WO2021233164A1 - 一种通信方法及装置 - Google Patents

一种通信方法及装置 Download PDF

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Publication number
WO2021233164A1
WO2021233164A1 PCT/CN2021/093149 CN2021093149W WO2021233164A1 WO 2021233164 A1 WO2021233164 A1 WO 2021233164A1 CN 2021093149 W CN2021093149 W CN 2021093149W WO 2021233164 A1 WO2021233164 A1 WO 2021233164A1
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WO
WIPO (PCT)
Prior art keywords
timer
terminal device
sidelink
time domain
harq process
Prior art date
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PCT/CN2021/093149
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English (en)
French (fr)
Inventor
赵力
徐海博
王君
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华为技术有限公司
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Publication of WO2021233164A1 publication Critical patent/WO2021233164A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/20—Manipulation of established connections
    • H04W76/28—Discontinuous transmission [DTX]; Discontinuous reception [DRX]
    • 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
    • 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
    • H04L1/1812—Hybrid protocols; Hybrid automatic repeat request [HARQ]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H04W72/044—Wireless resource allocation based on the type of the allocated resource
    • H04W72/0446—Resources in time domain, e.g. slots or frames

Definitions

  • the embodiments of the present application relate to the field of communication technologies, and in particular, to a communication method and device.
  • the communication interface between the UE and the base station is called the Uu air interface.
  • the link through which the UE sends data to the base station is called uplink (UL).
  • the link through which the base station sends data to the UE is called downlink (DL).
  • the communication interface between UE and UE is called PC5 interface.
  • the link for transmitting data between the UE and the UE is called a sidelink (SL).
  • SL sidelink
  • the UE autonomously selects resource allocation in the resource pool, that is, the UE itself selects resources to transmit Sidelink data in a resource pool configured or pre-configured by the network through system messages or dedicated signaling.
  • the other is a resource allocation method based on base station scheduling, that is, the base station schedules Sidelink resources for the transmission user equipment TXUE to transmit Sidelink data.
  • the base station sends downlink control information (DCI) in the physical downlink control channel (PDCCH) to dynamically allocate Sidelink resources, and the TXUE needs to monitor the PDCCH to obtain Sidelink authorization (grant) issued by the base station.
  • DCI downlink control information
  • PDCCH physical downlink control channel
  • the embodiments of the present application provide a communication method and device to enable the first terminal device to monitor the PDCCH.
  • a communication method is provided, which is applicable to the case where the PSSCH resource is associated with the PUCCH resource, and also applicable to the case where the PSSCH resource is not associated with the PUCCH resource.
  • the execution subject of the method is the first terminal device and the second terminal device. It can be understood that the first terminal device and the second terminal device may be terminal devices, or may be components (for example, chips, circuits, or others) configured in the terminal devices.
  • the method includes:
  • the first terminal device receives the first DCI from the network device.
  • the first DCI is used to schedule the i-th transmission of the Sidelink HARQ process.
  • the Sidelink HARQ process associates or maintains two timers, the first timer and the second timer.
  • Timer The first terminal device can use the aforementioned Sidelink HARQ process to send Sidelink data to the second terminal device according to the scheduling of the first DCI.
  • the first terminal device may start the first timer according to the time domain location of the PSSCH resource for sending the Sidelink data.
  • the second timer is directly started.
  • the first terminal device may start or not start the second timer according to the situation of receiving the HARQ feedback of the Sidelink HARQ process according to the PSFCH resource. Wherein, during the operation of the second timer, the first terminal device can monitor the PDCCH.
  • the first terminal device can start the first timer and the second timer according to the time domain position of the PSSCH resource. Therefore, in the case that no PUCCH resource is configured, the first timer and the second timer can be successfully started to meet the requirement of the first terminal device to monitor the PDCCH. Further, during the operation of the second timer, the i+1th transmission used for scheduling the Sidelink HARQ process can be monitored, which can reduce the communication delay of the Sidelink and meet the QoS requirements of the Sidelink.
  • the first terminal device may determine the first time domain position according to the time domain position of the PSSCH resource and the first time domain offset; or, after the end position of the time domain position of the PSSCH resource The first time unit is used as the first time domain position; and at the first time domain position, the first timer is started.
  • the foregoing first time domain offset may be specified by the protocol, or configured by the network device, or implemented internally by the terminal device, and is not limited.
  • the time domain unit that starts the first timer can be flexibly set.
  • the terminal device may also determine the number of times of sidelink data transmission associated with the Sidelink HARQ process before starting the first timer.
  • the number of transmissions is greater than or equal to the maximum number of transmissions or the preset number of transmissions, it indicates that the current transmission of Sidelink data has exceeded the maximum number of transmissions or the preset number of times.
  • the network device will no longer allocate PSSCH resources for the Sidelink data. Therefore, there is no need to start the first timer at this time.
  • the first timer is continued to be started.
  • the first timer is directly started. Through the above method, the power consumption of the terminal device can be reduced.
  • the first terminal device is configured with PSFCH resources. And before the first timer expires, if the first terminal device can determine the HARQ feedback of the Sidelink HARQ process. Then when the HARQ feedback is NACK, when the first timer expires, the second timer is directly started. When the HARQ feedback is ACK, the first timer can be directly stopped. At this time, there is no longer a situation that the first timer expires, so there is no need to start the second timer, or the first terminal device may not Stop the first timer, but do not start the second timer when the first timer expires.
  • the first terminal device decides whether to start the first timer according to the HARQ feedback situation. Compared with starting the first timer under any circumstances, the power consumption of the terminal device can be reduced.
  • the first terminal device if the first terminal device is configured with PSFCH resources, and the HARQ feedback of the Sidelink HARQ process cannot be determined before the first timer expires. Then, after the first timer expires, the first terminal device can directly start the second timer. During the operation of the second timer, if the HARQ feedback of the Sidelink HARQ process is ACK, the first terminal device can directly stop the second timer and no longer monitor the PDCCH. Alternatively, if the HARQ feedback of the Sidelink HARQ process is NAKC, the first terminal device may not stop the second timer and continue to monitor the PDCCH.
  • the first terminal device can directly stop the second timer, and further Reduce the power consumption of terminal equipment.
  • a communication method is provided, which is applicable to the case where the PSSCH resource is associated with the PUCCH resource, and also applicable to the case where the PSSCH resource is not associated with the PUCCH resource.
  • the execution subject of the method is the first terminal device and the second terminal device. It can be understood that the first terminal device and the second terminal device may be terminal devices, or may be components (for example, chips, circuits, or others) configured in the terminal devices.
  • the method includes:
  • the first terminal device receives the first DCI from the network device, and the first DCI is used to schedule the i-th transmission of the Sidelink HARQ process.
  • the Sidelink HARQ process maintains or associates two timers, which are the first timer and the second timer, respectively.
  • the first terminal device may use the Sidelink HARQ process to send Sidelink data to the second terminal device according to the scheduling of the first DCI.
  • the first terminal device may enable or disable the first timer according to the HARQ feedback of the Sidelink HARQ process and the time domain position of the PSFCH resource received by the HARQ feedback. For example, when the HARQ feedback of the Sidelink HARQ process is NACK, the first timer can be started according to the time domain position of the PSFCH resource.
  • the first timer When the HARQ feedback of the Sidelink HARQ process is ACK, the first timer is no longer started. In the case of starting the first timer, when the first timer expires, the second timer can be directly started. During the running of the second timer, the first terminal device monitors the PDCCH.
  • the first terminal device can start the first timer and the second timer according to the time domain position of the PSFCH resource. Therefore, in the case that no PUCCH resource is configured, the first timer and the second timer can be successfully started to meet the requirement of the first terminal device to monitor the PDCCH. Further, during the operation of the second timer, the i+1th transmission used for scheduling the Sidelink HARQ process can be monitored, which can reduce the communication delay of the Sidelink and meet the QoS requirements of the Sidelink.
  • the first terminal device determines the second time domain position according to the time domain resource position of the first PSFCH resource and the second time domain offset; or, the first terminal device determines the The first time unit after the end position of the time domain resource of the first PSFCH resource is used as the second time domain position.
  • the foregoing second time domain offset may be specified by the protocol, or configured by the network device, or implemented internally by the terminal device, and is not limited.
  • the time domain unit that starts the first timer can be flexibly set.
  • the first terminal device starts or does not start the first timer at the second time domain position according to the HARQ feedback. For example, when the first terminal device determines that the HARQ feedback of the Sidelink HARQ process is NACK, the first terminal device starts the first timer at the second time domain location; otherwise, the first terminal device starts the first timer. A terminal device at the second time domain location does not start the first timer any more.
  • the first terminal device determines whether to start the first timer according to the HARQ feedback of the Sidelink HARQ process. In contrast, the first terminal device is at the second time domain position regardless of the situation, and the first timer is started, which can reduce the power consumption of the terminal device.
  • the first terminal device is at the second time domain position and starting the first timer includes: the first terminal device determines the Sidelink data associated with the Sidelink HARQ process The number of transmissions; if the number of transmissions of the Sidelink data associated with the Sidelink HARQ process is less than or equal to the maximum number of transmissions or the preset number of transmissions, the first terminal device is at the second time domain position and starts the first timing Device. Otherwise, the first terminal device is at the second time domain position and does not start the first timer.
  • the maximum number of transmissions or the preset number of transmissions may be specified in the protocol, or configured by the network device, or implemented inside the terminal device.
  • the network device no longer schedules the i+1th transmission of the Sidelink HARQ process, and at this time, the first terminal device is set to no longer start the first timer, reducing The power consumption of the first terminal device.
  • the method when the first terminal device starts the second timer, the method further includes: during the operation of the second timer, if the first terminal device If the PDCCH used for scheduling sidelink data retransmission of the first terminal device is monitored, the first terminal device stops the second timer.
  • the embodiments of the present application also provide a device, and the beneficial effects can be referred to the description of the first aspect.
  • the device has the function of realizing the behavior in the method embodiment of the first aspect described above.
  • the functions can be realized by executing corresponding hardware or software.
  • the hardware or software may include one or more modules corresponding to the above-mentioned functions.
  • the apparatus may include: a transceiver unit, configured to receive first downlink control information DCI from a network device, and the first DCI is used to schedule initial transmission or retransmission of sidelink sidelink data.
  • the Sidelink hybrid automatic retransmission request HARQ process associated with the Sidelink data is associated with two timers, namely the first timer and the second timer; the processing unit is configured to use physical The sidelink shared channel PSSCH resource sends Sidelink data to the second terminal device; the processing unit is further configured to start the first timer according to the time domain position of the PSSCH resource; the processing unit is further configured to start the first timer according to the first A timer is used to turn on or not to turn on the second timer; wherein, when the second timer is turned on, during the operation of the second timer, the first terminal device monitors the physical downlink control channel PDCCH.
  • These units can perform the corresponding functions in the above-mentioned method example of the first aspect. For details, please refer to the detailed description in the method example, which will not be repeated here.
  • the embodiments of the present application also provide a device, and the beneficial effects can be referred to the description of the second aspect.
  • the device has the function of realizing the behavior in the method embodiment of the second aspect described above.
  • the functions can be implemented by corresponding hardware or software.
  • the hardware or software may include one or more modules corresponding to the above-mentioned functions.
  • the apparatus includes: a transceiving unit, configured to receive first downlink control information DCI from a network device, and the first DCI is used to schedule initial transmission or retransmission of sidelink sidelink data
  • the Sidelink hybrid automatic repeat request HARQ process associated with the Sidelink data is associated with two timers, namely the first timer and the second timer; the processing unit is configured to use the physical side according to the scheduling of the first DCI
  • the uplink shared channel PSSCH resource sends Sidelink data to the second terminal device;
  • the processing unit is further configured to use the physical side feedback channel PSFCH resource to receive HARQ feedback from the second terminal device to the Sidelink HARQ process, so
  • the HARQ feedback is a positive acknowledgement ACK or a negative acknowledgement NACK;
  • the processing unit is further configured to start or not start the first timer according to the HARQ feedback and the time domain position of the PSFCH resource; In the case of the first timer, when the first timer expires, the first terminal device starts the second
  • a device in a fifth aspect, is provided, and the device may be the terminal device in the above-mentioned method embodiment of the first aspect, or a chip set in the terminal device.
  • the device includes a communication interface, a processor, and optionally, a memory.
  • the memory is used to store computer programs or instructions
  • the processor is coupled with the memory and a communication interface.
  • the processor executes the computer programs or instructions
  • the device executes what is executed by the terminal device in the method embodiment of the first aspect. method.
  • a device in a sixth aspect, is provided, and the device may be the terminal device in the method embodiment of the second aspect described above, or a chip set in the terminal device.
  • the device includes a communication interface, a processor, and optionally, a memory.
  • the memory is used to store computer programs or instructions
  • the processor is coupled with the memory and a communication interface.
  • the processor executes the computer programs or instructions
  • the device executes what is executed by the terminal device in the method embodiment of the second aspect described above. method.
  • a computer program product includes: computer program code, which when the computer program code is running, causes the method executed by the terminal device in the first aspect to be executed.
  • a computer program product comprising: computer program code, when the computer program code is executed, the method executed by the terminal device in the second aspect described above is executed.
  • the present application provides a chip system, which includes a processor, configured to implement the functions of the terminal device in the method of the first aspect.
  • the chip system further includes a memory for storing program instructions and/or data.
  • the chip system can be composed of chips, and can also include chips and other discrete devices.
  • the present application provides a chip system, the chip system includes a processor, and is configured to implement the function of the terminal device in the method of the second aspect.
  • the chip system further includes a memory for storing program instructions and/or data.
  • the chip system can be composed of chips, and can also include chips and other discrete devices.
  • the present application provides a computer-readable storage medium that stores a computer program, and when the computer program is executed, the method executed by the terminal device in the first aspect described above is implemented.
  • the present application provides a computer-readable storage medium that stores a computer program, and when the computer program is executed, the method executed by the terminal device in the second aspect described above is implemented.
  • FIG. 1 is a schematic diagram of a network architecture provided by an embodiment of this application.
  • FIGS. 2A, 2B, and 2C are schematic diagrams of DRX provided by an embodiment of this application.
  • FIG. 3 is a flowchart of a communication method provided by an embodiment of this application.
  • FIG. 4 is a flowchart of a communication method provided by an embodiment of this application.
  • FIG. 5 is a flowchart of a communication method provided by an embodiment of this application.
  • FIG. 6 is a flowchart of a communication method provided by an embodiment of this application.
  • FIG. 7 is a flowchart of a communication method provided by an embodiment of this application.
  • FIG. 8 is a schematic structural diagram of a communication device provided by an embodiment of this application.
  • FIG. 9 is a schematic structural diagram of a communication device provided by an embodiment of this application.
  • Fig. 1 shows a wireless communication system 100 involved in the present application.
