A coordination method between UEs based on NR-V2X

Abstract

The present application provides a coordination method between UEs based on NR-V2X, which is used for coordination between UEs in unicast, multicast, and broadcast communications, and this coordination method is executed before or after the initial transmission. For the former, the first cooperating UE allocates / grants a resource set to the transmitting UE based on the information of the available resource set in the preconfigured resource pool according to the parameter information reported by the transmitting UE, so as to avoid resource conflicts and / or half-duplex effects; for the latter, after the second cooperating UE receives the initial data packets sent by at least two transmitting UEs in the same group in the same time slot, the SFCI is transmitted to each of the transmitting UEs through the PSFCH, notifying the transmitting UEs to perform retransmission of the initial data packets in different subsequent time slots, so as to assist the transmitting UEs that have simultaneously sent the initial data packets in the same time slot and are facing half-duplex effects after the initial transmission.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technologies, and in particular to a coordination method between UEs based on NR-V2X. Background Art

[0002] With the 3rd Generation Partnership Project (3 rd As part of the development of the 3rd Generation Partnership Project (3GPP), the New Radio (NR) - vehicle to everything (V2X) is being studied as a key technical direction of Release 16 (R16) of the protocol. NR-V2X, as an enhancement of the Long Term Evolution (LTE) V2X technology, enables key performance of the Internet of Vehicles based on the technology of Rel5 NR. NR-V2X is designated to support V2X services beyond LTE Rel-15 V2X services, but more broadly enhances the NR system and enhances the new NR sidelink to meet more stringent V2X service requirements. The improved NR-V2X system will have a flexible design to support services with low latency and high reliability. The NR-V2X system is also expected to have higher system capacity and better coverage.

[0003] Currently, there are multiple communication methods classified as V2X communications, requiring the transmission of V2X information with different performance requirements to the 3GPP system. There are four main application examples; vehicle platooning, advanced driving, extended sensor information transmission, and remote driving. These applications will have more stringent requirements, such as a maximum end-to-end latency of 3-10ms, 99.99-99.999% reliability, 25-1000Mbps data rate, and a minimum required communication range of 80-1000 meters.

[0004] In order to meet the various business needs of the Internet of Vehicles, NR-V2X not only supports broadcast on the physical layer, but also supports unicast and groupcast. In contrast, LTE V2X only supports broadcast on the physical layer. Therefore, while basically maintaining the same level of reliability and decoding complexity as LTE V2X, the NR-V2X system needs to support these different performance requirements. Summary of the invention

[0005] The object of the present invention is to provide a coordination method between UEs based on NR-V2X to solve the problems raised in the above technical background.

[0006] Professional terms involved:

[0007] UE (User Equipment), user equipment;

[0008] TB (Transport Block), transport block, or data packet;

[0009] RE (Resource Element), resource element, the smallest channel element for 5G communication;

[0010] Tx-UE (Transmitter UE), transmitting UE, used to transmit transport blocks to other UEs through unicast, multicast or broadcast;

[0011] Rx-UE (Receiver UE), receiving UE;

[0012] Co-UE (Coordinative UE), cooperative UE, whose function is to allocate / grant a set of resources to the Tx-UE;

[0013] PSCCH (physical Sidelink Control Channel), physical sidelink control channel;

[0014] PSSCH (Physical Sidelink Shared Channel), physical sidelink data channel; PSFCH (Physical Sidelink Feedback Channel), physical layer sidelink feedback channel;

[0015] SCCH (Sidelink control channel), sidelink control channel, used for unicast in NR sidelink communication;

[0016] SFCI (Sidelink Feedback Control Information), sidelink feedback control information;

[0017] SCI (Sidelink Control Information), sidelink control information;

[0018] PRR (Packet Reception Ratio), packet reception ratio;

[0019] HARQ (Hybrid Automatic Repeat reQuest), Hybrid Automatic Repeat Request;

[0020] RSRP (Reference Signal Receiving Power), Reference Signal Receiving Power, is one of the key parameters representing the wireless signal strength and the physical layer measurement requirements in the LTE network. It is the average value of the signal power received on all the RE (Resource Elements) carrying the reference signal within a certain symbol;

[0021] RRC (Radio Resource Control), Radio Resource Control;

[0022] DRB (Data Radio Bearer), Data Radio Bearer;

[0023] LCH (Logical CHannel), Logical Channel;

[0024] MAC-CE (MAC Control Element), MAC layer control element.

[0025] To achieve the above object, the present invention adopts the following technical solutions:

[0026] A method for coordinating between UEs based on NR-V2X provided by the present application, preferably for coordinating between UEs in unicast, multicast, and broadcast communications, includes at least one of the following:

[0027] Coordinating between UEs before the initial data packet transmission: The first cooperative UE allocates / grants a resource set to the sending UE according to the parameter information reported by the sending UE based on the information of the available resource set in the pre-configured resource pool;

[0028] Coordinating between UEs after the initial data packet transmission: The second cooperative UE receives the data packets sent by at least two sending UEs in the same group in the same time slot, where at least one sending UE sends the initial data packet. The second cooperative UE transmits the SFCI to each of the sending UEs through the PSFCH, notifying the sending UEs to perform an initial data packet retransmission in the next time slot, preferably in different next time slots.

[0029] Preferably, the parameter information reported by the sending UE applying for the resource set to the first cooperative UE includes one or more of geographical information, quality of service QoS, LCH priority, transmission type, and service type.

[0030] Preferably, before the first cooperative UE allocates / grants a resource set to the sending UE applying for the resource set, it further includes at least one of the following:

[0031] The first cooperative UE has been authorized or pre-authorized as a cooperative UE;

[0032] The first cooperative UE knows the parameter information of the transmitting UE of the application resource set, such as geographical information, quality of service (QoS), LCH priority, transmission type, service type;

[0033] When the number of the first cooperative UEs is at least two, the PC5 connection initialization has been completed among multiple first cooperative UEs, so that the information of the resource set granted to the transmitting UE can be exchanged.

[0034] Preferably, the process of the first cooperative UE allocating / granting a resource set to the transmitting UE of the application resource set includes:

[0035] The PC5 connection is established among multiple first cooperative UEs with a first destination L2-ID;

[0036] The information of the available resource sets in the configured resource pool is exchanged among multiple first cooperative UEs, and candidate resource sets are set for the associated transmitting UEs;

[0037] The PC5 connection is established between the first cooperative UE and its associated transmitting UE with a second destination L2-ID (Destination Layer-2 ID);

[0038] The transmitting UE uses the second destination L2-ID to send a resource set configuration request to its associated first cooperative UE through SCI or MAC-CE;

[0039] The first cooperative UE receives the resource set configuration request, selects the resource set to be granted to the transmitting UE; the first cooperative UE sends the resource set to the transmitting UE and other first cooperative UEs through the PC5 connection using a third destination L2-ID.

[0040] More preferably, the establishment of the PC5 connection between the first cooperative UE and its associated transmitting UE can be based on the geographical information (e.g., Geo ID list) between the first cooperative UE and the transmitting UE and an optional service type.

[0041] More preferably, before the transmitting UE sends a resource set configuration request to its associated first cooperative UE, it further includes:

[0042] The transmitting UE reports and / or updates the parameter information of the transmitting UE to its associated first cooperative UE; the first cooperative UE receives the reported and / or updated parameter information of its associated transmitting UE and stores it.

