Method executed by user equipment and user equipment

Abstract

The invention provides a method executed by user equipment and the user equipment. The method comprises the following steps: the sidewalk communication user equipment receives sidewalk communication control information SCI and a corresponding physical sidewalk communication shared channel PSSCH; and the user equipment determines the starting time of a sidewalk communication discontinuous reception (SL) DRX round trip timer (RTT) timer. Therefore, the receiving power consumption of the sidewalk communication user equipment on the unlicensed spectrum can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, and in particular to a method performed by a user equipment and a corresponding user equipment. BACKGROUND

[0002] In a conventional cellular network, all communications must pass through a base station. Different from this, D2D communication (Device-to-Device communication) refers to a communication mode in which two user equipments directly communicate without the forwarding of a base station or a core network. In March 2014, at the 63rd plenary session of the 3rd Generation Partnership Project (3GPP) RAN, a research project on the use of LTE devices to implement proximity D2D communication services was approved (see Non-Patent Literature 1). The functions introduced by LTE Release 12 D2D include:

[0003] 1) Discovery function between proximate devices under LTE network coverage scenario;

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

[0005] 3) High-level support for Unicast and Groupcast communication functions.

[0006] In December 2014, at the 66th plenary session of the 3GPP RAN, the research project of enhanced LTE eD2D (enhanced D2D) was approved (see Non-Patent Literature 2). The main functions introduced by LTE Release 13 eD2D include:

[0007] 1) D2D discovery in network coverage scenarios and partial network coverage scenarios;

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

[0009] Based on the design of the D2D communication mechanism, in June 2015, at the 68th plenary session of the 3GPP RAN, the V2X feasibility study based on D2D communication was approved. V2X means Vehicle to everything, and aims to realize the information interaction between vehicles and all entities that can affect vehicles, so as to reduce accidents, alleviate traffic congestion, reduce environmental pollution, and provide other information services. The application scenarios of V2X mainly include four aspects:

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

[0011] 2) V2P, Vehicle to Pedestrian, i.e., sending warnings from vehicles to pedestrians or non-motorized vehicles;

[0012] 3) V2N, Vehicle to Network, i.e., vehicles connecting to mobile networks;

[0013] 4) V2I, Vehicle to Infrastructure, i.e., vehicles communicating with road infrastructure, etc.

[0014] 3GPP divides the study and standardization of V2X into three stages. The first stage was completed in September 2016, and mainly focuses on V2V, based on LTE Release 12 and Release 13 D2D (also known as sidelink, i.e., adjacent communication technology) (see Non-Patent Literature 3). V2X stage 1 introduced a new D2D communication interface, called the PC5 interface. The PC5 interface is mainly used to solve the problem of cellular vehicle networking communication in high-speed (up to 250 kilometers / hour) and high node density environments. Vehicles can exchange information such as location, speed, and direction through the PC5 interface, i.e., vehicles can directly communicate through the PC5 interface. Compared with the adjacent communication between D2D devices, the functions introduced by LTE Release 14 V2X mainly include:

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

[0016] 2) Introduction of sub-channels, enhanced resource allocation method;

[0017] 3) Introduction of user equipment sensing mechanism with semi-persistent scheduling.

[0018] The second stage of the V2X study is attributed to the LTE Release 15 study (see Non-Patent Literature 4), and 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 stage of the V2X feasibility study based on 5G NR network technology (see Non-Patent Literature 5) was approved.

[0020] In the 5G NR V2X study item, a user equipment sensing based resource allocation mode 2, or transmission mode 2, is supported. For the user equipment sensing based resource allocation mode 2, the physical layer of the user equipment senses the transmission resources within the resource pool, which means that the user equipment determines whether to exclude the resources in the candidate resource set that overlap with the resources indicated in the indication information received from other user equipment in the SCI, and reports the non-excluded resources in the candidate resource set to the higher layer, and the higher layer randomly selects the resources for PSSCH / PSCCH transmission from the reported resource set.

[0021] At the 3GPP RAN#90e plenary meeting on December 3, 2020, the standardization study item of NR sidelink enhancement based on the already standardized NR sidelink (see Non-Patent Literature 6) was approved. The enhancement of sidelink communication includes the following three aspects:

[0022] 1) Standardize the resource allocation mode for reducing the power consumption of sidelink user equipment, including but not limited to: partial sensing based resource allocation mode, random resource selection based resource allocation mode;

[0023] 2) Study to improve the communication reliability and reduce the communication delay of resource allocation mode 2 in NR sidelink communication, which includes: Inter-UE coordination. Inter-UE coordination means that UE A determines a resource set and sends (indicates) the resource set to UE B. The resource allocation mode of UE B is resource allocation mode 2, and the resource set indicated by UE A is considered when selecting resources;

[0024] 3) Standardize the SL Discontinuous Reception (SL DRX) mechanism. In 5G NR communication, user equipment supports discontinuous reception of physical downlink control channel PDCCH in time, which is called DRX, which can effectively reduce the power consumption of the communication device. Similarly, corresponding to SL DRX, discontinuous reception refers to listening to sidelink control information SCI (including level 1 SCI and level 2 SCI) in part of the time in the time domain, which is called active period.