  • the wireless communication system 100 may be an LTE (long term evolution, LTE) system, a fifth-generation mobile communication (5 th generation, 5G) system, a new air interface (new radio, NR) system, may also be a machine in communication with the machine (machine to machine, M2M) system, the sixth-generation communication system that will evolve in the future, etc.
  • LTE long term evolution
  • 5G fifth-generation mobile communication
  • NR new air interface
  • M2M machine to machine
  • the wireless communication system 100 may include: one or more network devices 101, two or more terminal devices 103, and a core network (not shown). in:
  • the network device 101 can be used to communicate with the terminal device 103 through the Uu interface 105 under the control of a network device controller (not shown), such as a base station controller (BSC).
  • a network device controller such as a base station controller (BSC).
  • BSC base station controller
  • the network device controller may be a part of the core network, or may be integrated into the network device 101.
  • the network device 101 may also be used to transmit control information or user data to the core network through a blackhaul interface, such as an S1 interface.
  • a blackhaul interface such as an S1 interface.
  • the network device 101 and the network device 101 may also communicate with each other directly or indirectly through a backhaul (blackhaul) interface, such as an X2 interface.
  • a backhaul (blackhaul) interface such as an X2 interface.
  • the communication interface 107 between the terminal device 103 and the terminal device 103 is called a PC5 interface.
  • the data transmission link between the terminal device 103 and the terminal device 103 is called a side link (Sidelink, SL).
  • Sidelink may be point-to-point communication between two terminal devices 103, or may be multicast communication performed by a group of more than two terminal devices 103.
  • the network equipment 101 may be a base transceiver station (BTS) in a time division synchronous code division multiple access (TD-SCDMA) system, or an evolutional base station (evolutional base station) in an LTE system.
  • BTS base transceiver station
  • TD-SCDMA time division synchronous code division multiple access
  • evolutional base station evolutional base station
  • LTE Long Term Evolution
  • node B eNB
  • eNB evolved base station
  • 5G systems 5G systems
  • NR New Air Interface
  • the base station may also be an access point (AP), a transmission and reception point (TRP), a central unit (CU), or other network entities, and may include the functions of the above network entities.
  • the terminal device 103 may be a wireless communication device such as a vehicle-mounted terminal, a smart phone, a roadside unit (RSU), an Internet of Things terminal device, a machine type communication (MTC) terminal, and the like.
  • the terminal equipment may also include one or more base stations with partial UE functions, such as micro base stations.
  • the terminal equipment may be distributed in the entire wireless communication system 100, and may be stationary or mobile.
  • the wireless communication system 100 shown in FIG. 1 is only used to illustrate the technical solution of the application more clearly, and does not constitute a limitation to the application.
  • Those of ordinary skill in the art will know that with the evolution of the network architecture and new services In the emergence of scenarios, the technical solutions provided in this application are equally applicable to similar technical problems.
  • V2X refers to connecting vehicles to the Internet or connecting vehicles into a network.
  • V2V vehicle to vehicle
  • V2I vehicle to infrastructure
  • V2N vehicle to network
  • V2P vehicle to pedestrian
  • vehicles, roadside infrastructure, application servers and pedestrians collect, process and share status information of surrounding vehicles and the environment to provide more intelligent services, such as unmanned driving and autonomous driving (automated driving/ADS), driver assistance/ADAS, intelligent driving, connected driving, intelligent network driving, car sharing, etc.
  • ADS unmanned driving and autonomous driving
  • ADAS intelligent driving, connected driving, intelligent network driving, car sharing, etc.
  • the terminal device 103 may be a vehicle-mounted terminal.
  • the vehicle-mounted terminal and the vehicle-mounted terminal can exchange data through Sidelink, such as vehicle position, vehicle speed, driving direction, etc., indicating vehicle dynamics.
  • Sidelink such as vehicle position, vehicle speed, driving direction, etc.
  • the vehicle-mounted terminal A may send data to another vehicle-mounted terminal B through Sidelink, and the data is used to indicate the driving dynamics of the vehicle in which the vehicle-mounted terminal A is located.
  • Sidelink communication the vehicle-mounted terminal A is the TX UE, and the vehicle-mounted terminal B is the RX UE. After receiving the data, the vehicle-mounted terminal B can display the user interface 20.
  • the user interface 20 can display the content 21 expressed by the data, such as the license plate number of the rear vehicle (“FAF787”), the driving operation being performed by the rear vehicle (“the rear vehicle FAF787 is performing an overtaking operation”), and the current speed of the rear vehicle (“80km/h”), etc. In this way, the incidence of traffic accidents can be reduced and driving safety can be enhanced.
  • the data such as the license plate number of the rear vehicle (“FAF787”)
  • the driving operation being performed by the rear vehicle (“the rear vehicle FAF787 is performing an overtaking operation”
  • the current speed of the rear vehicle 80km/h
  • one of the main resource allocation methods for Sidelink communication is a resource allocation method based on base station scheduling.
  • the base station issues downlink control information DCI on the PDCCH to dynamically allocate resources, and the TXUE needs to monitor the PDCCH to obtain the Sidelink grant issued by the base station.
  • DRX discontinuous reception
  • the DRX mechanism is a DRX cycle (DRX cycle) configured by a network device for a UE in a radio control resource (RRC) connection state.
  • DRX cycle consists of two time periods: "On Duration” and "Opportunity for DRX".
  • On Duration can be called a duration
  • Opportunity for DRX can be called a DRX opportunity.
  • On Duration the UE monitors and receives the PDCCH.
  • UE does not monitor PDCCH to reduce power consumption.
  • On Duration (such as 10 ms) specifies the time that the UE needs to monitor the PDCCH from the start position of the DRX Cycle.
  • On Duration can be greater than 1ms or less than 1ms.
  • the UE In “On Duration”, the UE is in the active state, that is, the UE monitors the PDCCH.
  • the UE In “Opportunity for DRX”, the UE is in the dormant state, that is, the UE does not monitor the PDCCH.
  • the dormant state is only for monitoring the PDCCH, which means that the UE does not monitor the PDCCH.
  • the UE in the dormant state is still in the RRC connection state, and can transmit uplink data through physical uplink control channel (PUCCH), physical uplink shared channel (PUSCH), etc. on Uu interface 105 or through physical
  • the physical downlink shared channel (PDSCH) receives the downlink data sent by the base station, and can also use the physical side link shared channel (PSSCH) and the physical side link control channel on the PC5 interface 107. channel, PSCCH) etc. to transmit Sidelink data.
  • the DRX mechanism introduces a timer: drx-InactivityTimer. As shown in FIG.
  • the UE when the UE monitors and receives a PDCCH for scheduling new data, the UE starts (or restarts) the timer drx-InactivityTimer.
  • the UE will monitor the PDCCH in each subframe during the operation of the drx-InactivityTimer until the timer expires.
  • the indication information of the new data will be carried in the PDCCH, occupying 1 bit. It can be seen that the introduction of drx-InactivityTimer can ensure that the UE is in the active state during the operation of drx-InactivityTimer, and receives the scheduling of the next base station, which is equivalent to extending the "On Duration".
  • the UE will start (or restart) multiple drx-InactivityTimers one after another, which may make the UE be active throughout the DRX cycle, that is, "On Duration" may be extended to The entire DRX cycle.
  • HARQ hybrid automatic repeat request
  • the base station schedules retransmission resources for the TXUE according to the HARQ feedback (feedback) of the Sidelink data transmission.
  • HARQ feedback can be negative acknowledgment (NACK) or positive acknowledgment (acknowledgment, ACK).
  • the base station if the HARQ feedback of data a is NACK, the base station, after receiving the NACK, schedules resources for the retransmission of data a, and issues a Sidelink grant (grant) for the retransmission of data a on the PDCCH. .
  • the Tx UE when the HARQ of the data a sent by the Tx UE to the base station is confirmed as NACK, the Tx UE needs to receive the PDCCH issued by the base station to schedule the retransmission of data a to perform the retransmission of data a. .
  • the TX UE may have entered the "opportunity for DRX" state and no longer monitors the PDCCH.
  • the TX UE needs to wait until the "On Duration" of the next DRX cycle to monitor the PDCCH, and then can receive the PDCCH issued by the base station for scheduling the retransmission of data a, and then perform the retransmission of data a. This will cause the data retransmission of the TxUE on the Sidelink to be delayed, and cause the QoS requirements of the services transmitted on the Sidelink to not be met.
  • the solution includes: TX UE uses PUCCH resources to send HARQ feedback to the base station. That is, start the first timer, the first timer may be drx-HARQ-RTT-TimerSL and when the first timer expires, start the second timer, the second timer may be drx-RetransmissionTimerSL.
  • the TX UE monitors the PDCCH during the running period of the second timer, so as to prevent the TX UE from monitoring the PDCCH during the "On Duration" of the next DRX cycle, reducing the transmission delay of Sidelink data.
  • the TX UE starts the first timer and the second timer when it uses PUCCH resources to feed back HARQ to the base station.
  • the base station does not configure PUCCH resources for the TX UE, the TX UE cannot send HARQ feedback to the base station at this time, and thus cannot start the first timer and the second timer.
  • how to reduce the transmission delay of Sidelink data is a technical problem to be solved in the embodiment of the present application.
  • the embodiments of the present application provide a communication method and device, which can start the first timer and the second timer when the TX UE is not configured with PUCCH resources to reduce the transmission delay of Sidelink data.
  • the method may include two schemes: the first scheme is: after the TX UE sends the Sidelink data on the PSSCH resource, it starts the first timer according to the time domain position of the PSSCH resource, and then starts the second timer.
  • the first scheme is: after the TX UE sends the Sidelink data on the PSSCH resource, it starts the first timer according to the time domain position of the PSSCH resource, and then starts the second timer.
  • the second solution is: after the TX UE receives the HARQ feedback on the PSFCH resource, it starts the first timer according to the time domain position of the PSFCH resource, and then starts the second timer.
  • the third embodiment below please refer to the description in the third embodiment below.
  • the embodiments of this application also provide two solutions that do not involve the first timer and the second timer: the third solution, after the TX UE sends the Sidelink data on the PSSCH resource, it is based on the time domain position of the PSSCH resource , Monitor PDCCH.
  • the third solution after the TX UE sends the Sidelink data on the PSSCH resource, it is based on the time domain position of the PSSCH resource , Monitor PDCCH.
  • the TX UE receives the HARQ feedback on the PSFCH resource, it monitors the PDCCH according to the time domain position of the PSFCH resource.
  • the description in the fifth embodiment below please refer to the description in the fifth embodiment below.
  • a terminal device can be referred to as a terminal for short, which is a device with a wireless transceiver function.
  • Terminal devices can be deployed on land, including indoor or outdoor, handheld or vehicle-mounted; they can also be deployed on water (such as ships, etc.); they can also be deployed in the air (such as airplanes, balloons, and satellites, etc.).
  • the terminal device may be a mobile phone (mobile phone), a tablet computer (pad), a computer with wireless transceiver function, virtual reality (VR) terminal equipment, augmented reality (AR) terminal equipment, industrial control ( Wireless terminal equipment in industrial control, wireless terminal equipment in self-driving, wireless terminal equipment in remote medical, wireless terminal equipment in smart grid, transportation safety (transportation) Wireless terminal equipment in safety), wireless terminal equipment in a smart city (smart city), wireless terminal equipment in a smart home (smart home), and may also include user equipment (UE), etc.
  • UE user equipment
  • the terminal device can also be a cellular phone, a cordless phone, a session initiation protocol (session initiation protocol, SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (personal digital assistant, PDA), with wireless communication Functional handheld devices, computing devices or other processing devices connected to wireless modems, in-vehicle devices, wearable devices, terminal devices in the future 5th generation (5G) network or future evolution of the public land mobile communication network (public land mobile communication network) Land mobile network, PLMN) terminal equipment, etc.
  • 5G future 5th generation
  • PLMN public land mobile communication network
  • Terminal equipment can sometimes be called terminal, access terminal equipment, vehicle terminal equipment, industrial control terminal equipment, UE unit, UE station, mobile station, mobile station, remote station, remote terminal equipment, mobile equipment, UE terminal equipment, terminal Equipment, wireless communication equipment, UE agent or UE device, etc.
  • the terminal device can also be fixed or mobile. The embodiments of the present application are not limited to this.
  • the device used to implement the function of the terminal may be a terminal; it may also be a device capable of supporting the terminal to implement the function, such as a chip system, and the device may be installed in the terminal.
  • the chip system may be composed of chips, or may include chips and other discrete devices.
  • the device used to implement the functions of the terminal is a terminal, and the terminal is a UE as an example to describe the technical solutions provided in the embodiments of the present application.
  • the network device may be an access network device, and the access network device may also be called a radio access network (RAN) device, which is a device that provides wireless communication functions for terminal devices.
  • the access network equipment includes, for example, but is not limited to: next-generation base stations (generation nodeB, gNB), evolved node B (evolved node B, eNB), radio network controller (RNC), node B ( node B, NB), base station controller (BSC), base transceiver station (BTS), home base station (for example, home evolved nodeB, or home node B, HNB), baseband unit (baseband unit) , BBU), transmitting and receiving point (TRP), transmitting point (TP), mobile switching center, etc.
  • generation nodeB generation nodeB, gNB
  • evolved node B evolved node B
  • RNC radio network controller
  • node B node B, NB
  • BSC base station controller
  • BTS base transceiver station
  • home base station for example, home evolved node
  • the access network equipment can also be a wireless controller, a centralized unit (CU), and/or a distributed unit (DU) in a cloud radio access network (cloud radio access network, CRAN) scenario, or a network
  • the device may be a relay station, an access point, a vehicle-mounted device, a wearable device, and a network device in a future 5G network or a network device in a future evolved PLMN network.
  • the terminal device can communicate with multiple access network devices of different technologies.
  • the terminal device can communicate with an access network device that supports long term evolution (LTE), or can communicate with an access network device that supports 5G. , It can also be dual-connected with LTE-supporting access network equipment and 5G-supporting access network equipment.
  • LTE long term evolution
  • 5G 5G-supporting access network equipment
  • the embodiments of the application are not limited.
  • the device used to implement the function of the network device may be a network device; it may also be a device capable of supporting the network device to implement the function, such as a chip system, and the device may be installed in the network device.
  • the device used to implement the functions of the network equipment is the network equipment, and the network equipment is a base station as an example to describe the technical solutions provided by the embodiments of the present application.
  • the side link is used for the communication between the terminal equipment and the terminal equipment, and the communication interface between the terminal equipment and the terminal equipment can be a PC5 interface.
  • the channels involved in side link communication can include physical side link shared channel (PSSCH), physical side link control channel (physical sidelink control channel, PSCCH), and physical side link feedback channel (physical sidelink feedback) channel, PSFCH).
  • PSSCH physical side link shared channel
  • PSCCH physical side link control channel
  • PSFCH physical side link feedback channel
  • the PSSCH is used to carry side link data (SL data), and the PSCCH is used to carry side link control information (sidelink control information, SCI).