[0043] Furthermore, the sending UE may send an explicit report to its associated first cooperative UE, or implement an implicit report based on the Zone-ID when using option-1 HARQ in the MAC entity.

[0044] More preferably, when multiple first cooperative UEs establish unicast links on PC5, the first cooperative UE may use PC5 signaling to coordinate and perform reconfiguration of RRC parameters through a side-link signal radio bearer (SRB); alternatively, if the first cooperative UE uses PC5 multicast or broadcast, each first cooperative UE multicasts or broadcasts information related to the candidate resource set through SCI or MAC-CE, where the information included in SCI or MAC-CE at least includes the source ID associated with the sending UE and resource set information.

[0045] More preferably, the establishment of a PC5 connection between the first cooperative UE and its associated sending UE can be completed through multicast, unicast, or broadcast.

[0046] More preferably, the first cooperative UE broadcasts the information of the resource set to all reachable sending UEs and other first cooperative UEs within its communication range; alternatively, the first cooperative UE unicasts the information of the resource set to the set sending UE; or the first cooperative UE multicasts the information of the resource set to the sending UEs in the same group as it.

[0047] More preferably, the resource set configuration request sent by the sending UE to its associated first cooperative UE through SCI (the second-phase SCI can be used) or MAC-CE (using a dedicated LC-ID) includes one or more of the following information:

[0048] The source ID (Source ID) or group member ID associated with the sending UE;

[0049] The destination ID (Destination ID) associated with the group created by the first cooperative UE;

[0050] QoS requirements (e.g., LCH priority, communication range);

[0051] Transmission type (e.g., unicast, multicast, or broadcast);

[0052] Packet size;

[0053] Service type (e.g., V2X service ID);

[0054] Traffic type (periodic or aperiodic);

[0055] The first cooperative UE sends a UE notification that a resource set has been granted to it via an SCI or MAC-CE, where the SCI or MAC-CE includes at least the following information:

[0056] The source L2 ID of the sending UE;

[0057] The destination L2 ID for unicast, multicast, or broadcast;

[0058] Resource set information.

[0059] Preferably, each of the first cooperative UEs can create a unicast link with its peer sending UE and complete the sidelink RRC reconfiguration process when necessary.

[0060] Preferably, each of the first cooperative UEs has a group management function and has the ability to gather the nearby sending UEs and create a group for UE - to - UE coordination.

[0061] Preferably, each of the first cooperative UEs is equipped with an all - in - one MAC entity, which can select a resource set and broadcast or multicast it to the relevant sending UEs via a MAC-CE (using a dedicated LC-ID) or an SCI (the second - phase SCI can be used), and the relevant sending UEs belong to the group members created by this first cooperative UE.

[0062] Preferably, each of the first cooperative UEs has the ability to sense the sidelink channel and update the candidate resource sets that can be allocated / granted to the sending UEs in the group.

[0063] Preferably, if the first cooperative UE is within the communicable range of the gNB, the first cooperative UE can obtain the relevant time - domain and frequency - domain related resource sets in a timely manner from the gNB.

[0064] Preferably, the first cooperative UE can use a MAC-CE or an SCI to notify the sending UE of the allocated / granted resource set, and the information included at least includes: the source ID (Source ID) or group member ID (group memberID) associated with the sending UE, and the time - domain and frequency - domain related resource sets, the priority of L1, the optional source ID and destination ID of the first cooperative UE.

[0065] Preferably, if the sending UE that applies for a resource set to the first cooperative UE is not granted a resource set, the MAC entity of the sending UE triggers a resource selection process; if the sending UE that applies for a resource set to the first cooperative UE is granted a resource set, the MAC entity of the sending UE selects resources from the resource set.

[0066] More preferably, if the MAC entity of the sending UE triggers a resource selection process, then in time slot n (n is a natural number ≥ 1), for PSSCH / PSCCH transmission, the MAC layer provides one or several of the following parameter information to the physical layer:

[0067] A resource pool used for resource selection;

[0068] The resource set granted by the first cooperating UE for its associated sending UE in the above resource pool (if granted);

[0069] The resource set granted by the first cooperating UE for other sending UEs in the above resource pool (if granted);

[0070] The priority of L1;

[0071] The remaining packet delay budget;

[0072] The number of sub-channels used for PSSCH / PSCCH transmission in units of time slots;

[0073] The resource reservation interval.

[0074] Preferably, the resource set includes coordinated resource units in the time domain and the frequency domain.

[0075] Preferably, the granting of the resource set can be achieved through a dynamic granting mechanism or a configured granting mechanism (CG type 1 or CG type 2).

[0076] More preferably, the first cooperating UE also allocates / grants resource sets for different time slots to the sending UE based on the geographical location of the sending UE associated with it.

[0077] Furthermore, each first cooperating UE can divide multiple sending UEs into multiple groups according to the geographical location of the sending UEs associated with it, that is, the first cooperating UE creates multiple groups related to geographical location in the application layer; each sending UE is within the communication range of the first cooperating UE; the first cooperating UE allocates resource sets for different time slots to the sending UEs in the group to avoid the impact of half-duplex. However, there is no such restriction on the allocation of different time slots for the sending UEs between different groups.

[0078] Even further, when the first cooperating UE allocates resource sets for each group and each sending UE within the group, the following conditions should be met:

[0079] When the first cooperating UE allocates resource sets for the sending UEs belonging to the same group, different candidate resource sets cannot overlap with each other in the time domain, but there is no restriction in the frequency domain;

[0080] The first cooperative UE allocates resource sets for sending UEs in different groups. Different candidate resource sets may partially overlap in the frequency domain, but there is no restriction in the time domain.

[0081] Preferably, the second cooperative UE that notifies the sending UEs transmitting initial data packets in the same time slot to retransmit the initial data packets satisfies the following conditions:

[0082] The second cooperative UE is in the same group as at least two sending UEs that send data packets, and is used for multicast reception, where at least one sending UE sends an initial data packet;

[0083] The second cooperative UE knows that at least two sending UEs that send data packets are in the transmission mode state in one time slot, where at least one sending UE sends an initial data packet;

[0084] The second cooperative UE transmits side-chain feedback control information SFCI through the physical layer side-chain feedback channel PSFCH, without considering the state of its own PSSCH reception.

[0085] Preferably, in the coordination among UEs after the initial data packet transmission, the sending UEs in the same group include a first sending UE and a second sending UE. The first sending UE and the second sending UE multicast data packets in the same time slot, where at least one sending UE multicasts an initial data packet;

[0086] The second cooperative UE receives and decodes the initial data packets sent by the first sending UE and the second sending UE, and sends first side-chain feedback control information SFCI1 to the first sending UE according to the selected first physical layer side-chain feedback channel PSFCH1, and sends second side-chain feedback control information SFCI2 to the second sending UE according to the selected second physical layer side-chain feedback channel PSFCH2;

[0087] If the first sending UE receives the first side-chain feedback control information SFCI1 from the first physical layer side-chain feedback channel PSFCH1, the first sending UE retransmits its initial data packet by multicast in the first time slot;

[0088] If the second sending UE receives the second side-chain feedback control information SFCI2 from the second physical layer side-chain feedback channel PSFCH2, the second sending UE retransmits its initial data packet by multicast in the second time slot;

[0089] Wherein, the first time slot and the second time slot are the same or different time slots.