[0025] At the 3GPP RAN1#104bis-e meeting on April 3, 2021, the following conclusions were reached regarding Inter-UE coordination in mode 2 (IUC) (see Non-Patent Literature 7):

[0026] Inter-UE coordination supports two schemes as follows:

[0027] Inter-UE coordination scheme one: The coordination message sent by UE A to UE B is an indication of a set of resources. This set of resources is preferred for UE B’s transmission, and / or is non-preferred for UE B’s transmission;

[0028] Inter-UE coordination scheme two: The coordination message sent by UE A to UE B is an indication of an expected (or, potential) resource conflict on the resources indicated by the SCI sent by UE B, and / or is an indication of a detected resource conflict on the resources indicated by the SCI sent by UE B.

[0029] At the 3GPP RAN#95e plenary meeting in March 2022, the standardization study item on NR sidelink evolution (NR SL evo) was approved based on the already standardized NR sidelink communication (see Non-Patent Literature 8). The research objectives of NR SL evo include the following aspects:

[0030] 1) Study and standardize NR sidelink communication in unlicensed spectrum (SL-U). SL-U includes both resource allocation mode 1 and resource allocation mode 2 of NR sidelink communication. This study item specifically includes:

[0031] a. In SL-U, reuse the channel access techniques and operations of NR unlicensed (NR-U) for NR sidelink communication. The channel access techniques of NR-U refer to the Listen Before Talk (LBT) technique, 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 performed; otherwise, transmission is abandoned.

[0032] b. Study the design framework of physical channels in SL-U: i.e. make necessary modifications to the structure of existing NR sidelink physical channels to enable SL-U.

[0033] 2) Study and standardize LTE sidelink and NR sidelink co-channel coexistence, i.e. the scenario where the frequency of LTE sidelink and NR sidelink communication is the same or overlapping. For LTE sidelink and NR sidelink devices using the same communication frequency, design an efficient resource allocation method so as not to affect the communication of both sidelink devices.

[0034] Support the SL DRX mechanism described above in SL-U, i.e. when performing sidelink communication on unlicensed spectrum, the user equipment can listen to the sidelink communication control information SCI (including level 1 SCI and level 2 SCI) in part of the time domain.

[0035] Support the UE-to-UE coordination mechanism described above in co-channel coexistence, i.e. the NR sidelink module of the sidelink user equipment can still perform resource selection or resource reselection in combination with the coordination message (e.g. the preferred resource set) in UE-to-UE coordination.

[0036] The scheme of the present patent includes a method for the sidelink user equipment to determine the starting time of the SL DRX round trip timer (RTT timer) in SL-U, and also includes a method for the NR sidelink module to perform resource selection (or resource reselection) in co-channel coexistence.

[0037] Prior art documents

[0038] Non-patent documents

[0039] Non-patent document 1: RP-140518, Work item proposal on LTE Device to Device Proximity Services

[0040] Non-patent document 2: RP-142311, Work Item Proposal for Enhanced LTE Device to Device Proximity Services

[0041] NPL 3: RP-152293, New WI proposal: Support for V2V services based on LTE sidelink

[0042] NPL 4: RP-170798, New WID on 3GPP V2X Phase 2

[0043] NPL 5: RP-181480, New SID Proposal: Study on NR V2X

[0044] NPL 6: RP-202846, WID revision: NR sidelink enhancement

[0045] NPL 7: RAN1#104bis-e, Chairman's notes, section 8.11.1.2

[0046] NPL 8: RP-220300, WID revision: NR sidelink evolution SUMMARY

[0047] To solve at least part of the above problems, the present application provides a method executed by a user equipment and a user equipment.

[0048] According to a first aspect of the present application, a method executed by a user equipment (UE) is provided, comprising: receiving, by the sidelink user equipment, a sidelink control information (SCI) and a corresponding physical sidelink shared channel (PSSCH); determining, by the user equipment, a starting time of a sidelink discontinuous reception (SL DRX) round trip timer (RTT timer).

[0049] In the method of the above first aspect, the SCI associated sidelink grant configures a PSFCH resource.

[0050] In the method of the above first aspect, the user equipment determines the starting time of the SL DRX RTT timer according to indication information of the SCI.

[0051] In the method of the first aspect, if the SCI indicates that the sidelink HARQ feedback is disabled, and the SCI does not indicate one or more retransmission occasions, and if one PSCCH / PSSCH transmission is configured to correspond to one or more PSFCH transmission occasions, the user equipment starts the SL DRX RTT timer at the first slot after the end of the last PSFCH transmission occasion corresponding to the PSSCH transmission.

[0052] In the method of the first aspect, if the SCI indicates that the sidelink HARQ feedback is disabled, and the SCI does not indicate one or more retransmission occasions, and if one PSCCH / PSSCH transmission is not configured to correspond to one or more PSFCH transmission occasions, the user equipment starts the SL DRX RTT timer at the slot after the end of the PSFCH resource corresponding to the PSSCH.

[0053] In the method of the first aspect, if the SCI indicates that the sidelink HARQ feedback is disabled, and the SCI indicates one or more retransmission occasions, the user equipment starts the SL DRX RTT timer at the slot after the end of the PSSCH.

[0054] According to a second aspect of the present application, a user equipment is provided, comprising: a processor; and a memory storing instructions, wherein the instructions, when executed by the processor, perform the method according to any one of the first aspect.

