WO2022000177A1 - 一种基于nr-v2x的ue间的协调方法 - Google Patents

一种基于nr-v2x的ue间的协调方法 Download PDF

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Publication number
WO2022000177A1
WO2022000177A1 PCT/CN2020/098895 CN2020098895W WO2022000177A1 WO 2022000177 A1 WO2022000177 A1 WO 2022000177A1 CN 2020098895 W CN2020098895 W CN 2020098895W WO 2022000177 A1 WO2022000177 A1 WO 2022000177A1
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sending
relay
ues
cooperative
resource set
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PCT/CN2020/098895
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English (en)
French (fr)
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张波
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张波
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Priority to PCT/CN2020/098895 priority Critical patent/WO2022000177A1/zh
Priority to CN202080102518.XA priority patent/CN116326014A/zh
Publication of WO2022000177A1 publication Critical patent/WO2022000177A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/40—Resource management for direct mode communication, e.g. D2D or sidelink
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
    • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
    • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
    • H04L1/1829—Arrangements specially adapted for the receiver end
    • H04L1/1854—Scheduling and prioritising arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
    • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
    • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
    • H04L1/1867—Arrangements specially adapted for the transmitter end
    • H04L1/1887—Scheduling and prioritising arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
    • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
    • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
    • H04L1/1867—Arrangements specially adapted for the transmitter end
    • H04L1/1893—Physical mapping arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/30—Services specially adapted for particular environments, situations or purposes
    • H04W4/40—Services specially adapted for particular environments, situations or purposes for vehicles, e.g. vehicle-to-pedestrians [V2P]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L2001/0092—Error control systems characterised by the topology of the transmission link
    • H04L2001/0093—Point-to-multipoint
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L2001/0092—Error control systems characterised by the topology of the transmission link
    • H04L2001/0097—Relays
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H04W72/115—Grant-free or autonomous transmission

Definitions

  • the present invention relates to the technical field of wireless communication, and in particular, to a coordination method between UEs based on NR-V2X.
  • NR New Radio
  • V2X Vehicle to X
  • vehicle to everything the new wireless (New Radio, referred to as the new air interface) - exchange of information outside of the vehicle (vehicle to X, V2X for short, also known as vehicle to everything) is being researched as a key technical direction of the 16th (Release16, R16 for short) version of the protocol.
  • LTE Long Term Evolution
  • NR-V2X enables the key performance of the Internet of Vehicles to be realized based on the technology of Rel5 NR.
  • NR-V2X is specified to support V2X services in addition to LTE Rel-15 V2X services, but with broader enhancements to the NR system and a new NR sidelink (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.
  • NR-V2X systems are also expected to have higher system capacity and better coverage.
  • V2X communication there are various communication methods classified as V2X communication, which require the 3GPP system to transmit V2X information with different performance requirements.
  • vehicle platooning There are four main application cases; vehicle platooning, advanced driving, extended sensors, and remote driving.
  • These applications will have more stringent requirements, such as 3-10ms maximum end-to-end latency, 99.99-99.999% reliability, 25-1000Mbps data rates, and 80-1000 meters of minimum required communication range.
  • NR-V2X In order to meet various service requirements of the Internet of Vehicles, NR-V2X not only supports broadcasting on the physical layer, but also supports unicast (unicast) and multicast (groupcast). In contrast, LTE V2X only supports broadcast on the physical layer. Therefore, NR-V2X systems are required to support these different performance requirements while basically maintaining the same level of reliability and decoding complexity as those based on LTE V2X.
  • the purpose 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.
  • UE User Equipment
  • user equipment User Equipment
  • RE Resource Element
  • resource element the minimum channel element for 5G communication
  • Tx-UE Transmitter UE
  • Rx-UE (Receiver UE), receiving UE;
  • Co-UE Coordinative UE
  • its function is to allocate/grant a resource set (set of resources) to Tx-UE;
  • PSCCH Physical Sidelink Control Channel
  • Physical side link control channel Physical side link control channel
  • PSSCH Physical Sidelink Shared Channel
  • Physical side link data channel Physical side link data channel
  • PSFCH Physical Sidelink Feedback Channel
  • Physical layer side chain feedback channel Physical layer side chain feedback channel
  • SCCH Segment control channel
  • side link control channel used for unicast of NR side link communication
  • SFCI Segment Feedback Control Information
  • side chain feedback control information Side Chain feedback control information
  • SCI Servicelink Control Information
  • side chain control information side chain control information
  • PRR Packet Reception Ratio
  • HARQ Hybrid Automatic Repeat reQuest
  • RSRP Reference Signal Receiving Power
  • the reference signal received power is one of the key parameters that can represent the wireless signal strength and one of the physical layer measurement requirements in the LTE network. the average value of the received signal power;
  • RRC Radio Resource Control
  • radio resource control radio resource control
  • DRB Data Radio Bearer
  • data wireless bearer
  • LCH Logical CHannel
  • MAC-CE MAC Control Element
  • the present invention adopts the following technical solutions:
  • a method for coordination between UEs based on NR-V2X provided by this application preferably, the coordination between UEs for unicast, groupcast and broadcast communication includes at least one of the following:
  • 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 sets in the pre-configured resource pool;
  • the second cooperative UE receives data packets sent by at least two sending UEs in the same group in the same time slot, at least one sending UE sends the initial data packet, and the second cooperative UE passes the
  • the PSFCH transmits the SFCI to each of the sending UEs, and notifies the sending UE to perform initial data packet retransmission in the next time slot, preferably in the next different time slot to perform initial data packet retransmission.
  • the parameter information reported by the sending UE applying for the resource set to the first cooperative UE includes one or more of geographic information, quality of service QoS, LCH priority, transmission type, and service type.
  • the first cooperative UE allocates/grants the resource set to the sending UE applying for the resource set, it further includes at least one of the following:
  • the first cooperating UE has been authorized or pre-authorized as a cooperating UE
  • the first cooperative UE knows the parameter information of the sending UE that applies for the resource set, such as geographic information, quality of service QoS, LCH priority, transmission type, and service type;
  • the PC5 connection initialization has been completed among the multiple first coordinated UEs, so that the resource set information for sending the UE granted can be exchanged.
  • the process of allocating/granting the resource set by the first cooperative UE to the sending UE applying for the resource set includes:
  • a PC5 connection is established between the first cooperative UE and its associated sending UE with a second destination L2-ID (Destination Layer-2 ID);
  • the sending 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;
  • the first cooperative UE receives the resource set configuration request, and selects a resource set granted to the sending UE;
  • the first cooperative UE sends the resource set to the sending UE and other first cooperative UEs by using the third destination L2-ID through the PC5 connection.
  • establishing a PC5 connection between the first cooperative UE and its associated sending UE may be based on geographic information (for example, Geo ID list) and optional services between the first cooperative UE and the sending UE. type.
  • the method further includes:
  • the sending UE reports and/or updates the parameter information of the sending UE to its associated first cooperative UE;
  • the first cooperative UE receives and stores the parameter information reported and/or updated by the sending UE associated therewith.
  • the sending UE may send an explicit report to its associated first cooperating UE, or implement an implicit report based on the Zone-ID when option-1 HARQ is used in the MAC entity.
  • first cooperative UEs establish unicast links on PC5, then the first cooperative UEs can use PC5 signaling to coordinate and perform RRC through side link signal radio bearer (signal radio bearer, SRB for short) Reconfiguration of parameters; or, if the first cooperative UE uses PC5 multicast or broadcast, then each of the first cooperative UE multicasts or broadcasts the information related to the candidate resource set through SCI or MAC-CE, where SCI Or the information contained in the MAC-CE at least includes the source ID (Source ID) and resource set information associated with the sending UE.
  • SRB side link signal radio bearer
  • establishing a PC5 connection between the first cooperating UE and its associated sending UE may be accomplished through multicast, unicast, or broadcast.
  • 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; or, 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 UE in the same group.
  • the sending UE sends a resource set configuration request to its associated first cooperative UE through SCI (second-stage SCI can be used) or MAC-CE (use dedicated LC-ID), including one of the following information or Several:
  • Source ID (Source ID) or group member ID (group member ID) associated with the sending UE;
  • Destination ID (Destination ID) associated with the group created by the first cooperative UE
  • QoS requirements eg, LCH priority, communication range
  • Transmission type (eg, unicast, multicast, or broadcast);
  • Type of service (e.g. V2X service ID);
  • Type of traffic (periodic or aperiodic);
  • the first cooperative UE sends a UE notification to it by using SCI or MAC-CE to be granted a resource set, wherein the SCI or MAC-CE includes at least the following information:
  • each of the first cooperating UEs can create a unicast link with its peer sending UE, and complete the sidelink RRC reconfiguration process when necessary.
  • each of the first cooperating UEs has a group management function and has the ability to aggregate nearby transmitting UEs and create a group for inter-UE coordination.
  • each said first cooperating UE is equipped with an omnipotent MAC entity which can select a resource set and broadcast it via MAC-CE (using a dedicated LC-ID) or SCI (may use a second stage SCI) or Multicast to the relevant sending UEs, and the relevant sending UEs belong to the group members created by the first cooperative UE.
  • MAC-CE using a dedicated LC-ID
  • SCI may use a second stage SCI
  • Multicast Multicast
  • each said first cooperating UE has the capability to sense the sidelink channel and update candidate resource sets that can be allocated/granted to the sending UEs in the group.
  • the first coordinated UE can obtain the relevant time domain and frequency domain related resource sets in time through the gNB, if the first coordinated UE is within the communicable range of the gNB.
  • the first cooperative UE can use MAC-CE or SCI to notify the resource set allocated/granted by the sending UE, and the information contained therein at least includes: a source ID (Source ID) or a group member ID (group ID (group ID) associated with the sending UE member ID), and resource sets related to time domain and frequency domain, L1 priority, optional first cooperative UE source ID and destination ID.
  • a source ID Source ID
  • group ID group ID associated with the sending UE member ID
  • resource sets related to time domain and frequency domain L1 priority
  • optional first cooperative UE source ID and destination ID optional first cooperative UE source ID and destination ID.
  • the MAC entity of the sending UE triggers a resource selection process; the sending UE applying for a resource set to the first cooperative UE if If the resource set is granted, the MAC entity of the sending UE selects the resource from the resource set.
  • the MAC layer provides one or more of the following parameter information:
  • the resource set (if granted) in the above-mentioned resource pool that is granted by the first cooperating UE to its associated sending UE;
  • the resource set includes coordinated resource elements in the time and frequency domains.
  • the grant of the resource set can be achieved through a dynamic grant mechanism or a configured grant mechanism (CG type 1 or CG type 2).
  • the first cooperating UE also allocates/grants resource sets of different time slots to the transmitting UE based on the geographic location of the transmitting UE related thereto.
  • each first cooperative UE may divide the plurality of sending UEs into multiple groups according to the geographic locations of the sending UEs related thereto, that is, the first cooperative UE creates multiple geographically related groups in the application layer; each All sending UEs are within the communication range of the first cooperative UE; the first cooperative UE allocates resource sets of different time slots to the sending UEs in the group to avoid the influence of half-duplex, but the transmission between different groups The UE does not need to perform such allocation restriction of different time slots.
  • the first cooperative UE allocates a resource set to each group and each sending UE in the group, and the following conditions should be satisfied:
  • the first cooperative UE allocates a resource set to the sending UEs belonging to the same group, then different candidate resource sets cannot overlap each other in the time domain, and there is no restriction in the frequency domain;
  • the first cooperative UE allocates resource sets to different groups of sending UEs, and different candidate resource sets may partially overlap in the frequency domain, but there is no restriction on the time domain.
  • the second cooperative UE that notifies the sending UE that sends the initial data packet in the same time slot to retransmit the initial data packet satisfies the following conditions:
  • 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, wherein at least one sending UE sends an initial data packet;
  • the second cooperative UE knows that at least two sending UEs that send data packets are in a state of transmission mode in one time slot, wherein at least one sending UE sends an 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.
  • the sending UEs in the same group include a first sending UE and a second sending UE, and the first sending UE and the second sending UE are in the same time slot multicast data packets, at least one of which sends the UE multicast initial data packet;
  • the second cooperative UE receives and decodes the initial data packets sent by the first sending UE and the second sending UE, and sends the first sidechain feedback to the first sending UE according to the selected first physical layer sidechain feedback channel PSFCH1 Control information SFCI1, send the second side chain feedback control information SFCI2 to the second sending UE according to the selected second physical layer side chain feedback channel PSFCH2;
  • the first sending UE receives the first sidechain feedback control information SFCI1 from the first physical layer sidechain feedback channel PSFCH1, the first sending UE performs groupcast retransmission on its initial data packet in the first time slot;
  • 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 performs groupcast retransmission on its initial data packet in the second time slot;
  • first time slot and the second time slot are the same or different time slots.
  • the first sending UE transmits the first data packet TB1 on the first physical side link control channel PSCCH1 and the first physical side link data channel PSSCH1, wherein the sent side chain control information SCI includes information about The source ID, destination ID of the first sending UE, and the resources associated with the current transmission data packet and the reserved resources for possible retransmission;
  • the second sending UE transmits the second data packet TB2 on the second physical side link control channel PSCCH2 and the second physical side link data channel PSSCH2, wherein the sent side chain control information SCI includes information about the second sending UE The source ID, destination ID and resources associated with the current transmission packet and the reserved resources for possible retransmission;
  • 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;
  • the second cooperative UE will retransmit the original data packet according to The data packet judgment triggers a coordinated HARQ process between UEs, and generates first side chain feedback control information SFCI1 associated with the first data packet TB1 and/or second side chain feedback control information SFCI2 associated with the second data packet TB2;
  • the first sending UE receives the first side chain feedback control information SFCI1 from PSFCH1, the first sending UE re-multicasts the first data packet TB1 to the second sending UE and the second cooperative UE in the first time slot;
  • the second sending UE receives the second side chain feedback control information SFCI2 from PSFCH2, the second sending UE re-multicasts the second data packet TB2 to the first sending UE and the second cooperative UE in the second time slot;
  • the first time slot and the second time slot are different time slots.
  • the second cooperative UE considers the L1 priority of the initial data packet to determine whether to trigger the inter-UE coordinated HARQ process
  • the first time slot and the second time slot are the same time slot.
  • the second cooperative UE prioritizes the initial data packet to determine whether to trigger the inter-UE coordinated HARQ process
  • first time slot and the second time slot are the same or different time slots.
  • the second cooperative UE determines whether to trigger the inter-UE coordinated HARQ process for TB1 and TB2 by calculating the distance between the first sending UE and the second sending UE, and then comparing the distance between them and their respective communication ranges.
  • the first time slot and the second time slot are the same or different time slots.
  • Rx-UE3 Preferably, if the first sending UE and the second sending UE send initial data packets at the same time, and the HARQ mechanism of option-2 is used, Rx-UE3 generates two SFCIs (both send ACK) associated with the initial TB with lower priority .
  • the reserved resources retransmitted by the two Tx-UEs are in the same time slot and/or the reserved resources overlap (at least partially) in the frequency domain.
  • the NR-V2X-based coordination method between UEs further includes coordinated relay transmission between UEs, and the coordinated relay transmission between UEs selects at least one of the following methods:
  • Coverage extension from UE to network when a remote UE communicates with a gNB, at least one UE with relay capability within the network coverage of the gNB is semi-statically selected to act as a relay UE; The link communicates, and the relay UE communicates with the remote UE through the PC5 interface;
  • Coverage extension from UE to UE when the sending UE communicates with the receiving UE, at least one UE with relay capability within its communication range is dynamically selected to act as a relay UE; wherein, multiple relay UEs operate in different time slots
  • the corresponding sending UE and receiving UE communicate with each other through the PC5 interface.
  • the selection method of the relay UE includes:
  • a UE within the network coverage of the gNB is called a candidate relay UE if it satisfies the condition 1, and the condition 1 includes: having the ability to communicate with the gNB within the network coverage and the ability to undertake the relay task;
  • condition 2 includes: the candidate relay UE monitors the reference signal sent by the gNB, and obtains the reference signal of the reference signal from the gNB based on the monitored reference signal Received power RSRP, comparing the reference signal received power RSRP with a preset first threshold and a second threshold, where the reference signal received power RSRP is between the first threshold and the second threshold.
  • the judging factors for the ability to undertake the relay task include: the relay operation of the candidate relay UE does not affect its communication with the gNB and other UEs in the network; Remaining battery, acceptable service type and link quality with the gNB.
  • the semi-statically selected side-link communication between the relay UE and the remote UE includes side-link unicast, side-link multicast, or side-link broadcast.
  • all the remote UEs are located outside the network coverage of the gNB; or at least one of the remote UEs is located within the network coverage of the gNB.
  • the relay UE includes a primary relay UE (primary relay UE, denoted as P-relay UE) and optionally at least one secondary relay UE (secondary relay UE, denoted as S-relay UE).
  • primary relay UE primary relay UE
  • secondary relay UE secondary relay UE
  • the primary relay UE and the secondary relay UE perform initial data packet retransmission in the same time slot and the same frequency resource.
  • the gNB performs access control on the auxiliary relay UE according to the link quality of the auxiliary relay UE.
  • the gNB uses the RRC configuration radio bearer to replicate and generate PDCP PDUs at the PDCP layer, and send them through the primary relay UE and the secondary relay UE respectively.
  • the primary relay UE and the secondary relay UE should meet the following conditions:
  • the primary relay UE, the secondary relay UE and the remote UE are not in the same group;
  • the primary relay UE and the auxiliary relay UE are both located within the coverage of the gNB;
  • the primary relay UE and the secondary relay UE are within the communication range with all remote UEs, and perform multicast communication with all remote UEs through the side link;
  • the primary relay UE and the secondary relay UE continue to report the Uu link quality (eg, reference signal received power, RSRP) to the gNB, so that the gNB switches the relay UE or allows multiple relay UEs to participate in relay transmission;
  • the Uu link quality eg, reference signal received power, RSRP
  • the primary relay UE and the secondary relay UE acquire group-related information, such as group destination ID, group size, and group members.
  • the primary relay UE and the secondary relay UE should meet the following conditions:
  • the primary relay UE, the auxiliary relay UE and the remote UE are in the same group, and can perform multicast communication with other UEs in the group through a side link;
  • the primary relay UE and the auxiliary relay UE are both located within the network coverage of the gNB;
  • the primary relay UE and secondary relay UE have the strongest link with the gNB.