[0090] More preferably, the first transmitting UE transmits the first data packet TB1 on the first physical sidelink control channel PSCCH1 and the first physical sidelink data channel PSSCH1, wherein the transmitted sidelink control information SCI includes the source ID, destination ID of the first transmitting UE, the resources associated with the currently transmitted data packet, and the reserved resources for possible retransmissions;

[0091] The second transmitting UE transmits the second data packet TB2 on the second physical sidelink control channel PSCCH2 and the second physical sidelink data channel PSSCH2, wherein the transmitted sidelink control information SCI includes the source ID, destination ID of the second transmitting UE, the resources associated with the currently transmitted data packet, and the reserved resources for possible retransmissions;

[0092] The second cooperative UE receives the first data packet TB1 and the second data packet TB2, and first decodes PSCCH1 and PSCCH2, and then decodes PSSCH1 and PSSCH2 in the same time slot;

[0093] If the source ID of the first transmitting UE is different from the source ID of the second transmitting UE, but the destination ID of the first transmitting UE is the same as the destination ID of the second transmitting UE, the second cooperative UE determines whether to trigger the inter-UE coordinated HARQ process according to whether it is an initial data packet or a retransmitted data packet, and generates the first sidelink feedback control information SFCI1 associated with the first data packet TB1 and / or the second sidelink feedback control information SFCI2 associated with the second data packet TB2;

[0094] If the first transmitting UE receives the first sidelink feedback control information SFCI1 from PSFCH1, the first transmitting UE retransmits the first data packet TB1 to the second transmitting UE and the second cooperative UE by multicast in the first time slot;

[0095] If the second transmitting UE receives the second sidelink feedback control information SFCI2 from PSFCH2, the second transmitting UE retransmits the second data packet TB2 to the first transmitting UE and the second cooperative UE by multicast in the second time slot;

[0096] Wherein, the first time slot and the second time slot are different time slots.

[0097] More preferably, if the first transmitting UE and the second transmitting UE simultaneously transmit initial data packets, the second cooperative UE determines whether to trigger the inter-UE coordinated HARQ process by considering the L1 priority of the initial data packets;

[0098] Wherein, the first time slot and the second time slot are the same time slot.

[0099] More preferably, if the first transmitting UE and the second transmitting UE each send an initial data packet and a retransmitted data packet in the same time slot, the second cooperative UE preferentially considers the initial data packet to determine whether to trigger an inter-UE coordinated HARQ process;

[0100] Wherein, the first time slot and the second time slot are the same or different time slots.

[0101] Preferably, if the first transmitting UE and the second transmitting UE both send their own geographical location information (using the Zone_ID method) and the respective communication range information (Communication Range) of the first transmitting UE TB1 and the second transmitting UE TB2 through PSCCH1 and PSCCH2, the second cooperative UE calculates the distance between the first transmitting UE and the second transmitting UE, and then compares the distance between them with their respective communication ranges, so as to determine whether to trigger an inter-UE coordinated HARQ process for TB1 and TB2. Wherein, the first time slot and the second time slot are the same or different time slots.

[0102] Preferably, if the first transmitting UE and the second transmitting UE simultaneously send initial data packets and the HARQ mechanism of option-2 is used, Rx-UE3 generates two SFCI associated with the initial TB with lower priority (both send ACK).

[0103] The present application provides an inter-UE coordination method based on NR-V2X, and this coordination method is executed before or after the initial transmission. The former coordinates resources between transmitting UEs based on information pre-provided by the cooperative UE to avoid resource conflicts and / or half-duplex effects. The latter is to help the transmitting UEs that have simultaneously sent initial data packets in the same time slot and are facing half-duplex effects after the initial transmission. Description of the Drawings

[0104] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation to the present application. In the drawings:

[0105] Figure 1 It is a schematic diagram of resource configuration authorization using the CG type 1 scheduling mechanism;

[0106] Figure 2 It is a schematic diagram of the process in which the Co-UE indicates the authorized resource set to the Tx-UE that sends the V2X data packet (TB);

[0107] Figure 3 It is a schematic diagram of multicast for inter-UE coordination based on UE location;

[0108] Figure 4It is a schematic diagram of the process of data packet transmission and retransmission based on HARQ of Option 1;

[0109] Figure 5 It is a schematic diagram of the coordinated HARQ process between a Tx-UE and an Rx-UE that both belong to the same group;

[0110] Figure 6 It is a schematic diagram of the process of data packet transmission and retransmission with HARQ feedback process of UE-to-UE coordination completed in four stages; Detailed implementation manners

[0111] To make the objectives, technical solutions and effects of the present invention clearer and more definite, the present invention will be further described in detail below with reference to the accompanying drawings and by way of examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0112] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0113] Embodiment 1:

[0114] The gNB schedules / configures the resources for transmitting data packets on the PSCCH (Physical Sidelink Control Channel) and PSSCH (Physical Sidelink Shared Channel), where the resources include channel resources in terms of time and frequency. Currently, the NR-V2X system has the following several different scheduling mechanisms:

[0115] · Dynamic Grant: Scheduled by DCI (Downlink Control Information), using format 3_0;

[0116] · Configured grant type 1 (CG type 1): Follow the RRC (Radio Resource Control) configuration;

[0117] · Configured grant type 2 (CG type 2): Resources configured by RRC are activated by DCI and use format 3_0.

[0118] In dynamic grant, the gNB schedules resources through DCI according to what the Tx-UE requests by reporting the logical channel group.

[0119] In CG type 1 and CG type 2, sidelink resources are provided by RRC to the Tx-UE, and the Tx-UE stores the RRC parameters. The parameters specified in the RRC layer are sl-ConfigIndexCG, sl-CS-RNTI, sl-PeriodCG, and sl-CG-MaxTransNumList.

[0120] If using CG type 2, the Tx-UE needs to send a resource request to the gNB. After obtaining permission from the gNB through DCI, the Tx-UE can use the resources. The resource permission information includes the resource usage time, so the Tx-UE can use the permitted resources until they expire.

[0121] If using CG type 1, the Tx-UE can use the authorized resources for transmission without any additional authorization, but two additional RRC parameters are also required: sl-TimeOffsetCGType1 and sl-TimeResourceCGType1.

[0122] Figure 1 An example of CG type 1 is given, which describes the use of detailed RRC parameters.

[0123] In this application, a solution for UE - to - UE coordinated resource selection for unicast, multicast, and broadcast communications is proposed, that is, based on the information pre - provided by the Co - UE before the initial data packet transmission, resource cooperation is performed between the Tx - UEs. Among them, the Tx - UE is the transmitting UE, which is used to transmit data packets (TBs) to other UEs through unicast, multicast, or broadcast; the Co - UE is the cooperative UE, which is used to allocate / grant a set of resources to the Tx - UE.

[0124] For unicast or multicast or broadcast, this embodiment describes the process of authorizing the Co - UE to allocate / grant a set of resources to the Tx - UE. The pre - conditions are as follows:

[0125] · The Co - UE has been authorized or pre - authorized as a cooperative UE;

[0126] · The Co-UE knows the information of the Tx-UE, such as geographical information, QoS (Quality of Service) requirements, transmission type (casttype), etc.;

[0127] · The PC5 connection initialization has been completed among Co-UEs (if there are multiple Co-UEs), so that the resource set information for Tx-UE grant can be exchanged.

[0128] Figure 2 The process of indicating the authorized resource set for the Co-UE to the Tx-UE that sends the V2X data packet (TB). As Figure 2 shown, in this process, three destination L2 IDs (destination L2 ID-1, destination L2 ID-2, and destination L2 ID-3) should be used. These destination L2 IDs are used for different purposes.