[0055] Advantages of the present application

[0056] In SL-U, the scheme of the present application provides a method for determining the starting time of the SL DRX round trip timer RTT timer. Specifically, for the case where one PSSCH transmission corresponds to multiple PSFCH transmission occasions, when the SCI corresponding to the PSSCH transmission indicates SL HARQ disablement and the SCI does not indicate any retransmission resource, the user equipment starts the SL DRX round trip timer RTT timer at the first slot after the last PSFCH transmission occasion in the multiple PSFCH transmission occasions. The scheme of the present application ensures that the sidelink user equipment corresponding to one PSSCH transmission on the unlicensed frequency band only starts the SL DRX round trip timer RTT timer once, effectively implements SL DRX, and reduces the power consumption of the sidelink user equipment.

[0057] Meanwhile, the scheme of the present application also provides that, in co-channel coexistence, when the NR sidelink module considers the preferred resource set of the received transmission in resource selection (or, resource reselection), if the intersection of the sensed resource set and the preferred resource set of the transmission is not enough for the selection of the HARQ retransmission resource, the NR sidelink module can select, as the selected HARQ retransmission resource, the resource in the second time slot corresponding to the resource (initial transmission or retransmission) in the first time slot of the two time slots of the NR SL (subcarrier spacing of the NR SL is 30 kHz) that has been selected and that is located in the time domain and overlaps with the LTE SL subframe. The scheme of the present application ensures that, in the case where the NR sidelink module has selected the resource in the first time slot of the two time slots of the NR SL that overlaps with the LTE SL subframe, the resource in the second time slot can also be selected, effectively avoiding the reception interference caused to the LTE sidelink. BRIEF DESCRIPTION OF DRAWINGS

[0058] The above and other features of the present application will become more apparent by describing in detail the embodiments thereof with reference to the attached drawings, in which:

[0059] Figure 1 FIG. 1 is a schematic diagram illustrating the basic process of a method performed by a user equipment in Embodiment One of the present application.

[0060] Figure 2 FIG. 2 is a schematic diagram illustrating the basic process of a method performed by a user equipment in Embodiment Two of the present application.

[0061] Figure 3 FIG. 3 is a block diagram illustrating a user equipment according to an embodiment of the present application. DETAILED DESCRIPTION

[0062] The present application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the present application should not be limited to the specific embodiments described below. In addition, for the sake of brevity, detailed descriptions of well-known technology that is not directly related to the present application will be omitted so as not to cause confusion in understanding the present application.

[0063] The following describes in detail a plurality of embodiments according to the present application with reference to the 5G mobile communication system and its subsequent evolution versions as an example application environment. However, it should be noted that the present application is not limited to the following embodiments, but can be applied to more other wireless communication systems, such as the communication systems after 5G and the 4G mobile communication system before 5G, etc.

[0064] Some terms related to the present application are described below. Unless otherwise specifically stated, the terms used in the present application are defined as follows. The terms given in the present application can be used differently in LTE, LTE-Advanced, LTE-Advanced Pro, NR, and later communication systems, but uniform terms are used in the present application, and when applied to a specific system, the terms used in the corresponding system can be replaced.

[0065] 3GPP: 3rd Generation Partnership Project

[0066] LTE: Long Term Evolution

[0067] NR: New Radio

[0068] PDCCH: Physical Downlink Control Channel

[0069] DCI: Downlink Control Information

[0070] PDSCH: Physical Downlink Shared Channel

[0071] UE: User Equipment

[0072] eNB: evolved NodeB

[0073] gNB: NR base station

[0074] TTI: Transmission Time Interval

[0075] OFDM: Orthogonal Frequency Division Multiplexing

[0076] CP-OFDM: Cyclic Prefix Orthogonal Frequency Division Multiplexing

[0077] C-RNTI: Cell Radio Network Temporary Identifier

[0078] CSI: Channel State Information, channel state information

[0079] HARQ: Hybrid Automatic Repeat Request, hybrid automatic repeat request

[0080] CSI-RS: Channel State Information Reference Signal, channel state information reference signal

[0081] CRS: Cell Reference Signal, cell-specific reference signal

[0082] PUCCH: Physical Uplink Control Channel, physical uplink control channel

[0083] PUSCH: Physical Uplink Shared Channel, physical uplink shared channel

[0084] UL-SCH: Uplink Shared Channel, uplink shared channel

[0085] CG: Configured Grant, configured grant

[0086] Sidelink: sidelink communication

[0087] SCI: Sidelink Control Information, sidelink control information

[0088] PSCCH: Physical Sidelink Control Channel, physical sidelink control channel

[0089] MCS: Modulation and Coding Scheme, modulation and coding scheme

[0090] RB: Resource Block, resource block

[0091] RE: Resource Element, resource element

[0092] CRB: Common Resource Block, common resource block

[0093] CP: Cyclic Prefix, cyclic prefix

[0094] PRB: Physical Resource Block, physical resource block

[0095] PSSCH: Physical Sidelink Shared Channel, physical sidelink shared channel

[0096] FDM: Frequency Division Multiplexing, frequency division multiplexing

[0097] RRC: Radio Resource Control, radio resource control

[0098] RSRP: Reference Signal Receiving Power, reference signal receiving power

[0099] SRS: Sounding Reference Signal, sounding reference signal

[0100] DMRS: Demodulation Reference Signal, demodulation reference signal

[0101] CRC: Cyclic Redundancy Check, cyclic redundancy check

[0102] PSDCH: Physical Sidelink Discovery Channel, physical sidelink discovery channel

[0103] PSBCH: Physical Sidelink Broadcast Channel, physical sidelink broadcast channel

