equipment considers that the channel is idle within this time unit (or, it is called LBT success). It is worth noting that the channel (channel) that the base station or user equipment detects energy and uses to determine whether it is idle represents a carrier containing a set of continuous resource blocks RB, or a part of the carrier. The channel can also be called LBT bandwidth (LBT bandwidth), or LBT sub-band (LBT sub-band), or RB set (RB set). An LBT bandwidth or RB set can be equal to 20MHz in the frequency domain, that is, there can be one RB set on a 20MHz carrier. The number of resource blocks RBs corresponding to multiple RB sets contained in a carrier (carriers exceeding 20MHz, such as 40MHz, 60MHz, 80MHz) and the guard band (Guard Band, referred to as GB) between two continuous RB sets can be as shown in the following table:

[0169] Table 1: Number of RBs in all RB sets and GBs on a carrier at 15kHz and 30kHz subcarrier spacing

[0170]

[0171] In the figure above, taking the subcarrier spacing of 15kHz and the carrier bandwidth of 40MHz as an example, 105-6-105 indicates that the carrier contains two consecutive RB sets, each containing 105 RBs. Between the two RB sets, there is a guard band GB containing 6 consecutive RBs, which contains a total of 216 consecutive RBs, and so on for other items in Table 1.

[0172] It is worth pointing out that the LBT operations performed by the (sideline communication) user equipment on different RB sets may be independent of each other (i.e., the two are unrelated). For example, the user equipment detects that the channel is idle on RB set 1, and the channel is occupied (or busy) on RB set 2. If the resources selected by the sideline communication user equipment for transmitting PSSCH / PSCCH include (all or part of) the RBs corresponding to RB set 1 and RB set 2, the user equipment may send the corresponding PSSCH / PSCCH if and only if the user equipment detects that the channel is idle on both RB set 1 and RB set 2.

[0173] N associated candidate PSFCH resources (or transmission opportunities) corresponding to one PSCCH / PSSCH transmission occasion)

[0174] For side communications on unlicensed spectrum, when LBT fails, PSFCH may not be transmitted normally. Therefore, for SL-U, one PSCCH / PSSCH transmission can correspond to N associated candidate PSFCH resources, that is, when the LBT of one candidate PSFCH resource is unsuccessful, the LBT of one or more other candidate PSFCH resources may be successful, and PSFCH transmission can be performed. Among them, N is determined by configuration or pre-configuration information, and the value range is {1, 2, 3, 4}. Specifically, the N associated candidate PSFCH resources corresponding to one PSCCH / PSSCH transmission are in the same RB set in different time slots.

[0175] HARQ feedback mechanism in side-by-side multicast communication

[0176] For multicast sideline communications, two different HARQ feedback mechanisms are supported, namely HARQ feedback mechanism 1 and HARQ feedback mechanism 2. Among them, HARQ feedback mechanism 1 means that when the user equipment receiving PSCCH / PSSCH fails to decode successfully, NACK is sent on the associated PSFCH resource, and no information is sent when the decoding is successful; HARQ feedback mechanism 2 means that when the user equipment receiving PSCCH / PSSCH fails to decode successfully, NACK is sent on the associated PSFCH resource, and ACK is sent on the associated PSFCH resource when the decoding is successful. For HARQ feedback mechanism 1, all group member user equipment in the multicast communication can share the same associated PSFCH resource; for HARQ feedback mechanism 2, the associated PSFCH resources corresponding to all group member user equipment in the multicast communication can be different.

[0177] The cast type indicator field in SCI format 2-A (2-B)

[0178] For SCI format 2-A (2-B) in level 2 SCI, the communication type indication field may include two bits, namely, the values ​​are '00', '01', '10', and '11'. The indication information corresponding to each value is shown in Table 2.

[0179] Table 2. Cast type indicator

[0180] Indicates the value of the field Corresponding instructions 00 Broadcast 01 Multicast communication based on HARQ feedback mechanism II 10 Unicast 11 Multicast communication based on HARQ feedback mechanism 1

[0181] Hereinafter, specific examples and embodiments of the present invention will be described in detail. As described above, the examples and embodiments described in the present disclosure are provided for easy understanding of the present invention and are not intended to limit the present invention.