[0129] Step 1: Rely on unicast (or multicast / broadcast) to implement the PC5 connection initialization among Co-UEs. Among them, the PC5 connection is identified by destination L2 ID-1.

[0130] Step 2: The Co-UEs exchange the information of the available resource sets in the configured resource pool, and then set the candidate resource sets for the associated Tx-UE.

[0131] If a unicast link is established on PC5, the PC5 signaling can be used to coordinate and execute the reconfiguration of RRC parameters through the side-link signal radio bearer (SRB for short). Therefore, the Co-UEs can accurately identify the candidate resource sets from each other. If multiple Co-UEs participate in the coordinated resource selection among UEs, multiple unicast links need to be established. Among them, in addition to the RRC parameter reconfiguration, the Co-UEs can also exchange the information of the candidate resource sets through the unicast link via SCI or MAC-CE. In this case, the exchanged information can be stored in the MAC entity for the Co-UEs to update their own candidate resource sets.

[0132] If PC5 multicast or broadcast is used, each Co-UE will multicast or broadcast information related to the candidate resource set through SCI or MAC-CE. Based on the information received in the MAC entity and the resource set information configured in the configured resource pool, each Co-UE updates the candidate resource set stored in the MAC entity to avoid potential resource conflicts. Among them, if the information of the candidate resource set is sent by SCI, the information received by the Co-UE should be reported from its physical layer to its MAC layer. If the Co-UE needs to exchange RRC parameters, a new PC5 multicast or broadcast sidelink SRB is required to convey the RRC message. To transmit the RRC message, an SCCH (Sidelink Control Channel) carrying PC5-RRC information needs to be designed by adding a new LC-ID identification number. This SCCH will be transmitted by the sidelink SRB. The new LC-ID identification number can be selected from the existing reserved values 20 - 61. Alternatively, if the Co-UE is within the coverage area, the Co-UE can connect to the 5G core network and obtain RRC reconfiguration. In this case, the arrangement of the candidate resource set between Co-UEs is performed by the 5G core network.

[0133] If a highly coordinated resource selection mechanism is not required, the PC5 connection may not be needed. Therefore, each Co-UE can determine the candidate resource set separately. For example, the Co-UE simply relies on the Mode-2 sensing mechanism.

[0134] Step 3: The initialization of the PC5 connection between the Co-UE and the Tx UE can be achieved based on the geographical information between the Co-UE and the Tx-UE and the optional service type. This PC5 connection is identified by the destination L2 ID-2.

[0135] This PC5 connection may be completed depending on multicast or unicast or broadcast. For example, in multicast, the Tx-UE with the destination L2 ID-2 can continuously report the location information to the Co-UE by using its own source L2 ID. According to the geographical information indicating whether the Tx-UE tends to move away from or closer to the Co-UE, the Co-UE can determine whether to continue providing resource allocation services.

[0136] Unicast may incur more PC5 signaling (such as setup, management, leave), while multicast may promote efficient operation.

[0137] In addition, the QoS requirements for this PC5 connection do not need to be very high, and the relevant reliability can be relaxed, thereby reducing the overhead of maintaining this PC5 connection.

[0138] Step 4: Optionally, each Tx-UE reports and / or updates information as needed. This information can help the Co-UE effectively grant a resource set to the Tx-UE.

[0139] Information related to location information can be achieved through explicit reporting (e.g., through the location management function in the application layer), or in the case of using option-1 HARQ in the MAC entity, implicit reporting is based on the Zone-ID.

[0140] Step 5: If needed, the Co-UE can choose to store the information reported and / or updated by its associated Tx-UE.

[0141] Step 6: The Tx-UE requests a resource set for its data packet transmission through the SCI or MAC CE using the associated destination L2 ID-2. At the same time, the Tx-UE provides QoS requirements (e.g., LCH priority), service type (e.g., V2X service ID), etc. to the Co-UE.

[0142] Step 7: The Co-UE grants a resource set to the Tx-UE according to the required information related to QoS, LCH priority, and service type.

[0143] Among them, the service type can help the Co-UE select the periodic / aperiodic resource set required for the MAC PDU transmission assigned to the Tx-UE.

[0144] Step 8: The Co-UE broadcasts the information of the resource set to all reachable Co-UEs and Tx-UEs through the PC5 connection using the destination L2 ID-3. This information can be transmitted through the SCI or MAC CE, where the MAC-CE or SCI at least includes the source ID of the Tx-UE and the resource set information, the related L1 packet priority, the optional source ID of the Co-UE, and the destination L2 ID-3. In addition, the granted resource set can also be sent to a specific Tx-UE or a group of Tx-UEs by unicast or multicast.

[0145] (1) Sidelink SRB design for multicast / broadcast:

[0146] In the above content, the sidelink control channel (SCCH), as a logical channel, is designed for unicast in NR sidelink communication. It is used for sidelink SRB transmission (LCID = 3) of PC5 - RRC information, or for unprotected PC5 - S sidelink SRB transmission (LCID = 0); for example, direct communication requests. Or for sidelink SRB transmission of PC5 - S information to establish a PC5 - S with security functions (LCID = 1); for example, direct security mode commands and direct security mode completions. Or for sidelink SRB transmission of protected PC5 - S information (LCID = 2).

[0147] To exchange RRC information between Co - UEs, or for a Co - UE to configure RRC information for a Tx - UE within a group or communication range, it is necessary to use the SCCH to transmit sidelink SRBs. The SCCH can implement multicast and / or broadcast to carry the used RRC information. Additionally, new LCIDs that may be used for the SCCH can be selected from 20 to 61. In the PDCP layer, the designed sidelink SRB is mainly used to transfer the SCCH and can implement the interface between the PDCP layer and the RRC layer.

[0148] (2) Cooperative UE (Co - UE):

[0149] Each Co - UE in the above content has the following characteristics:

[0150] 1) Each Co - UE can create a unicast link with its peer Co - UE and complete the sidelink RRC re - configuration process when necessary;

[0151] 2) Each Co - UE has group management functions and has the ability to gather nearby Tx - UEs and create a group for UE - to - UE coordination;

[0152] 3) Each Co - UE is equipped with an all - in - one MAC entity that can select a resource set and broadcast, multicast, or unicast it to relevant Tx - UEs through MAC CE or SCI, and the relevant Tx - UEs belong to the group members created by this Co - UE;

[0153] 4) Each Co - UE has the ability to sense sidelink channels and update candidate resource sets that can be allocated / granted to Tx - UEs in the group.

[0154] To achieve the allocation / grant of resource sets for Tx - UEs, the Co - UE can use MAC - CE or SCI, which contains the necessary information: the source ID (Source ID) or group member ID associated with the Tx - UE, and the resource sets related to time domain and frequency domain.

[0155] (3) Transmitting UE (Tx-UE):

[0156] For the Tx-UE in the above content, its resource request process is as follows:

[0157] · Before or when the data packet arrives at the Tx-UE, the Tx-UE decides to obtain a resource set from the Co-UE and sends a request to the Co-UE via MAC-CE or SCI;

[0158] · The Tx-UE receives a transmission grant with a resource set. This resource set is broadcast from the Co-UE via MAC-CE or SCI with the Tx-UE source ID; if SCI is used, the physical layer entity shall report the granted resource set to its own MAC layer.