[0104] SFI: Slot Format Indication, slot format indication

[0105] TDD: Time Division Duplexing, time division duplexing

[0106] FDD: Frequency Division Duplexing, frequency division duplexing

[0107] SIB: System Information Block, system information block

[0108] SIB1: System Information Block Type 1, system information block type 1

[0109] SLSS: Sidelink synchronization Signal, sidelink synchronization signal

[0110] PSSS: Primary Sidelink Synchronization Signal, primary sidelink synchronization signal

[0111] SSSS: Secondary Sidelink Synchronization Signal, secondary sidelink synchronization signal

[0112] PCI: Physical Cell ID, physical cell identity

[0113] PSS: Primary Synchronization Signal, primary synchronization signal

[0114] SSS: Secondary Synchronization Signal, secondary synchronization signal

[0115] BWP: BandWidth Part, bandwidth part

[0116] GNSS: Global Navigation Satellite System, global navigation satellite system

[0117] SFN: System Frame Number, system (radio) frame number

[0118] DFN: Direct Frame Number, direct frame number

[0119] IE: Information Element, information element

[0120] SSB: Synchronization Signal Block, synchronization signal block

[0121] EN-DC: EUTRA-NR Dual Connection, LTE-NR dual connection

[0122] MCG: Master Cell Group, master cell group

[0123] SCG: Secondary Cell Group, secondary cell group

[0124] PCell: Primary Cell, primary cell

[0125] SCell: Secondary Cell

[0126] PSFCH: Physical Sidelink Feedback Channel

[0127] SPS: Semi-Persistant Scheduling

[0128] TA: Timing Advance

[0129] PT-RS: Phase-Tracking Reference Signals

[0130] TB: Transport Block

[0131] CB: Code Block

[0132] QPSK: Quadrature Phase Shift Keying

[0133] 16 / 64 / 256 QAM: 16 / 64 / 256 Quadrature Amplitude Modulation

[0134] AGC: Auto Gain Control

[0135] TDRA (field): Time Domain Resource Assignment indication (field)

[0136] FDRA (field): Frequency Domain Resource Assignment indication (field)

[0137] ARFCN: Absolute Radio Frequency Channel Number

[0138] SC-FDMA: Single Carrier-Frequency Division Multiple Access

[0139] MAC: Medium Access Control

[0140] PDU: Protocol Data Unit, protocol data unit

[0141] DRX: Discontinuous Reception, discontinuous reception

[0142] SL-U: Sidelink unlicensed, sidelink in unlicensed spectrum

[0143] NR-U: NR unlicensed, NR in unlicensed spectrum

[0144] LBT: Listen Before Talk, listen before talk

[0145] TBS: Transport Block Size, transport block size

[0146] CQI: Channel Quality Information, channel quality information

[0147] CPE: Cyclic Prefix extension, cyclic prefix extension

[0148] RTT: Round Trip Time, round trip time

[0149] The following is a description of the prior art associated with the present application. Unless otherwise specified, the meanings of the same terms in the specific embodiments are the same as in the prior art.

[0150] It is worth pointing out that the V2X referred to in the specification of the present application is the same as the sidelink. The V2X in the text can also represent the sidelink; similarly, the sidelink in the text can also represent the V2X, which will not be specifically distinguished and limited hereinafter.

[0151] The resource allocation mode of the V2X (sidelink) communication in the specification of the present application can be replaced with the transmission mode of the V2X (sidelink) communication. The resource allocation mode referred to in the specification can represent the transmission mode, and the transmission mode referred to can represent the resource allocation mode. In NR sidelink, transmission mode 1 represents a base station scheduling-based transmission mode (resource allocation mode); transmission mode 2 represents a user equipment sensing and resource selection-based transmission mode (resource allocation mode).

[0152] The PSCCH in the specification of the present application is used to carry SCI. The PSCCH referred to in the specification of the present application corresponds to, or corresponds to, or is associated with, or schedules the PSSCH. The meaning of the PSSCH referred to in the specification of the present application corresponds to, or corresponds to, or is associated with, or schedules the PSSCH. Similarly, the SCI (including the first stage SCI and the second stage SCI) referred to in the specification corresponds to, or corresponds to, or is associated with, or schedules the PSSCH. It is worth pointing out that the first stage SCI is called 1st stage SCI or SCI format 1-A, which is transmitted in the PSCCH; the second stage SCI is called 2nd stage SCI or SCI format 2-A (or SCI format 2-B), which is transmitted in the corresponding PSSCH resource.

[0153] The SL-U in the specification of the present application means that the NR sidelink communication on the unlicensed spectrum (also called shared spectrum channel access), that is, on the unlicensed spectrum, there may be user equipment accessing the channel through Wifi technology (wireless local area network technology based on IEEE 802.11 standard), and there may also be NR sidelink communication user equipment accessing through the PC5 interface.

[0154] Numerology in NR (including NR sidelink) and resource allocation in NR (including NR sidelink) Slot

[0155] The parameter set numerology contains two aspects of subcarrier spacing and cyclic prefix CP length. Among them, NR supports five kinds of subcarrier spacing, which are 15k, 30k, 60k, 120k and 240kHz (corresponding to μ = 0, 1, 2, 3, 4). Table 4.2-1 shows the supported transmission parameter set, as follows.