  • SCI may also be referred to as side link scheduling assistance (Sidelink Scheduling Assistance, SL SA).
  • SL SA is information related to data scheduling, such as resource allocation and/or modulation and coding scheme (MCS) information used to carry PSSCH.
  • MCS modulation and coding scheme
  • PSFCH can be used to transmit sidelink feedback control information (SFCI).
  • the side link feedback control information may include one or more of channel state information (CSI) and HARQ information.
  • HARQ information may include ACK or NACK, etc.
  • the Uu air interface can be referred to as Uu for short, and the Uu air interface is used for communication between terminal equipment and network equipment.
  • Uu air interface transmission can include uplink transmission and downlink transmission.
  • uplink transmission refers to the terminal device sending information to the network device, and the information transmitted in the uplink may be referred to as uplink information or uplink signal.
  • the uplink information or the uplink signal may include one or more of uplink data signal, uplink control signal, and sounding reference signal (sounding reference signal, SRS).
  • the channel used to transmit uplink information or uplink signals is called the uplink channel.
  • the uplink channel can include one or more of the physical uplink shared channel (PUSCH) and the physical uplink control channel (PUCCH) .
  • the PUSCH is used to carry uplink data, and the uplink data may also be referred to as uplink data information.
  • the PUCCH is used to carry the uplink control information (uplink control information, UCI) fed back by the terminal device.
  • the UCI may include one or more of channel state information (CSI), ACK and NACK, etc., fed back by the terminal device.
  • Downlink transmission refers to the network device sending information to the terminal device, and the downlink transmission information can be downlink information or downlink signals.
  • Downlink information or downlink signals may include one or more of downlink data signals, downlink control signals, channel state information reference signals (CSI-RS), and phase tracking reference signals (PTRS). kind.
  • the channel used to transmit downlink information or downlink signals is called a downlink channel.
  • the downlink channel may include one or more of a physical downlink shared channel (PDSCH) and a physical downlink control channel (PDCCH). kind.
  • the PDCCH is used to carry downlink control information (DCI), the PDSCH is used to carry downlink data (data), and the downlink data may also be referred to as downlink data information.
  • DCI downlink control information
  • data data
  • downlink data may also be referred to as downlink data information.
  • the TX UE may set a Sidelink HARQ process for each Sidelink data, such as the MAC PDU transmitted by the TX UE to the RX UE. That is, one Sidelink HARQ process is associated with one Sidelink data, and the Sidelink data can be stored in the Sidelink HARQ buffer associated with the Sidelink HARQ process.
  • a Sidelink HARQ process can maintain a state variable CURRENT_SL_TX_NB, which is used to indicate the number of transmissions of Sidelink data associated with the Sidelink HARQ process.
  • CURRENT_SL_TX_NB can be initialized to 0.
  • the HARQ feedback resource of the Sidelink HARQ process associated with a Sidelink data can be used for the RX UE to send the HARQ feedback of the Sidelink HARQ process to the TX UE.
  • the HARQ feedback resource is a PSFCH resource, which can be used to carry the RX UE to send the HARQ feedback to the TX UE.
  • the HARQ feedback may be used to indicate whether the reception of the previous transmission of the Sidelink HARQ process is successful, that is, whether the reception of the previous transmission of the Sidelink data associated with the Sidelink HARQ process is successful or not. If the HARQ feedback is ACK, it may indicate that the reception of the previous transmission of the Sidelink HARQ process was successful; if the HARQ feedback is NACK, it may indicate that the reception of the previous transmission of the Sidelink HARQ process was unsuccessful.
  • the TX UE is in the RRC connected state and is configured with DRX cycle. Within a period of time from the start time of the DRX cycle, the TX UE is in the active state and can monitor and receive a PDCCH.
  • the PDCCH is used to schedule one transmission of the Sidelink data.
  • the one-time transmission may be the initial transmission of the Sidelink data (initial transmission), or may be the retransmission of the Sidelink data, such as the second transmission, the third transmission, and so on.
  • the period of time starting from the start time of the DRX cycle can refer to the "On Duration" of the DRX cycle, or it can be the extended “On Duration” formed after the drx-InactivityTimer is turned on.
  • the extension of "On Duration” please refer to the related description in Figure 2B above. That is, the start time of the period of time is the start time of the DRX cycle, and the duration of the period of time is equal to or greater than the duration of "On Duration".
  • the Sidelink data involved in the embodiments of the present application may be media access control (MAC) layer data, such as MAC protocol data unit (protocol data unit, PDU), etc., which are not limited.
  • MAC media access control
  • the TX UE may be referred to as the first terminal device, and the RX UE may be referred to as the second terminal device.
  • the TX UE and RX UE may adopt a unicast transmission mode, or a multicast transmission mode, etc., which is not limited. When the multicast transmission mode is adopted, the number of RX UEs can be one or more.
  • At least one item (a) refers to any combination of these items, including any combination of a single item (a) or a plurality of items (a).
  • at least one of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple .
  • words such as “first” and “second” are used to distinguish the same or similar items with substantially the same function and effect. Those skilled in the art can understand that words such as “first” and “second” do not limit the quantity and order of execution, and words such as “first” and “second” do not limit the difference.
  • the embodiment of the present application provides a communication method, which can be used for the above-mentioned first solution.
  • the first terminal device and the second terminal device in this method may be terminal devices, or may be components in the terminal device (for example, chips, circuits, or others).
  • the network device may be an access network device, such as a base station.
  • the method can specifically be:
  • the network device sends the first DCI to the first terminal device, where the first DCI is used to schedule initial transmission or retransmission of the Sidelink data of the first terminal device.
  • the first terminal device uses the PSSCH resource to send the Sidelink data to the second terminal device according to the scheduling of the first DCI.
  • the first terminal device determines the first time domain location according to the time domain location of the PSSCH resource, and starts the first timer at the first time domain location. Then when the first timer expires, the second timer is started.
  • the first terminal device maintains two timers for each Sidelink HARQ process: the first timer and The second timer.
  • the foregoing process can also be described as: the first terminal device associates two timers for each Sidelink HARQ process, namely, the first timer and the second timer.
  • the first timer may be named drx-HARQ-RTT-TimerSL; the second timer may be named drx-RetransmissionTimerSL.
  • the first terminal device monitors the PDCCH.
  • the names of the first timer and the second timer may also be other, which is not limited in the embodiment of the present application.
  • Fig. 3 shows the specific flow of the communication method provided in the first embodiment.
  • S301 Establish an RRC connection between the first terminal device and the network device.
  • the first terminal device After the RRC connection is established, the first terminal device enters the RRC connected state.
  • S302 Establish a Sidelink between the first terminal device and the second terminal device.
  • the first terminal device After the Sidelink is established, the first terminal device transmits data to the second terminal device through the Sidelink.
  • the network device configures the DRX cycle for the first terminal device in the RRC connected state.
  • DRX cycle is composed of "On Duration” and "Opportunity for DRX": in “On Duration”, the first terminal device monitors and receives PDCCH (active state); in “Opportunity for DRX", the first terminal device does not monitor PDCCH ( Sleep state).
  • the network device configures timers for the first terminal device in the RRC connected state: drx-InactivityTimer, drx-HARQ-RTT-TimerSL, drx-RetransmissionTimerSL.
  • the drx-HARQ-RTT-TimerSL may be referred to as the first timer
  • the drx-RetransmissionTimerSL may be referred to as the second timer.
  • S302 can also be executed before S301.
  • this application does not limit it.
  • the first terminal device may also send a resource scheduling request to the network device to request the network device to schedule transmission resources for Sidelink data transmission.
  • the resource scheduling request may carry a buffer status report to indicate how much Sidelink data the first terminal device has to send on the Sidelink.
  • the network device can transmit the scheduling resource for the Sidelink, and deliver the scheduled Sidelink resource in the PDCCH.
  • the first terminal device can learn the Sidelink resource scheduled by the network device by monitoring the PDCCH.
  • the first terminal device may monitor and receive the PDCCH 1 issued by the network device.
  • PDCCH 1 can indicate the Sidelink resource scheduled for the i-th transmission of a certain Sidelink HARQ process (such as Sidelink HARQ process a), that is, PDCCH 1 can be used to schedule the i-th transmission of Sidelink HARQ process a.
  • Sidelink HARQ process a can be associated with data a.
  • the Sidelink HARQ process a can be used by the first terminal device to transmit data a to the second terminal device on the Sidelink established in S302.
  • Sidelink HARQ process a can maintain a state variable: CURRENT_SL_TX_NB.
  • CURRENT_SL_TX_NB can indicate the number of transmissions of data a
  • CURRENT_SL_TX_NB can be initialized to 0.
  • the initial value of the state variable CURRENT_SL_TX_NB associated with the sidelink HARQ process a can be set to 0.
  • the first terminal device may increase the CURRENT_SL_TX_NB associated with the Sidelink HARQ process a by 1.
  • the PDCCH used to schedule the transmission of the Sidelink HARQ process a may indicate the transmission resources allocated by the network device to the Sidelink HARQ process a.
  • PDCCH 1 can carry the following information: SL grant 1, NDI, Sidelink HARQ process a ID.
  • SL grant 1 may indicate that the network device is the resource scheduled for the i-th transmission of the Sidelink HARQ process a.
  • the NDI may indicate whether the i-th transmission of the Sidelink HARQ process a scheduled by the PDCCH 1 is an initial transmission (initial transmission) or a retransmission (retransmission).
  • PDCCH1 may carry DCI1, and DCI1 may carry information such as the ID of the above-mentioned SL grant1, ND1, and Sidelink HARQ process a.
  • the first terminal device can determine whether the i-th transmission of the Sidelink HARQ process a is the initial transmission or retransmission by whether the NDI in the PDCCH 1 is toggled: if the value of the NDI in the PDCCH 1 is the same as the above
  • the NDI in the PDCCH of Sidelink HARQ process a scheduled at one time is reversed, it means that the i-th transmission of Sidelink HARQ process a is the initial transmission; otherwise, it means that the i-th transmission of Sidelink HARQ process a is retransmission.
  • the so-called NDI inversion can mean that the value of NDI changes from 0 to 1, or from 1 to 0.
  • the first terminal device may transmit data a to the second terminal device through the Sidelink HARQ process a on the PSSCH resource indicated by the PDCCH 1, that is, perform the i-th transmission of the data a.
  • the second terminal device can receive data a sent by the first terminal device on the PSSCH resource indicated by the PDCCH 1.
  • the second terminal device may learn the PSSCH resources on which the first terminal device will transmit data a by monitoring the PSCCH. Because, after receiving the PDCCH 1, the first terminal device can send sidelink control information (SCI) on the PSCCH. The second terminal device can receive the SCI by listening to the PSCCH. The SCI is used to indicate the resource for the first terminal device to transmit data a.
  • SCI sidelink control information
  • the first terminal device starts a first timer according to the time domain position of the PSSCH resource for the i-th transmission of the data a.
  • PSSCH resources include time domain resources and frequency domain resources.
  • the time domain resource of the PSSCH for the i-th transmission of data a may occupy one or more time units.
  • the first time domain position for starting the first timer may be the first time unit after the last time unit in the time domain resource of the PSSCH for the i-th transmission of data a.
  • the first time domain position for starting the first timer may be a time unit offset from the first time domain from the last time domain unit in the time domain resource of the PSSCH transmitted for the i-th time.
  • the first time domain offset may include one or more time units.
  • the time unit may be a symbol, a time slot, and so on.
  • the timing units of the two timers and the first time domain offset can be symbols, time slots, or absolute time units (such as milliseconds).
  • the length of the symbol and the time slot may depend on the Numerology of the bandwidth part (BWP) parameter set of the Sidelink used to transmit the first data, such as subcarrier space (SCS). Not limited to this, the length of the symbol and the time slot may also depend on the Numerology of the BWP parameter set of the uplink bandwidth part of the HARQ feedback sent by the first terminal device to the network device, such as SCS.
  • BWP bandwidth part
  • SCS subcarrier space
  • the first terminal device may determine the first time domain position according to the time domain resource position of the PSSCH resource for the i-th transmission of the data a and the first time domain offset. At the first time domain position, start the first timer.
  • the first time domain offset may be specified by the protocol, or configured by the network device, or implemented internally by the first terminal device, and is not limited.
  • the network device can carry the configuration of the first time domain offset, etc. through SL-PSSCH-Config signaling.
  • the configuration method of the first time domain offset, the configuration signaling, and the naming of the first time domain offset are not limited.
  • the first time domain position may be a time domain offset from the end position of the time domain resource of the PSSCH resource for the i-th transmission of the data a.
  • the first terminal device may start the first timer at the first time unit after the i-th transmission of data a is sent on the PSSCH resource.
  • the concept of the first time domain offset is not defined, and the first terminal device will perform the first time unit after the end position of the time domain resource of the PSSCH resource for the i-th transmission of data a , As the first time domain position, and at the first time domain position, start the first timer.
  • the first terminal device determines whether the state variable CURRENT_SL_TX_NB associated with Sidelink HARQ process a indicates whether the number of transmissions of Sidelink HARQ process a Exceeded the maximum number of transmissions or the preset number of transmissions.
  • the first terminal device When the state variable CURRENT_SL_TX_NB associated with the Sidelink HARQ process a is less than the maximum number of transmissions or the preset number of transmissions, the first terminal device starts the first timer at the first time domain position; otherwise, at the first time domain position, no Then start the first timer. It should be noted that when the state variable CURRENT_SL_TX_NB associated with the Sidelink HARQ process a is equal to the maximum number of transmissions or the preset number of transmissions, the first timer may be started, or the first timer may not be started, which is not limited.
  • the maximum transmission times and the preset transmission times may be specified in the protocol, or configured by the network device, or implemented internally by the first terminal device, and are not limited.
  • the number of transmissions of the aforementioned Sidelink HARQ process a includes the initial and retransmission times of the Sidelink HARQ process a. For example, if the Sidelink HARQ process a is first transmitted once and retransmitted twice, it can be considered that the number of transmissions of the Sidelink HARQ process a is 3 times. If the aforementioned maximum number of transmissions is 5, it may be that the number of transmissions of the aforementioned Sidelink HARQ process a is less than the maximum number of transmissions. At this time, at the first time domain position, the first timer can be started.
  • S308 The first terminal device starts the second timer according to the first timer.
  • the first terminal device may start the second timer. During the running of the second timer, the first terminal device monitors the PDCCH.
  • the first terminal device may stop the second timer.
  • the resource indicated by the PDCCH 2 may be the resource scheduled by the network device for the i+1th transmission of the Sidelink HARQ process a, that is, the PDCCH 2 may be used to schedule the data a of the Sidelink HARQ process a.
  • PDCCH 2 can carry the following information: SL grant 2, NDI, Sidelink HARQ process a ID.
  • SL grant 2 is the resource scheduled by the network device for the i+1th transmission of the Sidelink HARQ process a.