[0159] The request sent via MAC-CE or SCI contains the following information:

[0160] 1) Source ID (Source ID) or group member ID (group member ID) associated with the Tx-UE;

[0161] 2) Destination ID (Destination ID) associated with the group created with the Co-UE;

[0162] 3) QoS requirements (e.g., LCH priority, communication range);

[0163] 4) Transmission type (e.g., unicast, multicast, or broadcast);

[0164] 5) Data packet size;

[0165] 6) Service type (e.g., V2X service ID);

[0166] 7) Traffic type (periodic or aperiodic); if it belongs to periodic traffic, the resources can be reserved periodically.

[0167] Since the resource set granted to each Tx-UE is broadcast by the Co-UE, all Tx-UEs know the information of the granted resources. This provides more space for channel sensing and reduces resource conflicts in Mode-2 transmissions.

[0168] The MAC entity of the Tx-UE can select resources for transmission as follows:

[0169] · If no resource set is granted to the Tx-UE, the Tx-UE MAC entity will trigger a resource selection procedure (Resource Selection Procedure);

[0170] · If a resource set is granted to the Tx-UE, the Tx-UE MAC entity can simply select resources from the resource set. In this case, the MAC entity can also trigger the resource selection process, but also consider the information of the granted resource set. This can provide a more accurate resource selection from the resource set granted to the Tx-UE.

[0171] If the resource selection process is triggered, in time slot n, for PSSCH / PSCCH transmission, the MAC layer will provide the following parameter information to the physical layer:

[0172] 1) The resource pool used for resource selection;

[0173] 2) The resource set granted by the Co-UE to its Tx-UE in the above resource pool (if granted);

[0174] 3) The resource sets granted by the Co-UE to other Tx-UEs in the above resource pool (if granted);

[0175] 4) The priority of L1;

[0176] 5) The remaining packet delay budget;

[0177] 6) The number of sub-channels for PSSCH / PSCCH transmission in time slot units;

[0178] 7) Resource reservation intervals, etc.

[0179] The Tx-UE performs resource selection using the same process as in NR-V2X, except that:

[0180] 1) In the sensing process, the Tx-UE excludes any candidate resources granted by the Co-UE to other Tx-UEs. The exclusion process can follow the rules of the exclusion priority of the sensed resources. For example, the exclusion priority of the resources reserved by SCI in each TB transmission is higher (should be excluded first), while the exclusion priority of the resource sets granted by the Co-UE to other Tx-UEs is lower (the exclusion method can be performed first on the resources with higher resource priority, and then on the resources with lower resource priority). In addition, if the Tx-UE knows the resource sets granted by the Co-UE to other Tx-UEs, the Tx-UE can exclude the part that will generate a half-duplex resource set for the other Tx-UEs, thus reducing the impact of half-duplex.

[0181] 2) In the candidate resource selection process, the reserved candidate resources should be included in the resource set granted by the Co-UE. When the required ratio is reached, the physical layer will report the candidate resources to the MAC layer for the MAC layer to make the final selection.

[0182] (4) Resource Set:

[0183] The resource set consists of coordinated resource units in the time domain and the frequency domain. The resource set related to the Tx UE shall be broadcast to all Tx-UEs via SCI or MAC-CE to avoid resource conflicts. Alternatively, the resource set associated with the Tx UE can also be unicast to a specific Tx-UE via PC5-signaling to update the resource set related to the RRC parameters. The grant of the resource set can depend on a dynamic grant mechanism or a configured grant mechanism (CG type 1 or CG type 2). In addition, to solve the half-duplex problem, the Co-UE shall also allocate / grant different time-slot resource sets to the Tx-UE based on the geographical location of the Tx-UE.

[0184] If a dynamic grant mechanism is adopted, each Co-UE will sense the channel, including the resources used or reserved by the Tx-UE and the resource sets authorized by other Co-UEs. Alternatively, by establishing a unicast link between Co-UEs, the Co-UEs can exchange information on candidate resource sets granted to the Tx-UE. However, the resource set finally granted to the Tx UE will be indicated by SCI or MAC CE.

[0185] If a configured grant mechanism is adopted, each Co-UE will exchange information on configured multi-resource sets that may be granted to the Tx-UE by establishing a unicast link between Co-UEs. The multi-resource set can be determined by RRC parameters, with an indication of the resource set ID, time domain, and frequency domain resources. Which resource sets are specifically used by the Tx UE is indicated by SCI or MAC CE or RRC signaling. The configuration of the resource set can be completed in a dynamically indicated manner or in the same way as the configuration of CG type 1 or CG type 2. For CG type 1 or CG type 2, the resource set contains one or more CG resources, each with a separate ID (sl-ConfigIndexCG) and other separate parameters.

[0186] When the Co-UE determines the resource set, the correlation between resource sets in the time domain is minimized as much as possible to avoid the impact of half-duplex on the Tx-UE.

[0187] Each Co-UE can divide the Tx-UEs into multiple groups according to the geographical location of the Tx-UE, that is, the Co-UE creates multiple groups related to the geographical location in the application layer. Then, the Co-UE allocates resource sets in different time slots to the Tx-UEs in the group to avoid the impact of half-duplex. However, there is no such restriction on the allocation of different time slots for Tx-UEs in different groups.

[0188] It should be noted that in standard drafting, the focus is on how to form a group associated with the Co-UE based on the geographical locations between the Co-UE and the Tx-UE. The request from the Tx-UE is carried out via multicast through a MAC-CE or SCI with the Tx-UE source L2 ID (source L2 ID) and the destination L2 ID (destination L2 ID), while the resource set grant notification for the Co-UE is broadcast via a MAC-CE or SCI with the Tx-UE source L2 ID (aiming to identify whether the resource set granted to the Tx-UE is its own resource set) and the destination L2 ID. The request and grant can also be completed via unicast, but at the cost of having to establish more unicast links, which will make the system more complex. Moreover, unicast restricts the PC5 communication between two UEs. As a result, other Tx-UEs cannot know the reservation information of their resources during the sensing process.

[0189] The reason for using multicast to request the resource set is that the Co-UE can indirectly obtain the relative geographical location information between each group by relying on the information provided by the application layer to judge the group unit, so as to allocate / grant the resource set to the Tx-UE more effectively. It should be noted that unless Option 1 HARQ is used, the MAC entity in the Co-UE will not know the location information of the nearby Tx-UE. However, by creating location-based groups in the application layer, the MAC entity in the Co-UE can know the area where the Tx-UE is located and grant the resource set to the Tx-UE, thus avoiding resource conflicts and half-duplex effects.

[0190] The reason for using broadcast to grant the resource set to the Tx-UE is to let all other Tx-UEs know the granted resource set information, so as to provide more dimensions for channel sensing and reduce resource conflicts in Mode-2 transmission.

[0191] Figure 3 An example illustrates the multicast of UE-to-UE coordination based on UE location; it consists of four groups all associated with the Co-UE, each group contains four Tx-UEs, and each Tx-UE is within the communication range of the Co-UE.

[0192] The Co-UE arranges the resource set for each group and each Tx-UE using the following rules.

[0193] · If resources are allocated to Tx-UEs belonging to the same group, different candidate resource sets cannot overlap with each other in the time domain, while there is no restriction in the frequency domain. This can avoid the half-duplex effect and resource conflicts.

[0194] · If resources are allocated to different groups of Tx-UEs, different candidate resource sets can partially overlap in the frequency domain, but there is no restriction in the time domain. This can improve resource utilization efficiency and enhance the Packet Reception Ratio (PRR) performance.