  • the method for selecting the relay UE includes:
  • a UE that is within the communication range of the sending UE and simultaneously within the communication range of the receiving UE is called a candidate relay UE if it satisfies the condition 1, and the condition 1 includes: within the communication range, there is a relay UE capable of communicating with the sending UE and the receiving UE.
  • a relay UE capable of communicating with the sending UE and the receiving UE.
  • condition 2 includes: the candidate relay UE monitors the reference signal sent by the sending UE, and obtains the reference signal from the sending UE based on the monitored reference signal.
  • the reference signal received power RSRP is compared with a preset first threshold and a second threshold, and the reference signal received power RSRP is between the first threshold and the second threshold.
  • the judging factors for the ability to undertake the relay task include at least: the relay operation of the candidate relay UE does not affect its communication with the sending UE and other UEs in the network; and the candidate relay The remaining battery power, acceptable service type and link quality of the UE.
  • the dynamically selected sidelink communication between the relay UE and the receiving UE includes sidelink unicast, sidelink multicast, or sidelink broadcast.
  • the dynamically selected relay UE includes at least one primary relay UE (primary relay UE, denoted as P-relay UE) and optionally at least one secondary relay UE (secondary relay UE, denoted as S-relay UE). relay UE).
  • primary relay UE primary relay UE
  • secondary relay UE secondary relay UE, denoted as S-relay UE. relay UE).
  • the primary relay UE and the secondary relay UE perform initial data packet retransmission in the same time slot.
  • the V2X layer has certain flexibility, and can select any number of primary relay UEs and any number of auxiliary relay UEs according to the services that group members are interested in.
  • the number of primary relay UEs and/or secondary relay UEs may be set to zero.
  • the auxiliary relay UE decodes the received initial data packet correctly, and the RSRP of the direct path strength drops to the pre-configured RSRP threshold level, the auxiliary relay UE will participate in the relay operation and put the received data packet in the received data packet. Continue to the nearby receiving UE.
  • the sending UE multicasts the initial data packet to its group members, and the group members include the primary relay UE, the auxiliary relay UE, the first receiving UE and the second receiving UE;
  • the primary relay UE decodes the initial packet correctly and is ready to perform relay-based retransmission
  • the auxiliary relay UE decodes the initial data packet correctly, and measures the received signal strength (such as L1 RSRP or L3 RSRP). If the signal strength meets the preset threshold requirements, the auxiliary relay UE also participates in relay-based retransmission;
  • the primary relay UE and the secondary relay UE retransmit the initial data packet
  • the first receiving UE and the second receiving UE receive the retransmitted initial data packet, and feed back the status of whether the detection is correct or not to the relay UE and the auxiliary relay UE respectively;
  • the relay UE and the auxiliary relay UE respectively receive feedback information from the first receiving UE and the second receiving UE, and forward the feedback information to the sending UE.
  • the relay is implemented by a Layer-2 relay (Layer-2 Relay) or a Layer-3 relay (Layer-3 Relay).
  • Layer-2 Relay Layer-2 Relay
  • Layer-3 Relay Layer-3 Relay
  • relay transmission when the relay is implemented by Layer-2 relay, if only the MAC layer only participates in the relay operation, there are two options for relay transmission:
  • Option 1 The MAC entity in the relay UE does not check the HARQ feedback and performs blind retransmission;
  • Option 2 The MAC entity in the relay UE checks the HARQ feedback and retransmits if a NAK is received.
  • the gNB or the sending UE replicates and generates a PDCP PDU data packet at the PDCP layer, and sends the PDCP PDU data packet through the primary relay UE and the auxiliary relay UE respectively.
  • the technical scheme of the present invention has the following beneficial effects:
  • the present application provides an NR-V2X based inter-UE coordination method, which is performed before or after initial transmission.
  • the former is to coordinate resources between transmitting UEs based on information provided in advance by the cooperating UEs to avoid resource conflicts and/or half-duplex effects.
  • the latter is to help transmitting UEs that have simultaneously transmitted initial data packets in the same time slot and are facing half-duplex effects after the initial transmission.
  • the present application also proposes a coordinated relay transmission between UEs, which mainly considers the coverage expansion from the UE to the network and the coverage expansion from the UE to the UE.
  • FIG. 1 is a schematic diagram of resource configuration authorization using a CG type 1 scheduling mechanism
  • FIG. 2 is a schematic diagram of a process in which a Co-UE indicates an authorized resource set to a Tx-UE that sends a V2X data packet (TB);
  • FIG. 3 is a schematic diagram of multicast of UE coordination based on UE location
  • Fig. 4 is the process schematic diagram of the data packet transmission and retransmission based on the HARQ of option 1;
  • 5 is a schematic diagram of a coordinated HARQ process between two Tx-UEs that belong to the same group and one Rx-UE;
  • FIG. 6 is a process schematic diagram of data packet transmission and retransmission with an inter-UE coordinated HARQ feedback process completed in four stages;
  • FIG. 7 is a schematic diagram of a relay scenario of a unicast UE-to-Network (UE-to-Network) with a gNB, a relay UE and a remote UE;
  • UE-to-Network unicast UE-to-Network
  • FIG. 8 is a schematic diagram of coordinated relay transmission between UEs where all remote UEs are located outside the network coverage of the gNB;
  • 9 is a schematic diagram of coordinated relay transmission between UEs where some remote UEs are located within the network coverage of the gNB;
  • 10 is a schematic diagram of a UE-to-UE relay scenario between Tx-UE, relay UE and Rx-UE;
  • FIG. 11 is a schematic diagram of a UE-to-UE relay scenario implemented by a primary relay UE and a secondary relay UE;
  • FIG. 12 is a schematic diagram of a UE-to-UE relay process implemented by a primary relay UE and a secondary relay UE;
  • FIG. 13 is a timing diagram of initial transmission and relay-based retransmission.
  • the PSCCH (physical sidelink control channel, physical sidelink control channel) and PSSCH (physical sidelink data channel, Physical Sidelink Shared Channel) are scheduled/configured by the gNB to transmit data packet resources, where the resources include channel resources in time and frequency.
  • PSCCH physical sidelink control channel
  • PSSCH physical sidelink data channel, Physical Sidelink Shared Channel
  • ⁇ Type 1 configuration authorization (Configured grant type 1, CG type 1): follow the RRC (Radio Resource Control) configuration;
  • ⁇ Type 2 configuration authorization (Configured grant type 2, CG type 2): The resource configured by RRC is activated by DCI, and the format is format 3_0.
  • the gNB schedules resources through DCI according to the content requested by the Tx-UE by reporting the logical channel group.
  • CG type 1 and CG type 2 side link resources are provided by RRC to Tx-UE, and RRC parameters are stored by Tx-UE.
  • the parameters sl-ConfigIndexCG, sl-CS-RNTI, sl-PeriodCG, and sl-CG-MaxTransNumList are specified in the RRC layer.
  • the Tx-UE needs to send a resource request to the gNB, and the Tx-UE can use the resource only after obtaining permission from the gNB through DCI.
  • the resource grant information includes the resource usage time, so the Tx-UE can use the granted resource until it expires.
  • the Tx-UE can utilize the authorized resources for transmission without any additional authorization, but two additional RRC parameters are required; sl-TimeOffsetCGType1 and sl-TimeResourceCGType1.
  • CG type 1 An example of CG type 1 is given in Figure 1, which describes the use of detailed RRC parameters.
  • Tx-UE is a sending UE, which is used to transmit data packets (TB) to other UEs through unicast, multicast or broadcast;
  • Co-UE is a cooperative UE, which is used to allocate/grant a resource set (set of resources).
  • this embodiment describes the process of authorizing the Co-UE to allocate/grant resource sets to the Tx-UE.
  • the prerequisites are as follows:
  • the Co-UE has been authorized or pre-authorized as a cooperating UE
  • the Co-UE knows the information of the Tx-UE, such as geographic information, QoS (Quality of Service) requirements, transmission type (cast type), etc.;
  • FIG. 2 is a process for the Co-UE to indicate an authorized resource set to a Tx-UE that sends a V2X data packet (TB).
  • TB V2X data packet
  • destination L2 ID three destination L2 IDs (destination L2 ID) should be used, namely destination L2 ID-1, destination L2 ID-2, and destination L2 ID-3. These destination L2 IDs are used for different purposes.
  • Step 1 Rely on unicast (or multicast/broadcast) to realize PC5 connection initialization between Co-UEs.
  • the PC5 connection is identified by destination L2 ID-1.
  • Step 2 The information of available resource sets in the configured resource pool is exchanged between Co-UEs, and then candidate resource sets are set for the associated Tx-UEs.
  • PC5 signaling can be used to coordinate and perform reconfiguration of RRC parameters through the side link signal radio bearer (SRB).
  • SRB side link signal radio bearer
  • candidate resource sets are accurately identified from each other.
  • the Co-UE can also exchange the information of the candidate resource set through the SCI or the MAC-CE through the unicast link. In this case, the exchanged information may be stored in the MAC Entity (MAC Entity) for the Co-UE to update its own candidate resource set.
  • MAC Entity MAC Entity
  • each Co-UE will multicast or broadcast the 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 the SCI, the information received by the Co-UE shall 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.
  • the SCCH Servicelink Control Channel
  • the SCCH carrying the 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.
  • the Co-UE can connect to the 5G core network and obtain RRC reconfiguration. In this case, the arrangement of candidate resource sets between Co-UEs is performed by the 5G core network.
  • each Co-UE may determine candidate resource sets separately, eg Co-UEs simply rely on a Mode-2 sensing mechanism.
  • Step 3 PC5 connection initialization between Co-UE and Tx UE may be implemented based on geographic information and optional service type between Co-UE and Tx-UE. This PC5 connection is identified by destination L2 ID-2.
  • This PC5 connection may be done relying on multicast or unicast or broadcast.
  • a Tx-UE with destination L2 ID-2 can continuously report this location information to the Co-UE by using its own source L2 ID.
  • the Co-UE can determine whether to continue to provide the resource allocation service.
  • Unicast may cost more PC5 signaling (eg setup, manage, leave), while multicast may facilitate efficient operation.
  • Step 4 Each Tx-UE optionally reports and/or updates information as needed. This information can help the Co-UE to effectively grant the resource set to the Tx-UE.
  • Information related to location information can be reported explicitly (e.g., by location management functions in the application layer), or implicitly based on Zone-ID in the case of option-1 HARQ in the MAC entity.
  • Step 5 If desired, the Co-UE may choose to store the information reported and/or updated by its associated Tx-UE.
  • Step 6 Using the associated destination L2 ID-2, the Tx-UE requests the resource set for its packet transmission via SCI or MAC CE. Meanwhile, the Tx-UE provides the Co-UE with QoS requirements (eg, LCH priority), service type (eg, V2X service ID), and the like.
  • QoS requirements eg, LCH priority
  • service type eg, V2X service ID
  • 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.
  • the service type can help the Co-UE to select the periodic/aperiodic resource set allocated to the Tx-UE for MAC PDU transmission.
  • Step 8 The Co-UE uses destination L2 ID-3 through the PC5 connection to broadcast the information of the resource set to all reachable Co-UEs and Tx-UEs.
  • This information can be transmitted through SCI or MAC CE, wherein MAC-CE or SCI at least include Tx-UE source ID (source ID) and resource set information, related L1 packet priority, optional Co-UE source ID and destination L2 ID-3.
  • unicast or multicast may also be used to send the granted resource set to a specific Tx-UE or group-unit Tx-UE.
  • SCCH Segmentlink control channel
  • SCCH may implement multicast and/or broadcast to carry RRC information for.
  • new LCIDs that may be used can be selected from 20 to 61.
  • the designed side link SRB is mainly used to transmit the SCCH, and can realize the interface between the PDCP layer and the RRC layer.
  • Co-UE Cooperative UE
  • Each Co-UE can create a unicast link with its peer Co-UE and complete the sidelink RRC reconfiguration process if necessary;
  • Each Co-UE has a group management function and the ability to aggregate nearby Tx-UEs and create groups for inter-UE coordination;
  • Each Co-UE is equipped with an omnipotent MAC entity that can select a resource set and broadcast or multicast or unicast it through MAC CE or SCI to the relevant Tx-UEs belonging to the Co-UE UE-created group members;
  • Each Co-UE has the ability to sense the sidelink channel and update candidate resource sets that can be allocated/granted to the Tx-UEs in the group.
  • the Co-UE can use the MAC-CE or SCI, which contains the necessary information: the source ID (Source ID) or the group member ID (group ID) associated with the Tx-UE member ID), and resource sets related to time domain and frequency domain.
  • Source ID the source ID
  • group ID group ID associated with the Tx-UE member ID
  • the resource request process of the Tx-UE in the above content is as follows:
  • the Tx-UE decides to obtain the resource set from the Co-UE and sends a request to the Co-UE through MAC-CE or SCI;
  • the Tx-UE receives the transmission grant with the resource set.
  • This resource set is broadcast from the Co-UE via MAC-CE or SCI with Tx-UE source ID; if SCI is used, the physical layer entity shall report the granted resource set to its own MAC layer.
  • the request sent by the MAC-CE or SCI contains the following information:
  • Source ID Source ID
  • group member ID group member ID
  • QoS requirements eg, LCH priority, communication range
  • Transmission type eg, unicast, multicast, or broadcast
  • Service type for example, V2X service ID
  • Traffic type (periodic or aperiodic); if it belongs to periodic traffic, resources can be reserved periodically.
  • the MAC entity of the Tx-UE can select resources for transmission as follows:
  • the Tx-UE MAC entity will trigger the Resource Selection Procedure
  • the Tx-UE MAC entity can simply select the resource from the resource set. In this case, the MAC entity can also trigger the resource selection process, but also take into account the information of the granted resource set. This can provide more precise resource selection from the resource set granted by the Tx-UE.
  • the MAC layer will provide the following parameter information to the physical layer:
  • Tx-UE adopts the same process as in NR-V2X for resource selection, except:
  • the sensing process adds that the Tx-UE excludes any candidate resources that the Co-UE grants to other Tx-UEs.
  • the exclusion process may follow rules for the exclusion priority of sensing resources. For example, the exclusion priority of resources reserved with SCI in each TB transmission is higher (should be excluded first), while the exclusion priority of Co-UE granting resource sets to other Tx-UEs is lower (the exclusion method can be first Resource with higher priority, then resource with lower priority).
  • the Tx-UE knows the resource set granted by the Co-UE for other Tx-UEs, the Tx-UE can exclude that the part of the Tx-UE granted to him will generate a half-duplex resource set, thereby mitigating the impact of half-duplex.
  • the reserved candidate resources should be included in the Co-UE grant resource set.
  • the physical layer will report the candidate resources to the MAC layer for final selection by the MAC layer.
  • a resource set consists of coordinated resource elements in the time and frequency domains.
  • the resource set related to Tx UE shall be notified to all Tx-UEs by SCI or MAC-CE broadcast to avoid resource conflict.
  • the resource set associated with the Tx UE may also be unicast via PC5-signaling to a specific Tx-UE to update the resource set related to the RRC parameters. Granting of resource sets may depend on a dynamic grant mechanism or a configured grant mechanism (CG Type 1 or CG Type 2).
  • the Co-UE should also allocate/grant different time slot resource sets to the Tx-UE based on the geographical location of the Tx-UE.
  • each Co-UE will perceive the channel, which includes the resources used or reserved by the Tx-UE and the set of resources granted by other Co-UEs.
  • Co-UEs can exchange candidate resource set information for granting Tx-UEs. But the resource set finally granted to Tx UE will be indicated by SCI or MAC CE.
  • each Co-UE will exchange the configured multiple resource set information that may be granted to the Tx-UE by establishing a unicast link between the Co-UEs.
  • Multiple resource sets can be determined through RRC parameters, with resource set ID (Resource set ID), indication of time domain and frequency domain resources. Which resource sets are used by the specific Tx UE are indicated by SCI or MAC CE or RRC signaling.
  • the configuration of the resource set can be completed in the way of dynamic indication, and the configuration of the resource set can also be completed in the same way as the configuration of CG type 1 or CG type 2.
  • the resource set contains one or more CG resources, each CG resource has a separate ID (sl-ConfigIndexCG) and other separate parameters.
  • the Co-UE decides the resource set
  • the correlation between the resource sets in the time domain should be minimized as much as possible, so as to avoid the influence of the half-duplex of the Tx-UE.
  • Each Co-UE can divide the Tx-UEs into multiple groups according to the geographic location of the Tx-UE, that is to say, the Co-UE creates multiple geographic location-related groups in the application layer. Then, the Co-UE allocates resource sets of different time slots to the Tx-UEs in the group to avoid the half-duplex effect. However, Tx-UEs between different groups do not need to perform such different time slot allocation restrictions.
  • the request from the Tx-UE is performed via multicast via the MAC-CE or SCI with the Tx-UE source L2 ID (source L2 ID) and destination L2 ID (destination L2 ID), while the Co-UE's resource set grants Notification is via broadcast via MAC-CE or SCI with the Tx-UE source L2 ID (the purpose is to identify whether it is its own resource set for the Tx-UE granted the resource set) and the destination L2 ID.
  • Requests and grants can also be done through unicast, but at the cost of having to establish more unicast links, which complicates the system. Also, unicast restricts PC5 communication between two UEs, as a result, other Tx-UEs cannot know the reservation information of their resources during the sensing process.
  • Co-UE can indirectly obtain relative geographic location information between groups by relying on the information provided by the application layer to provide group unit information, so as to allocate/grant resources to Tx-UE more effectively. set. 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-UEs. However, by creating a location-based group in the application layer, the MAC entity in the Co-UE can know the region of the group where the Tx-UE is located, and grant the Tx-UE a resource set, thereby avoiding resource conflict and half-duplex effects.
  • Figure 3 illustrates UE-location-based coordinated inter-UE multicast; it consists of four groups all associated with Co-UEs, each group contains four Tx-UEs, each Tx-UE is in the Co-UE within the communication range.
  • the Co-UE uses the following rules to arrange resource sets for each group and each Tx-UE.
  • different candidate resource sets may partially overlap in the frequency domain, but there is no restriction on the time domain. This can improve resource usage efficiency and improve packet reception ratio PRR performance.
  • Tx-UE can be a vehicle or a pedestrian
  • Co-UE can be a roadside RSU (roadside unit).
  • Embodiment 2 is a diagrammatic representation of Embodiment 1:
  • NR-V2X in order to meet the ultra-high requirements such as packet reception ratio PRR, NR-V2X supports retransmission based on Hybrid Automatic Repeat reQuest (HARQ).