[0156] Table 4.2-1 NR supported subcarrier spacing

[0157] μ Δf = 2 μ · 15 [kHz] ] > CP (Cyclic Prefix) 0 15 Normal 1 30 Normal 2 60 Normal, extended 3 120 Normal 4 240 Normal

[0158] Extended CP is supported only for μ = 2, i.e. 60 kHz subcarrier spacing, and normal CP is supported for other subcarrier spacings. For normal CP, each slot contains 14 OFDM symbols; for extended CP, each slot contains 12 OFDM symbols. For μ = 0, i.e. 15 kHz subcarrier spacing, 1 slot = 1 ms; for μ = 1, i.e. 30 kHz subcarrier spacing, 1 slot = 0.5 ms; for μ = 2, i.e. 60 kHz subcarrier spacing, 1 slot = 0.25 ms, and so on.

[0159] NR and LTE have the same definition of subframe, which represents 1 ms. For a subcarrier spacing configuration μ, the slot number within 1 subframe (1 ms) can be expressed as ranging from 0 to The slot number within 1 system frame (10 ms) can be expressed as ranging from 0 to where and The definitions for different subcarrier spacings μ are shown in the following table.

[0160] Table 4.3.2-1: Number of symbols contained in each slot, number of slots contained in each system frame, number of slots contained in each subframe for normal CP

[0161]

[0162] Table 4.3.2-2: Number of symbols contained in each slot, number of slots contained in each system frame, number of slots contained in each subframe for extended CP (60 kHz)

[0163]

[0164] On an NR carrier, the number of system frame (or simply frame) SFN ranges from 0 to 1023. The concept of direct frame number DFN is introduced in sidelink, the number range is also from 0 to 1023, the above description of the relationship between system frame and numerology can also be applied to direct system frame, for example, the duration of a direct system frame is also equal to 10 ms, for a subcarrier spacing of 15 kHz, a direct system frame includes 10 slots, etc. DFN is applied to the timing on the sidelink carrier.

[0165] Resource block, RB, and resource element, RE

[0166] A resource block RB is defined in the frequency domain as A RB is 180 kHz in the frequency domain, for example, for a subcarrier spacing of 15 kHz. μ A resource element (RE) represents 1 subcarrier in the frequency domain and 1 OFDM symbol in the time domain.

[0167] Scenarios of sidelink communication

[0168] 1) Out-of-Coverage sidelink: both UEs performing sidelink communication are out of network coverage (e.g., a UE does not detect any cell satisfying the “cell selection criteria” on the frequency on which sidelink communication is needed, indicating that the UE is out of network coverage).

[0169] 2) In-Coverage sidelink: both UEs performing sidelink communication are in network coverage (e.g., a UE detects at least one cell satisfying the “cell selection criteria” on the frequency on which sidelink communication is needed, indicating that the UE is in network coverage).

[0170] 3) Partial-Coverage sidelink: one of the UEs performing sidelink communication is out of network coverage, and the other UE is in network coverage.

[0171] From the perspective of a UE, there are only two scenarios: out-of-coverage and in-coverage. Partial-coverage is described from the perspective of sidelink communication.

[0172] Sidelink resource pool

[0173] In sidelink communication, the transmission and reception resources of a UE belong to a resource pool. For example, for a base station scheduling-based transmission mode in sidelink communication, the base station schedules transmission resources for sidelink UEs in the resource pool, or for a UE sensing-based transmission mode in sidelink communication, the UE determines transmission resources in the resource pool.

[0174] For NR sidelink communication, sub-channel-based resource allocation is supported in the frequency domain, i.e., for PSSCH transmission, the occupied resources in the frequency domain are an integer number of sub-channels. A sub-channel can represent a number of consecutive resource blocks (RBs) in the frequency domain.

[0175] Sensing-based resource allocation manner

[0176] For the sensing-based resource allocation manner (resource allocation manner 2), the sidelink user equipment selects candidate resources within a time window (optionally, resource selection window [n+T1, n+T2]) and determines candidate resources that overlap with the reserved resources indicated by the PSCCH transmitted by other user equipments in the listening time slot, and excludes these overlapping candidate resources. The physical layer reports (or indicates) the set of candidate resources that are not excluded to the MAC layer, and the MAC layer selects the transmission resources for the PSSCH / PSCCH. It is worth noting that when the physical layer reports or indicates the set of resources to the MAC layer, it can also be referred to as the user equipment having sensing results in the specification of the present application. The set of transmission resources selected by the MAC layer is referred to as the selected sidelink grant. One selected sidelink grant contains sidelink resources that can be used for the initial transmission and all retransmissions of one MAC PDU (corresponding to one transport block TB), or can be used for the initial transmission and all retransmissions of multiple MAC PDUs (corresponding to multiple transport blocks TB). The present application does not make any limitation on this.

[0177] Resource selection window [n+T1, n+T2]

[0178] In the sensing-based (or partial sensing) resource allocation manner, the higher layer requests or triggers the physical layer to determine the resources for PSSCH / PSCCH transmission (sensing or partial sensing) at time slot n. The resource selection window is defined as [n+T1, n+T2], i.e., the user equipment selects the transmission resources within this window. Wherein, T1 satisfies the condition The selection of T1 depends on the implementation of the user equipment; the RRC configuration information contains a configuration list sl-Selection WindowList of one resource selection window, wherein the element corresponding to a given priority prio TX (the priority of transmitting PSSCH) is represented as T 2min If T 2min is less than the remaining packet delay budget (remaining PDB), then T2 satisfies the condition T 2min ≤T2≤remaining PDB, and the selection of T2 depends on the implementation of the user equipment; otherwise, T2 is set to remaining PDB. The definition of T SL is as follows (μ represents the subcarrier spacing parameter of sidelink, i.e., the subcarrier spacing is

[0179] Table 8.1.4-2: The value of

[0180]

[0181] Table 8.1.4-1: The value of

[0182]

[0183] Physical sidelink feedback channel, PSFCH

[0184] In sidelink communication, PSFCH is used to carry HARQ feedback (HARQ-ACK) for sidelink communication. For example, a transmitting user equipment transmits PSSCH and PSCCH, and a receiving user equipment feeds back ACK on PSFCH if it correctly receives and decodes the PSCCH and PSSCH; otherwise, it feeds back NACK.