  • the NDI may indicate whether the i+1th transmission of the Sidelink HARQ process a scheduled by the PDCCH 2 is an initial transmission (initial transmission) or a retransmission (retransmission).
  • the i+1th transmission is a retransmission with respect to the i-th transmission, and the i-th transmission is the previous transmission of the i+1th transmission.
  • the resource indicated by the PDCCH 2 may be the resource scheduled by the network device for the initial transmission of the Sidelink HARQ process a.
  • the Sidelink HARQ process a is associated with new data, such as data b. That is, the Sidelink HARQ process a has been used for the first terminal device to transmit new data instead of data a.
  • this possible situation can occur when the transmission of data a has reached the maximum number of transmissions (for example, 5 times).
  • the first terminal device may also stop the second timer.
  • the first terminal device may transmit data a to the second terminal device through the Sidelink HARQ process a on the resource indicated by the PDCCH 2, that is, perform the (i+1)th transmission of the data a.
  • the second terminal device can receive the data a sent by the first terminal device on the resource indicated by the PDCCH 2.
  • the first terminal device can start the first timer, and when the first timer expires, start the second timer. That is to say, after the data of Sidelink HARQ process a is sent, during the second timer is running, the first terminal device is in the active state, and can monitor and receive the sidelink HARQ process issued by the network device during this period. PDCCH for retransmission of a. In this way, the retransmission efficiency of the Sidelink HARQ process a can be improved, and the delay of sidelink data retransmission can be avoided.
  • the above scheme can be applied to both point-to-point unicast transmission and point-to-multipoint multicast transmission. It can be applied to the situation where PSFCH resources are configured, and it can also be applied to situations where PSFCH resources are not configured. .
  • the embodiment of the present application also provides another possible implementation manner. Similar to the above method, the difference is that the first terminal device can default the HARQ feedback of the i-th transmission of data a as ACK.
  • the above-mentioned process of S307 can be replaced as follows: the first terminal device is at the first time domain location and does not start the first timer any more.
  • the manner in which the first terminal device determines the first time domain position reference may be made to the foregoing record, which will not be described again.
  • embodiment (2) of the present application provides another possible implementation manner, which may correspond to the above-mentioned first solution.
  • the difference from the above-mentioned embodiment (1) is that: when the first timer When the timeout expires, the first terminal device no longer directly starts the second timer. Whether the first terminal device starts the second timer also needs to consider the HARQ feedback fed back by the second terminal device through the PSFCH resource.
  • the first terminal device maintains two timers for each Sidelink HARQ process: the first timer and the second timer. Two timers.
  • the foregoing process can also be described as: the first terminal device associates two timers for each Sidelink HARQ process, namely, the first timer and the second timer.
  • the first timer may be named drx-HARQ-RTT-TimerSL; the second timer may be named drx-RetransmissionTimerSL.
  • the first terminal device monitors the PDCCH.
  • the naming of the first timer and the second timer may also be other, which is not limited in this application.
  • Fig. 4 shows the specific flow of the communication method provided in the second embodiment.
  • S401 An RRC connection is established between the first terminal device and the network device.
  • the first terminal device After the RRC connection is established, the first terminal device enters the RRC connected state.
  • S402 Establish a Sidelink between the first terminal device and the second terminal device.
  • the first terminal device After the Sidelink is established, the first terminal device transmits data to the second terminal device through the Sidelink.
  • the network device configures the DRX cycle for the first terminal device in the RRC connected state.
  • DRX cycle is composed of "On Duration” and "Opportunity for DRX": in “On Duration”, the first terminal device monitors and receives PDCCH (active state); in “Opportunity for DRX", the first terminal device no longer monitors PDCCH (Hibernation).
  • the network device configures timers for the first terminal device in the RRC connected state: drx-InactivityTimer, drx-HARQ-RTT-TimerSL, drx-RetransmissionTimerSL.
  • the drx-HARQ-RTT-TimerSL may be referred to as the first timer
  • the drx-RetransmissionTimerSL may be referred to as the second timer.
  • S402 can also be executed before S401.
  • this application does not limit it.
  • the first terminal device may also send a resource scheduling request to the network device to request the network device to schedule transmission resources for Sidelink data transmission.
  • the resource scheduling request may carry a buffer status report to indicate how much Sidelink data the first terminal device has to send on the Sidelink.
  • the network device can transmit scheduling resources for the Sidelink, and deliver the scheduled resources in the PDCCH.
  • the first terminal device can learn the resources scheduled by the network device by monitoring the PDCCH.
  • the first terminal device may monitor and receive the PDCCH 1 issued by the network device.
  • the PDCCH 1 may indicate the resource scheduled for the ith transmission of a certain Sidelink HARQ process (for example, Sidelink HARQ process a), that is, the PDCCH 1 can be used to schedule the ith transmission of the Sidelink HARQ process a.
  • Sidelink HARQ process a may be associated with data a.
  • the Sidelink HARQ process a may be used by the first terminal device to transmit data a to the second terminal device on the Sidelink established in S402.
  • Sidelink HARQ process a can maintain a state variable: CURRENT_SL_TX_NB.
  • CURRENT_SL_TX_NB may indicate the number of transmissions of data a
  • CURRENT_SL_TX_NB may be initialized to 0.
  • the initial value of the state variable CURRENT_SL_TX_NB associated with the sidelink HARQ process a can be set to 0.
  • the first terminal device may increase the CURRENT_SL_TX_NB associated with the Sidelink HARQ process a by 1.
  • the PDCCH used to schedule the transmission of the Sidelink HARQ process a may indicate the transmission resources allocated by the network device to the Sidelink HARQ process a.
  • PDCCH 1 can carry the following information: SL grant 1, NDI, Sidelink HARQ process a ID.
  • SL grant 1 may indicate that the network device is the resource scheduled for the i-th transmission of the Sidelink HARQ process a.
  • NDI can indicate whether the i-th transmission of Sidelink HARQ process a scheduled by PDCCH 1 is initial transmission or retransmission.
  • the first terminal device can determine whether the i-th transmission of the Sidelink HARQ process a is the initial transmission or retransmission by whether the NDI in the PDCCH 1 is toggled: if the value of the NDI in the PDCCH 1 is the same as the above
  • the NDI in the PDCCH of Sidelink HARQ process a scheduled at one time is reversed, it means that the i-th transmission of Sidelink HARQ process a is the initial transmission; otherwise, it means that the i-th transmission of Sidelink HARQ process a is retransmission.
  • the so-called NDI inversion can mean that the value of NDI changes from 0 to 1, or from 1 to 0.
  • the first terminal device may transmit data a to the second terminal device through the Sidelink HARQ process a on the PSSCH resource indicated by the PDCCH 1, that is, perform the i-th transmission of the data a.
  • the second terminal device may receive the data a sent by the first terminal device on the PSSCH resource indicated by the PDCCH 1.
  • the second terminal device may learn the PSSCH resources on which the first terminal device will transmit data a by monitoring the PSCCH. Because, after receiving the PDCCH 1, the first terminal device can send sidelink control information (SCI) on the PSCCH. The second terminal device can receive the SCI by listening to the PSCCH. The SCI is used to indicate the resource for the first terminal device to transmit data a.
  • SCI sidelink control information
  • the first terminal device starts a first timer according to the time domain position of the PSSCH resource for the i-th transmission of the data a.
  • the manner in which the first terminal device starts the first timer refer to the record in FIG. 3 above, which will not be described here.
  • the first terminal device receives the HARQ feedback of the ith transmission of the Sidelink HARQ process a on the PSFCH resource, and the PSFCH resource can be used to carry the second terminal device to send the ith transmission of the Sidelink HARQ process a to the first terminal device.
  • HARQ feedback can be used to carry the second terminal device to send the ith transmission of the Sidelink HARQ process a to the first terminal device.
  • the first terminal device determines the HARQ feedback of the i-th transmission of the Sidelink HARQ process a.
  • the HARQ feedback of the ith transmission of the sidelink HARQ process a is used to indicate whether the reception of the ith transmission of the data a is successful or not. How to determine whether the reception of the i-th transmission of data a is successful or not will be described later.
  • the first terminal device starts or does not start or stops the second timer according to the HARQ feedback of the i-th transmission of the Sidelink HARQ process a.
  • the first terminal device may determine the HARQ feedback of the i-th transmission of the Sidelink HARQ process a. If the first terminal device determines that the HARQ feedback of the ith transmission of the Sidelink HARQ process a is NACK, that is, it determines that the reception of the ith transmission of the Sidelink HARQ process a is unsuccessful, then when the first timer expires, the first terminal device The second timer can be started. During the running of the second timer, the first terminal device monitors the PDCCH.
  • the first terminal device determines that the HARQ feedback of the ith transmission of the Sidelink HARQ process a is ACK, that is, it determines that the reception of the ith transmission of the Sidelink HARQ process a is successful, the first terminal device directly stops the first timer, and also There is no longer a situation where the first timer expires, and the second timer is no longer started, or the first terminal device may not stop the first timer, but when the first timer expires, the second timer is no longer started.
  • the first terminal device before the first timer expires, the first terminal device cannot determine the HARQ feedback of the i-th transmission of the Sidelink HARQ process a. Since the first timer has timed out, the second timer has been started. During the running of the second timer, if the first terminal device determines that the HARQ feedback of the i-th transmission of Sidelink HARQ process a is NACK, it is determined that the sidelink HARQ process a The reception of the i-th transmission is unsuccessful, and the first terminal device does not stop the second timer. During the running of the second timer, the first terminal device monitors the PDCCH.
  • the first terminal device determines that the HARQ feedback of the ith transmission of Sidelink HARQ process a is ACK, that is, it determines that the reception of the ith transmission of Sidelink HARQ process a is successful, the first terminal device directly Stop the second timer and no longer monitor the PDCCH.
  • the resource indicated by PDCCH 2 can be the resource scheduled by the network device for the i+1th transmission of Sidelink HARQ process a, that is, PDCCH 2 can be used to schedule the i+1th transmission of Sidelink HARQ process a.
  • Transfers. PDCCH 2 can carry the following information: SL grant 2, NDI, Sidelink HARQ process a ID.
  • SL grant 2 is the resource scheduled by the network device for the i+1th transmission of the Sidelink HARQ process a.
  • the NDI may indicate whether the i+1th transmission of the Sidelink HARQ process a scheduled by the PDCCH 2 is an initial transmission (initial transmission) or a retransmission (retransmission).
  • the i+1th transmission is a retransmission with respect to the i-th transmission, and the i-th transmission is the previous transmission of the i+1th transmission.
  • the second timer can be stopped.
  • the resource indicated by the PDCCH 2 may be the resource scheduled by the network device for the initial transmission of the Sidelink HARQ process a.
  • the Sidelink HARQ process a is associated with new data, such as data b. That is, the Sidelink HARQ process a has been used for the first terminal device to transmit new data instead of data a.
  • this possible situation can occur when the transmission of data a has reached the maximum number of transmissions (for example, 5 times). In this case, the first terminal device can also stop the second timer.
  • the first terminal device may transmit data a to the second terminal device through the Sidelink HARQ process a on the resource indicated by the PDCCH 2, that is, perform the (i+1)th transmission of the data a.
  • the second terminal device can receive the data a sent by the first terminal device on the resource indicated by the PDCCH 2.
  • the first terminal device can start the first timer, and start the second timer according to the HARQ feedback of the i-th transmission of the Sidelink HARQ process a, or, Do not start or stop the second timer. Specifically, before the first timer expires, the first terminal device may determine the HARQ feedback of the i-th transmission of the Sidelink HARQ process a. If the first terminal device determines that the HARQ feedback of the i-th transmission of the Sidelink HARQ process a is NACK, when the first timer expires, the first terminal device may start the second timer.
  • the first terminal device determines that the HARQ feedback of the i-th transmission of the Sidelink HARQ process a is an ACK, the first terminal device no longer starts the second timer. Before the first timer expires, the first terminal device cannot determine the HARQ feedback of the ith transmission of Sidelink HARQ process a. During the operation of the second timer, if the first terminal device determines the ith time of Sidelink HARQ process a The transmitted HARQ feedback is NACK, and the first terminal device does not stop the second timer.
  • the first terminal device determines that the HARQ feedback of the i-th transmission of the Sidelink HARQ process a is an ACK, the first terminal device directly stops the second timer.
  • the above solution of directly starting the second timer when the first timer expires can reduce the power consumption of the first terminal device.
  • one PDCCH is used to schedule sidelink data transmission as an example for description.
  • one PDCCH may also schedule multiple transmissions of one Sidelink data, for example, it may be 2 or 3 times.
  • one PDCCH schedules multiple transmissions of sidelink data one PDCCH can indicate multiple PSSCH resources.
  • the first time domain position is determined according to the time domain position of the PSSCH resource, and the first timer is started.
  • determining the first time domain position according to the time domain position of transmitting the first repetition PSSCH resource, starting the first timer, and specifically how to determine the first time domain position refer to the description in S307 or S407 ,No longer.
  • the above is only illustrative. It is also possible to determine the first time domain position according to the time domain position of the last repeated PSSCH resource, start the first timer, or even determine the time domain position of any repeated PSSCH resource.
  • a time domain position, starting the first timer, etc., are not limited.
  • the first repetition refers to the first transmission among multiple transmissions of one Sidelink data scheduled by the PDCCH.
  • Embodiment (3) of the present application provides another possible implementation manner, which may correspond to the above-mentioned second solution, and the solution may be: the network device sends the first DCI to the first terminal device , The first DCI is used to schedule the first terminal device to perform the initial transmission or retransmission of the Sidelink data.
  • the first terminal device uses the PSSCH resource to send the Sidelink data to the second terminal device according to the scheduling of the first DCI.
  • the second terminal device After receiving the Sidelink data, the second terminal device sends HARQ feedback to the first terminal device.
  • the first terminal device uses the PSFCH resource to receive the above HARQ feedback. And according to the HARQ feedback and the time domain position of the PSFCH resource, the first timer is turned on or not. Further, in the case of starting the first timer, when the first timer expires, the second timer is started. And during the operation of the second timer, the first terminal device is in the active state and monitors the PDCCH.
  • the first terminal device maintains two timers for each Sidelink HARQ process: the first timer and the second timer. Two timers.
  • the foregoing process can also be described as: the first terminal device associates two timers for each Sidelink HARQ process, namely, the first timer and the second timer.
  • the first timer may be named drx-HARQ-RTT-TimerSL; the second timer may be named drx-RetransmissionTimerSL.
  • the first terminal device monitors the PDCCH.
  • the naming of the first timer and the second timer may also be other, which is not limited in this application.
  • Fig. 5 shows the specific flow of the communication method provided in the third embodiment.
  • S501 Establish an RRC connection between the first terminal device and the network device.
  • the first terminal device After the RRC connection is established, the first terminal device enters the RRC connected state.
  • S502 Establish a Sidelink between the first terminal device and the second terminal device.