  • HARQ relies on the physical layer side chain feedback channel (Physical Sidelink Feedback Channel, PSFCH), and the HARQ feedback process can be based on the option-1 (Option-1) or option-2 (Option-2) mechanism.
  • PSFCH Physical Sidelink Feedback Channel
  • Option-1 If the Rx UE fails to decode the corresponding TB (Transport Block) after decoding the associated PSCCH, the Rx-UE sends a HARQ-NAK on the PSFCH. Otherwise it does not send any signal on PSFCH.
  • Option-2 If the Rx UE successfully decodes the corresponding TB, a HARQ-ACK is sent 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.
  • Coordination between UEs can also be performed after the initial transmission to mitigate the effects of half-duplexing.
  • Figure 4 illustrates TB transmission and retransmission with HARQ based on option-1, wherein UE-1 and UE-2 are sending Tx-UEs, UE-3 is receiving Rx-UEs, and the whole transmission is specifically divided into three stages.
  • UE-1 and UE-2 transmit initial data TB1 and TB2 through PSSCH1 and PSSCH2 in the same time slot, respectively.
  • UE-3 successfully received TB1 from UE-1, but failed to receive TB2 from UE-2.
  • UE-1 and UE-2 face the half-duplex problem due to transmitting data packets in the same time slot.
  • UE-3 In Phase 2, based on the Option-1 HARQ process, UE-3 will only feed back a NAK on PSFCH2 to UE-2 and request its retransmission. In Phase 3, UE-2 retransmits TB2 via PSSCH2, enabling UE-1 and UE-3 to successfully receive TB2. Therefore, UE-2 has no chance to receive TB1 from UE-1 due to the half-duplex effect.
  • Co-UE a cooperative UE
  • the Co-UE notifies the two Tx-UEs to perform retransmission in the next different time slots.
  • Each Co-UE includes the following features:
  • ⁇ Co-UE is in the group and can receive multicast
  • the Co-UE knows that two Tx-UEs in the same group are in the transmission mode state by detecting the PSCCH sent by the Tx-UE;
  • the Co-UE can trigger the inter-UE coordinated HARQ process by transmitting SFCI on the PSFCH without considering the status of its own PSSCH reception.
  • Figure 5 illustrates the coordinated HARQ process between two Tx-UEs and one Rx-UE, all of which belong to the same group.
  • the following description is mainly based on the Option-1 HARQ process, but some mechanisms are also adapted to the Option-2 HARQ process. Note that the same procedure can be extended to multiple NTx-UEs and multiple MRx-UEs belonging to the same group.
  • Step 1 Tx-UE1 and Tx-UE2 belonging to the same group perform multicasting of data packets TB in the same time slot (including two initial data packets TB, or one initial data packet TB and one retransmission data packet TB) .
  • the initial data packet and the retransmitted data packet are distinguished by the NDI (New Data Indicator) bit in the SCI.
  • NDI New Data Indicator
  • Tx-UE1 transmits data packet TB1 on PSCCH1 and PSSCH1, where the sent SCI contains source L1 ID-1, destination L1 ID-1 and resources associated with the current transmission data packet and reservations for possible retransmissions resource.
  • Tx-UE2 transmits packet TB2 on PSCCH2 and PSSCH2, where the transmitted SCI contains source L1 ID-2, destination L1 ID-2 and resources associated with the currently transmitted packet and possibly reserved resources for retransmission .
  • Step 2 Rx-UE3 receives two 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 it needs to trigger the 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, Rx-UE3 triggers the inter-UE coordination HARQ process for the initial data packet TB.
  • the Rx-UE3 calculates the distance between the Tx-UEs and then compares the relevant communication ranges of TB1 and TB2 to determine whether The inter-UE coordinated HARQ process needs to be triggered.
  • Rx-UE3 additionally receives two location-related Zone-IDs from Tx-UE1 and Tx-UE2, and calculates the distance between Tx-UE1 and Tx-UE2. If source L1 ID-1, source L1 ID-2 are different, but destination L1 ID-1 and destination L1 ID-2 are the same, and if the distance between Tx-UE1 and Tx-UE2 is less than or equal to Tx-UE1 The communication range related to TB1, then Rx-UE3 triggers the inter-UE coordinated HARQ process of Tx-UE1.
  • Rx-UE3 if the distance between Tx-UE1 and Tx-UE2 is less than or equal to the communication range related to TB2 of Tx-UE2, then Rx-UE3 triggers the inter-UE coordinated HARQ process of Tx-UE2. If the inter-UE coordinated HARQ process is triggered, Rx-UE3 will generate SFCI1 (sidelink feedback control information) and/or SFCI2 associated with TB1 and/or TB2, regardless of whether the decoding process of the two TBs is successful.
  • SFCI1 sidelink feedback control information
  • Rx-UE3 must generate an SFCI (send NAK only) associated with the initial TB with high priority. Which TB is selected depends on the L1 priority of the TB.
  • the Rx-UE3 determines whether TB1 and TB2 are initial transmission or retransmission through the SCI information. Rx-UE3 generates only SFCI associated with the initial TB (only sends NAK).
  • the Rx-UE3 must generate the initial TB1 and the initial TB1 and initial Two SFCIs (two NAKs) associated with TB2.
  • the Rx-UE3 determines whether TB1 and TB2 are initial transmission or retransmission through the SCI information. If TB1 or TB2 is the initial transmission, Rx-UE3 must generate an SFCI (NAK) related to TB1 or TB2, otherwise Rx-UE3 does not generate SFCI. If one of TB1 and TB2 is a retransmission, if Rx-UE3 can judge that TB1 and TB2 also overlap in the time slot of the previous transmission, and the retransmitted TB is the initial transmission in the time slot of the previous transmission, then Rx- UE3 also generates SFCI for the retransmitted TB.
  • NAK SFCI
  • the Rx-UE3 implements the decision on its own whether to generate the SFCI associated with the initial TB (only send NAK). If the reserved resources retransmitted by the two Tx-UEs are in the same time slot and/or the reserved resources overlap (at least partially) in the frequency domain, and the HARQ mechanism of option-2 is used, the Rx-UE3 generates two Low priority initial TB associated SFCI (both send ACK). One of the SFCIs is fed back for the Rx-UE3 itself, and the other SFCI is fed back for the Tx-UE of the initial TB with high priority. Thus, the initial TB with low priority will not be sent in the reserved resources.
  • Step 3 The Rx-UE3 sends the generated SFCI to the corresponding Tx-UE through the PSFCH.
  • Step 4 If Tx-UE1 receives SFCI-1 from PSFCH1, Tx-UE1 retransmits the TB as a multicast.
  • the retransmitted TB is received by Tx-UE2 and Rx-UE3, if Rx-UE3 also failed in the previous decoding process of the TB (packet initial transmission and retransmission), then Rx-UE3 decodes it, otherwise Rx-UE3 - UE3 ignores the reception of the TB.
  • Step 5 If Tx-UE2 receives SFCI-2 from PSFCH2, Tx-UE2 retransmits the TB as a multicast.
  • the retransmitted TB is received by Tx-UE1 and Rx-UE3, if Rx-UE3 also failed in the previous decoding process of the TB (packet initial transmission and retransmission), then Rx-UE3 decodes it, otherwise Rx-UE3 - UE3 ignores the reception of the TB.
  • Figure 6 depicts the process of TB transmission and retransmission with inter-UE coordinated HARQ feedback process completed in four stages:
  • Stage 1 for initial TB transfer
  • the second stage for SFCI NAK feedback
  • the third stage is the retransmission of TB1;
  • the fourth stage is the retransmission of TB2.
  • Table 1 summarizes the combinations of SFCI generation under different TB1 and TB2 scenarios.
  • the V2X application layer creates a group, and the inter-UE coordinated HARQ process is performed within the group.
  • the Rx-UEs in other groups can identify the same information obtained by the same group of Rx-UEs (such as source L1 IDs, destination L1 IDs, location information, TB-related NDI information and QoS requirements, etc.), this coordination process is also
  • the extension can be performed between different groups of Tx-UEs and Rx-UEs.
  • L2 relay layer-2 relay
  • L3 relay layer-3 relay
  • UE-to-network coverage extension The coverage of Uu is indispensable for the UE to reach the server in the central network or the peer UE outside the adjacent area.
  • UE-to-UE coverage extension In the absence of Uu coverage, the coverage of sidelink communications must meet the required requirements.
  • the positional relationship between the gNB and the relay UE (relay UE) and the positional relationship between the relay UE and the remote UE (remote UE) are relatively stable. Therefore, it can be determined semi-statically. following the UE.
  • the location relationship between Tx-UE and relay UE and between relay UE and Rx-UE are unpredictable, especially in multicast and broadcast communication
  • the mid-range is significant, so the relay UE has to be determined dynamically.
  • the relay UE determination also depends on who is the Tx-UE and who is the Rx-UE.
  • the 5G core network can provide services to remote UEs through unicast or broadcast communication.
  • the coverage between the 5GC and the remote UE can be extended, which can be achieved through the Uu link between the 5GC and the relay UE and through the side link between the relay UE and the remote UE.
  • 5GC can also provide services to remote UEs in groups through multicast communication.
  • the relay mechanism can be performed based on layer-2 (L2) relaying or layer-3 (L3) relaying.
  • the relay UE In the UE to network coverage extension, at least the gNB is always in a fixed location for transmission and reception. Taking this as a fixed reference point, the relay UE can be selected relatively statically by the gNB or the remote UE.
  • Figure 7 depicts a typical relay scenario of a unicast UE-to-Network with gNB, relay UE and remote UE, where gNB transmits and receives with the same relay UE, and the remote UE also transmits and receives with the same relay UE take over.
  • This scenario can be considered as, if the remote UE is interested in the service provided by the gNB, the gNB can provide the corresponding service by relaying the UE. Therefore, in the coverage extension of the UE to the network, the relay UE should be determined semi-statically. For a UE to become a relay UE, the following conditions must be met:
  • the UE needs to be pre-authorized as a candidate relay UE according to its UE capabilities.
  • the capabilities of the UE include endurance battery life, UE type, acceptable service type, sending and receiving capabilities, etc.;
  • a candidate relay UE should satisfy a (pre)configured threshold condition
  • a threshold (eg, RSRP) can be set as a high threshold (denoted ThreshHigh) and a low threshold (denoted ThreshLow), and a candidate relay UE can become a relay UE only if the RSRP measurement is between ThreshHigh and ThreshLow .
  • the remote UE Based on RSRP measurements from the gNB as well as from the relay UE, the remote UE also needs to meet (pre-configured) threshold conditions.
  • 5GC For side-link multicast communication from UE to network coverage extension, 5GC provides services of interest to all group members through gNB.
  • gNB For relay UE discovery/maintenance/release, we consider two scenarios and propose the following two schemes (Scheme 1 and Scheme 2).
  • Scheme 1 is for a scenario where all group members are not covered by the gNB.
  • the gNB discovers and authorizes the candidate relay UE as the primary relay UE (primary relay UE, denoted as P-relay UE) and optionally one or more secondary relay UEs (secondary relay UE) by setting the threshold. , denoted as S-relay UE).
  • P-relay UE and S-relay UE shall meet the following conditions:
  • ⁇ P-relay UE and S-relay UE(s) are not group members;
  • ⁇ P-relay UE and S-relay UE(s) should be within the communication range with gNB;
  • ⁇ P-relay UE and S-relay UE(s) are within the communication range with all group members, and can perform multicast communication with all members through the side link;
  • the P-relay UE and S-relay UE(s) shall continue to report their Uu link quality (eg, reference signal received power, RSRP) to the gNB in order for the gNB to switch relay UEs or allow multiple relay UEs to participate in relaying transmission;
  • Uu link quality eg, reference signal received power, RSRP
  • ⁇ P-relay UEs and S-relay UE(s) as cooperative UEs shall obtain group related information, such as group destination L2 ID, group size, group members, etc.
  • the relay UE discovered and designated by the gNB has two tasks: one task is to relay data from the gNB to the relevant group members, and the other task is to transfer the resources as a cooperating UE (Co-UE) Sets are coordinated and assigned to relevant group members.
  • one task is to relay data from the gNB to the relevant group members
  • the other task is to transfer the resources as a cooperating UE (Co-UE) Sets are coordinated and assigned to relevant group members.
  • Co-UE cooperating UE
  • the reason for specifying P-relay UE and S-relay UE is to provide a robust relay link and ensure seamless service continuity.
  • the gNB determines how and when the S-relay UE participates in relay transmission. For example, based on the requirements of transmitting data packets (such as communication range and reliability), the gNB can use RRC to configure the radio bearer (radio bearer) to replicate the PDCP PDU at the PDCP layer, and send it through the P-relay UE and the S-relay UE respectively.
  • This is an L2 relay performed on top of the RLC sublayer, especially for demanding V2X services, which can achieve multiple transmit diversity, improve reliability and reduce latency.
  • Figure 8 illustrates scenario 1, where all group members are out of coverage of the gNB.
  • Scheme 2 is for a scenario where at least one UE member is within the coverage of the gNB.
  • the gNB discovers and authorizes one UE as the primary relay UE (denoted as P-relay UE) and one or more secondary relay UEs (denoted as S-relay UE).
  • P-relay UE and S-relay UE shall meet the following conditions:
  • ⁇ P-relay UE and S-relay UE are members of this group and can communicate with other members through the side link multicast.
  • the advantage of authorizing a group member UE as a relay UE is to simplify the discovery and authorization process of the relay UE, in which other member UEs do not need to report group information, such as group destination L2 ID, group member information, etc., to the relay UE.
  • ⁇ P-relay UE and S-relay UE are within the communication range of gNB.
  • ⁇ P-relay UEs and S-relay UEs have the strongest link with the gNB, which depends on the measurement report from the relay candidate UE to the gNB, such as Reference Signal Received Power (RSRP), etc.
  • RSRP Reference Signal Received Power
  • the relay UE discovered and designated by the gNB has two tasks: one task is to relay data from the gNB to other members of the relevant group, and the other task is to coordinate the resource set and the cooperating UE (Co-UE) Assigned to other members of the relevant group.
  • the reason for specifying P-relay UE and S-relay UE is to provide a robust relay link and ensure seamless service continuity.
  • the gNB determines how and when the S-relay UE participates in relay transmissions. For example, based on the requirements of transmitting data packets (such as communication range and reliability), the gNB can use RRC to configure the radio bearer (radio bearer) to replicate the PDCP PDU at the PDCP layer, and send it through the P-relay UE and the S-relay UE respectively. .
  • Figure 9 illustrates scenario 2, where a portion of the group members are within the coverage of the gNB.
  • the gNB can configure RRC parameters (such as a system information block, System Information Block, SIB for short) for the remote UE through the relay UE.
  • RRC parameters such as a system information block, System Information Block, SIB for short
  • the transmission of configuration information is done through the Uu interface between the gNB and the remote UE.
  • L2 relay or L3 relay can be relied on, and the relay solution adopted in rel-13 can be reused, including relay UE discovery/maintenance/release.
  • the gNB can configure the RRC parameters for the remote UE through the relay UE using PC5 signaling.
  • P-relay UE and S-relay UE can also be considered, including PDCP replication mechanism, to improve reliability and reduce latency.
  • the gNB For UE-to-network coverage-extended side-link broadcast communications, the gNB discovers and assigns relay UEs in coverage.
  • the relay UE supports forwarding data packets of remote UEs located out of coverage.
  • the relay process is the same as that of the relay UE participating in the multicast, including the PDCP replication mechanism to improve reliability and reduce delay time.
  • the present application may also use UE-to-UE coverage extension to implement coordinated relay transmission between UEs.
  • UE-to-UE coverage extension especially in multicast and broadcast communication, the relationship between Tx-UE and relay UE and the relationship between relay UE and Rx-UE are not constant.
  • Figure 10 depicts a typical UE-to-UE scenario of co-group multicast between Tx-UE, Relay UE and Rx-UE; where Tx-UE-1 is multicast by Relay-UE in one slot One data packet is sent to Rx-UE-2, and Tx-UE-2 will multicast another data packet to Rx-UE-1 by Relay-UE-2 in another time slot due to the limitation of communication range.
  • the relay UE is then dynamically determined according to who is the Tx-UE and who is the Rx-UE. For a UE to become a relay UE, the following conditions must be met:
  • the UE is (pre-)authorized as a candidate relay UE according to its UE capabilities.
  • its UE capabilities include battery life tolerance, UE type (eg, vehicle, RSU), transmit and receive capabilities, etc.;
  • a (pre)configured threshold condition When a candidate relay UE becomes a relay UE, a (pre)configured threshold condition must be met;
  • a threshold (eg, RSRP) can be set as a high threshold (denoted as ThreshHigh) and a low threshold (denoted as ThreshLow), and a candidate relay UE can become a relay UE only when the RSRP measurement is between ThreshHigh and ThreshLow.
  • the threshold can be adjusted by the relay UE depending on the communication range and the desired QoS (eg, reliability and delay budget) indicated in the received data packets. For example, ThreshHigh and ThreshLow can be set to relatively low values if the desired communication range is large, and vice versa.
  • QoS eg, reliability and delay budget
  • the application layer creates a group, either depending on the geographic location of the UEs or on the type of service between the UEs of interest.
  • the former may not need to know information between group members, as long as all group members know the communication range and destination L2 ID.
  • the latter may need to know information between group members, such as group size, member ID, and destination L2 ID. Participating in the relay between multicast UEs is to extend the communication range and improve the communication quality between group members.
  • the V2X application layer can provide the V2X application requirements, otherwise, the V2X layer will determine the PC5 QoS parameters. This means that the V2X application layer or the V2X layer will decide whether to use the relay function according to the service requirements or PC5 QoS.
  • P-relay UE(s) and S-relay UE(s) shall be determined by the respective V2X layers before multicast implementation and updated by the V2X layer during multicast implementation.
  • the P-relay UE can be a single relay UE or multiple relay UEs. Unless the relay cannot correctly receive the Tx UE data packet, they always participate in the relay operation.
  • the S-relay UE can optionally participate in the relay operation. Whether or not the S-relay UE is involved in the relay operation depends on the direct path strength based on the received RSRP measured in the S-relay UE. If the S-relay UE decodes the received initial packet correctly and the RSRP of the direct path strength drops to the pre-configured RSRP threshold level, the S-relay UE will participate in the relay operation to relay the received packet to nearby Rx-UE.
  • a threshold eg, RSRP
  • ThreshHigh a threshold
  • ThreshLow a threshold
  • the S-relay UE becomes the relay UE for relay transmission only when the measured power value from the Tx-UE to the S-Relay UE is between ThreshHigh and ThreshLow.