[0182] [Example 1]

[0183] Figure 1 It is a schematic diagram showing the basic process of the method executed by the user equipment according to the first embodiment of the present invention.

[0184] Next, combine Figure 1 The basic process diagram shown is used to describe in detail the method executed by the user equipment according to the first embodiment of the present invention.

[0185] like Figure 1 As shown, in the first embodiment of the present invention, the steps performed by the user equipment include:

[0186] In step S101, a sideline communication user equipment sends sideline communication control information SCI on an unlicensed spectrum (or on a shared spectrum).

[0187] Optionally, the sent SCI is a multicast communication, that is, the number of user equipments receiving the SCI is greater than 1, or equal to 1.

[0188] Optionally, if the upper layer provides the group size (group size) and / or the identifier (member ID) of the group members (in the multicast communication), and the group size is not greater than the number of candidate PSFCH resources in a single (or one) time slot, then the communication type indicator field (cast type indicator field) in the SCI is set to '01', or '11', indicating multicast communication of HARQ feedback mechanism two, or multicast communication of HARQ feedback mechanism one. Optionally, otherwise, the communication type indicator field in the SCI is set to '11', indicating multicast communication of the HARQ feedback mechanism one. Optionally, the candidate PSFCH resources represent (all) candidate PSFCH resources in N time slots corresponding to one PSCCH / PSSCH transmission, where N is a positive integer obtained through configuration or pre-configuration information.

[0189] Optionally, the value of the communication type indication field in the SCI is '11', which indicates multicast communication of HARQ feedback mechanism 1. In step S102, the user equipment attempts to receive (attempt to) the PSFCH associated with (or corresponding to) the SCI.

[0190] Optionally, if the user equipment determines that PSFCH reception is absent (absence of PSFCH reception) on (all) the N candidate PSFCH resources (occasion) associated with (or corresponding to) the SCI, then the user equipment reports an ACK to the upper layer (MAC layer); optionally, otherwise, a NACK is reported to the upper layer.

[0191] According to this embodiment, the communication reliability of sideline communication on unlicensed spectrum can be effectively improved. For example, in SL-U, the scheme of the present invention ensures that the physical layer reports ACK to the MAC layer when and only when there is no PSFCH reception on the N associated PSFCH resources corresponding to a PSCCH / PSSCH transmission. This scheme effectively improves the communication reliability of sideline communication on unlicensed spectrum.

[0192] At the same time, the solution of the present invention can be used for the MAC layer to determine the HARQ feedback mechanism of the multicast sideline communication, and can also improve the communication reliability of the sideline communication on the unlicensed spectrum.

[0193] Figure 2 is a block diagram showing a user equipment UE involved in the present invention. Figure 2 As shown, the user equipment UE80 includes a processor 801 and a memory 802. The processor 801 may include, for example, a microprocessor, a microcontroller, an embedded processor, etc. The memory 802 may include, for example, a volatile memory (such as a random access memory RAM), a hard disk drive (HDD), a non-volatile memory (such as a flash memory), or other memories, etc. The memory 802 stores program instructions. When the instructions are executed by the processor 801, the above method performed by the user equipment described in detail in the present invention may be executed.

[0194] The method of the present invention and the related equipment have been described above in conjunction with the preferred embodiments. Those skilled in the art will appreciate that the method shown above is only exemplary, and the embodiments described above can be combined with each other without contradiction. The method of the present invention is not limited to the steps and sequence shown above. The network node and user equipment shown above may include more modules, for example, modules that can be developed or developed in the future and can be used for base stations, MMEs, or UEs, etc. The various identifiers shown above are only exemplary and not restrictive, and the present invention is not limited to the specific information elements that serve as examples of these identifiers. Those skilled in the art may make many changes and modifications based on the teachings of the illustrated embodiments.

[0195] It should be understood that the above embodiments of the present invention can be implemented by software, hardware, or a combination of software and hardware. For example, the various components inside the base station and user equipment in the above embodiments can be implemented by a variety of devices, including but not limited to: analog circuit devices, digital circuit devices, digital signal processing (DSP) circuits, programmable processors, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), programmable logic devices (CPLDs), and the like.