  • the first terminal device After the Sidelink is established, the first terminal device transmits data to the second terminal device through the Sidelink.
  • the network device configures the DRX cycle for the first terminal device in the RRC connected state.
  • DRX cycle is composed of "On Duration” and "Opportunity for DRX": in “On Duration”, the first terminal device monitors and receives PDCCH (active state); in “Opportunity for DRX", the first terminal device does not receive PDCCH to Save power consumption (sleep state).
  • the network device configures timers for the first terminal device in the RRC connected state: drx-InactivityTimer, drx-HARQ-RTT-TimerSL, drx-RetransmissionTimerSL.
  • the drx-HARQ-RTT-TimerSL may be referred to as the first timer
  • the drx-RetransmissionTimerSL may be referred to as the second timer.
  • S502 may also be executed before S501.
  • this application does not limit it.
  • the first terminal device may also send a resource scheduling request to the network device to request the network device to schedule transmission resources for Sidelink data transmission.
  • the resource scheduling request may carry a buffer status report to indicate how much Sidelink data the first terminal device has to send on the Sidelink.
  • the network device can transmit scheduling resources for the Sidelink, and deliver the scheduled resources in the PDCCH.
  • the first terminal device can learn the resources scheduled by the network device by monitoring the PDCCH.
  • the first terminal device may monitor and receive the PDCCH 1 issued by the network device.
  • the PDCCH 1 may indicate the resource scheduled for the ith transmission of a certain Sidelink HARQ process (for example, Sidelink HARQ process a), that is, the PDCCH 1 can be used to schedule the ith transmission of the Sidelink HARQ process a.
  • Sidelink HARQ process a may be associated with data a.
  • the Sidelink HARQ process a can be used by the first terminal device to transmit data a to the second terminal device on the Sidelink established in S502.
  • Sidelink HARQ process a can maintain a state variable: CURRENT_SL_TX_NB.
  • CURRENT_SL_TX_NB may indicate the number of transmissions of data a
  • CURRENT_SL_TX_NB may be initialized to 0.
  • the initial value of the state variable CURRENT_SL_TX_NB associated with the Sidelink HARQ process a can be set to 0.
  • the first terminal device may increase the CURRENT_SL_TX_NB associated with the Sidelink HARQ process a by 1.
  • the PDCCH used to schedule the transmission of the Sidelink HARQ process a may indicate the transmission resources allocated by the network device to the Sidelink HARQ process a.
  • the first terminal device may transmit data a to the second terminal device through the Sidelink HARQ process a on the PSSCH resource indicated by the PDCCH 1, that is, perform the i-th transmission of the data a.
  • the second terminal device may receive the data a sent by the first terminal device on the PSSCH resource indicated by the PDCCH 1.
  • the second terminal device may learn the PSSCH resources on which the first terminal device will transmit data a by monitoring the PSCCH. Because, after receiving the PDCCH 1, the first terminal device can send the SCI on the PSCCH. The second terminal device can receive the SCI by listening to the PSCCH. The SCI is used to indicate the resource for the first terminal device to transmit data a.
  • the first terminal device receives the HARQ feedback of the ith transmission of the Sidelink HARQ process a on the PSFCH resource, and the PSFCH resource can be used to carry the second terminal device to send the ith transmission of the Sidelink HARQ process a to the first terminal device.
  • HARQ feedback can be used to carry the second terminal device to send the ith transmission of the Sidelink HARQ process a to the first terminal device.
  • the first terminal device determines the i-th transmission HARQ feedback of the Sidelink HARQ process a.
  • the ith transmission HARQ feedback of the Sidelink HARQ process a is used to indicate whether the reception of the ith transmission of the data a is successful or not. How to determine whether the reception of the i-th transmission of data a is successful or not will be described later.
  • the first terminal device starts or does not start the first timer according to the time domain position of the PSFCH resource of the HARQ feedback of the ith transmission of the Sidelink HARQ process a and the HARQ feedback of the ith transmission of the Sidelink HARQ process a.
  • the first terminal device determines that the HARQ feedback of the ith transmission of the Sidelink HARQ process a is NACK, that is, it determines that the reception of the ith transmission of the Sidelink HARQ process a is unsuccessful, then the first terminal The device is at the second time domain position and starts the first timer; if the first terminal device determines that the HARQ feedback of the ith transmission of the Sidelink HARQ process a is ACK, it determines that the reception of the ith transmission of the Sidelink HARQ process a is successful, Then the first terminal device is at the second time domain location and does not start the first timer. How to determine the second time domain position, there are the following possible implementation methods:
  • the PSFCH resources include time domain resources and frequency domain resources.
  • the time domain resource of the PSFCH that receives the HARQ feedback of the i-th transmission of the Sidelink HARQ process a may occupy one or more time units.
  • the second time domain position where the first timer is started may be the first time unit after the last time unit in the time domain resource of the PSFCH resource that receives the HARQ feedback of the i-th transmission of the Sidelink HARQ process a. Or, it may be a time unit that is a second time domain offset from the last time unit in the time domain resource of the PSFCH resource that receives the HARQ feedback of the i-th transmission of the Sidelink HARQ process a.
  • the second time domain offset may include one or more time units.
  • the first terminal device may determine the second time domain position according to the time domain resource position and the second time domain offset of the PSFCH resource received from the HARQ feedback of the i-th transmission of the Sidelink HARQ process a .
  • start the first timer At the second time domain position, start the first timer.
  • the second time domain offset may be predefined by the protocol, or configured by the network device, or implemented internally by the first terminal device.
  • the network device uses SL-PSFCH-Config signaling Carrying the configuration of the second time domain offset, the specific configuration method of the second time domain offset, configuration signaling, and the naming of the second time domain offset are not limited.
  • the second time domain position may be a time domain offset from the end position of the time domain resource of the PSFCH resource that receives the HARQ feedback of the i-th transmission of the Sidelink HARQ process a.
  • the first terminal device starts the first timer at the first time unit after the HARQ feedback of the i-th transmission of data a is received on the PSFCH resource.
  • the first terminal device starts the first timer at the first time unit after receiving the end position of the PSFCH resource of the HARQ feedback of the i-th transmission of the Sidelink HARQ process a.
  • the concept of the second time domain offset is not defined, and the first terminal device will receive the end position of the time domain resource of the PSFCH resource after the HARQ feedback of the i-th transmission of the Sidelink HARQ process a
  • the first time unit is used as the second time domain position, and at the second time domain position, the first timer is started.
  • the first terminal device determines that the state variable CURRENT_SL_TX_NB associated with the Sidelink HARQ process a indicates the number of transmissions of the Sidelink HARQ process a; Whether it exceeds the maximum number of transmissions or the preset number of transmissions.
  • the first terminal device reports the HARQ feedback in the second time domain according to the i-th transmission of the Sidelink HARQ process a and is turned on or not turned on The first timer; for example, if the HARQ feedback of the i-th transmission of the Sidelink HARQ process a is ACK, that is, it is determined that the i-th transmission of the Sidelink HARQ process a is successfully received, then the first terminal device is not turned on at the second time domain position The first timer.
  • the first terminal device If the HARQ feedback of the ith transmission of the Sidelink HARQ process a is NACK, that is, it is determined that the ith transmission of the Sidelink HARQ process a has failed, the first terminal device starts the first timer at the second time domain position.
  • the state variable CURRENT_SL_TX_NB associated with the Sidelink HARQ process a is greater than the maximum number of transmissions or the preset number of transmissions, the first terminal device is at the second time domain position and no longer starts the first timer.
  • the first timer may be started, or the first timer may not be started, which is not limited.
  • the maximum transmission times and the preset transmission times may be specified in the protocol, or configured by the network device, or implemented internally by the first terminal device, and are not limited.
  • the first terminal device may start the second timer. During the running of the second timer, the first terminal device monitors the PDCCH.
  • the first terminal device may stop the second timer.
  • the resource indicated by PDCCH 2 can be the resource scheduled by the network device for the i+1th transmission of Sidelink HARQ process a, that is, PDCCH 2 can be used to schedule the i+1th transmission of Sidelink HARQ process a. Transfers.
  • the i+1th transmission is a retransmission with respect to the i-th transmission, and the i-th transmission is the previous transmission of the i+1th transmission.
  • the second timer can be stopped.
  • the resource indicated by the PDCCH 2 may be the resource scheduled by the network device for the initial transmission of the Sidelink HARQ process a.
  • the Sidelink HARQ process a is associated with new data, such as data b. That is, the Sidelink HARQ process a has been used for the first terminal device to transmit new data instead of data a.
  • this possible situation can occur when the transmission of data a has reached the maximum number of transmissions (for example, 5 times). In this case, the first terminal device can also stop the second timer.
  • the first terminal device may transmit data a to the second terminal device through the Sidelink HARQ process a on the resource indicated by the PDCCH 2, that is, perform the i+1th transmission of the data a.
  • the second terminal device can receive the data a sent by the first terminal device on the resource indicated by the PDCCH 2.
  • the first terminal device turns on or off the time domain position of the PSFCH resource based on the HARQ feedback of the ith transmission of the Sidelink HARQ process a and the HARQ feedback of the ith transmission of the Sidelink HARQ process a.
  • Start the first timer For example, when the HARQ feedback of the i-th transmission of the Sidelink HARQ process a is ACK, the first terminal device may no longer start the first timer.
  • the HARQ feedback of the i-th transmission of the Sidelink HARQ process a is NACK, the first terminal device starts the first counter, and when the first timer times out, starts the second timer.
  • the first terminal device is in the active state and can monitor and receive the PDCCH issued by the network device during this period for scheduling the retransmission of the Sidelink process a. In this way, not only can the retransmission efficiency of the Sidelink process a be improved, but the delay of the retransmission of the Sidelink data can be avoided. Further, the power consumption of the first terminal device can be reduced.
  • the process in which the first terminal device determines that the HARQ feedback of the Sidelink HARQ process a is ACK or NACK first introduce the following HAQR feedback in several communication modes.
  • the RX UE may feed back HARQ to the TX UE every time it receives a data packet sent by the TX UE.
  • the RX UE successfully receives the data packet and the decoding is correct, it will feed back an ACK to the TX UE, otherwise it will feed back a NACK.
  • HARQ feedback modes are divided into two types.
  • the first is the NACK-only feedback method.
  • the RX UE in a group only feeds back NACK to TX UE, not ACK.
  • the TX UE receives at least one NACK, it considers the HARQ feedback of this data packet to be NACK. If the TX does not receive the HARQ feedback, it is considered that the HARQ feedback of this data packet is ACK.
  • the second is the HARQ feedback mode of ACK-NACK.
  • the RX UE in a group can either feed back ACK or NACK to the TXUE.
  • the NACK-only feedback method may refer to a location-based (distance-based) NACK-only feedback, or it may refer to a non-distance-based NACK-only feedback.
  • location-based NACK-only feedback means that when the TX UE can obtain location information, only RX UEs within a location range can be indicated by the SCI to perform NACK-only feedback, which can avoid receiving long-distance RX UEs. The sent NACK caused unnecessary retransmissions.
  • SL LCH sidelink logical channel
  • SL-HARQ-Feedback-Enabled parameter of an SL LCH is configured as Enable, it means that the SL LCH supports HARQ feedback. If the SL-HARQ-Feedback-Enabled parameter of an SL LCH is configured as Disable, it means that the SL LCH does not support HARQ feedback.
  • the logical channel prioritization process cannot multiplex SL LCHs with different HARQ attributes into a media access control (media access control, MAC) protocol data unit (protol data unit, PDU). )in.
  • media access control media access control
  • PDU protocol data unit
  • the TX UE can set the HARQ feedback bit in the SCI to enable, and request the RX UE to perform HARQ feedback on the MAC PDU.
  • the TX UE can set the HARQ feedback bit in the SCI to disable, requesting the RX UE not to perform HARQ feedback on the MAC PDU.
  • the first terminal device can determine that the HARQ feedback of the ith transmission of the Sidelink HARQ process a is NACK, and can determine that the reception of the ith transmission of the Sidelink HARQ process a is unsuccessful:
  • Case 1 In the unicast communication mode, the HARQ feedback sent by the second terminal device received by the first terminal device is NACK.
  • the HARQ feedback is used to indicate whether the i-th transmission of the data a associated with the Sidelink HARQ process a is successfully received by the second terminal device.
  • the HARQ feedback is NACK, it may indicate that the second terminal device has not successfully received the i-th transmission of the data a associated with the Sidelink HARQ process a.
  • the second terminal device did not successfully receive the i-th transmission of the data a associated with the Sidelink HARQ process a.
  • the reasons may include but are not limited to: the second terminal device did not successfully decode the data a.
  • Case 2 In the unicast communication mode or the ACK-NACK feedback mode of the multicast communication mode, the first terminal device does not receive the HARQ feedback sent by the second terminal device.
  • the first terminal device does not receive the HARQ feedback of the i-th transmission of the data a associated with the Sidelink HARQ process a sent by the second terminal device, which may specifically refer to the PSFCH associated with the first terminal device in the Sidelink HARQ process a
  • the resource does not receive the HARQ feedback of the i-th transmission of the data a associated with the Sidelink HARQ process a sent by the second terminal device.
  • the PSFCH resource associated with the sidelink HARQ process a can be configured by the network device.
  • Case 3 The first terminal device does not transmit the Sidelink data to the second terminal device on the PSSCH resource.
  • the PSSCH resource is a resource scheduled by the network device for the i-th transmission of the Sidelink HARQ process a.
  • the cause of case 3 may be resource conflict, that is, the first terminal device transmits other data on the PSSCH resource instead of data a.
  • Case 3 is applicable to unicast communication mode, or NACK-only feedback or ACK-NACK feedback in multicast communication mode.
  • Case 4 In the NACK-only feedback mode of the multicast communication mode, the first terminal device receives at least one NACK feedback for the i-th transmission of the Sidelink HARQ process a.
  • the first terminal device may send the data a to at least one terminal device (including the second terminal device) in the multicast transmission mode. For any one of the above-mentioned at least one terminal device, if the data a is successfully received, the HARQ is no longer fed back. If receiving data a fails, NACK is fed back. When the first terminal device receives the NACK sent by any terminal device, it is considered that the transmission of the current data a has failed.
  • Case 5 In the ACK-NACK feedback mode of the multicast transmission mode, the first terminal device receives at least one NACK feedback and/or at least one discontinuous transmission (DTX) for the i-th transmission of the Sidelink HARQ process a
  • the DTX means that the first terminal device does not receive the HARQ feedback sent by any terminal device in the group.
  • the first terminal device may send the data a to at least one terminal device (including the second terminal device) in the multicast transmission mode. If any one of the aforementioned at least one terminal device successfully receives the aforementioned data a, it will feed back an ACK to the first terminal device, otherwise it will feed back a NACK to the first terminal device. Therefore, if the first terminal device receives a NACK sent by any terminal device, it is considered that the transmission of the current data a has failed. Or, since any one of the aforementioned at least one terminal device, after receiving the data a, it will feed back ACK or NACK to the first terminal device. Therefore, if the first terminal device does not receive the HARQ feedback of any terminal device in the group, it can be considered that the current transmission of data a has failed.