  • the location information of the Tx-UE can be obtained through the relay UE, the distance between the Tx-UE and the relay UE can replace the RSRP-based threshold. Deciding whether an S-relay UE becomes a relay UE may depend on the distance and the desired communication range indicated in the received data packet.
  • the V2X layer has a certain flexibility, and can select any number of P-relay UEs and any number of S-relay UEs according to the services that group members are interested in. Of course, the number of P-relay UEs and/or S-relay UEs can be set to zero.
  • FIG 11 gives an example where a Tx-UE multicasts packets to its group members (including Rx-UE-1 and Rx-UE-2), consisting of P-relay UEs and optionally S-relay UEs relay.
  • Figure 12 illustrates the process of multicast-based relay operation:
  • Step 1 Tx-UE-1 multicasts the packet to all group members, including P-relay UE and S-relay UE, and Rx-UE-1 and Rx-UE-2.
  • the data packet should be the MAC PDU (or TB) sent by PSCCH and PSSCH, otherwise, the data packet should be a higher layer PDU.
  • Rx-UE-1 and Rx-UE-2 are far away from Tx-UE-1 and cannot decode the packets correctly, so relay based retransmission is required.
  • Step 2 The P-Relay-UE decodes the packet and prepares to perform relay-based retransmission.
  • the S-Relay-UE decodes the packet and measures the received signal strength (e.g. L1 RSRP or L3 RSRP) and compares it to a (pre)configured threshold.
  • the received signal strength e.g. L1 RSRP or L3 RSRP
  • the received signal strength is between the (pre)configured thresholds ThreshHigh and ThreshLow, so the S-Relay-UE also participates in relay-based retransmissions.
  • Step 3 P-Relay-UE and S-Relay-UE relay and retransmit data packets.
  • the MAC entity can directly use the resources reserved for retransmission in the physical layer for retransmission.
  • the reserved resources for retransmission are indicated by the SCI detected in the initial data packet or the last received data packet. .
  • the resources used by the physical layer for relaying transmissions shall be re-determined by the MAC entity.
  • Step 4 Rx-UE-1 and Rx-UE-2 receive the retransmitted data packets, and feed back whether the detection is correct or not to P-Relay-UE and S-Relay-UE, respectively.
  • the HARQ entity in each Rx-UE triggers the HARQ mechanism and feeds back ACK/NAK information through the PSFCH.
  • the feedback resources are associated with PSSCH resources dedicated to retransmissions.
  • Step 5 P-Relay-UE and S-Relay-UE receive feedback information from Rx-UE-1 and Rx-UE-2, respectively, and forward the feedback information to Tx-UE-1.
  • the HARQ entities in the P-Relay-UE and S-Relay-UE will feed back ACK/NAK information through the PSFCH.
  • This feedback resource is associated with the PSSCH resource dedicated to the initial transmission. In this case, the feedback process should consider the round-trip time (RTT, Round-Trip Time) and relay processing time for forwarding HARQ feedback.
  • Relay can be performed as an L2 function or as an L3 function, but the relay steps are different.
  • Option 1 The MAC entity in the relay UE does not check the HARQ feedback and performs blind retransmission.
  • Option 2 The MAC entity in the relay UE checks the HARQ feedback and retransmits if a NAK is received.
  • the SCI indication is used in the initial TB transmission and the retransmission resources are reserved at the same time, and these reserved retransmission resources can be used in the relay retransmission. This is because the relay UE decodes the TB after correctly decoding the received SCI, and knows the PSCCH/PSSCH resources reserved for retransmission and the associated PSFCH resources. Note that the time interval between PSSCH and PSFCH resources for initial transmission should be greater than the time interval between PSSCH and PSFCH resources for relay-based retransmission.
  • Figure 13 illustrates the timing of the initial transmission and relay-based retransmission, where the HARQ RTT (inner RTT) based relay transmission and its associated RTT from the relay UE to the Tx-UE (outer RTT) are considered.
  • the resources of the PSFCH transmitted by Rx-UE-1 and Rx-UE-2 are associated with the PSSCH resources of the relay-based retransmission of P-Relay-UE and S-Relay-UE, respectively, while the resources of P-Relay-UE and S-Relay-UE
  • the resources of the PSFCH transmitted by the Relay-UE are associated with the PSSCH resources transmitted by the Tx-UE-1 based on the initial transmission.
  • the resources of the PSFCH associated with PSSCH transmission shall be determined either explicitly or implicitly.
  • the MAC entity shall re-determine the resources to use for its relay-based retransmissions.
  • the PDCP replication mechanism can be implemented, and the replicated PDCP PDUs generated by the P-relay UE and S-relay UE(s) can be sent in a (pre)configured radio bearer. Therefore, multi-relay UE transmission can achieve multi-transmission diversity gain, increase reliability and reduce latency, which is especially important for strictly demanding V2X services.
  • the corresponding solution can also rely on L2 relay or L3 relay.
  • RRC link can be established between Tx-UE, relay UE and remote UE, and RRC parameters can be exchanged through PC5 signaling. Therefore, the relay UE can be determined after establishing the sidelink unicast connection and exchanging RRC parameters.
  • P-relay UE and S-relay UE(s) can also be adopted to improve reliability and reduce delay time. How many relay UEs are involved in relay retransmissions depends on the specific service and the requirements of each transmission. PDCP replication mechanisms may also be implemented.
  • the same solution as used in multicast can be adopted, where the thresholds for candidate relay UEs are considered as, for example, ThreshHigh and ThreshLow, and then based on each transmission pair Service-specific requirements to determine whether relay transfers are involved.
  • the PDCP replication mechanism can also be implemented.
  • the present application proposes an inter-UE coordination method, which can be performed before or after initial data packet transmission.
  • the former is to coordinate resources between Tx-UEs based on information provided in advance by cooperative UEs to avoid resource conflicts and/or half-duplex effects.
  • the latter is to help Tx-UEs that have simultaneously transmitted initial packets in the same time slot and are facing half-duplex effects after the initial transmission.
  • the present application also proposes a coordinated relay transmission between UEs, which mainly considers the coverage expansion from the UE to the network and the coverage expansion from the UE to the UE.
  • relay UEs are semi-statically designated and used for UE-to-network coverage extension, while relay UEs are dynamically designated and used for UE-to-UE coverage extension.

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Abstract

本申请提供了一种基于NR-V2X的UE间的协调方法，用于单播、组播和广播通信的UE间的协调，该协调方法在初始传输之前或之后执行。前者通过第一协作UE基于预先配置的资源池中可用的资源集的信息，根据发送UE上报的参数信息向发送UE分配/授予资源集，以避免资源冲突和/或半双工影响；后者通过第二协作UE接收同一组内的至少两个发送UE在同一时隙发送的初始数据包后，通过PSFCH传输SFCI至每一个所述发送UE，通知所述发送UE在接下来的不同时隙进行初始数据包重传，以帮助已经在同一时隙中同时发送初始数据包并在初始发送之后面临半双工影响的发送UE。此外，本申请还提出了一种UE之间的协调中继传输。

Description

一种基于NR-V2X的UE间的协调方法
本申请请求____年___月___日申请的申请号为___(发明名称：___)的中国专利申请的优先权。
技术领域
本发明涉及无线通信技术领域，尤其涉及一种基于NR-V2X的UE间的协调方法。
背景技术
随着第三代合作伙伴计划(3 rd Generation Partnership Project，简称3GPP)的发展，新无线(New Radio，简称NR，也可称为新空口)——车对外界的信息交换(vehicle to X，简称V2X，也可称为vehicle to everything)作为协议第16(Release16，简称R16)版本的一个关键技术方向正在进行研究。NR-V2X作为长期演进(Long Term Evolution，简称LTE)V2X技术的增强，在Rel5 NR的技术基础上使能车联网的关键性能得以实现。NR-V2X被指定为支持LTE Rel-15 V2X服务之外的V2X服务，但是更广泛地增强了NR系统和提升了新的NR侧链路(NR sidelink)来满足更严格的V2X服务要求。提升性能后的NR-V2X系统将具有灵活的设计，以支持具有低延迟和高可靠性的服务。NR-V2X系统也有望具有更高的系统容量和更好的覆盖范围。
目前，存在多种被分类为V2X通信的通信方法，要求对3GPP系统拥有对不同性能要求的V2X信息进行传输。主要的应用例有四种；车辆编队(vehicle platooning)，自动驾驶(advanced driving)，扩展传感器信息传输(extended sensors)，和远程驾驶(remote driving)。这些应用将具有更严格的要求，例如3-10ms的最大端到端延迟，99.99-99.999％的可靠性，25-1000Mbps的数据速率以及80-1000米的最低要求通讯范围。
NR-V2X为满足车联网的各种业务需求，不仅支持物理层上广播，也支持单播(unicast)与组播(groupcast)。相比之下，LTE V2X仅支持物理层上广播。因此，在基本维持如基于LTE V2X的相同水平可靠性以及解码复杂度情况下，需要NR-V2X系统支持这些不同的性能要求。
发明内容
本发明的目的在于提供一种基于NR-V2X的UE间的协调方法，以解决上述技术背景中提出的问题。
涉及的专业术语：
UE(User Equipment)，用户设备；
TB(Transport Block)，传输块，或数据包；
RE(Resource Element)，资源元素，用于5G通信的最小信道元素；
Tx-UE(Transmitter UE)，发送UE，用于通过单播、组播或广播向其他UE传输传输块；
Rx-UE(Receiver UE)，接收UE；
Co-UE(Coordinative UE)，协作UE，其功能是向Tx-UE分配/授予资源集(set of resources)；
PSCCH(physical Sidelink Control Channel)，物理侧链路控制信道；
PSSCH(Physical Sidelink Shared Channel)，物理侧链路数据信道；
PSFCH(Physical Sidelink Feedback Channel)，物理层侧链反馈信道；