[0185] LBT (Listen Before Talk) mechanism

[0186] For wireless communication over unlicensed spectrum, some countries or regions (e.g., European region) require user equipment to perform LBT operation, i.e., listen-before-talk mechanism, also known as channel access operation, which means a mechanism for sensing channel to determine channel availability, before performing transmission for wireless communication. Specifically, within a period of time before communication transmission, user equipment will only perform transmission if it senses that the channel is idle; otherwise, user equipment will not perform transmission.

[0187] Specifically, for NR communication over unlicensed spectrum (NR-U) (or, for SL-U), the basic time unit for sensing channel can be T sl = 9 μs. Within this time unit, if the energy detected by the base station or user equipment on the channel is lower than an energy threshold value X ThreshWhen the duration of the time period is equal to or longer than 4 μs, the base station or the user equipment considers that the channel is idle (or, referred to as LBT success) in the time period. It is worth noting that the base station or the user equipment detects the energy and uses it to determine whether the idle channel represents a carrier containing a set of contiguous RBs or a part of the carrier. The channel can also be referred to as LBT bandwidth, or LBT sub-band, or RB set. One LBT bandwidth or RB set can be equal to 20 MHz in the frequency domain, i.e., there can be one RB set in a 20 MHz carrier. The number of RBs corresponding to a plurality of RB sets contained in one carrier (more than 20 MHz, such as 40 MHz, 60 MHz, 80 MHz) and the guard band (GB) between two contiguous RB sets can be as shown in the following table:

[0188] Table 1: Number of RBs contained in all RB sets and GB in one carrier under 15 kHz and 30 kHz subcarrier spacing

[0189]

[0190] In the above table, taking 15 kHz subcarrier spacing and 40 MHz carrier bandwidth as an example, 105-6-105 means that the carrier contains two contiguous RB sets, each containing 105 RBs. Between the two RB sets, there is a guard band GB containing 6 contiguous RBs, a total of 216 contiguous RBs, and the other items in Table 1 are similar.

[0191] It is worth noting that the LBT operations of the (sidelink communication) user equipment on different RB sets can be independent of each other (i.e., irrelevant to each other). For example, the user equipment detects that the channel is idle on RB set 1, and detects that the channel can be occupied (or busy) on RB set 2. If the sidelink user equipment selects the resources for transmitting PSSCH / PSCCH to contain (all or part of) the RBs corresponding to RB set 1 and RB set 2, the user equipment can send the corresponding PSSCH / PSCCH only when the user equipment detects that the channel is idle on both RB set 1 and RB set 2.

[0192] Sidelink discontinuous reception, SL DRX, and round trip timer, RTT timer

[0193] For SL DRX, a sidelink user equipment monitors PSCCH in active time; in in-active time, the user equipment does not need to monitor PSCCH.

[0194] In SL DRX, a user equipment determines whether the current time is in active time or in in-active time by some timers (running or expires). For RTT timer, it means that the user equipment assumes that the peer user equipment will not send PSCCH to schedule retransmission or other sidelink transmission when the timer is running, so the user equipment is in in-active time and does not monitor PSCCH before the RTT timer expires. RTT timer generally means the minimum time length that the user equipment assumes the peer user equipment will not schedule retransmission.

[0195] In the specification of the present application, the expiration of the timer means that the running time of the timer exceeds the time length of the timer, that is, the timer expires.

[0196] N associated candidate PSFCH resources (or transmission occasions) corresponding to one PSCCH / PSSCH transmission Sidelink communication user equipment with dual module

[0197] For sidelink communication on unlicensed spectrum, when LBT fails, it may cause PSFCH to be unable to be normally transmitted. 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 candidate PSFCH resources can be successful, and the transmission of PSFCH can be performed. Wherein, N is determined by configuration or pre-configuration information (the corresponding RRC parameter is numPSFCHOccasions), 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 slots.

[0198] Inter-UE coordination, IUC

[0199] In the scenario of LTE sidelink and NR sidelink co-channel coexistence, at least a sidelink user equipment equipped with both LTE sidelink module and NR sidelink module is supported, i.e., the sidelink user equipment can perform both LTE sidelink transceiving function and NR sidelink transceiving function. It is worth pointing out that in this type of user equipment, the LTE sidelink module (LTE sidelink module) can share (or indicate) information to the NR sidelink module (NR sidelink module), which can be LTE sidelink resource reservation information, or sensing information, etc. The NR sidelink module can also obtain LTE sidelink resource pool configuration information, LTE sidelink SLSS configuration information, etc., i.e., including but not limited to the above information without the need for LTE sidelink module sharing (or indicating). In the co-channel coexistence, NR SL only supports 15kHz or 30kHz subcarrier spacing. When the subcarrier spacing of NR SL is 30kHz, if the LTE SL subframe boundary and the NR SL subframe boundary overlap, then one LTE SL subframe (1ms) overlaps with two consecutive NR SL slots (one NR SL slot is 0.5ms) in the time domain.