  • the first terminal device can determine that the HARQ feedback of the i-th transmission of Sidelink HARQ process a is ACK, and it can determine that the reception of the i-th transmission of Sidelink HARQ process a is successful:
  • Case 1 In the unicast communication mode, the HARQ feedback sent by the second terminal device received by the first terminal device is an ACK.
  • the HARQ feedback is ACK, it may indicate that the second terminal device successfully receives the i-th transmission of the Sidelink HARQ process a.
  • Case 2 In the NACK-only feedback mode in the multicast communication mode, the first terminal device does not receive the NACK feedback for the i-th transmission of the Sidelink HARQ process a.
  • Case 3 In the ACK-NACK feedback mode in the multicast communication mode, the first terminal device transmits the i-th sidelink HARQ process a, and the received HARQ feedback is all ACK feedback, that is, all the members in the multicast group The feedback from the terminal equipment at the receiving end is ACK.
  • the first terminal device In unicast communication mode, or NACK-only feedback in multicast communication mode or ACK-NACK feedback in multicast communication mode, if the HARQ attribute of data a associated with Sidelink HARQ process a is disabled, the first The terminal device disables the HARQ feedback bit in the SCI, that is, the first terminal device instructs the second terminal device not to perform HARQ feedback for the i-th transmission of the Sidelink HARQ process a. Therefore, the first terminal device cannot receive the HARQ feedback of the i-th transmission of the Sidelink HARQ process a from the second terminal device.
  • the first terminal device may determine that the HARQ feedback of the i-th transmission of Sidelink HARQ process a is NACK, or determine that the HARQ feedback of the i-th transmission of Sidelink HARQ process a is ACK, which is not limited.
  • the specific determination that the HARQ feedback of the i-th transmission of the Sidelink HARQ process a is NACK or ACK depends on the internal implementation of the first terminal device.
  • the embodiment of the present application also provides a communication method, which can correspond to the third solution mentioned above.
  • no timer is introduced, and the first terminal device can send the Sidelink data according to the time domain position of the PSSCH resource, Directly monitor the PDCCH of the network device.
  • Fig. 6 shows the specific flow of the communication method of the fourth embodiment.
  • S601 Establish an RRC connection between the first terminal device and the network device. After the RRX connection is established, the first terminal device can enter the RRC connection state.
  • S602 Establish a Sidelink between the first terminal device and the second terminal device. After the Sidelink is established, the first terminal device can transmit data to the second terminal device through the Sidelink.
  • the network device configures the DRX cycle for the first terminal device in the RRC connected state.
  • DRX cycle consists of "On Duration” and "Opportunity for DRX”: in “On Duration”, the first terminal device monitors and receives PDCCH (active state); in “Opportunity for DRX", the first terminal device does not monitor PDCCH To save power consumption (sleep state).
  • the first terminal device may also send a resource scheduling request to the network device to request the network device to schedule transmission resources for Sidelink data transmission.
  • the resource scheduling request may carry a buffer status report to indicate how much Sidelink data the first terminal device has to send on the Sidelink.
  • the network device can transmit scheduling resources for the Sidelink, and deliver the scheduled resources in the PDCCH.
  • the first terminal device can learn the resources scheduled by the network device by monitoring the PDCCH.
  • the first terminal device may monitor and receive the PDCCH1 issued by the network device.
  • PDCCH1 may indicate the resource scheduled for the i-th transmission of a certain Sidelink HARQ process (such as Sidelink HARQ process a), that is, PDCCH1 can be used to schedule the i-th transmission of Sidelink HARQ process a.
  • Sidelink HARQ process a such as Sidelink HARQ process a
  • Sidelink HARQ process a may be associated with data a.
  • the Sidelink HARQ process a can be used by the first terminal device to transmit data a to the second terminal device on the Sidelink established in S602.
  • Sidelink HARQ process a can maintain a state variable: CURRENT_SL_TX_NB.
  • CURRENT_SL_TX_NB may indicate the number of transmissions of data a
  • CURRENT_SL_TX_NB may be initialized to 0.
  • the initial value of the state variable CURRENT_SL_TX_NB associated with the sidelink HARQ process a can be set to 0.
  • the first terminal device may increase the CURRENT_SL_TX_NB associated with the Sidelink HARQ process a by 1.
  • the PDCCH used to schedule the transmission of the Sidelink HARQ process a may indicate the transmission resources allocated by the network device to the Sidelink HARQ process a.
  • the first terminal device may transmit data a to the second terminal device through the Sidelink HARQ process a on the PSSCH resource indicated by the PDCCH1, that is, perform the i-th transmission of the data a.
  • the second terminal device can receive the data a sent by the first terminal device on the PSSCH resource indicated by the PDCCH1.
  • the first terminal device starts to monitor the PDCCH according to the time domain position of the PSSCH resource for the i-th transmission of the data a.
  • PSSCH resources include time domain resources and frequency domain resources.
  • the time domain resource of the PSSCH for the i-th transmission of data a may occupy one or more time units.
  • the third time domain position where the first terminal device monitors the PDCCH may be the first time unit after the last time unit in the time domain resources of the PSSCH for the i-th transmission of data a.
  • the third time domain position for monitoring the PDCCH may be a time unit offset from the last time domain unit in the time domain resource of the PSSCH transmitted for the i-th time from the third time domain.
  • the third time domain offset may include one or more time units.
  • the first terminal device may determine the third time domain position according to the time domain resource position of the PSSCH resource for the i-th transmission of data a and the third time domain offset. At the third time domain position, start monitoring the PDCCH.
  • the third time domain offset may be specified by the protocol, or configured by the network device, or implemented internally by the first terminal device, and is not limited.
  • the network device can carry the configuration information of the third time domain offset, etc. through SL-PSSCH-Config signaling.
  • the configuration mode of the third time domain offset, configuration signaling, and the naming of the third time domain offset are not limited.
  • the third time domain offset may be a time domain offset from the end position of the time domain resource of the PSSCH resource for the i-th transmission of the data a.
  • the first terminal device may monitor the PDCCH at the first time unit after the i-th transmission of data a is sent on the PSSCH resource.
  • the concept of the third time domain offset is not defined, and the first terminal device will perform the first time unit after the end position of the time domain resource of the PSSCH resource for the i-th transmission of data a , As the third time domain position, and at the third time domain position, start monitoring the PDCCH.
  • the first terminal device monitors the PDCCH, and can also meet the following conditions: the first terminal device determines that the state variable CURRENT_SL_TX_NB associated with the Sidelink HARQ process a indicates the number of transmissions of the Sidelink HARQ process a; whether it exceeds the maximum number of transmissions or is preset Number of transfers.
  • the first terminal device When the state variable CURRENT_SL_TX_NB associated with the Sidelink HARQ process a is less than the maximum number of transmissions or the preset number of transmissions, the first terminal device is at the third time domain position according to the i-th transmission HARQ feedback of the Sidelink HARQ process a and monitors the PDCCH; otherwise , In the third time domain position, no longer monitor the PDCCH. It should be noted that when the state variable CURRENT_SL_TX_NB associated with the Sidelink HARQ process a is equal to the maximum number of transmissions or the preset number of transmissions, the first terminal device may monitor the PDCCH, or the first terminal device may not monitor the PDCCH, which is not limited.
  • the maximum transmission times and the preset transmission times may be specified in the protocol, or configured by the network device, or implemented internally by the first terminal device, and are not limited.
  • S607 The first terminal device receives PDCCH2.
  • the resource indicated by PDCCH2 can be the resource scheduled by the network device for the i+1th transmission of Sidelink HARQ process a, that is, PDCCH2 can be used to schedule the i+1th transmission of Sidelink HARQ process a .
  • the i+1th transmission is a retransmission relative to the i-th transmission, and the i-th transmission is relative to the previous transmission of the i+1th transmission.
  • the resource indicated by the PDCCH2 may be a resource scheduled by the network device for the initial transmission of the Sidelink HARQ process a.
  • the Sidelink HARQ process a is associated with new data, such as data b. That is, the Sidelink HARQ process a has been used for the first terminal device to transmit new data instead of data a.
  • the first terminal device may also stop the second timer.
  • the first terminal device may stop monitoring the PDCCH. After that, the first terminal device may perform the i+1th transmission of the Sidelink HARQ process a to the second terminal device according to the scheduling of the PDCCH2.
  • the first terminal device may stop monitoring the PDCCH at a preset moment.
  • the preset time may be specified by the protocol, or configured by the network device, or based on the internal implementation of the first terminal device, and is not limited.
  • the above scheme can be applied to both point-to-point unicast transmission and point-to-multipoint multicast transmission. It can be applied to the situation where PSFCH resources are configured, and it can also be applied to situations where PSFCH resources are not configured. , Not limited.
  • no timer is introduced, and the first terminal device directly monitors the PDCCH of the network device according to the time domain position of the PSSCH resource.
  • This method can also reduce the transmission delay of Sidelink data and meet the QoS requirements of Sidelink services.
  • one PDCCH is used to schedule sidelink data transmission as an example for description.
  • one PDCCH can also schedule multiple transmissions of one Sidelink data.
  • one PDCCH can indicate multiple PSSCH resources.
  • the time domain position of the PSSCH resource of the first terminal device is determined, the third time domain position is determined, and the PDCCH is started to be monitored. Domain location, determine the third time domain location, and start monitoring the PDCCH. For details on how to determine the third time domain location, please refer to the description in S606, which will not be repeated. Of course, the above is only illustrative.
  • the embodiment of the present application also provides a communication method, which can correspond to the above-mentioned fourth solution. In this solution, no timer is introduced, and the first terminal device can receive HARQ feedback on the PSFCH resource according to the PSFCH The time domain location of the resource directly monitors the PDCCH.
  • S701 Establish an RRC connection between the first terminal device and the network device.
  • the first terminal device After the RRC connection is established, the first terminal device enters the RRC connected state.
  • S702 Establish a Sidelink between the first terminal device and the second terminal device.
  • the first terminal device can transmit data to the second terminal device through the Sidelink.
  • the network device configures a DRX cycle for the first terminal device in the RRC connected state.
  • the DRX cycle is composed of "On Duration” and "Opportunity for DRX": in “On Duration”, the first terminal device monitors and receives the PDCCH (active state); in “Opportunity for DRX", the first terminal device Do not monitor PDCCH (sleep state).
  • the first terminal device may also send a resource scheduling request to the network device to request the network device to schedule transmission resources for Sidelink data transmission.
  • the resource scheduling request may carry a buffer status report to indicate how much Sidelink data the first terminal device has to send on the Sidelink.
  • the network device can transmit scheduling resources for the Sidelink, and deliver the scheduled resources in the PDCCH.
  • the first terminal device can learn the resources scheduled by the network device by monitoring the PDCCH.
  • the first terminal device may monitor and receive the PDCCH1 issued by the network device.
  • PDCCH1 may indicate the resource scheduled for the i-th transmission of a certain Sidelink HARQ process (such as Sidelink HARQ process a), that is, PDCCH1 can be used to schedule the i-th transmission of Sidelink HARQ process a.
  • Sidelink HARQ process a such as Sidelink HARQ process a
  • Sidelink HARQ process a may be associated with data a.
  • the Sidelink HARQ process a can be used by the first terminal device to transmit data a to the second terminal device on the Sidelink established in S702.
  • Sidelink HARQ process a can maintain a state variable: CURRENT_SL_TX_NB.
  • CURRENT_SL_TX_NB may indicate the number of transmissions of data a
  • CURRENT_SL_TX_NB may be initialized to 0.
  • the initial value of the state variable CURRENT_SL_TX_NB associated with the sidelink HARQ process a can be set to 0.
  • the first terminal device may increase the CURRENT_SL_TX_NB associated with the Sidelink HARQ process a by 1.
  • the PDCCH used to schedule the transmission of the Sidelink HARQ process a may indicate the transmission resources allocated by the network device to the Sidelink HARQ process a.
  • the first terminal device may transmit data a to the second terminal device through the Sidelink HARQ process a on the PSSCH resource indicated by the PDCCH1, that is, perform the i-th transmission of the data a.
  • the second terminal device can receive the data a sent by the first terminal device on the PSSCH resource indicated by the PDCCH1.
  • the second terminal device may learn the PSSCH resources on which the first terminal device will transmit data a by monitoring the PSCCH. Therefore, after receiving the PDCCH1, the first terminal device can send the SCI on the PSCCH. The second terminal device can receive the SCI by listening to the PSCCH. The SCI is used to indicate the resource for the first terminal device to transmit data a.
  • the first terminal device receives the HARQ feedback of the i-th transmission of the Sidelink HARQ process a on the PSFCH resource, and the PSFCH resource can be used to carry the second terminal device to send the i-th transmission of the Sidelink HARQ process a to the first terminal device.
  • HARQ feedback can be used to carry the second terminal device to send the i-th transmission of the Sidelink HARQ process a to the first terminal device.
  • the first terminal device determines the HARQ feedback for the i-th transmission of the Sidelink HARQ process a.
  • the ith transmission HARQ feedback of the Sidelink HARQ process a is used to indicate whether the reception of the ith transmission of the data a is successful or not.
  • the process for the first terminal device to determine whether the HARQ feedback of the i-th transmission of the Sidelink HARQ process a is successful refer to the above description, which will not be described here.
  • the first terminal device monitors or does not monitor the PDCCH according to the time domain position of the PSFCH resource of the HARQ feedback of the ith transmission of the Sidelink HARQ process a and the HARQ feedback of the ith transmission of the Sidelink HARQ process a.
  • the PDCCH2 can be used to schedule the i+1th transmission of the Sidelink HARQ process a.
  • the first device may transmit data a to the second terminal device through the Sidelink HARQ process a on the PSSCH resource indicated by the PDCCH2, that is, perform the i+1th transmission of the data a.
  • the first terminal device may determine the fourth time domain position according to the time domain position of the PSFCH resource fed back by the HARQ for the i-th transmission of the Sidelink HARQ process a; the first terminal device is at the fourth time domain position and monitors the PDCCH. After that, when the first terminal device monitors and receives PDCCH2, the first terminal device stops monitoring the PDCCH. Alternatively, the first terminal device may stop monitoring the PDCCH at a preset moment. The preset time may be specified in the protocol, or configured by the network device, or implemented internally by the first terminal device, etc., and is not limited.
  • the first terminal device may determine the fourth time domain position according to the time domain resource position and the fourth time domain offset of the PSFCH resource fed back by the HARQ that receives the i-th transmission of the Sidelink HARQ process a.
  • the PDCCH is monitored.
  • the fourth time domain offset may be predefined by the protocol, or configured by the network device, or implemented internally by the first terminal device, etc., and is not limited.