SCCH(Sidelink control channel)，侧链路控制信道，用于NR侧链路通信的单播；
SFCI(Sidelink Feedback Control Information)，侧链反馈控制信息；
SCI(Sidelink Control Information)，侧链控制信息；
PRR(Packet Reception Ratio)，数据包接收比；
HARQ(Hybrid Automatic Repeat reQuest)，混合自动重传请求；
RSRP(Reference Signal Receiving Power)，参考信号接收功率，是LTE网络中可以代表无线信号强度的关键参数以及物理层测量需求之一，是在某个符号内承载参考信号的所有RE(资源元素)上接收到的信号功率的平均值；
RRC(Radio Resource Control)，无线资源控制；
DRB(Data Radio Bearer)，数据无线承载；
LCH(Logical CHannel)，逻辑信道；
MAC-CE(MAC Control Element)，MAC层的控制元素。
为实现上述目的，本发明采用以下技术方案：
本申请提供的一种基于NR-V2X的UE间的协调方法，优选地，用于单播、组播和广播通信的UE间的协调，包括以下至少之一：
在初始数据包传输之前进行UE间的协调：第一协作UE基于预先配置的资源池中可用的资源集的信息，根据发送UE上报的参数信息向发送UE分配/授予资源集；
在初始数据包传输之后进行UE间的协调：第二协作UE接收同一组内的至少两个发送UE在同一时隙发送的数据包，其中至少一个发送UE发送初始数据包，第二协作UE通过PSFCH传输SFCI至每一个所述发送UE，通知所述发送UE在接下来的时隙进行初始数据包重传，优选为接下来的不同时隙进行初始数据包重传。
优选地，申请资源集的发送UE向第一协作UE上报的参数信息包括地理信息、服务质量QoS、LCH优先级、传输类型、服务类型中的一种或多种。
优选地，在第一协作UE向申请资源集的发送UE分配/授予资源集之前，还包括以下至少之一：
所述第一协作UE已被授权或预先授权为协作UE；
所述第一协作UE已知申请资源集的发送UE的参数信息，例如地理信息、服务质量QoS、LCH优先级、传输类型、服务类型；
所述第一协作UE的数量至少为两个时，多个所述第一协作UE之间已经完成PC5连接初始化，从而可以交换用于发送UE授予的资源集信息。
优选地，所述第一协作UE向申请资源集的发送UE分配/授予资源集的过程包括：
多个所述第一协作UE之间以第一目的地L2-ID建立PC5连接；
多个所述第一协作UE之间交换已配置资源池中可用资源集的信息，为其关联的发送UE设置候选的资源集；
所述第一协作UE和与其关联的发送UE之间以第二目的地L2-ID(Destination Layer-2 ID)建立PC5连接；
所述发送UE使用第二目的地L2-ID，通过SCI或MAC-CE向其关联的第一协作UE发送资源集配置请求；
所述第一协作UE接收所述资源集配置请求，选择授予给所述发送UE的资源集；
所述第一协作UE通过PC5连接使用第三目的地L2-ID，将资源集发送至所述发送UE和其他第一协作UE。
更优选地，所述第一协作UE和与其关联的发送UE之间建立PC5连接，可以基于所述第一协作UE和发送UE之间的地理信息(例如，Geo ID list)以及可选的服务类型。
更优选地，所述发送UE向其关联的第一协作UE发送资源集配置请求之前，还包括：
所述发送UE向其关联的第一协作UE报告和/或更新发送UE的参数信息；
所述第一协作UE接收与其关联的发送UE报告和/或更新的参数信息，并进行存储。
进一步地，所述发送UE可以向其关联的第一协作UE发送显式报告，或者在MAC实体中使用选项-1 HARQ的情况下，基于Zone-ID来实现隐式报告。
更优选地，多个第一协作UE在PC5上建立单播链路，则第一协作UE可以使用PC5信令通过侧链路信号无线承载(signal radio bearer，简称为SRB)来协调并执行RRC参数的重新配置；或者，所述第一协作UE使用PC5组播或广播，则每个所述第一协作UE通过SCI或MAC-CE组播或广播与候选的资源集有关的信息，其中SCI或MAC-CE包含的信息至少包括与发送UE关联的源ID(Source ID)和资源集信息。
更优选地，所述第一协作UE和与其关联的发送UE之间建立PC5连接，可以是通过组播、或单播、或广播完成。
更优选地，所述第一协作UE将资源集的信息广播至其通信范围内所有可到达的发送UE和其他第一协作UE；或者，所述第一协作UE将资源集的信息单播至设定的发送UE；或者，所述第一协作UE将资源集的信息组播至与其同组的发送UE。
更优选地，所述发送UE通过SCI(可以使用第二阶段SCI)或MAC-CE(使用专用LC-ID)向其关联的第一协作UE发送资源集配置请求包括以下信息中的一种或几种：
与发送UE关联的源ID(Source ID)或组成员ID(group member ID)；
与第一协作UE创建的组关联的目的地ID(Destination ID)；
QoS要求(例如，LCH优先级，通信范围)；
传输类型(例如，单播，组播，或广播)；
数据包大小；
服务类型(例如，V2X service ID)；
流量类型(周期性或非周期性)；
所述第一协作UE通过SCI或MAC-CE向其发送UE通知被授予资源集，其中SCI或MAC-CE至少包括以下信息：
发送UE的源L2 ID；
单播，组播，或广播的目的地L2 ID；
资源集信息。
优选地，每个所述第一协作UE可以与其对等的发送UE创建单播链路，并在必要时完 成侧链路RRC重新配置过程。
优选地，每个所述第一协作UE具有组管理功能，并具有汇集其附近的发送UE并创建用于UE间协调的组的能力。
优选地，每个所述第一协作UE配备了一个全能MAC实体，该实体可以选择资源集并通过MAC-CE(使用专用LC-ID)或SCI(可以使用第二阶段SCI)将其广播或组播到相关的发送UE，而相关的发送UE属于该第一协作UE创建的组成员。
优选地，每个所述第一协作UE具有感知侧链路信道并更新候选资源集的能力，这些资源集能够被分配/授予给组中的发送UE。
优选地，所述第一协作UE可以通过gNB及时地得到相关的时域和频域相关的资源集，如果所述第一协作UE在gNB的可通信范围内。
优选地，所述第一协作UE可以使用MAC-CE或SCI通知发送UE分配/授予的资源集，其中包含的信息至少包括：与发送UE关联的源ID(Source ID)或组成员ID(group member ID)，以及时域和频域相关的资源集，L1的优先度，可选的第一协作UE源ID和目的地ID。
优选地，向所述第一协作UE申请资源集的发送UE如果没有被授予资源集，则所述发送UE的MAC实体触发资源选择过程；向所述第一协作UE申请资源集的发送UE如果被授予资源集，则所述发送UE的MAC实体从资源集中选择资源。
更优选地，若所述发送UE的MAC实体触发资源选择过程，则在时隙n(n为≥1的自然数)中，针对PSSCH/PSCCH传输，MAC层提供以下参数信息中的一种或几种给物理层：
用作选择资源的资源池；
上述资源池中由第一协作UE为其关联的发送UE授予的资源集(如果授予)；
第一协作UE在上述资源池中为其他发送UE授予的资源集(如果授予)；
L1的优先度；
剩余的数据包延迟预算(packet delay budget)；
以时隙为单位，用于PSSCH/PSCCH传输的子信道数(sub-channels)；
资源预留间隔。
优选地，所述资源集包括时域和频域中的协调资源单元。
优选地，资源集的授予可以通过动态授予机制或配置的授予机制(CG类型1或CG类型2)实现。
更优选地，所述第一协作UE还基于与其相关的发送UE的地理位置，分配/授予所述发送UE不同时隙的资源集。
进一步地，每个第一协作UE可以根据与其相关的发送UE的地理位置将多个发送UE划分为多个组，即第一协作UE在应用层中创建多个和地理位置相关的组；每个发送UE均在第一协作UE的通信范围之内；第一协作UE将不同时隙的资源集分配给组中的发送UE，以避免半双工的影响，但是，不同组之间的发送UE则不需要进行这种不同时隙的分配限制。
更进一步地，所述第一协作UE为每个组和组内的每个发送UE分配资源集，应满足以下条件：
所述第一协作UE为属于同一组的发送UE分配资源集，则不同的候选的资源集不能在时域上相互重叠，而在频域上没有限制；
所述第一协作UE为不同组的发送UE分配资源集，则不同的候选的资源集在频域上可以部分重叠，但对时域没有限制。
优选地，通知同一时隙发送初始数据包的发送UE进行初始数据包重传的第二协作UE满足以下条件：
所述第二协作UE与发送数据包的至少两个发送UE在同一组中，用于进行组播接收，其中至少一个发送UE发送初始数据包；
所述第二协作UE知道发送数据包的至少两个发送UE在一个时隙中都处于传输模式的状态，其中至少一个发送UE发送初始数据包；
所述第二协作UE通过物理层侧链反馈信道PSFCH传输侧链反馈控制信息SFCI，无需考虑其自身PSSCH接收的状态。
优选地，在初始数据包传输之后进行UE间的协调中，位于同一组内的发送UE包括第一发送UE和第二发送UE，所述第一发送UE和第二发送UE在同一时隙中组播数据包，其中至少一个发送UE组播初始数据包；
所述第二协作UE接收并解码所述第一发送UE和第二发送UE发送的初始数据包，根据选定的第一物理层侧链反馈信道PSFCH1向第一发送UE发送第一侧链反馈控制信息SFCI1，根据选定的第二物理层侧链反馈信道PSFCH2向第二发送UE发送第二侧链反馈控制信息SFCI2；
如果第一发送UE从第一物理层侧链反馈信道PSFCH1接收到第一侧链反馈控制信息SFCI1，则第一发送UE将其初始数据包在第一时隙进行组播重传；
如果第二发送UE从第二物理层侧链反馈信道PSFCH2接收到第二侧链反馈控制信息SFCI2，则第二发送UE将其初始数据包在第二时隙进行组播重传；
其中，所述第一时隙与所述第二时隙为相同或不同的时隙。
更优选地，所述第一发送UE在第一物理侧链路控制信道PSCCH1和第一物理侧链路数据信道PSSCH1上传输第一数据包TB1，其中，被发送的侧链控制信息SCI包括关于第一发送UE的源ID、目的地ID和与当前传输数据包相关联的资源以及可能重传的预留资源；
所述第二发送UE在第二物理侧链路控制信道PSCCH2和第二物理侧链路数据信道PSSCH2上传输第二数据包TB2，其中，被发送的侧链控制信息SCI包括关于第二发送UE的源ID、目的地ID和与当前传输数据包相关联的资源以及可能重传的预留资源；
第二协作UE接收第一数据包TB1和第二数据包TB2，并在同一时隙中先解码PSCCH1、PSCCH2，然后解码PSSCH1、PSSCH2；
如果第一发送UE的源ID与第二发送UE的源ID不同，但第一发送UE的目的地ID和第二发送UE的目的地ID相同，则第二协作UE根据初始数据包还是重传数据包判断触发UE间协调HARQ过程，生成与第一数据包TB1关联的第一侧链反馈控制信息SFCI1和/或与第二数据包TB2关联的第二侧链反馈控制信息SFCI2；
如果第一发送UE从PSFCH1接收到第一侧链反馈控制信息SFCI1，则第一发送UE将第一数据包TB1在第一时隙重新组播发送给第二发送UE和第二协作UE；
如果第二发送UE从PSFCH2接收到第二侧链反馈控制信息SFCI2，则第二发送UE将第二数据包TB2在第二时隙重新组播发送给第一发送UE和第二协作UE；
其中，所述第一时隙与所述第二时隙为不同的时隙。
更优选地，如果第一发送UE与第二发送UE同时发送初始数据包，第二协作UE考虑初始数据包的L1优先度判断是否触发UE间协调HARQ过程；
其中，所述第一时隙与所述第二时隙为相同的时隙。
更优选地，如果第一发送UE与第二发送UE各自在同一时隙各发送初始数据包和重传数据包，第二协作UE优先考虑初始数据包来判断是否触发UE间协调HARQ过程；
其中，所述第一时隙与所述第二时隙为相同或不同的时隙。
优选地，如果第一发送UE与第二发送UE均通过PSCCH1、PSCCH2发送自己的地理位置信息(用Zone_ID的方法)和第一发送UE TB1与第二发送UE TB2的各自的通信范围信息(Communication Range)，第二协作UE通过计算第一发送UE与第二发送UE 间的距离，然后比较他们之间的距离和各自的通信范围，从而判断是否触发针对TB1和TB2的UE间协调HARQ过程。其中，所述第一时隙与所述第二时隙为相同或不同的时隙。
优选地，如果第一发送UE与第二发送UE同时发送初始数据包，并且选项-2的HARQ机制被使用，Rx-UE3生成两个与优先级低的初始TB关联的SFCI(均发送ACK)。
其中，所述两Tx-UE重传的保留资源在相同的时隙中和/或保留资源在频域上有重叠(至少部分重叠)。优选地，所述基于NR-V2X的UE间的协调方法还包括UE间的协调中继传输，所述UE间的协调中继传输选用如下方式中至少之一：
UE到网络的覆盖范围扩展：远程UE与gNB进行通信时，半静态选择gNB的网络覆盖范围内且具有中继能力的至少一个UE充当中继UE；其中，所述中继UE与gNB通过Uu链路进行通信，所述中继UE与远程UE通过PC5接口进行通信；
UE到UE的覆盖范围扩展：发送UE与接收UE进行通信时，动态选择位于其通信范围内且具有中继能力的至少一个UE充当中继UE；其中，多个中继UE在不同的时隙内与其对应的发送UE和接收UE分别通过PC5接口进行通信。
更优选地，在UE到网络的覆盖范围扩展中，所述中继UE的选择方法包括：
gNB的网络覆盖范围的UE如果满足条件1则称为候选中继UE，所述条件1包括：在网络覆盖范围内具有与gNB进行通信的能力且具有承担中继任务的能力；
候选中继UE如果满足条件2则称为中继UE，所述条件2包括：候选中继UE监听由gNB发送的参考信号，并基于所监听的参考信号，得到来自gNB的参考信号的参考信号接收功率RSRP，将参考信号接收功率RSRP与预设的第一阈值和第二阈值进行比较，所述参考信号的接收功率RSRP在第一阈值和第二阈值之间。
进一步地，所述具有承担中继任务的能力的判断因素包括：所述候选中继UE的中继操作不影响其与所述gNB和其它网内UE的通信；以及所述候选中继UE的剩余电量、可接受的业务类型和与所述gNB的链路质量。
更优选地，半静态选择的所述中继UE与远程UE之间的侧链路通信包括侧链路单播、或侧链路组播、或侧链路广播。
更优选地，所述远程UE均位于gNB的网络覆盖范围之外；或者至少一个所述远程UE位于gNB的网络覆盖范围之内。
进一步地，所述中继UE包括主中继UE(primary relay UE，表示为P-relay UE)以及可选的至少一个辅助中继UE(secondary relay UE，表示为S-relay UE)。
更进一步地，所述主中继UE与所述辅助中继UE在同一个时隙和同一频率资源进行初始数据包重传。
更进一步地，所述gNB根据所述辅助中继UE的链路质量，对所述辅助中继UE进行接入控制。
更进一步地，所述gNB利用RRC配置无线承载在PDCP层复制生成PDCP PDU，并通过所述主中继UE和辅助中继UE各自发送。
更进一步地，所述远程UE均位于gNB的网络覆盖范围之外时，所述主中继UE和辅助中继UE应满足以下条件：
所述主中继UE、辅助中继UE与所述远程UE不在一个组内；
所述主中继UE和辅助中继UE均位于gNB的覆盖范围内；
所述主中继UE和辅助中继UE与所有远程UE在通信范围内，并且通过侧链路与所有远程UE进行组播通信；
所述主中继UE和辅助中继UE继续向gNB报告Uu链路质量(例如，参考信号接收功率，RSRP)，以便gNB切换中继UE或允许多个中继UE参与中继传输；
所述主中继UE和辅助中继UE获取组的相关信息，例如，组的目的地ID、组大小、组成员。
更进一步地，至少一个所述远程UE位于gNB的覆盖范围之内时，所述主中继UE和辅助中继UE应满足以下条件：
所述主中继UE、辅助中继UE与所述远程UE在同一个组内，并能够通过侧链路与该组内的其他UE进行组播通信；
所述主中继UE和辅助中继UE均位于gNB的网络覆盖范围内；
所述主中继UE和辅助中继UE具有与gNB的最强链路。
更优选地，在UE到UE的覆盖范围扩展中，所述中继UE的选择方法包括：
在发送UE的通信范围内且同时在接收UE的通信范围内的UE如果满足条件1则称为候选中继UE，所述条件1包括：在通信范围内具有与发送UE、接收UE进行通信的能力且具有承担中继任务的能力；
候选中继UE如果满足条件2则称为中继UE，所述条件2包括：候选中继UE监听由发送UE发送的参考信号，并基于所监听的参考信号，得到来自发送UE的参考信号的参考信号接收功率RSRP，将参考信号接收功率RSRP与预设的第一阈值和第二阈值进行比较， 所述参考信号的接收功率RSRP在第一阈值和第二阈值之间。
进一步地，所述具有承担中继任务的能力的判断因素至少包括：所述候选中继UE的中继操作不影响其与所述发送UE和其它网内UE的通信；以及所述候选中继UE的剩余电量、可接受的业务类型和链路质量。
更优选地，动态选择的所述中继UE与接收UE之间的侧链路通信包括侧链路单播、或侧链路组播、或侧链路广播。
更优选地，动态选择的所述中继UE包括至少一个主中继UE(primary relay UE，表示为P-relay UE)以及可选的至少一个辅助中继UE(secondary relay UE，表示为S-relay UE)。
进一步地，所述主中继UE与所述辅助中继UE在同一个时隙进行初始数据包重传。
其中，V2X层具有一定的灵活性，可以根据组成员感兴趣的服务来选择任意数量的主中继UE和任意数量的辅助中继UE。当然，主中继UE和/或辅助中继UE的数量可以设置为零。
进一步地，如果辅助中继UE正确解码接收到的初始数据包，并且直接路径强度的RSRP下降到预先配置的RSRP阈值水平，则辅助中继UE将参与中继操作，把接收到的数据包中继到附近的接收UE。
在一种优选实施例中，发送UE将初始数据包组播到其组成员，其组成员包括主中继UE、辅助中继UE、第一接收UE和第二接收UE；
主中继UE对初始数据包正确解码，并准备执行基于中继的重传；
辅助中继UE正确解码初始数据包，并测量接收到的信号强度(例如L1 RSRP或L3RSRP)，若信号强度符合预设阈值要求，则辅助中继UE也参与基于中继的重传；
主中继UE和辅助中继UE重传所述初始数据包；
所述第一接收UE、第二接收UE接收重传的初始数据包，并将检测正确与否状况分别反馈到中继UE和辅助中继UE；
所述中继UE和辅助中继UE分别从所述第一接收UE、第二接收UE接收反馈信息，并将反馈信息转发至所述发送UE。
更优选地，所述中继通过Layer-2中继(Layer-2 Relay)或Layer-3中继(Layer-3 Relay)来实现。
进一步地，所述中继通过Layer-2中继实现时，如果仅MAC层为只参与中继操作，则中继传输有两种选择：
选项1：中继UE中的MAC实体不检查HARQ反馈，进行实施盲目重传(blind retransmission)；
选项2：中继UE中的MAC实体检查HARQ反馈，如果接收到NAK，则进行重传。
更进一步地，在任何场景下，gNB或发送UE在PDCP层复制生成PDCP PDU数据包，并通过所述主中继UE与所述辅助中继UE各自发送PDCP PDU数据包。与现有技术相比，本发明的技术方案具有以下有益效果：
本申请提供了一种基于NR-V2X的UE间的协调方法，该协调方法在初始传输之前或之后执行。前者是基于协作UE预先提供的信息来协调在发送UE之间的资源，以避免资源冲突和/或半双工影响。后者是为了帮助已经在同一时隙中同时发送初始数据包并在初始发送之后面临半双工影响的发送UE。此外，本申请还提出了一种UE之间的协调中继传输，主要考虑在UE到网络的覆盖范围扩展和UE到UE的覆盖范围扩展。
附图说明
构成本申请的一部分附图用来提供对本申请的进一步理解，本申请的示意性实施例及其说明用于解释本申请，并不构成对本申请的不当限定。在附图中：
图1是采用CG类型1调度机制进行资源配置授权的示意图；
图2是Co-UE向发送V2X数据包(TB)的Tx-UE指示授权资源集的过程示意图；
图3是基于UE位置的UE间协调的组播示意图；
图4是基于选项1的HARQ的数据包传输和重传的过程示意图；
图5是两个都同属一组的Tx-UE和一个Rx-UE间的协调HARQ过程示意图；