[0195] This example can be applied to the situation of intersections, where the Tx-UE can be a vehicle or a pedestrian, and the Co-UE can be a roadside RSU (roadside unit).

[0196] Embodiment 2:

[0197] In NR-V2X, to meet ultra-high requirements such as the Packet Reception Ratio (PRR), NR-V2X supports retransmission based on Hybrid Automatic Repeat reQuest (HARQ). HARQ relies on the Physical Sidelink Feedback Channel (PSFCH), and the HARQ feedback process can be based on the Option-1 or Option-2 mechanism.

[0198] Option-1: If the Rx UE fails to decode the corresponding Transport Block (TB) after decoding the associated PSCCH, the Rx-UE sends a HARQ-NAK on the PSFCH. Otherwise, it does not send any signal on the PSFCH.

[0199] Option-2: If the Rx UE successfully decodes the corresponding TB, it sends a HARQ-ACK on the PSFCH. If the Rx UE fails to decode the corresponding TB after decoding the associated PSCCH, the Rx UE sends a HARQ-NAK on the PSFCH.

[0200] Coordination between UEs can also be performed after the initial transmission to mitigate the impact of half-duplex. Here, we consider the HARQ feedback mechanism for UE-to-UE coordination, which can effectively help the transmitting Tx UEs in the same time slot mitigate the impact of half-duplex. That is, these Tx UEs have used Option 1 HARQ to multicast TBs simultaneously in the same time slot, thus facing the half-duplex problem, where at least one of the simultaneously multicast TBs is an initial TB.

[0201] Figure 4Illustrates TB transmission and retransmission with Option-1 based HARQ, where UE-1 and UE-2 are transmitting Tx-UEs, UE-3 is the receiving Rx-UE, and the entire transmission is specifically divided into three phases. In Phase 1, UE-1 and UE-2 respectively send the initial data TB1 and TB2 through PSSCH1 and PSSCH2 in the same time slot. In this case, UE-3 successfully receives TB1 from UE-1, but fails to receive TB2 from UE-2. At the same time, UE-1 and UE-2 face the half-duplex problem due to transmitting data packets in the same time slot. In Phase 2, based on the Option-1 HARQ process, UE-3 only feeds back NAK to UE-2 on PSFCH2 and requests its retransmission. In Phase 3, UE-2 retransmits TB2 through PSSCH2, enabling UE-1 and UE-3 to successfully receive TB2. Therefore, due to the impact of half-duplex, UE-2 has no opportunity to receive TB1 from UE-1.

[0202] To mitigate the impact of half-duplex, this application introduces a cooperative UE (referred to as Co-UE), which notifies the two Tx-UEs to perform retransmissions in different subsequent time slots. Each Co-UE includes the following features:

[0203] · The Co-UE is in a group and can perform multicast reception;

[0204] · The Co-UE knows that the two Tx-UEs in the same group are both in the transmission mode state in one time slot by detecting the PSCCH sent by the Tx-UEs;

[0205] · The Co-UE can trigger the coordinated HARQ process between UEs through the SFCI transmitted on the PSFCH without considering the state of its own PSSCH reception.

[0206] Figure 5 Illustrates the coordinated HARQ process among two Tx-UEs and one Rx-UE, all belonging to the same group. The following description is mainly based on the Option-1 HARQ process, but some mechanisms are also applicable to the Option-2 HARQ process. Note that the same process can be extended and applied to multiple N Tx-UEs and multiple M Rx-UEs belonging to the same group.

[0207] Step 1: Tx-UE1 and Tx-UE2 belonging to the same group perform multicast of data packet TB in the same time slot (including two initial data packets TB, or one initial data packet TB and one retransmitted data packet TB). The initial data packet and the retransmitted data packet are distinguished by the NDI (New Data Indicator) bit in the SCI.

[0208] Specifically, Tx-UE1 transmits data packet TB1 on PSCCH1 and PSSCH1, where the transmitted SCI includes source L1 ID-1, destination L1 ID-1, and resources associated with the current transmitted data packet as well as reserved resources for possible retransmissions.

[0209] Similarly, Tx-UE2 transmits data packet TB2 on PSCCH2 and PSSCH2, where the transmitted SCI includes source L1 ID-2, destination L1 ID-2, and resources associated with the current transmitted data packet as well as reserved resources for possible retransmissions.

[0210] Step 2: Rx-UE3 receives both TB1 and TB2 and decodes PSCCH first and then PSSCH in the same time slot. By checking the source L1 ID and destination L1 ID, Rx-UE3 determines whether to trigger an inter-UE coordinated HARQ process. Specifically, if source L1 ID-1 and source L1 ID-2 are different, but destination L1 ID-1 and destination L1 ID-2 are the same, then Rx-UE3 triggers an inter-UE coordinated HARQ process for the initial data packet TB.

[0211] If the PSCCH contains the location information of the Tx-UE, similarly, after considering the source L1 ID and destination L1 ID, Rx-UE3 determines whether to trigger an inter-UE coordinated HARQ process by calculating the distance between the Tx-UEs and then comparing the respective relevant communication ranges of TB1 and TB2.

[0212] Specifically, if the Rx-UE3 additionally receives two location-related Zone-IDs from the Tx-UE1 and the Tx-UE2 and calculates the distance between the Tx-UE1 and the Tx-UE2. If the source L1 ID-1 and the source L1 ID-2 are different, but the destination L1 ID-1 and the destination L1 ID-2 are the same, and if the distance between the Tx-UE1 and the Tx-UE2 is less than or equal to the communication range associated with the TB1 of the Tx-UE1, the Rx-UE3 triggers the inter-UE coordinated HARQ process of the Tx-UE1. Similarly, if the distance between the Tx-UE1 and the Tx-UE2 is less than or equal to the communication range associated with the TB2 of the Tx-UE2, the Rx-UE3 triggers the inter-UE coordinated HARQ process of the Tx-UE2. If the inter-UE coordinated HARQ process is triggered, the Rx-UE3 generates the SFCI1 (sidelink feedback control information) and / or the SFCI2 associated with the TB1 and / or the TB2, regardless of whether its decoding process of the two TBs is successful.

[0213] If the two retransmission resources reserved by the SCI are in the same time slot, the Rx-UE3 must generate an SFCI (only sending NAK) associated with the initial TB with a higher priority. Which TB to select depends on the L1 priority of the TB.

[0214] If the two retransmission resources reserved by the SCI are in the same time slot, the Rx-UE3 determines whether the TB1 and the TB2 are initial transmissions or retransmissions through the SCI information. The Rx-UE3 only generates the SFCI (only sending NAK) associated with the initial TB.

[0215] If the reserved resources for the retransmissions of the two Tx-UEs are in different time slots, and optionally the two Tx-UEs are within the communication range, the Rx-UE3 must generate two SFCIs (two NAKs) associated with the initial TB1 and the initial TB2 indicated by the SCI received in the initial transmission.