[0196] In this application, "base station" may refer to a mobile communication data and control exchange center with a large transmission power and a wide coverage area, including functions such as resource allocation scheduling, data reception and transmission, etc. "User equipment" may refer to a user mobile terminal, such as a mobile phone, a notebook, etc., which can communicate wirelessly with a base station or a micro base station.

[0197] In addition, the embodiments of the present invention disclosed herein can be implemented on a computer program product. More specifically, the computer program product is a product as follows: having a computer-readable medium, on which a computer program logic is encoded, and when executed on a computing device, the computer program logic provides relevant operations to implement the above-mentioned technical solution of the present invention. When executed on at least one processor of a computing system, the computer program logic causes the processor to perform the operation (method) described in the embodiment of the present invention. This arrangement of the present invention is typically provided as software, code and / or other data structures arranged or encoded on a computer-readable medium such as an optical medium (e.g., CD-ROM), a floppy disk or a hard disk, or other media such as firmware or microcode on one or more ROM or RAM or PROM chips, or downloadable software images in one or more modules, shared databases, etc. The software or firmware or such a configuration can be installed on a computing device so that one or more processors in the computing device execute the technical solution described in the embodiment of the present invention.

[0198] In addition, each functional module or each feature of the base station equipment and terminal equipment used in each of the above embodiments can be implemented or executed by a circuit, and the circuit is generally one or more integrated circuits. The circuit designed to perform the various functions described in this specification may include a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC) or a general-purpose integrated circuit, a field programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic, or a discrete hardware component, or any combination of the above devices. The general-purpose processor may be a microprocessor, or the processor may be an existing processor, a controller, a microcontroller or a state machine. The above-mentioned general-purpose processor or each circuit may be configured by a digital circuit, or may be configured by a logic circuit. In addition, when, due to the progress of semiconductor technology, an advanced technology that can replace the current integrated circuit appears, the present invention may also use the integrated circuit obtained by using the advanced technology.

[0199] Although the present invention has been illustrated above in conjunction with the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that various modifications, substitutions and changes may be made to the present invention without departing from the spirit and scope of the present invention. Therefore, the present invention should not be limited by the above-described embodiments, but by the appended claims and their equivalents.

Claims

1. A method performed by a user equipment, comprising: In the unlicensed spectrum, the user equipment sends side communication control information SCI; and The user equipment attempts to receive a physical sideline communication feedback channel PSFCH associated with the SCI.

2. The method according to claim 1, characterized in that The SCI sent by the user equipment is multicast communication.

3. The method according to claim 2, characterized in that When the high layer provides the size of the group in the multicast communication and / or the identifiers of the group members, and the size of the group is not greater than the number of candidate PSFCH resources in a single time slot, the communication type indication field in the SCI is set to a value representing multicast communication of hybrid automatic repeat request HARQ feedback mechanism one, or a value representing multicast communication of HARQ feedback mechanism two.

4. The method according to claim 3, characterized in that In the case where the size of the group is greater than the number of candidate PSFCH resources in a single time slot, the communication type indication field in the SCI is set to a value indicating multicast communication of HARQ feedback mechanism one.

5. The method according to claim 3 or 4, characterized in that: The candidate PSFCH resources represent all candidate PSFCH resources on N time slots corresponding to a physical sideline communication control channel PSCCH and / or a physical sideline communication shared channel PSSCH transmission, wherein N is a positive integer.

6. The method according to claim 5, characterized in that The N is obtained through configuration or pre-configuration information.

7. The method according to claim 2, characterized in that The communication type indication field in the SCI is set to a value indicating multicast communication of HARQ feedback mechanism one.

8. The method according to claim 5, characterized in that When the user equipment determines that PSFCH reception is missing on all the candidate PSFCH resources associated with the SCI, the user equipment reports ACK to a higher layer.

9. The method according to claim 8, characterized in that When the user equipment determines that PSFCH reception is not missed on all the candidate PSFCH resources, the user equipment reports NACK to a higher layer.

10. A user equipment, comprising: processor; as well as Memory, which stores instructions, Wherein, when the instructions are executed by the processor, the method according to any one of claims 1 to 9 is executed.

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