图6是具有四个阶段完成的具有UE间协调HARQ反馈过程的数据包传输和重传的过程示意图；
图7是有gNB、中继UE和远程UE的单播UE到网络(UE-to-Network)的中继场景示意图；
图8是所有远程UE均位于gNB的网络覆盖范围之外的UE间协调中继传输示意图；
图9是部分远程UE均位于gNB的网络覆盖范围之内的UE间协调中继传输示意图；
图10是Tx-UE、中继UE与Rx-UE间的UE到UE的中继场景示意图；
图11是由一个主中继UE和一个辅助中继UE实施的UE到UE的中继场景示意图；
图12是由一个主中继UE和一个辅助中继UE实施的UE到UE的中继过程示意图；
图13是初始传输和基于中继重传的时序示意图。
具体实施方式
为使本发明的目的、技术方案及效果更加清楚、明确，以下参照附图并举实例对本发明进一步详细说明。应当理解，此处所描述的具体实施例仅用以解释本发明，并不用于限定本发明。
需要说明的是，本发明的说明书和权利要求书及上述附图中的术语“第一”、“第二”等是用于区别类似的对象，而不必用于描述特定的顺序或先后次序，应该理解这样使用的数据在适当情况下可以互换。此外，术语“包括”和“具有”以及它们的任何变形，意图在于覆盖不排他的包含，例如，包含了一系列步骤或单元的过程、方法、系统、产品或设备不必限于清楚地列出的那些步骤或单元，而是可包括没有清楚地列出的或对于这些过程、方法、产品或设备固有的其它步骤或单元。
实施例一：
由gNB调度/配置PSCCH(物理侧链路控制信道，physical sidelink control channel)和PSSCH(物理侧链路数据信道，Physical Sidelink Shared Channel)传输数据包资源，其中资源包括时间和频率上的信道资源。目前，NR-V2X系统具有以下几种不同的调度机制：
●动态授权(Dynamic Grant)：由DCI(下行控制信息，Downlink Control.Information)调度，使用格式为format 3_0；
●类型1配置授权(Configured grant type 1，CG类型1)：遵循RRC(无线资源控制)配置；
●类型2配置授权(Configured grant type 2，CG类型2)：由DCI激活RRC配置的资源，使用格式为format 3_0。
在动态授权中，gNB根据Tx-UE通过汇报逻辑信道组(logical channel group)所请求的内容，通过DCI调度资源。
在CG类型1和CG类型2中，侧链路资源由RRC提供给Tx-UE，并由Tx-UE存储RRC参数。在RRC层中指定的有参数sl-ConfigIndexCG，sl-CS-RNTI，sl-PeriodCG，sl-CG-MaxTransNumList。
如果使用CG类型2，Tx-UE需要将资源请求发送到gNB，通过DCI从gNB获得许可后，Tx-UE方能使用资源。资源许可信息包括资源使用时间，因此Tx-UE可以一直使用被 许可的资源直到过期为止。
如果使用CG类型1，Tx-UE可以利用授权的资源进行传输，而无需任何额外的授权，但是还需要额外的两个RRC参数；sl-TimeOffsetCGType1和sl-TimeResourceCGType1。
图1给出了CG类型1的示例，其中描述了详细的RRC参数的使用。
本申请中提出了用于单播，组播和广播通信的UE间协调资源选择的解决方法，即在初始数据包传输之前基于Co-UE预先提供的信息，Co-UE来执行Tx-UE之间的资源协作。其中，Tx-UE为发送UE，用于通过单播、组播或广播向其他UE传输数据包(TB)；Co-UE为协作UE，用于向Tx-UE分配/授予资源集(set of resources)。
针对单播或组播或广播，本实施例描述了授权Co-UE向Tx-UE分配/授予资源集的过程。前提条件如下：
●Co-UE已被授权或预先授权为协作UE；
●Co-UE已知Tx-UE的信息，例如地理信息，QoS(服务质量)要求，传输类型(cast type)等；
●Co-UE(如果是多个Co-UE)之间已经完成PC5连接初始化，从而可以交换用于Tx-UE授予的资源集信息。
图2为Co-UE向发送V2X数据包(TB)的Tx-UE指示授权资源集的过程。如图2所示，在该过程中，应使用三个目的地L2 ID(destination L2 ID)，即destination L2 ID-1、destination L2 ID-2和destination L2 ID-3。这些目的地L2 ID用于不同的目的。
步骤1：依赖单播(或组播/广播)，实现Co-UE之间PC5连接初始化。其中，PC5连接是以destination L2 ID-1来识别的。
步骤2：Co-UE之间交换已配置资源池中可用资源集的信息，然后为关联的Tx-UE设置候选资源集。
如果在PC5上建立单播链路，则可以使用PC5信令通过侧链路信号无线承载(signal radio bearer，简称为SRB)来协调并执行RRC参数的重新配置，因此，Co-UE之间可以彼此准确地识别候选资源集。如果多个Co-UE协同参与UE间的协调资源选择，则需要建立多个单播链路。其中，除了RRC参数重新配置外，Co-UE还可以通过单播链路通过SCI或MAC-CE交换候选资源集的信息。在这种情况下，交换的信息可以存储在MAC实体(MAC Entity)中供Co-UE更新其自身的候选资源集。
如果使用PC5组播或广播，则每个Co-UE都会通过SCI或MAC-CE组播或广播与候 选资源集有关的信息。基于在MAC实体中接收到的信息以及在配置的资源池中配置的资源集信息，每个Co-UE更新储存在MAC实体中的候选资源集，以避免潜在的资源冲突。其中，如果候选资源集的信息由SCI发送，则Co-UE收到的信息应从其物理层报告给其MAC层。如果Co-UE需要交换RRC参数，则需要新的PC5组播或广播的侧链路SRB从而传达RRC消息。为了传递RRC消息，需要通过添加新LC-ID识别号来设计承载PC5-RRC信息的SCCH(Sidelink Control Channel)。此SCCH将由侧链路SRB传送。新LC-ID识别号可以从现有保留值20-61中选择。或者，如果Co-UE处于覆盖范围内，则Co-UE可以连接5G核心网并获得RRC的重新配置。在这种情况下，Co-UE之间候选资源集的安排是由5G核心网执行的。
如果不需要高度协调的资源选择机制，则可以不需要PC5连接，因此，每个Co-UE可以分别确定候选资源集，例如Co-UE简单地依赖于模式2(Mode-2)感应机制。
步骤3：Co-UE和Tx UE之间PC5连接初始化可以基于Co-UE和Tx-UE之间的地理信息以及可选的服务类型来实现。此PC5连接是以destination L2 ID-2来识别的。
此PC5连接可能依赖于组播或单播或广播完成。例如，在组播中，拥有destination L2 ID-2的Tx-UE可以通过使用自己的source L2 ID不断地向Co-UE报告该位置信息。根据地理信息显示Tx-UE是否倾向于远离或接近Co-UE，则Co-UE可以确定是否继续提供资源分配服务。
单播可能会花费更多的PC5信令(例如设置，管理，离开)，而组播可能会促进高效率的操作。
另外，此PC5连接的QoS要求不需要很高，可以放宽相关的可靠性，从而减小维持此PC5连接的开销。
步骤4：根据需要，每个Tx-UE可选地报告和/或更新信息。该信息可以帮助Co-UE有效地将资源集授予给Tx-UE。
与位置信息相关的信息可以通过显式报告(例如，通过应用层中的位置管理功能)，或者在MAC实体中使用选项-1 HARQ的情况下，基于Zone-ID来实现隐式报告。
步骤5：如果需要，Co-UE可以选择存储由其关联的Tx-UE报告和/或更新的信息。
步骤6：Tx-UE使用关联的destination L2 ID-2，通过SCI或MAC CE请求用于其数据包传输的资源集。同时，Tx-UE向Co-UE提供QoS要求(例如，LCH优先级)，服务类型(例如，V2X服务ID)等。
步骤7：Co-UE根据与QoS，LCH优先级和服务类型有关的所需信息，授予给Tx-UE资源集。
其中，服务类型可以帮助Co-UE选择分配给Tx-UE的MAC PDU传输所需的周期性/非周期性的资源集。
步骤8：Co-UE通过PC5连接使用destination L2 ID-3，将资源集的信息广播到所有可到达的Co-UE和Tx-UE。该信息可以通过SCI或MAC CE传输，其中MAC-CE或SCI至少包括具有Tx-UE源ID(source ID)和资源集信息，相关的L1的数据包优先度，可选的Co-UE源ID和destination L2 ID-3。另外，也可以采用单播或组播将授予的资源集发送给特定的Tx-UE或组单位的Tx-UE。
(一)用于组播/广播的侧链路SRB设计：
上述内容中，作为逻辑信道的侧链路控制信道SCCH(Sidelink control channel)是设计用于NR侧链路通信的单播的，它用于PC5-RRC信息的侧链路SRB传输(LCID＝3)。或者用于未受保护的PC5-S侧链路SRB传输(LCID＝0)；例如，直接通信请求。或者用于PC5-S信息的侧链路SRB传输来建立拥有安全功能的PC5-S(LCID＝1)；例如，直接安全模式命令和直接安全模式完成。或者用于受保护PC5-S信息的侧链路SRB传输(LCID＝2)。
为了在Co-UE之间交换RRC信息，或由Co-UE在组内或通信范围内给Tx-UE配置RRC信息，用SCCH来传输侧链路SRB是必须的。SCCH可以实现组播和/或广播携带用于的RRC信息。另外，针对SCCH，可能使用的新的LCID可以在20～61选择。在PDCP层中，设计的侧链路SRB主要是用来传递SCCH，并能够实现PDCP层与RRC层之间的接口。
(二)协作UE(Co-UE)：
上述内容中的每个Co-UE有以下特征：
1)每个Co-UE可以与其对等Co-UE创建单播链路，并在必要时完成侧链路RRC重新配置过程；
2)每个Co-UE具有组管理功能，并具有汇集附近的Tx-UE并创建用于UE间协调的组的能力；
3)每个Co-UE配备了一个全能MAC实体，该实体可以选择资源集并通过MAC CE或SCI将其广播或组播或单播到相关Tx-UE，而相关Tx-UE属于该Co-UE创建的组成员；
4)每个Co-UE具有感知侧链路信道并更新候选资源集的能力，这些资源集能够被分配/授予给组中的Tx-UE。
为了实现对Tx-UE的资源集的分配/授予，Co-UE可以使用MAC-CE或SCI，其中包含的必要信息有：与Tx-UE关联的源ID(Source ID)或组成员ID(group member ID)，以及时域和频域相关的资源集。
(三)发送UE(Tx-UE)：
上述内容中的Tx-UE，其资源请求过程如下：
●在数据包到达Tx-UE或到达之前，Tx-UE决定从Co-UE获取资源集，并通过MAC-CE或SCI向Co-UE发送请求；
●Tx-UE接收带有资源集的传输许可。该资源集是通过带有Tx-UE源ID的MAC-CE或SCI从Co-UE广播的；如果使用SCI，则物理层实体应将许可的资源集报告给其自己的MAC层。
MAC-CE或SCI发送的请求包含以下信息：
1)与Tx-UE关联的源ID(Source ID)或组成员ID(group member ID)；
2)与Co-UE创建的组关联的目的地ID(Destination ID)；
3)QoS要求(例如，LCH优先级，通信范围)；
4)传输类型(例如，单播，组播，或广播)；
5)数据包大小；
6)服务类型(例如，V2X service ID)；
7)流量类型(周期性或非周期性)；如果属于周期性流量，则资源可以被周期性预留。
由于为每个Tx-UE授予的资源集是由Co-UE广播的，因此所有Tx-UE都知道所授予资源的信息。这为信道感测提供了更大的空间，并减少了模式-2(Mode-2)传输中的资源冲突。
Tx-UE的MAC实体可以选择用于传输的资源，如下：
●如果没有为Tx-UE授予资源集，则Tx-UE MAC实体将触发资源选择过程(Resource Selection Procedure)；
●如果为Tx-UE授予了资源集，则Tx-UE MAC实体可以简单地从资源集中选择资源。在这种情况下，MAC实体也可以触发资源选择过程，但还要考虑已授予资源集的信息。这样可以从Tx-UE授予的资源集中提供更精确的资源选择。
如果触发资源选择过程，在时隙n中，针对PSSCH/PSCCH传输，MAC层将提供了以下参数信息给物理层：
1)用作选择资源的资源池；
2)上述资源池中由Co-UE为其Tx-UE授予的资源集(如果授予)；
3)Co-UE在上述资源池中为其他Tx-UE授予的资源集(如果授予)；
4)L1的优先度；
5)剩余的数据包延迟预算(packet delay budget)；
6)以时隙为单位，用于PSSCH/PSCCH传输的子信道数(sub-channels)；
7)资源预留间隔等。
Tx-UE采用与NR-V2X中相同的过程进行资源选择，不同之处在于：
1)感测过程增加了Tx-UE排除Co-UE授予其他Tx-UE的任何候选资源。排除过程可以遵循感测资源的排除优先级的规则。例如，每个TB传输中用SCI预留资源的排除优先级较高(应该最先被排除)，而Co-UE为其他Tx-UE授予资源集的排除优先级较低(排除方法可以先在资源优先级较高的资源进行，然后在资源优先级较低的资源进行)。另外，如果Tx-UE知道Co-UE为其他Tx-UE授予的资源集，Tx-UE可以排除授予他Tx-UE的部分会产生半双工资源集，从而减轻半双工的影响。
2)在候选资源选择过程中，被预留的候选资源应该包含在Co-UE授予资源集中。当达到所要求的比例后，物理层将汇报候选资源到MAC层，以供MAC层最后选择。
(四)资源集：
资源集由时域和频域中的协调资源单元组成。与Tx UE相关的资源集应通过SCI或MAC-CE广播通知所有Tx-UE，以避免资源冲突。备选地，与Tx UE相关联的资源集也可以经由PC5-信令单播传输到特定的Tx-UE，以更新与RRC参数有关的资源集。资源集的授予可以依赖于动态授予机制或配置的授予机制(CG类型1或CG类型2)。此外，为了解决半双工问题，Co-UE还应基于Tx-UE的地理位置，分配/授予Tx-UE不同时隙资源集。
如果采用动态授予机制，则每个Co-UE都将感知信道，其中包括Tx-UE使用或预留的资源以及其他Co-UE所授权的资源集。备选地，通过在Co-UE之间建立单播链路，Co-UE可以交换授予Tx-UE的候选资源集信息。但是最后授予给Tx UE的资源集将由SCI或MAC CE指示。
如果采用配置的授权机制，则每个Co-UE将通过在Co-UE之间建立单播链路来交换可 能为Tx-UE授予的配置的多资源集信息。可以通过RRC参数确定多资源集，并带有资源集ID(Resource set ID)，时域和频域资源的指示。具体Tx UE使用哪些资源集由SCI或MAC CE或RRC信令指示。可以通过动态指示的方式完成资源集的配置，也可以通过与CG类型1或CG类型2的配置相同的方式来完成资源集的配置。对于CG类型1或CG类型2，资源集包含一个或多个CG资源，每个CG资源具有单独的ID(sl-ConfigIndexCG)和其他单独的参数。
Co-UE在决定资源集时，资源集之间在时域上的相关性尽量达到最小化，从而避免Tx-UE的半双工的影响。
每个Co-UE可以根据Tx-UE地理位置将Tx-UE划分为多组，也就是说Co-UE在应用层中创建多个和地理位置相关的组。然后，Co-UE将不同时隙的资源集分配给组中的Tx-UE，以避免半双工的影响。但是，不同组之间的Tx-UE则不需要进行这种不同时隙分配限制。
应该注意，在标准起草中，重点是如何基于Co-UE和Tx-UE之间的地理位置形成与Co-UE相关联的组。来自Tx-UE的请求是通过具有Tx-UE源L2 ID(source L2 ID)和目的地L2 ID(destination L2 ID)的MAC-CE或SCI通过组播执行的，而Co-UE的资源集授予通知是通过具有Tx-UE源L2 ID(目的是为被授予资源集的Tx-UE鉴别是否是自己的资源集)和目的地L2 ID的MAC-CE或SCI通过广播进行的。请求和授予也可以通过单播来完成，但是代价是必须建立更多单播链路，这会使系统更加复杂。而且，单播限制了两个UE之间的PC5通信，其结果是，其他Tx-UE在执行感测过程中无法知道其资源的预留信息。
之所以采用组播来请求资源集是因为Co-UE通过依赖于应用层提供组单位的信息判断，可以间接得到各组间的相对地理位置信息，从而更有效地向Tx-UE分配/授予资源集。应该注意的是，除非选项1 HARQ被使用以外，Co-UE中的MAC实体不会知道附近的Tx-UE的位置信息。但是，通过在应用层中创建基于位置的组，Co-UE中的MAC实体可以知道Tx-UE所在组的区域，并为Tx-UE授予资源集，从而避免资源冲突和半双工影响。
之所以采用广播为Tx-UE授予资源集的原因是让所有其他的Tx-UE知道所授予的资源集信息，从而为信道感知提供更多维度，并减少模式2(Mode-2)传输中的资源冲突。
图3举例说明了基于UE位置的UE间协调的组播；它由四个均与Co-UE相关联的组组成，每个组包含四个Tx-UE，每个Tx-UE在Co-UE的通信范围之内(Communication  Range)。
Co-UE使用以下规则为每个组和每个Tx-UE安排资源集。
●如果为属于同一组的Tx-UE分配资源，则不同候选资源集不能在时域上相互重叠，而在频域上没有限制。这样可以避免半双工的影响和资源冲突。
●如果为不同组的Tx-UE分配资源，则不同候选资源集可以在频域上部分重叠，但对时域没有限制。这可以提高资源使用效率并提高数据包接收比PRR性能。
该示例可应用于交叉路口的情况，其中Tx-UE可以是车辆或行人，而Co-UE可以是路边RSU(roadside unit)。
实施例二：
在NR-V2X中，为了实现诸如数据包接收比PRR的超高要求，NR-V2X支持基于混合自动重传请求(Hybrid Automatic Repeat reQuest，HARQ)的重传。HARQ是依赖于物理层侧链反馈信道(Physical Sidelink Feedback Channel，PSFCH)，而HARQ反馈过程可以基于选项-1(Option-1)或选项-2(Option-2)机制。
选项-1(Option-1)：如果在解码相关联的PSCCH之后Rx UE未能解码相应的TB(Transport Block)，则Rx-UE在PSFCH上发送HARQ-NAK。否则它在PSFCH上不发送任何信号。
选项-2(Option 2)：如果Rx UE成功解码相应的TB，则在PSFCH上发送HARQ-ACK。如果在解码相关联的PSCCH之后Rx UE未能解码相应的TB，则Rx UE在PSFCH上发送HARQ-NAK。
UE间的协调也可以在初始传输之后执行，以减轻半双工的影响。在这里，我们考虑UE间协调HARQ反馈机制，该机制可有效地帮助在同一时隙中的传输Tx UE减轻半双工的影响。也就是说，这些Tx UE已使用选项1 HARQ在同一时隙中同时对TB进行组播，从而面临半双工问题，其中同时组播的TB中至少一个是初始TB。
图4示例了具有基于选项-1的HARQ的TB传输和重传，其中UE-1和UE-2是发送Tx-UE，UE-3是接受Rx-UE，整个传输具体分三个阶段。在阶段1中，UE-1和UE-2分别同一时隙中通过PSSCH1和PSSCH2发送初始数据TB1和TB2。在这种情况下，UE-3成功接收了来自UE-1的TB1，但对UE-2的TB2接收失败。同时，UE-1和UE-2由于在相同时隙中传输数据包，从而面临半双工问题。在阶段2中，基于选项-1 HARQ过程，UE-3仅将在PSFCH2上反馈NAK给UE-2，并请求其重传。在阶段3中，UE-2通过PSSCH2 重传TB2，使UE-1和UE-3成功接收TB2。因此，由于半双工的影响，UE-2没有机会从UE-1接收TB1。
为了减轻半双工的影响，本申请引入了一个协作UE(称为Co-UE)，该Co-UE通知两个Tx-UE在接下来的不同时隙进行重传。每个Co-UE包括以下特征：
●Co-UE在组中，可以进行组播接收；
●Co-UE通过检测Tx-UE发送的PSCCH知道两个同组的Tx-UE在一个时隙中都处于传输模式的状态；
●Co-UE可以通过PSFCH传输SFCI触发UE间协调HARQ过程，而无需考虑其自身PSSCH接收的状态。