[0216] If the reserved resources for the retransmissions of the two Tx-UEs are in different time slots, the Rx-UE3 determines whether TB1 and TB2 are initial transmissions or retransmissions through the SCI information. If TB1 or TB2 is an initial transmission, the Rx-UE3 must generate an SFCI (NAK) related to TB1 or TB2, otherwise the Rx-UE3 does not generate an SFCI. If one of TB1 and TB2 is a retransmission, if the Rx-UE3 can determine that TB1 and TB2 also overlapped in the time slot of the previous transmission, and the retransmitted TB was an initial transmission in the time slot of the previous transmission, then the Rx-UE3 also generates an SFCI for the retransmitted TB. If no resources are reserved for the retransmission of the initial TB, the Rx-UE3 itself makes a decision on whether to generate an SFCI associated with the initial TB (only send NAK). If the reserved resources for the retransmissions of the two Tx-UEs are in the same time slot and / or the reserved resources overlap in the frequency domain (at least partially), and the HARQ mechanism of option-2 is used, the Rx-UE3 generates two SFCIs associated with the initial TB with lower priority (both send ACK). One of the SFCIs is for the Rx-UE3 to feedback by itself, and the other SFCI is for the Tx-UE of the initial TB with higher priority to feedback. Thus, the initial TB with lower priority will not be transmitted in the reserved resources.

[0217] Step 3: The Rx-UE3 sends the generated SFCI to the corresponding Tx-UE through the PSFCH.

[0218] Step 4: If the Tx-UE1 receives the SFCI-1 from the PSFCH1, the Tx-UE1 retransmits the TB as a multicast.

[0219] The retransmitted TB is received by the Tx-UE2 and the Rx-UE3. If the Rx-UE3 also failed in the previous decoding process of the TB (including the initial transmission and retransmission), the Rx-UE3 decodes it, otherwise the Rx-UE3 ignores the reception of the TB.

[0220] Step 5: If the Tx-UE2 receives the SFCI-2 from the PSFCH2, the Tx-UE2 retransmits the TB as a multicast.

[0221] The retransmitted TB is received by the Tx-UE1 and the Rx-UE3. If the Rx-UE3 also failed in the previous decoding process of the TB (including the initial transmission and retransmission), the Rx-UE3 decodes it, otherwise the Rx-UE3 ignores the reception of the TB.

[0222] Figure 6 Describes the process of TB transmission and retransmission with UE - to - UE coordinated HARQ feedback process completed in four phases:

[0223] The first stage: for initial TB transmission;

[0224] The second stage: for SFCI NAK feedback;

[0225] The third stage: is the retransmission of TB1;

[0226] The fourth stage: is the retransmission of TB2.

[0227] Table 1 summarizes the combinations of SFCI generation in different TB1 and TB2 scenarios.

[0228]

[0229] Generally, the V2X application layer creates groups, and the HARQ process coordination among UEs is executed within the group. However, as long as the Rx-UEs in other groups can identify the same information as that obtained by the Rx-UEs in the same group (such as source L1 IDs, destination L1 IDs, location information, TB-related NDI information, and QoS requirements, etc.), this coordination process can also be extended to be executed between the Tx-UEs and Rx-UEs in different groups.

[0230] The specific embodiments of the present invention have been described in detail above, but they are only examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions to the present invention are also within the scope of the present invention. Therefore, all equivalent transformations and modifications made without departing from the spirit and scope of the present invention should be covered within the scope of the present invention.

Claims

1. A coordination method between UEs based on NR-V2X, characterized in that including: coordinating between UEs before initial data packet transmission: the first cooperating UE allocates / grants a resource set to the transmitting UE according to the parameter information reported by the transmitting UE based on the information of the available resource sets in the pre-configured resource pool; if the transmitting UE that applies for a resource set to the first cooperating UE is not granted a resource set, the MAC entity of the transmitting UE triggers a resource selection process; if the transmitting UE that applies for a resource set to the first cooperating UE is granted a resource set, the MAC entity of the transmitting UE selects a resource from the resource set; if the MAC entity of the transmitting UE triggers a resource selection process, in time slot n, where n is a natural number greater than or equal to 1, for PSSCH / PSCCH transmission, the MAC layer provides one or several of the following parameter information to the physical layer: the resource pool used for resource selection; the resource set granted by the first cooperating UE to its associated transmitting UE in the above resource pool; the resource sets granted by the first cooperating UE to other transmitting UEs in the above resource pool; the priority of L1; the remaining data packet delay budget; the number of sub-channels for PSSCH / PSCCH transmission in time slot units; the resource reservation interval; the process by which the first cooperating UE allocates / grants a resource set to the transmitting UE that applies for the resource set includes: establishing a PC5 connection between multiple first cooperating UEs with a first destination L2-ID; exchanging information of the available resource sets in the configured resource pool between multiple first cooperating UEs and setting candidate resource sets for their associated transmitting UEs; establishing a PC5 connection between the first cooperating UE and its associated transmitting UE with a second destination L2-ID; the transmitting UE uses the second destination L2-ID to send a resource set configuration request to its associated first cooperating UE through SCI or MAC-CE; the first cooperating UE receives the resource set configuration request and selects the resource set to be granted to the transmitting UE; the first cooperating UE uses a third destination L2-ID through the PC5 connection to send the resource set to the transmitting UE and other first cooperating UEs; the transmitting UE sending a resource set configuration request to its associated first cooperating UE through SCI or MAC-CE includes one or several of the following information: the source ID or group member ID associated with the transmitting UE; the destination ID associated with the group created by the first cooperating UE; QoS requirements; transmission type; data packet size; service type; traffic type; the first cooperating UE notifies the transmitting UE of the granted resource set through SCI or MAC-CE, where the SCI or MAC-CE includes at least the following information: the source L2 ID of the transmitting UE; the unicast, multicast, or broadcast destination L2 ID; resource set information.

2. The coordination method between UEs based on NR-V2X according to claim 1, characterized in that: also includes, UE - to - UE coordination after the initial data packet transmission: The second cooperative UE receives data packets transmitted by at least two transmitting UEs in the same group in the same time slot, where at least one transmitting UE transmits the initial data packet. The second cooperative UE transmits the SFCI to each of the transmitting UEs through the PSFCH to notify the transmitting UEs to perform an initial data packet re - transmission in the next time slot.

3. A method for coordinating between UEs based on NR-V2X according to claim 1 or 2, characterized in that: The parameter information reported by the transmitting UE applying for the resource set to the first cooperative UE includes one or more of geographical information, quality of service (QoS), LCH priority, transmission type, and service type.

4. A method for coordinating between UEs based on NR-V2X according to claim 1 or 2, characterized in that, Before the first cooperative UE allocates / grants a resource set to the transmitting UE applying for the resource set, it further includes at least one of the following: The first cooperative UE has been authorized or pre - authorized as a cooperative UE; The first cooperative UE knows the parameter information of the transmitting UE applying for the resource set; When the number of the first cooperative UEs is at least two, the initialization of the PC5 connection has been completed among multiple first cooperative UEs, so that information on the resource set granted to the transmitting UE can be exchanged.

5. A method for coordination between UEs based on NR-V2X according to claim 1 or 2, characterized in that Before the transmitting UE sends a resource set configuration request to its associated first cooperative UE, it further includes: The transmitting UE reports and / or updates the parameter information of the transmitting UE to its associated first cooperative UE; The first cooperative UE receives the parameter information reported and / or updated by its associated transmitting UE and stores it.

6. The method for coordinating between UEs based on NR-V2X according to claim 1 or 2, characterized in that: When multiple first cooperative UEs establish a unicast link on PC5, the first cooperative UE uses PC5 signaling to coordinate and perform the re - configuration of RRC parameters through the side - link signal radio bearer (SRB); or, if the first cooperative UE uses PC5 multicast or broadcast, each first cooperative UE multicasts or broadcasts information related to the candidate resource set through the SCI or MAC - CE, where the information contained in the SCI or MAC - CE includes at least the source ID associated with the transmitting UE and the resource set information.