  • the network device carries the configuration of the fourth time domain offset through the SL-PSFCH-Config signaling, the specific configuration method of the fourth time domain offset, the configuration signaling, and the configuration of the fourth time domain offset.
  • the naming of the offset is not limited.
  • the fourth time domain position may be a time domain offset from the end position of the time domain resource of the PSFCH resource that receives the HARQ feedback of the i-th transmission of the Sidelink HARQ process a.
  • the fourth time domain offset is 0, the first terminal device monitors the PDCCH at the first time unit after the HARQ feedback of the i-th transmission of data a is received on the PSFCH resource. Or, it can be described as that the first terminal device monitors the PDCCH in the first time unit after the end position of the PSFCH resource of the HARQ feedback of the i-th transmission of the Sidelink HARQ process a.
  • the concept of the fourth time domain offset is not defined, and the first terminal device will receive the end position of the time domain resource of the PSFCH resource after the HARQ feedback of the i-th transmission of the Sidelink HARQ process a
  • the first time unit is used as the fourth time domain position, and at the fourth time domain position, the PDCCH is monitored.
  • the first terminal device determines that the HARQ feedback of the ith transmission of the Sidelink HARQ process a is ACK, that is, it determines that the reception of the ith transmission of the Sidelink HARQ process a is successful, then the first terminal The device no longer monitors the PDCCH at the fourth time domain position.
  • the first terminal device monitors the PDCCH, and can also meet the following conditions: the first terminal device determines that the state variable CURRENT_SL_TX_NB associated with the Sidelink HARQ process a indicates the number of transmissions of the Sidelink HARQ process a; whether it exceeds the maximum number of transmissions or is preset Number of transfers.
  • the first terminal device can listen to the HARQ feedback of the i-th transmission of the Sidelink HARQ process a at the fourth time domain position. Or the PDCCH is not monitored; for example, if the HARQ feedback of the ith transmission of the Sidelink HARQ process a is ACK, that is, it is determined that the ith transmission of the Sidelink HARQ process a is successfully received, the first terminal device may not monitor the PDCCH.
  • the first terminal device monitors the PDCCH.
  • the state variable CURRENT_SL_TX_NB associated with the Sidelink HARQ process a is greater than the maximum number of transmissions or the preset number of transmissions, the first terminal device is at the fourth time domain position and no longer monitors the PDCCH.
  • the first terminal device may monitor the PDCCH, or the first terminal device may not monitor the PDCCH, which is not limited.
  • the maximum transmission times and the preset transmission times may be specified in the protocol, or configured by the network device, or implemented internally by the first terminal device, and are not limited.
  • no timer is introduced, and the first terminal device can directly monitor the PDCCH of the network device according to the time domain position of the PSFCH resource.
  • This method can also reduce the transmission delay of Sidelink data and meet the QoS requirements of Sidelink services.
  • the foregoing Embodiments 1 to 5 can be applied to the case where PUCCH resources are configured, and can also be applied to the case where PUCCH resources are not configured, and are not limited.
  • the configured PUCCH resource can also be referred to as the PSSCH resource (the PSSCH resource of the i-th transmission of data a) is associated with the PUCCH resource, and the PUCCH resource not configured can also be referred to as the PSSCH resource (the i-th transmission of data a).
  • the transmitted PSSCH resource) has no associated PUCCH resource.
  • the PUCCH resource may be a resource for the HARQ feedback of the i-th transmission of the data a sent by the first terminal device to the network device.
  • Embodiments 1 to 5 can be applied to the case of Sidelink transmission scheduled by dynamic DCI, that is, the i-th transmission of data a is Sidelink transmission dynamically scheduled by PDCCH, and can also be applied to pre-configured Sidelink authorization (configured In the case of Sidelink grant), that is, the i-th transmission of data a is the Sidelink transmission on the pre-configured Sidelink authorization.
  • the pre-configured Sidelink authorization may not have an associated PUCCH resource.
  • the PUSCCH resource may be used by the first terminal device to send the data a to the network device.
  • the HARQ feedback resource of the i-th transmission may be used by the first terminal device to send the data a to the network device.
  • the pre-configured Sidelink authorization may refer to the resources required for Sidelink transmission pre-configured by the network device for the terminal in the NR Sidelink.
  • the resources required for transmission of the pre-configured Sidelink may be referred to as Sidelink CG configuration, or pre-configured Sidelink authorization configuration.
  • the terminal can perform Sidelink transmission on the Sidelink CG configuration without the need for dynamic scheduling of network equipment.
  • Sidelink CG configuration includes, but is not limited to, two pre-configured authorized resources adopted by the fifth-generation mobile communication technology (5th-Generation, 5G).
  • the two pre-configured authorization resources used by 5G are obtained through two authorization methods respectively.
  • the two authorization methods include configured authorization method 1 (configured grant type 1) and configured authorization method 2 (configured grant type 2).
  • configuration authorization method 1 means that the network device pre-configures the resources required for uplink transmission (CG configuration) for the terminal through the semi-static configuration method, that is, the CG configuration activated by periodic configuration, which does not require the terminal to send uplink data every time. Both obtain the uplink authorization of the CG configuration from the network device.
  • the network device may configure a CG configuration for uplink transmission for the terminal through RRC signaling, and the RRC signaling may also include the period of the CG configuration.
  • Sidelink CG configuration it means that the network equipment pre-configures the resources required for Sidelink transmission (Sidelink CG configuration) for the terminal through a semi-static configuration method, that is, the Sidelink CG configuration activated by periodic configuration, which does not require the terminal to send Sidelink data every time.
  • a semi-static configuration method that is, the Sidelink CG configuration activated by periodic configuration, which does not require the terminal to send Sidelink data every time.
  • the network device may configure the Sidelink CG configuration for Sidelink transmission for the terminal through RRC signaling, and the RRC signaling may also include the period of the Sidelink_CG configuration.
  • Configuring authorization mode 2 means that the network device can configure part of the information used for uplink transmission for the terminal through RRC signaling, for example, the period of the CG configuration used for uplink transmission. Then, the network device activates the CG configuration through the physical layer signaling carrying the CG configuration for uplink transmission, so that the terminal can perform uplink transmission in the CG configuration.
  • the physical layer signaling includes DCI.
  • Sidelink configuration it means that the network device can configure part of the information used for Sidelink transmission for the terminal through RRC signaling, for example, the period of Sidelink_CG configuration used for Sidelink transmission. Then, the network device activates the Sidelink CG configuration through the physical layer signaling carrying the CG configuration used for Sidelink transmission, so that the terminal can perform Sidelink transmission in the Sidelink CG configuration.
  • the physical layer signaling includes DCI.
  • the naming of the above two authorization modes is not limited to configuration authorization mode 1 and configuration authorization mode 2, and other naming is also possible, and the embodiment of the present application does not limit the naming of these two authorization modes.
  • the communication system to which the above two authorization methods are applicable can also be an LTE communication system or other communication systems. The embodiments of the present application do not limit the communication systems to which these two authorization methods are applicable.
  • FIG. 8 is a schematic block diagram of an apparatus 800 provided by an embodiment of the present application, which is used to implement the function of the first terminal device in the foregoing method embodiment.
  • the device can be a software unit or a chip system.
  • the chip system can be composed of chips, and can also include chips or other discrete devices.
  • the device may include a communication unit 801 for communicating with the outside.
  • the device may also include a processing unit 802 for processing.
  • the foregoing apparatus 800 is used to implement the steps of the first terminal device in the first embodiment and the second embodiment of the foregoing method.
  • the apparatus 800 may be a terminal device, or a chip or circuit configured in the terminal device.
  • the communication unit 801 is configured to perform the transceiving-related operations on the first terminal device side in the first embodiment or the second embodiment, and the processing unit 802 is configured to perform processing related operations on the first terminal device side in the first embodiment or the second embodiment.
  • the communication unit 801 is configured to receive first downlink control information DCI from a network device, where the first DCI is used to schedule initial transmission or retransmission of sidelink sidelink data, and the Sidelink hybrid associated with the Sidelink data
  • the automatic repeat request HARQ process is associated with two timers, namely the first timer and the second timer; the processing unit 802 is configured to use the physical side uplink shared channel PSSCH resource to transfer according to the scheduling of the first DCI
  • the second terminal device sends Sidelink data; the processing unit 802 is further configured to start a first timer according to the time domain position of the PSSCH resource, and start or not start the second timer according to the first timer; wherein In the case of starting the second timer, during the operation of the second timer, the first terminal device monitors the physical downlink control channel PDCCH.
  • the processing unit 802 starts the first timer according to the time domain position of the PSSCH resource, including: determining the first time domain position according to the time domain resource position of the PSSCH resource and the first time domain offset; Alternatively, the first time unit after the end position of the time domain resource of the PSSCH resource is used as the first time domain position; at the first time domain position, the first timer is started.
  • the processing unit 802 starts the first timer at the first time domain position, including: determining the number of transmissions of the Sidelink data associated with the Sidelink HARQ process; when the number of transmissions of the Sidelink data associated with the Sidelink HARQ process When the number of transmissions is less than or equal to the maximum number of transmissions or the preset number of transmissions, the first timer is started at the first time domain position.
  • the processing unit 802 is further configured to: when the number of transmissions of the Sidelink data associated with the Sidelink HARQ process is greater than the maximum number of transmissions or the preset number of transmissions, at the first time domain position, no longer open the second A timer.
  • the processing unit 802 turning on or not turning on the second timer according to the first timer includes: directly turning on the second timer when the first timer expires.
  • the processing unit 802 starts or does not start the second timer according to the first timer, including: before the first timer expires, determining that the HARQ feedback of the Sidelink HARQ process is a negative acknowledgement NACK , When the first timer expires, start the second timer; or, before the first timer expires, if it is determined that the HARQ feedback of the Sidelink HARQ process is a positive acknowledgement ACK, then directly stop If the first timer does not expire at this time, the second timer is not started again, or the first timer is not stopped, but the first timer is not stopped. When the timeout expires, the second timer is no longer started.
  • the processing unit 802 starts or does not start the second timer according to the first timer, including: the HARQ feedback of the Sidelink HARQ process cannot be determined before the first timer expires; When the first timer expires, the second timer is started.
  • the processing unit 802 is further configured to: during the operation of the second timer, if it is determined that the HARQ feedback of the Sidelink HARQ process is NACK, the second timer is not stopped, and the second timer is not stopped. During the operation of the second timer, continue to monitor the PDCCH; or, during the operation of the second timer, if it is determined that the HARQ feedback of the Sidelink HARQ process is ACK, the second timer is directly stopped , No longer monitor PDCCH.
  • the processing unit 802 is further configured to: during the operation of the second timer, if it monitors and receives a message for scheduling retransmission of the Sidelink data PDCCH, stop the second timer.
  • the foregoing apparatus 800 is used to implement the steps of the first terminal device in the third method embodiment above.
  • the apparatus 800 may be a terminal device, or a chip or circuit configured in the terminal device.
  • the communication unit 801 is configured to perform the transceiving-related operations on the first terminal device side in the third embodiment above
  • the processing unit 802 is configured to perform the processing related operations on the first terminal device side in the third embodiment above.
  • the communication unit 801 is configured to receive first downlink control information DCI from a network device, where the first DCI is used to schedule initial transmission or retransmission of sidelink sidelink data, and the Sidelink hybrid associated with the Sidelink data
  • the automatic repeat request HARQ process is associated with two timers, namely the first timer and the second timer; the first terminal device uses the physical side uplink shared channel PSSCH resource according to the scheduling of the first DCI The second terminal device sends Sidelink data; the communication unit 801 is also configured to use the physical side feedback channel PSFCH resource to receive HARQ feedback from the second terminal device on the Sidelink HARQ process, and the HARQ feedback is a positive confirmation ACK or negative acknowledgment NACK; a processing unit 802, configured to enable or disable the first timer according to the HARQ feedback and the time domain position of the PSFCH resource;
  • the first terminal device in the case of starting the first timer, when the first timer expires, the first terminal device starts a second timer, and during the operation of the second timer, the first A terminal device monitors the physical downlink control channel PDCCH.
  • the processing unit 802 starts or does not start the first timer according to the HARQ feedback and the time domain position of the PSFCH resource, including: according to the time domain resource position of the first PSFCH resource and the second time domain Offset, determine the second time domain position; or, use the first time unit after the end position of the time domain resource of the first PSFCH resource as the second time domain position; according to the HARQ feedback, In the second time domain position, the first timer is turned on or not.
  • the processing unit 802 starts or does not start the first timer at the second time domain position according to the HARQ feedback, including: determining that the HARQ feedback of the Sidelink HARQ process is ACK, Then, at the second time domain position, the first timer is not started; or, in the case where it is determined that the HARQ feedback of the Sidelink HARQ process is NACK, then at the second time domain position, the first timer is turned on. A timer.
  • the processing unit 802 starts the first timer at the second time domain position, including: determining the number of transmissions of the Sidelink data associated with the Sidelink HARQ process; if the Sidelink data associated with the Sidelink HARQ process If the number of transmissions is less than or equal to the maximum number of transmissions or the preset number of transmissions, the first timer is started at the second time domain position.
  • the processing unit 802 is further configured to: when the number of transmissions of the Sidelink data associated with the Sidelink HARQ process is greater than the maximum number of transmissions or the preset number of transmissions, then at the second time domain position, no longer open the The first timer.
  • the processing unit 802 is further configured to:
  • the second timer if a PDCCH for scheduling sidelink data retransmission of the first terminal device is monitored, the second timer is stopped.
  • the division of units in the embodiments of this application is illustrative, and is only a logical function division. In actual implementation, there may be other division methods.
  • the functional units in the various embodiments of this application can be integrated into one processing unit. In the device, it can also exist alone physically, or two or more units can be integrated into one unit.
  • the above-mentioned integrated unit can be implemented in the form of hardware or software functional unit.
  • the functions of the communication unit in the foregoing embodiments may be realized by a transceiver, and the functions of the processing unit may be realized by a processor.
  • the transceiver may include a transmitter and/or a receiver, etc., which are used to implement the functions of the transmitting unit and/or the receiving unit, respectively.
  • FIG. 9 The following description will be given with reference to FIG. 9 as an example.
  • the communication device 900 shown in FIG. 9 includes at least one processor 901.
  • the communication device 900 may also include at least one memory 902 for storing program instructions and/or data.
  • the memory 902 is coupled with the processor 901.
  • the coupling in the embodiments of the present application is an indirect coupling or communication connection between devices, units, or modules, which can be electrical, mechanical, or other forms, and is used for information exchange between devices, units, or modules.
  • the processor 901 may operate in cooperation with the memory 902, the processor 901 may execute program instructions stored in the memory 902, and at least one of the at least one memory 902 may be included in the processor 901.
  • the apparatus 900 may further include a communication interface 903 for communicating with other devices through a transmission medium, so that the communication apparatus 900 may communicate with other devices.