图5中说明了三个都同属一组的两个Tx-UE和一个Rx-UE间的协调HARQ过程。以下说明主要是基于选项-1 HARQ过程，但部分机制也适应选项-2 HARQ过程。注意，相同的过程可以扩展应用于同属一组的多个N Tx-UE和多个M Rx-UE。
步骤1：同属一组的Tx-UE1和Tx-UE2在同一时隙中进行数据包TB的组播(包聒两个初始数据包TB，或一个初始数据包TB和一个重传数据包TB)。初始数据包和重传数据包是通过SCI中的NDI(New Data Indicator)比特来区分的。
具体地，Tx-UE1在PSCCH1和PSSCH1上传输数据包TB1，其中被发送的SCI包含source L1 ID-1，destination L1 ID-1和与当前传输数据包相关联的资源以及可能重传的预留资源。
同样，Tx-UE2在PSCCH2和PSSCH2上传输数据包TB2，其中被发送的SCI包含source L1 ID-2，destination L1 ID-2和与当前传输数据包相关联的资源以及可能重传的预留资源。
步骤2：Rx-UE3接收到两个TB1和TB2，并在同一时隙中先解码PSCCH，然后解码PSSCH。通过检查source L1 ID和destination L1 ID，Rx-UE3确定是否需要触发UE间协调HARQ过程。具体地，如果source L1 ID-1，source L1 ID-2不同，但destination L1 ID-1和destination L1 ID-2相同，则Rx-UE3针对初始数据包TB触发UE间协调HARQ过程。
如果PSCCH中包含Tx-UE的位置信息，相同地，Rx-UE3在考虑source L1 ID和destination L1 ID后，通过计算Tx-UE间的距离，然后比较TB1和TB2各自的相关通信范围来确定是否需要触发UE间协调HARQ过程。
具体地，如果Rx-UE3附加地接收到来自Tx-UE1和Tx-UE2的两个和位置相关的Zone-ID，并计算出Tx-UE1和Tx-UE2之间的距离。如果source L1 ID-1，source L1 ID-2不同，但目的destination L1 ID-1和destination L1 ID-2相同，同时如果Tx-UE1和Tx-UE2之间的距离小于或等于与Tx-UE1的TB1相关的通信范围，则Rx-UE3触发Tx-UE1的UE间协调HARQ过程。同样的，如果Tx-UE1和Tx-UE2之间的距离小于或等于与Tx-UE2的TB2相关的通信范围，则Rx-UE3触发Tx-UE2的UE间协调HARQ过程。如果触发了UE间协调HARQ过程，则Rx-UE3会生成与TB1和/或TB2关联的SFCI1(sidelink feedback control information)和/或SFCI2，而不用介意自己对两TB解码过程是否成功。
如果两个通过SCI预留的重传资源都在同一时隙中，则Rx-UE3必须生成一个与优先级高的初始TB关联的SFCI(仅发送NAK)。选择哪个TB取决于TB的L1优先级(L1priority)。
如果两个通过SCI预留的重传资源都在同一时隙中，则Rx-UE3通过SCI信息判断TB1和TB2是初始传输还是重传。Rx-UE3仅生成和初始TB关联的SFCI(仅发送NAK)。
如果两Tx-UE重传的保留资源在不同的时隙中，并且选择性的两Tx-UE在通信范围内，则Rx-UE3必须生成与初始传输中收到的SCI指示的初始TB1和初始TB2相关的两个SFCI(两个NAK)。
如果两Tx-UE重传的保留资源在不同的时隙中，则Rx-UE3通过SCI信息判断TB1和TB2是初始传输还是重传。如果TB1或TB2是初始传输，Rx-UE3必须生成TB1或TB2相关的一个SFCI(NAK)，否则Rx-UE3不生成SFCI。如果TB1和TB2有一个是重传，如果Rx-UE3能够判断TB1和TB2在前一次发送的时隙中也是重叠，并且重传的TB在前一次发送的时隙中是初始传输，那么Rx-UE3针对重传的TB也生成SFCI。如果初始TB没有预留任何资源用于重传，则Rx-UE3自己实施决定是否生成与初始TB相关联的SFCI(仅发送NAK)。如果两Tx-UE重传的保留资源在相同的时隙中和/或保留资源在频域上有重叠(至少部分重叠)，并且选项-2的HARQ机制被使用，Rx-UE3生成两个与优先级低的初始TB关联的SFCI(均发送ACK)。其中一个SFCI是为Rx-UE3自己反馈的，而另一个SFCI是为优先级高的初始TB的Tx-UE反馈的。从而使优先级低的初始TB不会在保留资源中被发送。
步骤3：Rx-UE3通过PSFCH将生成的SFCI发送到相应的Tx-UE。
步骤4：如果Tx-UE1从PSFCH1接收到SFCI-1，则Tx-UE1将TB作为组播重传。
重新发送的TB被Tx-UE2和Rx-UE3接收，如果Rx-UE3在以前对TB的解码过程中也失败的话(包聒初始传输和重传)，则Rx-UE3对其进行解码，否则Rx-UE3忽略TB的接收。
步骤5：如果Tx-UE2从PSFCH2接收到SFCI-2，则Tx-UE2将TB作为组播重传。
重新发送的TB被Tx-UE1和Rx-UE3接收，如果Rx-UE3在以前对TB的解码过程中也失败的话(包聒初始传输和重传)，则Rx-UE3对其进行解码，否则Rx-UE3忽略TB的接收。
图6描绘了具有四个阶段完成的具有UE间协调HARQ反馈过程的TB传输和重传的过程：
第一阶段：用于初始TB传输；
第二阶段：用于SFCI NAK反馈；
第三阶段：是TB1的重传；
第四阶段：是TB2的重传。
表1总结了不同TB1和TB2场景下的SFCI生成的组合。
Figure PCTCN2020098895-appb-000001
通常，V2X应用层创建组，UE间协调HARQ过程是在组内执行。但是，只要其他组内的Rx-UE能够识别和同组Rx-UE得到的同样信息(如source L1 IDs，destination L1 IDs，位置信息，TB相关的NDI信息和QoS要求等)，此协调过程也可以扩展在不同组的Tx-UE和Rx-UE之间执行。
实施例三：
考虑到更广泛的应用和服务范围，3GPP工作组将进一步研究基于侧链路的中继功能，以扩展侧链路/网络覆盖范围并提高功耗效率。为了进一步探索基于侧链路通信的覆盖范围扩展，我们将考虑以下范围来实现L2中继(layer-2 relay)和L3中继(layer-3 relay)：
UE到网络的覆盖范围扩展(UE-to-network coverage extension)：Uu的覆盖范围对于UE到达中心网络中的服务器或邻近区域外的对等UE是不可缺少的。
UE到UE的覆盖范围扩展(UE-to-UE coverage extension)：在没有Uu覆盖的情况下，侧链路通信的覆盖范围必须达到所需的要求。
在UE到网络的覆盖范围扩展中，gNB与中继UE(relay UE)之间的位置关系以及中继UE与远程UE(remote UE)之间的位置关系相对稳定，因此，可以半静态确定中继UE。但是，在UE到UE的覆盖范围扩展中，Tx-UE与中继UE之间的位置关系以及中继UE与Rx-UE之间的位置关系是不可预测的，尤其是在组播和广播通信中特为显著，因此，不得不动态确定中继UE。并且，中继UE确定还取决于谁是Tx-UE和谁是Rx-UE。
(一)UE到网络的覆盖范围扩展
使用Uu链路，5G核心网络(5GC)可以通过单播或广播通信向远程UE提供服务。通过引入中继UE，可以扩展5GC与远程UE之间的覆盖范围，这可以通过5GC与中继UE之间的Uu链路以及通过中继UE与远程UE之间的侧链路来实现。另外，在支持组播的情况下，5GC也可以通过组播通信将服务提供给以组为单位的远程UE。可以基于layer-2(L2)中继或layer-3(L3)中继执行中继机制。
在UE到网络的覆盖范围扩展中，至少gNB始终处于固定位置以进行发送和接收。以此作为固定参考点，可以通过gNB或远程UE相对静态地选择中继UE。图7描绘了具有gNB、中继UE和远程UE的单播UE-to-Network的中继典型场景，其中gNB和同一中继UE进行发送和接收，远程UE也和同一中继UE进行发送和接收。此场景可以考虑为，如果远程UE对gNB提供的服务感兴趣，gNB可以通过中继UE来提供相应的服务。因此，在UE到网络的覆盖范围扩展中，应该半静态地确定中继UE。UE要成为中继UE需要满足以下条件：
●根据其UE的能力，UE需要被预先授权为候选中继UE。UE的能力包括耐受的电池寿命，UE类型，可接受的业务类型，发送和接收能力等；
●候选中继UE要成为中继UE，应满足(预先)配置的阈值条件；
●可以将阈值(例如，RSRP)设置为高阈值(表示为ThreshHigh)和低阈值(表示为ThreshLow)，只有当RSRP测量值介于ThreshHigh和ThreshLow之间时，候选中继UE才能成为中继UE。
基于来自gNB以及来自中继UE的RSRP测量，远程UE也同样需要满足(预先配置)阈值条件。
1、侧链路组播相关中继：
针对UE到网络覆盖扩展的侧链路组播通信，5GC通过gNB提供对所有组成员感兴趣的服务。对于中继UE发现/维护/释放，我们考虑两种场景，提出以下两种方案(方案1和 方案2)。
方案1是针对所有组成员均不在gNB的覆盖范围内的场景。gNB根据RSRP测量，通过设置阈值来发现并授权候选中继UE作为主中继UE(primary relay UE，表示为P-relay UE)，以及可选的一个或多个辅助中继UE(secondary relay UE，表示为S-relay UE)。P-relay UE和S-relay UE应满足以下条件：
●P-relay UE和S-relay UE(s)不属于小组成员；
●P-relay UE和S-relay UE(s)应与gNB在通信范围内；
●P-relay UE和S-relay UE(s)与所有组成员在通信范围之内，并且可以通过侧链路与所有成员进行组播通信；
这可以扩展到中继UE与组成员通信范围内的多跳场景。因此，多跳机制将在组内的远程UE之间执行。
●P-relay UE和S-relay UE(s)须继续向gNB报告其Uu链路质量(例如，参考信号接收功率，RSRP)，以便gNB切换中继UE或允许多个中继UE参与中继传输；
●作为协作UE的P-relay UE和S-relay UE(s)应获取组相关信息，例如组destination L2 ID，组大小，组成员等。
在这种情况下，由gNB发现并指定的中继UE有两个任务：一个任务是将数据从gNB中继传输到相关的组成员，另一个任务是作为协作UE(Co-UE)将资源集协调和分配给相关的组成员。
指定P-relay UE和S-relay UE的原因是为了提供健全的中继链路并确保无缝的服务连续性。基于从S-relay UE报告的链路质量，gNB确定S-relay UE如何以及何时参与中继传输。例如，基于传输数据包的要求(如，通信范围和可靠性)，gNB可以利用RRC配置无线承载(radio bearer)在PDCP层复制生成PDCP PDU，并通过P-relay UE和S-relay UE各自发送。这属于在RLC子层之上执行的L2中继，尤其对于严格要求的V2X服务而言，它可以实现多次发射分集，提高可靠性并减少迟延时间。
图8举例说明了方案1，其中所有组成员均不在gNB的覆盖范围内。
方案2是针对至少有一位UE成员在gNB的覆盖范围内的场景。gNB发现并授权一个UE作为主中继UE(表示为P-relay UE)，以及一个或多个辅助中继UE(表示为S-relay UE)。P-relay UE和S-relay UE应满足以下条件：
●P-relay UE和S-relay UE是该组的成员，并能够通过侧链路与其他成员的进行组 播通信。
将组成员UE授权为中继UE的好处是简化了中继UE的发现和授权过程，其中其他成员UE不需要向中继UE报告组信息，例如组destination L2 ID，组成员信息等。
●P-relay UE和S-relay UE在gNB的通信范围内。
●P-relay UE和S-relay UE具有与gNB的保持最强链路，这取决于从中继候选UE到gNB的测量报告，例如参考信号接收功率(RSRP)等。
因此，由gNB发现并指定的中继UE有两个任务：一个任务是将数据从gNB中继传输到相关的组中其他成员，另一个任务是协作UE(Co-UE)将资源集协调和分配给相关的组中其他成员。
指定P-relay UE和S-relay UE的原因是为了提供健全的中继链路并确保无缝的服务连续性。基于报告的链路质量，gNB确定S-relay UE如何以及何时参与中继传输。例如，基于传输数据包的要求(如，通信范围和可靠性)，gNB可以利用RRC配置无线承载(radio bearer)在PDCP层复制生成PDCP PDU，并通过P-relay UE和S-relay UE各自发送。
图9举例说明了方案2，其中组成员的一部分在gNB的覆盖范围内。
在方案1和方案2中，gNB可以通过中继UE为远程UE配置RRC参数(例如系统信息块，System Information Block，简称为SIB)。配置信息的传输是通过gNB和远程UE的Uu接口完成。
2、侧链路单播相关中继：
针对UE到网络覆盖扩展的侧链路单播通信，可依赖于L2中继或L3中继，可重复使用rel-13中采用的中继解决方案，包括中继UE发现/维护/释放。在这种情况下，gNB可以使用PC5信令通过中继UE为远程UE配置RRC参数。
另外，也可以考虑使用P-relay UE和S-relay UE的相同概念，包括PDCP复制机制，以提高可靠性并减少迟延时间。
3、侧链路广播相关中继：
针对UE到网络的覆盖扩展的侧链路广播通信，gNB发现并指定处于覆盖范围的中继UE。中继UE支持转发位于覆盖范围外的远程UE的数据包。中继过程与中继UE参与组播的过程相同方法，包括PDCP复制机制，以提高可靠性并减少迟延时间。
(二)UE到UE的覆盖范围扩展
本申请也可以采用UE到UE的覆盖范围扩展，来实现UE间的协调中继传输。在UE 到UE的覆盖范围扩展中，尤其是在组播和广播通信中，Tx-UE与中继UE之间的关系以及中继UE与Rx-UE之间的关系是不恒定的。图10描绘了Tx-UE，中继UE和Rx-UE之间的同组组播的UE-to-UE典型场景；其中Tx-UE-1在一个时隙中由Relay-UE中继组播一个数据包到Rx-UE-2，而Tx-UE-2由于通信范围的限制，将在另一个时隙中由Relay-UE-2中继组播另一个数据包到Rx-UE-1。这意味着在组播通信中，不同的Tx-UE可能链接到不同的中继UE来中继组播数据包，因此，组播场景中需要(预先)授权多个候选中继UE(如图10中的中继UE-1和中继UE-2)。
因此，在UE到UE的覆盖范围扩展中，根据谁是Tx-UE和谁是Rx-UE，然后动态确定中继UE。UE要成为中继UE需要满足以下条件：
●根据其UE能力，UE被(预)授权为候选中继UE。例如，其UE能力包括容忍电池寿命，UE类型(例如，车辆，RSU)，发送和接收能力等；
●候选中继UE成为中继UE时，必须满足(预先)配置的阈值条件；
可以将阈值(例如，RSRP)设置为高阈值(表示为ThreshHigh)和低阈值(表示为ThreshLow)，只有当RSRP测量值介于ThreshHigh和ThreshLow之间时，候选中继UE才能成为中继UE。
阈值可以通过中继UE进行调整，具体如何调整取决于通信范围和接收到的数据包中指示的所需QoS(例如，可靠性和延迟预算)。例如，如果所需的通信范围较大，则可以将ThreshHigh和ThreshLow设置为相对较低的值，反之亦然。
1、针对侧链路组播的中继
应用层创建一个组，要么依赖于UE的地理位置，要么依赖于感兴趣的UE之间的服务类型。前者可能不需要知道组成员之间的信息，只要所有组成员都知道通信范围和destination L2 ID。后者可能需要知道组成员之间的信息，例如组大小，成员ID和destination L2 ID。参与组播UE之间的中继是为了扩展通信范围并提高组成员之间的通信质量。
在组建立期间，V2X应用层可以提供V2X应用要求，否则，V2X层将确定PC5 QoS参数。这意味着，V2X应用层或V2X层将根据服务要求或PC5 QoS来确定是否使用中继功能。另外，P-relay UE(s)和S-relay UE(s)应在组播实施之前由各自的V2X层确定，并在组播实施期间由V2X层加以更新。
其中，P-relay UE，可以是单个中继UE，也可以是多个中继UE，除非中继不能正确 接收Tx UE数据包，否则它们始终参与中继操作。
其中，S-relay UE，可选地参与中继操作。中继操作中是否涉及S-relay UE取决于S-relay UE中测量的基于接收到的RSRP的直接路径强度。如果S-relay UE正确解码接收到的初始数据包，并且直接路径强度的RSRP下降到预先配置的RSRP阈值水平，则S-relay UE将参与中继操作，把接收到的数据包中继到附近的Rx-UE。
例如，可以将阈值(例如，RSRP)设置为高阈值(表示为ThreshHigh)和低阈值(表示为ThreshLow)。仅当测量到的从Tx-UE到S-Relay UE的功率值在ThreshHigh和ThreshLow之间时，S-relay UE才成为中继传输的中继UE。或者，如果可以通过中继UE获取Tx-UE的位置信息，那么Tx-UE与中继UE之间的距离可以代替基于RSRP的阈值。决定是否S-relay UE成为中继UE可以取决于距离和接收到的数据包中指示的所需通信范围。
V2X层具有一定的灵活性，可以根据组成员感兴趣的服务来选择任意数量的P-relay UE和任意数量的S-relay UE。当然，P-relay UE和/或S-relay UE数量可以设置为零。
图11给出了一个示例，其中Tx-UE将数据包组播到它的组成员(包括Rx-UE-1和Rx-UE-2)，由P-relay UE和可选的S-relay UE中继。图12说明了基于组播的中继操作的过程：
步骤1：Tx-UE-1将数据包组播到所有组成员，包括P-relay UE和S-relay UE，以及Rx-UE-1和Rx-UE-2。
其中，如果涉及L2层，那么数据包应该为PSCCH和PSSCH发送的MAC PDU(或TB)，否则，数据包应该为较高层PDU。
在此示例中，Rx-UE-1和Rx-UE-2远离Tx-UE-1，并且无法正确解码数据包，因此需要基于中继的重传。
步骤2：P-Relay-UE对数据包进行解码，并准备执行基于中继的重传。S-Relay-UE解码数据包并测量接收到的信号强度(例如L1 RSRP或L3 RSRP)，然后将其与(预)配置的阈值进行比较。
在此示例中，接收信号强度在(预)配置的阈值ThreshHigh和ThreshLow之间，因此，S-Relay-UE也参与基于中继的重传。
步骤3：P-Relay-UE和S-Relay-UE中继重传数据包。
如果仅涉及到L2层中继，则MAC实体可以直接利用物理层中为重传预留的资源进行 重传，重传预留资源是由初始数据包或最后接受数据包中检测到的SCI表示。
如果在RLC子层之上进行中继，则物理层用于中继传输的资源应由MAC实体重新确定。
步骤4：Rx-UE-1和Rx-UE-2接收重传的数据包，并将检测正确与否状况分别反馈到P-Relay-UE和S-Relay-UE。
如果仅涉及到L2层中继，每个Rx-UE中的HARQ实体触发HARQ机制，通过PSFCH反馈ACK/NAK信息。该反馈资源与专用于重传的PSSCH资源相关联。
步骤5：P-Relay-UE和S-Relay-UE分别从Rx-UE-1和Rx-UE-2接收到反馈信息，并将反馈信息转发到Tx-UE-1。
如果仅涉及到L2层中继，P-Relay-UE和S-Relay-UE中的HARQ实体将通过PSFCH反馈ACK/NAK信息。该反馈资源与专用于初始传输的PSSCH资源相关联。在这种情况下，反馈过程应考虑转发HARQ反馈往返时间(RTT，Round-Trip Time)和中继处理时间。
中继可以作为L2功能或L3功能执行，但是中继步骤有所不同。
在L2中继中，如果仅MAC层为止参与中继操作，则中继传输有两种选择：
●选项1：中继UE中的MAC实体不检查HARQ反馈，进行实施盲目重传(blind retransmission)。
●选项2：中继UE中的MAC实体检查HARQ反馈，如果接收到NAK，则进行重传。