7. A method for coordinating between UEs based on NR-V2X according to claim 1 or 2, characterized in that: The establishment of the PC5 connection between the first cooperative UE and its associated transmitting UE is completed through multicast, or unicast, or broadcast.

8. A method for coordinating between UEs based on NR-V2X according to claim 1 or 2, characterized in that: The first cooperative UE broadcasts the information of the resource set to all reachable transmitting UEs and other first cooperative UEs within its communication range; or, the first cooperative UE unicasts the information of the resource set to the set transmitting UEs; or, the first cooperative UE multicasts the information of the resource set to the transmitting UEs in the same group as it.

9. A method for coordination between UEs based on NR-V2X according to claim 1 or 2, characterized in that: The granting of the resource set is achieved through a dynamic granting mechanism or a configured granting mechanism, and the configured granting mechanism includes CG type 1 or CG type 2.

10. The coordination method between UEs based on NR-V2X according to claim 9, characterized in that: The first cooperative UE also allocates / grants a set of resources in different time slots to the transmitting UE associated with it; wherein, each first cooperative UE divides multiple transmitting UEs into multiple groups according to the geographical locations of the transmitting UEs associated with it, that is, the first cooperative UE creates multiple groups related to geographical locations at the application layer, and each transmitting UE is within the communication range of the first cooperative UE. The first cooperative UE allocates a set of resources in different time slots to the transmitting UEs in the group to avoid the impact of half-duplex. However, there is no such allocation limit for different time slots for the transmitting UEs between different groups.

11. A method for coordinating between UEs based on NR-V2X according to claim 10, wherein, The first cooperative UE allocates a set of resources for each group and each transmitting UE in the group, and should meet the following conditions: When the first cooperative UE allocates a set of resources for the transmitting UEs belonging to the same group, different candidate resource sets cannot overlap with each other in the time domain, but there is no restriction in the frequency domain; When the first cooperative UE allocates a set of resources for the transmitting UEs in different groups, different candidate resource sets partially overlap in the frequency domain, but there is no restriction in the time domain.

12. The coordination method between UEs based on NR-V2X according to claim 2, wherein, The second cooperative UE that notifies the transmitting UEs sending the initial data packets in the same time slot to retransmit the initial data packets meets the following conditions: The second cooperative UE is in the same group as at least two transmitting UEs sending data packets and is used for multicast reception, and at least one transmitting UE sends the initial data packet; The second cooperative UE knows that at least two transmitting UEs sending data packets are in the transmission mode state in one time slot, and at least one transmitting UE sends the initial data packet; The second cooperative UE transmits the side-chain feedback control information SFCI through the physical layer side-chain feedback channel PSFCH without considering the state of its own PSSCH reception.

13. The coordination method between UEs based on NR-V2X according to claim 2, wherein, In the coordination between UEs after the initial data packet transmission, the transmitting UEs in the same group include a first transmitting UE and a second transmitting UE. The first transmitting UE and the second transmitting UE multicast data packets in the same time slot, and at least one transmitting UE multicasts the initial data packet; The second cooperative UE receives and decodes the initial data packets sent by the first transmitting UE and the second transmitting UE, and sends the first side-chain feedback control information SFCI1 to the first transmitting UE according to the selected first physical layer side-chain feedback channel PSFCH1, and sends the second side-chain feedback control information SFCI2 to the second transmitting UE according to the selected second physical layer side-chain feedback channel PSFCH2; If the first transmitting UE receives the first side-chain feedback control information SFCI1 from the first physical layer side-chain feedback channel PSFCH1, the first transmitting UE retransmits its initial data packet by multicast in the first time slot; If the second transmitting UE receives the second side-chain feedback control information SFCI2 from the second physical layer side-chain feedback channel PSFCH2, the second transmitting UE retransmits its initial data packet by multicast in the second time slot; Wherein, the first time slot and the second time slot are the same or different time slots.

14. A method for coordination between UEs based on NR-V2X according to claim 13, characterized in that: The first transmitting UE transmits the first data packet TB1 on the first physical sidelink control channel PSCCH1 and the first physical sidelink data channel PSSCH1, where the transmitted sidelink control information SCI includes the source ID, destination ID of the first transmitting UE, and the resources associated with the currently transmitted data packet as well as the reserved resources for possible retransmissions; The second transmitting UE transmits the second data packet TB2 on the second physical sidelink control channel PSCCH2 and the second physical sidelink data channel PSSCH2, where the transmitted sidelink control information SCI includes the source ID, destination ID of the second transmitting UE, and the resources associated with the currently transmitted data packet as well as the reserved resources for possible retransmissions; The second cooperative UE receives the first data packet TB1 and the second data packet TB2, and first decodes PSCCH1 and PSCCH2 in the same time slot, and then decodes PSSCH1 and PSSCH2; If the source ID of the first transmitting UE is different from the source ID of the second transmitting UE, but the destination ID of the first transmitting UE is the same as the destination ID of the second transmitting UE, the second cooperative UE determines whether to trigger the inter-UE coordinated HARQ process based on whether it is an initial data packet or a retransmitted data packet, and generates the first sidelink feedback control information SFCI1 associated with the first data packet TB1 and / or the second sidelink feedback control information SFCI2 associated with the second data packet TB2; If the first transmitting UE receives the first sidelink feedback control information SFCI1 from PSFCH1, the first transmitting UE re-multicasts the first data packet TB1 to the second transmitting UE and the second cooperative UE in the first time slot; If the second transmitting UE receives the second sidelink feedback control information SFCI2 from PSFCH2, the second transmitting UE re-multicasts the second data packet TB2 to the first transmitting UE and the second cooperative UE in the second time slot; Wherein, the first time slot and the second time slot are different time slots.

15. A method for coordinating between UEs based on NR-V2X according to claim 13, wherein: The first transmitting UE and the second transmitting UE simultaneously transmit initial data packets, and the second cooperative UE determines whether to trigger the inter-UE coordinated HARQ process by considering the L1 priority of the initial data packets; Wherein, the first time slot and the second time slot are the same time slot.

16. A method for coordination between UEs based on NR-V2X according to claim 13, characterized in that: The first transmitting UE and the second transmitting UE each transmit an initial data packet and a retransmitted data packet in the same time slot, and the second cooperative UE preferentially considers the initial data packet to determine whether to trigger the inter-UE coordinated HARQ process; Wherein, the first time slot and the second time slot are the same or different time slots.

17. A method for coordinating between UEs based on NR-V2X according to claim 13, characterized in that: The first transmitting UE sends its own geographical location information and communication range information through PSCCH1; the second transmitting UE sends its own geographical location information and communication range information through PSCCH2; The second cooperative UE calculates the distance between the first transmitting UE and the second transmitting UE, and then compares the distance between them and their respective communication ranges to determine whether to trigger the inter-UE coordinated HARQ process for TB1 and TB2; Wherein, the first time slot and the second time slot are the same or different time slots.

18. A method for coordinating between UEs based on NR-V2X according to claim 13, characterized in that: The first transmitting UE and the second transmitting UE simultaneously transmit the initial data packets TB1 and TB2, and the HARQ mechanism of option-2 is used. The second cooperative UE generates two SFCIs associated with the initial TBs with lower priority. Among them, the reserved resources for retransmission of the two Tx-UEs are in the same time slot and / or the reserved resources overlap at least partially in the frequency domain.

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