[0200] Figure 1

[0201] Two schemes are cooperatively supported between UEs as follows:

[0202] ■UE between the cooperative scheme one: UE A sends the cooperative message to UE B is the indication of the resource set. The resource set is the preferred resource set for UE B transmission, and / or is the non-preferred resource set for UE B transmission;

[0203] ■UE between the cooperative scheme two: UE A sends the cooperative message to UE B is to indicate that there is an expected (or potential) resource conflict on the resource indicated by the SCI sent by UE B, and / or is to indicate that there is a detected resource conflict on the resource indicated by the SCI sent by UE B.

[0204] Hereinafter, specific examples and embodiments relating to the present application will be described in detail. In addition, as described above, the examples and embodiments described in the present disclosure are exemplary descriptions for easy understanding of the present application, and are not limitations of the present application.

[0205] [Embodiment One]

[0206] Figure 1 is a schematic diagram showing the basic process of the method performed by the user equipment according to Embodiment One of the present application.

[0207] Hereinafter, the method performed by the user equipment according to Embodiment One of the present application will be described in detail with reference to the basic process diagram shown in Figure 1

[0208] As shown in Figure 2 , in Embodiment One of the present application, the steps performed by the user equipment include:

[0209] In step S101, the sidelink communication user equipment receives sidelink communication control information SCI and corresponding physical sidelink shared channel PSSCH.

[0210] Among them, the sidelink communication scheduling permission (sidelink grant) associated with the SCI configures sidelink communication HARQ feedback resource (that is, configures PSFCH resource).

[0211] In step S102, the user equipment determines the starting time of the sidelink discontinuous reception (SL DRX) round trip timer (RTT timer).

[0212] Optionally, the user equipment determines the starting time of the SL DRX RTT timer according to the indication information of the SCI.

[0213] Optionally, if the SCI indicates that the sidelink communication HARQ feedback is disabled, and the SCI does not indicate one or more retransmission transmission opportunities,

[0214] Then,

[0215] If (the sidelink grant, or the SCI, or the resource pool associated with the sidelink grant or the SCI) configures one PSCCH / PSSCH transmission corresponding to one or more PSFCH transmission opportunities (that is, configures numPSFCHOccasions),

[0216] Then,

[0217] ​The user equipment starts the SL DRX RTT timer in the (first) slot after the end of the last PSFCH transmission opportunity (or, the last PSFCH resource) corresponding to the PSSCH transmission;

[0218] Otherwise,

[0219] The user equipment starts the SL DRX RTT timer in the slot following the end of the PSFCH resource corresponding to the PSSCH.

[0220] Optionally, if the SCI indicates that the sidelink HARQ feedback is disabled, and the SCI indicates one or more retransmission transmission opportunities,

[0221] Then,

[0222] The user equipment starts the SL DRX RTT timer in the slot following the end of the PSSCH.

[0223] [Embodiment Two]

[0224] Figure 2 is a schematic diagram showing the basic process of the method performed by the user equipment according to Embodiment Two of the present application.

[0225] In the following, the method performed by the user equipment according to Embodiment Two of the present application will be explained in detail with reference to the basic process diagram shown in Figure 2 .

[0226] As shown in Figure 3 , in Embodiment Two of the present application, the steps performed by the user equipment include:

[0227] In step S201, the sidelink user equipment physical layer indicates (or, reports) the (candidate) resource set to the MAC layer.

[0228] The indication can also be referred to as the sensing results possessed by the user equipment.

[0229] In step S202, the user equipment performs resource selection or resource reselection.

[0230] Optionally, the user equipment selects one or more HARQ retransmissions.

[0231] Optionally, if inter-UE coordination scheme one is enabled (i.e., sl-InterUE-CoordinationScheme1 is RRC configured), and the user equipment receives a preferred resource set for a transmission, and,

[0232] For the case of NR sidelink and LTE sidelink co-channel coexistence (i.e., sl-NRPSSCH-EUTRA-ThresRSRP-List is RRC configured), and,

[0233] If the subcarrier spacing of the NR sidelink is 30 kHz, then,

[0234] The user equipment selects a first time-frequency resource for a transmission opportunity.

[0235] Optionally, the transmission opportunity is an initial transmission opportunity.

[0236] Optionally, the first time-frequency resource is located in a first of two consecutive NR sidelink slots that overlap with the LTE sidelink subframe in time domain, and,

[0237] If there are left available resources in the intersection of the (candidate) resource set and the preferred resource set for the one or more HARQ retransmission opportunities, then the user equipment selects a second time-frequency resource for the one or more HARQ retransmission opportunities.

[0238] Optionally, the second time-frequency resource is located in a second of the two consecutive NR sidelink slots that overlap with the LTE sidelink subframe in time domain corresponding to the first time-frequency resource (i.e., the first of the two consecutive NR sidelink slots that overlap with the LTE sidelink subframe corresponds to the first time-frequency resource, and the second of the two consecutive NR sidelink slots that overlap with the LTE sidelink subframe corresponds to the second time-frequency resource).