关于通过中继重传的资源，一般初始TB传输时会使用SCI指示并同时预留重传资源，这些预留重传资源可以在中继重传中被使用。这是因为中继UE在正确解码接收到的SCI后，再解码TB，并知道被预留用于重传的PSCCH/PSSCH资源和关联的PSFCH资源。注意，用于初始传输的PSSCH和PSFCH资源之间的时间间隔应大于用于基于中继的重传的PSSCH和PSFCH资源之间的时间间隔。图13说明了初始传输和基于中继的重传的时序，其中考虑了基于中继传输的HARQ RTT(内RTT)及其从中继UE到Tx-UE的相关RTT(外RTT)。Rx-UE-1和Rx-UE-2传输的PSFCH的资源分别与P-Relay-UE和S-Relay-UE基于中继的重传的PSSCH资源相关联，而P-Relay-UE和S-Relay-UE传输的PSFCH的资源与Tx-UE-1基于初始传输的PSSCH资源相关联。与PSSCH传输关联的PSFCH的资源应通过显式或隐式方式确定。
在L3中继或L2中继中(但在RLC子层之上执行的情况下)，MAC实体应重新确定用 于其基于中继重传的资源。在这种情况下，可以执行PDCP复制机制，可以在(预)配置的无线承载(radio bearer)中发送由P-relay UE和S-relay UE(s)生成复制的PDCP PDU。因此，多中继UE传输可以实现多传输分集增益，增加可靠性并减少迟延时间，特别是对于严格要求的V2X服务来说尤其重要。
2、针对侧链路单播的中继
针对UE到UE覆盖扩展的侧链路单播通信，对应的解决方案也可以依赖L2中继或L3中继。在这种情况下，可以在Tx-UE，中继UE和远程UE之间建立RRC链接，并且可以通过PC5信令交换RRC参数。因此，可以在建立侧链路单播连接和交换RRC参数之后确定中继UE。
另外，也可以相同采用P-relay UE和S-relay UE(s)的概念，以提高可靠性并减少迟延时间。中继重传中涉及多少个中继UE取决于特定服务和每次传输的要求。也可以执行PDCP复制机制。
3、针对侧链路广播的中继
针对UE到UE覆盖扩展的侧链路广播通信，可以采用与组播中使用的解决方案相同的解决方案，其中将候选中继UE的阈值考虑为，例如ThreshHigh和ThreshLow，然后根据每次传输对服务的特定要求，确定是否涉及中继传输。同样，也可以执行PDCP复制机制。
综上所述，本申请提出了一种UE间的协调方法，该协调方法可以在初始数据包传输之前或之后执行。前者是基于协作UE预先提供的信息来协调在Tx-UE之间的资源，以避免资源冲突和/或半双工影响。后者是为了帮助已经在同一时隙中同时发送初始数据包并在初始发送之后面临半双工影响的Tx-UE。此外，本申请还提出了一种UE之间的协调中继传输，主要考虑在UE到网络的覆盖范围扩展和UE到UE的覆盖范围扩展。在解决方案中，我们考虑了中继UE被半静态地指定并用于UE到网络的覆盖范围扩展，而中继UE被动态地指定并用于UE到UE的覆盖范围扩展。
以上对本发明的具体实施例进行了详细描述，但其只是作为范例，本发明并不限制于以上描述的具体实施例。对于本领域技术人员而言，任何对本发明进行的等同修改和替代也都在本发明的范畴之中。因此，在不脱离本发明的精神和范围下所作的均等变换和修改，都应涵盖在本发明的范围内。

Claims (32)

  1. 一种基于NR-V2X的UE间的协调方法，其特征在于，包括以下至少之一：
    在初始数据包传输之前进行UE间的协调：第一协作UE基于预先配置的资源池中可用的资源集的信息，根据发送UE上报的参数信息向发送UE分配/授予资源集；
    在初始数据包传输之后进行UE间的协调：第二协作UE接收同一组内的至少两个发送UE在同一时隙发送的数据包，其中至少一个发送UE发送初始数据包，第二协作UE通过PSFCH传输SFCI至每一个所述发送UE，通知所述发送UE在接下来的时隙进行初始数据包重传。
  2. 根据权利要求1所述的一种基于NR-V2X的UE间的协调方法，其特征在于：申请资源集的发送UE向第一协作UE上报的参数信息包括地理信息、服务质量QoS、LCH优先级、传输类型、服务类型中的一种或多种。
  3. 根据权利要求1所述的一种基于NR-V2X的UE间的协调方法，其特征在于，在第一协作UE向申请资源集的发送UE分配/授予资源集之前，还包括以下至少之一：
    所述第一协作UE已被授权或预先授权为协作UE；
    所述第一协作UE已知申请资源集的发送UE的参数信息；
    所述第一协作UE的数量至少为两个时，多个所述第一协作UE之间已经完成PC5连接初始化，从而可以交换用于发送UE授予的资源集信息。
  4. 根据权利要求1所述的一种基于NR-V2X的UE间的协调方法，其特征在于，所述第一协作UE向申请资源集的发送UE分配/授予资源集的过程包括：
    多个所述第一协作UE之间以第一目的地L2-ID建立PC5连接；
    多个所述第一协作UE之间交换已配置资源池中可用资源集的信息，为其关联的发送UE设置候选的资源集；
    所述第一协作UE和与其关联的发送UE之间以第二目的地L2-ID建立PC5连接；
    所述发送UE使用第二目的地L2-ID，通过SCI或MAC-CE向其关联的第一协作UE发送资源集配置请求；
    所述第一协作UE接收所述资源集配置请求，选择授予给所述发送UE的资源集；
    所述第一协作UE通过PC5连接使用第三目的地L2-ID，将资源集发送至所述发送UE和其他第一协作UE。
  5. 根据权利要求4所述的一种基于NR-V2X的UE间的协调方法，其特征在于，所述发送UE向其关联的第一协作UE发送资源集配置请求之前，还包括：
    所述发送UE向其关联的第一协作UE报告和/或更新发送UE的参数信息；
    所述第一协作UE接收与其关联的发送UE报告和/或更新的参数信息，并进行存储。
  6. 根据权利要求4所述的一种基于NR-V2X的UE间的协调方法，其特征在于：多个第一协作UE在PC5上建立单播链路，则第一协作UE使用PC5信令通过侧链路信号无线承载SRB来协调并执行RRC参数的重新配置；或者，所述第一协作UE使用PC5组播或广播，则每个所述第一协作UE通过SCI或MAC-CE组播或广播与候选的资源集有关的信息，其中SCI或MAC-CE包含的信息至少包括与发送UE关联的源ID和资源集信息。
  7. 根据权利要求4所述的一种基于NR-V2X的UE间的协调方法，其特征在于：所述第一协作UE和与其关联的发送UE之间建立PC5连接，通过组播、或单播、或广播完成。
  8. 根据权利要求4所述的一种基于NR-V2X的UE间的协调方法，其特征在于：所述第一协作UE将资源集的信息广播至其通信范围内所有可到达的发送UE和其他第一协作UE；或者，所述第一协作UE将资源集的信息单播至设定的发送UE；或者，所述第一协作UE将资源集的信息组播至与其同组的发送UE。
  9. 根据权利要求4所述的一种基于NR-V2X的UE间的协调方法，其特征在于：所述发送UE通过SCI或MAC-CE向其关联的第一协作UE发送资源集配置请求包括以下信息中的一种或几种：
    与发送UE关联的源ID或组成员ID；
    与第一协作UE创建的组关联的目的地ID；
    QoS要求；
    传输类型；
    数据包大小；
    服务类型；
    流量类型；
    所述第一协作UE通过SCI或MAC-CE向其发送UE通知被授予资源集，其中SCI或MAC-CE至少包括以下信息：
    发送UE的源L2 ID；
    单播，组播，或广播的目的地L2 ID；
    资源集信息。
  10. 根据权利要求1所述的一种基于NR-V2X的UE间的协调方法，其特征在于：向所述第一协作UE申请资源集的发送UE如果没有被授予资源集，则所述发送UE的MAC实体触发资源选择过程；向所述第一协作UE申请资源集的发送UE如果被授予资源集，则所述发送UE的MAC实体从资源集中选择资源。
  11. 根据权利要求10所述的一种基于NR-V2X的UE间的协调方法，其特征在于：若所述发送UE的MAC实体触发资源选择过程，则在时隙n中，n为≥1的自然数，针对PSSCH/PSCCH传输，MAC层提供以下参数信息中的一种或几种给物理层：
    用作选择资源的资源池；
    上述资源池中由第一协作UE为其关联的发送UE授予的资源集；
    第一协作UE在上述资源池中为其他发送UE授予的资源集；
    L1的优先度；
    剩余的数据包延迟预算；
    以时隙为单位，用于PSSCH/PSCCH传输的子信道数；
    资源预留间隔。
  12. 根据权利要求1所述的一种基于NR-V2X的UE间的协调方法，其特征在于：资源集的授予通过动态授予机制或配置的授予机制实现，所述配置的授予机制包括CG类型1或CG类型2。
  13. 根据权利要求12所述的一种基于NR-V2X的UE间的协调方法，其特征在于：所述第一协作UE还基于与其相关的发送UE的地理位置，分配/授予所述发送UE不同时隙的资源集；其中，每个第一协作UE根据与其相关的发送UE的地理位置将多个发送UE划分为多个组，即第一协作UE在应用层中创建多个和地理位置相关的组，每个发送UE均在第一协作UE的通信范围之内，第一协作UE将不同时隙的资源集分配给组中的发送UE，以避免半双工的影响，但是，不同组之间的发送UE则不需要进行这种不同时隙的分配限制。
  14. 根据权利要求13所述的一种基于NR-V2X的UE间的协调方法，其特征在于，所述第一协作UE为每个组和组内的每个发送UE分配资源集，应满足以下条件：
    所述第一协作UE为属于同一组的发送UE分配资源集，则不同的候选的资源集不能在时域上相互重叠，而在频域上没有限制；
    所述第一协作UE为不同组的发送UE分配资源集，则不同的候选的资源集在频域上部 分重叠，但对时域没有限制。
  15. 根据权利要求1所述的一种基于NR-V2X的UE间的协调方法，其特征在于，通知同一时隙发送初始数据包的发送UE进行初始数据包重传的第二协作UE满足以下条件：
    所述第二协作UE与发送数据包的至少两个发送UE在同一组中，用于进行组播接收，其中至少一个发送UE发送初始数据包；
    所述第二协作UE知道发送数据包的至少两个发送UE在一个时隙中都处于传输模式的状态，其中至少一个发送UE发送初始数据包；
    所述第二协作UE通过物理层侧链反馈信道PSFCH传输侧链反馈控制信息SFCI，无需考虑其自身PSSCH接收的状态。
  16. 根据权利要求1所述的一种基于NR-V2X的UE间的协调方法，其特征在于，在初始数据包传输之后进行UE间的协调中，位于同一组内的发送UE包括第一发送UE和第二发送UE，所述第一发送UE和第二发送UE在同一时隙中组播数据包，其中至少一个发送UE组播初始数据包；
    所述第二协作UE接收并解码所述第一发送UE和第二发送UE发送的初始数据包，根据选定的第一物理层侧链反馈信道PSFCH1向第一发送UE发送第一侧链反馈控制信息SFCI1，根据选定的第二物理层侧链反馈信道PSFCH2向第二发送UE发送第二侧链反馈控制信息SFCI2；
    如果第一发送UE从第一物理层侧链反馈信道PSFCH1接收到第一侧链反馈控制信息SFCI1，则第一发送UE将其初始数据包在第一时隙进行组播重传；
    如果第二发送UE从第二物理层侧链反馈信道PSFCH2接收到第二侧链反馈控制信息SFCI2，则第二发送UE将其初始数据包在第二时隙进行组播重传；
    其中，所述第一时隙与所述第二时隙为相同或不同的时隙。
  17. 根据权利要求16所述的一种基于NR-V2X的UE间的协调方法，其特征在于：所述第一发送UE在第一物理侧链路控制信道PSCCH1和第一物理侧链路数据信道PSSCH1上传输第一数据包TB1，其中，被发送的侧链控制信息SCI包括关于第一发送UE的源ID、目的地ID和与当前传输数据包相关联的资源以及可能重传的预留资源；
    所述第二发送UE在第二物理侧链路控制信道PSCCH2和第二物理侧链路数据信道PSSCH2上传输第二数据包TB2，其中，被发送的侧链控制信息SCI包括关于第二发送UE的源ID、目的地ID和与当前传输数据包相关联的资源以及可能重传的预留资源；
    第二协作UE接收第一数据包TB1和第二数据包TB2，并在同一时隙中先解码PSCCH1、PSCCH2，然后解码PSSCH1、PSSCH2；
    如果第一发送UE的源ID与第二发送UE的源ID不同，但第一发送UE的目的地ID和第二发送UE的目的地ID相同，则第二协作UE根据初始数据包还是重传数据包判断触发UE间协调HARQ过程，生成与第一数据包TB1关联的第一侧链反馈控制信息SFCI1和/或与第二数据包TB2关联的第二侧链反馈控制信息SFCI2；
    如果第一发送UE从PSFCH1接收到第一侧链反馈控制信息SFCI1，则第一发送UE将第一数据包TB1在第一时隙重新组播发送给第二发送UE和第二协作UE；
    如果第二发送UE从PSFCH2接收到第二侧链反馈控制信息SFCI2，则第二发送UE将第二数据包TB2在第二时隙重新组播发送给第一发送UE和第二协作UE；
    其中，所述第一时隙与所述第二时隙为不同的时隙。
  18. 根据权利要求16所述的一种基于NR-V2X的UE间的协调方法，其特征在于：所述第一发送UE与第二发送UE同时发送初始数据包，第二协作UE考虑初始数据包的L1优先度判断是否触发UE间协调HARQ过程；
    其中，所述第一时隙与所述第二时隙为相同的时隙。
  19. 根据权利要求16所述的一种基于NR-V2X的UE间的协调方法，其特征在于：所述第一发送UE与第二发送UE各自在同一时隙各发送初始数据包和重传数据包，第二协作UE优先考虑初始数据包来判断是否触发UE间协调HARQ过程；
    其中，所述第一时隙与所述第二时隙为相同或不同的时隙。
  20. 根据权利要求16所述的一种基于NR-V2X的UE间的协调方法，其特征在于：第一发送UE通过PSCCH1发送自己的地理位置信息和通信范围信息；第二发送UE通过PSCCH2发送自己的地理位置信息和通信范围信息；第二协作UE计算第一发送UE与第二发送UE间的距离，然后比较他们之间的距离和各自的通信范围，从而判断是否触发针对TB1和TB2的UE间协调HARQ过程；
    其中，所述第一时隙与所述第二时隙为相同或不同的时隙。
  21. 根据权利要求16所述的一种基于NR-V2X的UE间的协调方法，其特征在于：所述第一发送UE与第二发送UE同时发送初始数据包TB1和TB2，并且选项-2的HARQ机制被使用，第二协作UE生成两个与优先级低的初始TB关联的SFCI；
    其中，所述两Tx-UE重传的保留资源在相同的时隙中和/或保留资源在频域上至少部分 重叠。
  22. 根据权利要求1所述的一种基于NR-V2X的UE间的协调方法，其特征在于，所述基于NR-V2X的UE间的协调方法还包括UE间的协调中继传输，所述UE间的协调中继传输选用如下方式中至少之一：
    UE到网络的覆盖范围扩展：远程UE与gNB进行通信时，半静态选择gNB的网络覆盖范围内且具有中继能力的至少一个UE充当中继UE；其中，所述中继UE与gNB通过Uu链路进行通信，所述中继UE与远程UE通过PC5接口进行通信；
    UE到UE的覆盖范围扩展：发送UE与接收UE进行通信时，动态选择位于其通信范围内且具有中继能力的至少一个UE充当中继UE；其中，多个中继UE在不同的时隙内与其对应的发送UE和接收UE分别通过PC5接口进行通信。
  23. 根据权利要求22所述的一种基于NR-V2X的UE间的协调方法，其特征在于：半静态选择的所述中继UE与远程UE之间的侧链路通信包括侧链路单播、或侧链路组播、或侧链路广播；动态选择的所述中继UE与接收UE之间的侧链路通信包括侧链路单播、或侧链路组播、或侧链路广播。
  24. 根据权利要求22所述的一种基于NR-V2X的UE间的协调方法，其特征在于，在UE到网络的覆盖范围扩展中，所述中继UE的选择方法包括：
    gNB的网络覆盖范围的UE如果满足条件1则称为候选中继UE，所述条件1包括：在网络覆盖范围内具有与gNB进行通信的能力且具有承担中继任务的能力；
    候选中继UE如果满足条件2则称为中继UE，所述条件2包括：候选中继UE监听由gNB发送的参考信号，并基于所监听的参考信号，得到来自gNB的参考信号的参考信号接收功率RSRP，将参考信号接收功率RSRP与预设的第一阈值和第二阈值进行比较，所述参考信号的接收功率RSRP在第一阈值和第二阈值之间。
  25. 根据权利要求24所述的一种基于NR-V2X的UE间的协调方法，其特征在于，所述具有承担中继任务的能力的判断因素包括：所述候选中继UE的中继操作不影响其与所述gNB和其它网内UE的通信；以及所述候选中继UE的剩余电量、可接受的业务类型和与所述gNB的链路质量。
  26. 根据权利要求22所述的一种基于NR-V2X的UE间的协调方法，其特征在于：在UE到网络的覆盖范围扩展中，所述远程UE均位于gNB的网络覆盖范围之外；或者至少一个所述远程UE位于gNB的网络覆盖范围之内。
  27. 根据权利要求26所述的一种基于NR-V2X的UE间的协调方法，其特征在于：所述中继UE包括主中继UE以及可选的至少一个辅助中继UE，所述主中继UE与所述辅助中继UE在同一个时隙和同一频率资源进行初始数据包重传；
    当所述远程UE均位于gNB的网络覆盖范围之外时，所述主中继UE和辅助中继UE应满足以下条件：
    所述主中继UE、辅助中继UE与所述远程UE不在一个组内；
    所述主中继UE和辅助中继UE均位于gNB的覆盖范围内；
    所述主中继UE和辅助中继UE与所有远程UE在通信范围内，并且通过侧链路与所有远程UE进行组播通信；
    所述主中继UE和辅助中继UE继续向gNB报告Uu链路质量，以便gNB切换中继UE或允许多个中继UE参与中继传输；
    所述主中继UE和辅助中继UE获取组的相关信息；
    当至少一个所述远程UE位于gNB的覆盖范围之内时，所述主中继UE和辅助中继UE应满足以下条件：
    所述主中继UE、辅助中继UE与所述远程UE在同一个组内，并能够通过侧链路与该组内的其他UE进行组播通信；
    所述主中继UE和辅助中继UE均位于gNB的网络覆盖范围内；
    所述主中继UE和辅助中继UE具有与gNB的最强链路。
  28. 根据权利要求22所述的一种基于NR-V2X的UE间的协调方法，其特征在于：在UE到UE的覆盖范围扩展中，所述中继UE的选择方法包括：
    在发送UE的通信范围内且同时在接收UE的通信范围内的UE如果满足条件1则称为候选中继UE，所述条件1包括：在通信范围内具有与发送UE、接收UE进行通信的能力且具有承担中继任务的能力；
    候选中继UE如果满足条件2则称为中继UE，所述条件2包括：候选中继UE监听由发送UE发送的参考信号，并基于所监听的参考信号，得到来自发送UE的参考信号的参考信号接收功率RSRP，将参考信号接收功率RSRP与预设的第一阈值和第二阈值进行比较，所述参考信号的接收功率RSRP在第一阈值和第二阈值之间。
  29. 根据权利要求28所述的一种基于NR-V2X的UE间的协调方法，其特征在于：所述具有承担中继任务的能力的判断因素至少包括：所述候选中继UE的中继操作不影响其与 所述发送UE和其它网内UE的通信；以及所述候选中继UE的剩余电量、可接受的业务类型和链路质量。
  30. 根据权利要求22所述的一种基于NR-V2X的UE间的协调方法，其特征在于：动态选择的所述中继UE包括至少一个主中继UE以及可选的至少一个辅助中继UE，所述主中继UE与所述辅助中继UE在同一个时隙进行初始数据包重传。
  31. 根据权利要求30所述的一种基于NR-V2X的UE间的协调方法，其特征在于：所述中继通过Layer-2中继或Layer-3中继来实现；其中，所述中继通过Layer-2中继实现时，如果仅MAC层为只参与中继操作，则中继传输有两种选择：
    选项1：中继UE中的MAC实体不检查HARQ反馈，进行实施盲目重传；
    选项2：中继UE中的MAC实体检查HARQ反馈，如果接收到NAK，则进行重传。
  32. 根据权利要求22所述的一种基于NR-V2X的UE间的协调方法，其特征在于：gNB或发送UE在PDCP层复制生成PDCP PDU数据包，并通过所述主中继UE与所述辅助中继UE各自发送PDCP PDU数据包。
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