[0239] If the number of the second time-frequency resources (that are maximally selected) is less than the number of the selected HARQ retransmissions, and if there are left available resources in the (candidate) resource set for the one or more HARQ retransmission opportunities, then the user equipment selects a third time-frequency resource for the one or more HARQ retransmission opportunities.

[0240] Optionally, the third time-frequency resource is located in the second one of the two continuous NR sidelink slots corresponding to the LTE sidelink subframe in the time domain.

[0241] Figure 3 is a block diagram of a user equipment UE involved in the present application. As shown in ​ the user equipment UE 80 includes a processor 801 and a memory 802. The processor 801 can include, for example, a microprocessor, a microcontroller, an embedded processor, etc. The memory 802 can 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 memory, etc. The memory 802 stores program instructions. When the instructions are run by the processor 801, the above-mentioned method performed by the user equipment can be executed, which is described in detail in the present application.

[0242] The method and the involved devices of the present application have been described above in connection with preferred embodiments. It is understood by those skilled in the art that the above-mentioned method is only exemplary, and the above-mentioned embodiments can be combined with each other without contradiction. The method of the present application is not limited to the above-mentioned steps and order. The above-mentioned network node and user equipment can include more modules, for example, modules that can be developed or developed in the future, which can be used for base stations, MME, or UE, etc. The various identifiers shown above are only exemplary and not limiting, and the present application is not limited to the specific information elements as examples of these identifiers. Those skilled in the art can make many changes and modifications according to the teachings of the embodiments shown.

[0243] It should be understood that the above-mentioned embodiments of the present application can be realized by software, hardware, or a combination of software and hardware. For example, various components inside the base station and user equipment in the above-mentioned embodiments can be realized by various 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), etc.

[0244] In this application, "base station" can refer to a mobile communication data and control switching center with large transmission power and wide coverage area, including resource allocation scheduling, data receiving and sending, etc. "User equipment" can refer to a user mobile terminal, such as a mobile phone, a notebook, etc. which can communicate wirelessly with the base station or micro base station.

[0245] Furthermore, embodiments of the present application disclosed herein can be implemented on a computer program product. More specifically, the computer program product is a product having a computer readable medium having encoded thereon computer program logic, which, when executed on an computing device, provides related operations to implement the above described technical solutions of the present application. The computer program logic, when executed on at least one processor of the computing system, causes the processor to perform the operations (methods) described in the embodiments of the present application. This arrangement of the present application is typically provided as software, code and / or other data structures arranged on a computer readable medium such as an optical medium (e.g., CD-ROM), floppy disk, or hard disk, or other media, or as firmware or microcode in one or more ROM or RAM or PROM chips, or as software downloadable into the memory of the computing device from a network or other source, or as one or more modules of downloadable software images, shared databases, etc. The software or firmware or such configuration can be installed onto the computing device to cause one or more processors in the computing device to perform the technical solutions described in the embodiments of the present application.

[0246] Furthermore, each functional module or each feature used in each of the above-described embodiments of the base station device and the terminal device can be realized by or performed by a circuitry, typically one or a combination of integrated circuits. The circuitry designed to perform the functions described in the present specification can include a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), or a combination of a general purpose processor and a DSP, an ASIC, field programmable gate array (FPGA), or other programmable logic devices, discrete gates or transistor logic, or discrete hardware components, or any combination thereof. The general purpose processor can be a microprocessor, or the processor can be a controller, a microcontroller, or a state machine. The above-described general purpose processor or each circuitry can be configured by one or combination of a hardware component and a software component. Furthermore, when a technology of a programmable logic device appears due to advancement of semiconductor technology, the application can be realized using the advanced technology as well as the integrated circuit.

[0247] While the present application has been shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details can be made therein without departing from the spirit and scope of the application. Therefore, the present application should not be defined with the only above described embodiments but by the appended claims and their equivalents.

Claims

1.A method performed by a user equipment, comprising: receiving, by the sidelink user equipment, a sidelink control information (SCI) and a corresponding physical sidelink shared channel (PSSCH) ; determining, by the user equipment, a sidelink discontinuous reception (SL DRX) round trip time (RTT) timer start time. 2.The method of claim 1, wherein: a sidelink grant associated with the SCI configures a PSFCH resource. 3.The method of claim 1, wherein: the user equipment determines the SL DRX RTT timer start time according to an indication in the SCI. 4.The method of claim 2 and 3, wherein: if the SCI indicates that sidelink HARQ feedback is disabled, and the SCI does not indicate one or more retransmission opportunities, and, if one PSCCH / PSSCH transmission is configured to correspond to one or more PSFCH transmission opportunities, the user equipment starts the SL DRX RTT timer at the first slot after the end of the last PSFCH transmission opportunity corresponding to the PSSCH transmission. 5.The method of claim 2 and 3, wherein: if the SCI indicates that sidelink HARQ feedback is disabled, and the SCI does not indicate one or more retransmission opportunities, and, if one PSCCH / PSSCH transmission is not configured to correspond to one or more PSFCH transmission opportunities, the user equipment starts the SL DRX RTT timer at the slot after the end of the PSSCH corresponding PSFCH resource. 6.The method of claim 2 and 3, wherein: if the SCI indicates that sidelink HARQ feedback is disabled, and the SCI indicates one or more retransmission opportunities, the user equipment starts the SL DRX RTT timer at the slot after the end of the PSSCH. 7.A user equipment, comprising: a processor; and a memory storing instructions, wherein the instructions, when executed by the processor, perform the method of any one of claims 1 to 6. ​

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