  • the communication interface may be a transceiver, circuit, bus, module, or other type of communication interface.
  • the transceiver when the communication interface is a transceiver, the transceiver may include an independent receiver and an independent transmitter; it may also be a transceiver with integrated transceiver functions, or an interface circuit.
  • connection medium between the processor 901, the memory 902, and the communication interface 903 is not limited in the embodiment of the present application.
  • the memory 902, the processor 901, and the communication interface 903 are connected by a communication bus 904 in FIG. 9.
  • the bus is represented by a thick line in FIG. , Not as a limitation.
  • the bus may include an address bus, a data bus, a control bus, and so on. For ease of representation, only one thick line is used in FIG. 9, but it does not mean that there is only one bus or one type of bus.
  • the apparatus 900 is used to implement the steps performed by the first terminal device in the first embodiment or the second embodiment of the foregoing method.
  • the communication interface 903 is used to perform the transceiving-related operations on the first terminal device side in the above embodiment
  • the processor 901 is used to perform the processing related operations on the first terminal device side in the first or second embodiment of the above method.
  • the communication interface 903 is configured to receive first downlink control information DCI from a network device, and the first DCI is used to schedule the initial transmission or retransmission of sidelink sidelink data, and the Sidelink hybrid associated with the Sidelink data
  • the automatic repeat request HARQ process is associated with two timers, the first timer and the second timer, respectively; the processor 901 is configured to use the physical side uplink shared channel PSSCH resource according to the scheduling of the first DCI
  • the second terminal device sends Sidelink data; the processor 901 is further configured to start a first timer according to the time domain position of the PSSCH resource, and enable or disable the second timer according to the first timer; wherein In the case of starting the second timer, during the operation of the second timer, the first terminal device monitors the physical downlink control channel PDCCH.
  • the processor 901 starts the first timer according to the time domain position of the PSSCH resource, including:
  • the first time domain position is determined according to the time domain resource position of the PSSCH resource and the first time domain offset; or, the first time unit after the end position of the time domain resource of the PSSCH resource is used as the first time unit A time domain position; at the first time domain position, start the first timer.
  • the processor 901 starts a first timer at the first time domain position, including: determining the number of times the Sidelink data associated with the Sidelink HARQ process is transmitted; when the Sidelink data associated with the Sidelink HARQ process is transmitted When the number of times is less than or equal to the maximum number of transmissions or the preset number of transmissions, the first timer is started at the first time domain position.
  • the processor 901 is further configured to: when the number of transmissions of the Sidelink data associated with the Sidelink HARQ process is greater than the maximum number of transmissions or the preset number of transmissions, at the first time domain position, no longer open the second A timer.
  • the processor 901 turning on or not turning on the second timer according to the first timer includes: directly turning on the second timer when the first timer times out.
  • the processor 901 starts or does not start the second timer according to the first timer, including: before the first timer expires, determining that the HARQ feedback of the Sidelink HARQ process is a negative acknowledgement NACK When the first timer expires, the second timer is started; or when it is determined that the HARQ feedback of the Sidelink HARQ process is a positive acknowledgement ACK, the first timer is directly stopped. Timer. At this time, the first timer does not expire, and the second timer is not started, or the first timer is not stopped, but when the first timer expires, no Then start the second timer.
  • the processor 901 starts or does not start the second timer according to the first timer includes: the HARQ feedback of the Sidelink HARQ process cannot be determined before the first timer expires; When the first timer expires, the second timer is started.
  • the processor 901 is further configured to: during the operation of the second timer, determine that the HARQ feedback of the Sidelink HARQ process is NACK, then not stop the second timer, During the operation of the timer, continue to monitor the PDCCH; or, during the operation of the second timer, if it is determined that the HARQ feedback of the Sidelink HARQ process is ACK, the second timer is directly stopped and no longer Monitor PDCCH.
  • the processor 901 is further configured to: during the operation of the second timer, if it monitors and receives a message for scheduling retransmission of the Sidelink data PDCCH, stop the second timer.
  • the apparatus 900 is used to implement the steps performed by the first terminal device in the third method embodiment.
  • the communication interface 903 is used to perform the transceiving-related operations on the first terminal device side in the above embodiment
  • the processor 901 is used to perform the processing related operations on the first terminal device side in the third embodiment of the above method.
  • the communication interface 903 is configured to receive first downlink control information DCI from a network device, and the first DCI is used to schedule the initial transmission or retransmission of sidelink sidelink data, and the Sidelink hybrid associated with the Sidelink data
  • the automatic retransmission request HARQ maintains two timers in association with each other, namely the first timer and the second timer; the first terminal equipment uses the physical side uplink shared channel PSSCH resource to communicate according to the scheduling of the first DCI.
  • the second terminal device sends Sidelink data;
  • the communication interface 903 is also used to use the physical side feedback channel PSFCH resource to receive HARQ feedback from the second terminal device on the Sidelink HARQ process, and the HARQ feedback is a positive confirmation ACK or negative acknowledgement NACK;
  • processor 901 configured to enable or disable the first timer according to the HARQ feedback and the time domain position of the PSFCH resource;
  • the first terminal device in the case of starting the first timer, when the first timer expires, the first terminal device starts a second timer, and during the operation of the second timer, the first A terminal device monitors the physical downlink control channel PDCCH.
  • the processor 901 starts or does not start the first timer according to the HARQ feedback and the time domain location of the PSFCH resource, including: according to the time domain resource location of the first PSFCH resource and the second time domain Offset, determine the second time domain position; or, use the first time unit after the end position of the time domain resource of the first PSFCH resource as the second time domain position; according to the HARQ feedback, In the second time domain position, the first timer is turned on or not.
  • the processor 901 starts or does not start the first timer at the second time domain position according to the HARQ feedback, including: determining that the HARQ feedback of the Sidelink HARQ process is ACK, then In the second time domain position, the first timer is not started; or, if it is determined that the HARQ feedback of the Sidelink HARQ process is NACK, then the first timer is started at the second time domain position.
  • the processor 901 starts the first timer at the second time domain position, including: determining the number of transmissions of the Sidelink data associated with the Sidelink HARQ process; if the Sidelink data associated with the Sidelink HARQ process If the number of transmissions is less than or equal to the maximum number of transmissions or the preset number of transmissions, the first timer is started at the second time domain position.
  • the processor 901 is further configured to: when the number of transmissions of the Sidelink data associated with the Sidelink HARQ process is greater than the maximum number of transmissions or the preset number of transmissions, at the second time domain position, no longer open the The first timer.
  • the processor 901 is further configured to:
  • the second timer if a PDCCH for scheduling sidelink data retransmission of the first terminal device is monitored, the second timer is stopped.
  • an embodiment of the present application also provides a device, which is configured to execute the method in the above method embodiment.
  • a computer-readable storage medium includes a program. When the program is executed by a processor, the method in the above method embodiment is executed.
  • a computer program product, the computer program product includes computer program code, when the computer program code runs on a computer, the computer realizes the method in the above method embodiment.
  • a chip comprising: a processor, the processor is coupled with a memory, the memory is used to store a program or an instruction, and when the program or an instruction is executed by the processor, the device executes the above method embodiment Methods.
  • the processor may be a general-purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, which can implement or execute The methods, steps, and logical block diagrams disclosed in the embodiments of the present application.
  • the general-purpose processor may be a microprocessor or any conventional processor or the like.
  • the steps of the method disclosed in combination with the embodiments of the present application may be directly embodied as being executed and completed by a hardware processor, or executed and completed by a combination of hardware and software modules in the processor.
  • the memory may be a non-volatile memory, such as a hard disk drive (HDD) or a solid-state drive (SSD), etc., or a volatile memory (volatile memory), for example Random-access memory (random-access memory, RAM).
  • the memory is any other medium that can be used to carry or store desired program codes in the form of instructions or data structures and that can be accessed by a computer, but is not limited to this.
  • the memory in the embodiments of the present application may also be a circuit or any other device capable of realizing a storage function for storing program instructions and/or data.
  • the methods provided in the embodiments of the present application may be implemented in whole or in part by software, hardware, firmware, or any combination thereof.
  • software When implemented by software, it can be implemented in the form of a computer program product in whole or in part.
  • the computer program product includes one or more computer instructions.
  • the computer may be a general-purpose computer, a special-purpose computer, a computer network, network equipment, user equipment, or other programmable devices.
  • the computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from a website, computer, server, or data center.
  • the computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server or a data center integrated with one or more available media.
  • the usable medium may be a magnetic medium (for example, a floppy disk, a hard disk, a magnetic tape), an optical medium (for example, a digital video disc (digital video disc, DVD for short)), or a semiconductor medium (for example, SSD).

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Abstract

一种通信方法及装置，该方法可解决在第一终端设备未配置 PUCCH 资源的情况下，如何开启第一计时器和第二计时器，从而降低Sidelink的通信时延，满足Sidelink的 QoS 需求。该方法包括两种方案，一种为第一终端设备在 PSSCH 资源上发送 Sidelink 数据之后，根据 PSSCH 资源的时域位置，开启第一计时器，之后，开启第二计时器。另一种为在 PSFCH 资源上接收到 HARQ 反馈之后，根据 PSFCH 资源的时域位置，开启第一计时器，之后，开启第二计时器。

Description

一种通信方法及装置
相关申请的交叉引用
本申请要求在2020年05月21日提交中国专利局、申请号为202010438317.9、申请名称为“一种通信方法及装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请实施例涉及通信技术领域，尤其涉及一种通信方法及装置。
背景技术
在长期演进(long term evolution，LTE)系统或新无线电(new radio，NR)系统中，UE和基站间的通信接口称为Uu空口。在Uu空口上，UE向基站发送数据的链路，称为上行链路(uplink，UL)。基站向UE发送数据的链路，称为下行链路(downlink，DL)。UE和UE之间的通信接口称为PC5接口。在PC5接口上，UE与UE之间传输数据的链路称为侧行链路(sidelink，SL)。目前，Sidelink的资源分配方式有两种。一种是UE在资源池中自主选择资源的分配方式，即由UE自己在网络通过系统消息或者专用信令配置或者预配置的资源池中自己选择资源来传输Sidelink的数据。另一种是基于基站调度的资源分配方式，即由基站为传输用户设备TXUE调度Sidelink资源来传输Sidelink的数据。在基站调度Sidelink资源的分配方式中，基站在物理下行控制信道(physical downlink control channel，PDCCH)中下发下行控制信息(downlink control information，DCI)来动态的分配Sidelink资源，TXUE需要监听PDCCH以获得基站下发的Sidelink授权(grant)。关于TX UE如何监听PDCCH，是本申请实施例待解决的技术问题。
发明内容
本申请实施例提供一种通信方法及装置，以实现第一终端设备监听PDCCH。
第一方面，提供一种通信方法，该方法可适用于PSSCH资源有关联PUCCH资源的情况下，也可适用于PSSCH资源没有关联PUCCH资源的情况下。该方法的执行主体为第一终端设备和第二终端设备。可以理解的是，第一终端设备和第二终端设备可以为终端设备，也可以为配置于终端设备中的部件(例如，芯片、电路或其它等)。该方法包括：
第一终端设备接收来自网络设备的第一DCI，第一DCI用于调度Sidelink HARQ进程的第i次传输，所述Sidelink HARQ进程关联或维护两个计时器，分别为第一计时器和第二计时器；第一终端设备可根据第一DCI的调度，利用上述Sidelink HARQ进程向第二终端设备发送Sidelink数据。第一终端设备可根据发送Sidelink数据的PSSCH资源的时域位置，开启第一计时器。当第一计时器超时，直接开启第二计时器。或者，第一终端设备可根据PSFCH资源接收Sidelink HARQ进程的HARQ反馈的情况，开启或不开启第二计时器。其中，在第二计时器的运行期间，第一终端设备可监听PDCCH。
通过上述方法，第一终端设备可根据PSSCH资源的时域位置，开启第一计时器和第 二计时器。因此，在没有配置PUCCH资源的情况下，也能成功开启第一计时器和第二计时器，满足第一终端设备监听PDCCH的需求。进一步，在第二计时器的运行期间，可监听用于调度Sidelink HARQ进程的第i+1次传输，可降低Sidelink的通信时延，满足Sidelink的QoS需求。
在一种可能的设计中，第一终端设备可根据PSSCH资源的时域位置和第一时域偏移，确定第一时域位置；或者，将所述PSSCH资源的时域位置结束位置后的第一个时间单元，作为第一时域位置；且在第一时域位置，开启第一计时器。
上述第一时域偏移可为协议规定的，或者，网络设备配置的，或者，终端设备内部实现的，不作限定。通过灵活的设置第一时域偏移，可灵活的设置开启第一计时器的时域单元。
在一种可能的设计中，终端设备在开启第一计时器之前，还可以确定下Sidelink HARQ进程关联的Sidelink数据的传输次数。当所述传输次数大于或等于最大传输次数或预设传输次数时，说明当前Sidelink数据的传输已超过最大次数或预设次数。此时，网络设备不会再为该Sidelink数据继续分配PSSCH资源。因此，此时没有必要开启第一计时器。而当所述传输次数小于最大传输次数或预设传输次数时，则继续开启第一计时器。
相对于完全不考虑Sidelink HARQ进程的HARQ反馈，直接开启第一定时器，通过上述方法，可降低终端设备的功耗。
在一种可能的设计中，若第一终端设备配置有PSFCH资源。且在第一计时器超时之前，若第一终端设备可确定Sidelink HARQ进程的HARQ反馈。则当所述HARQ反馈为NACK时，则当第一计时器超时时，直接开启第二计时器。而当所述HARQ反馈为ACK时，则可直接停止第一计时器，此时不再存在第一计时器超时的情况，因此也无需再开启第二计时器，或者，第一终端设备也可不停止第一计时器，但在第一计时超时的情况下，不再开启第二计时器。
通过上述方法，第一终端设备根据HARQ反馈的情况，再决定是否开启第一计时器。相对于无论在何种情况下，均开启第一计时器，可降低终端设备的功耗。
在一种可能的设计中，若第一终端设备配置有PSFCH资源，且在第一计时器超时之前，不能确定Sidelink HARQ进程的HARQ反馈。则第一终端设备在第一计时器超时之后，可直接开启第二计时器。在第二计时器的运行期间，若所述Sidelink HARQ进程的HARQ反馈为ACK，则第一终端设备可直接停止第二计时器，不再监听PDCCH。或者，若所述Sidelink HARQ进程的HARQ反馈为NAKC，则第一终端设备可不停止第二计时器，且继续监听PDCCH。
通过上述方法，在确定HARQ反馈为ACK时，说明网络设备不会再为第一终端设备调度PSSCH资源，此时停止第二计时器，可降低终端设备的功耗。
在一种可能的设计中，在第二计时器的运行期间，若第一终端设备监听并接收到用于调度Sidelink数据重传的PDCCH，则第一终端设备可直接停止第二计时器，进一步降低终端设备的功耗。
第二方面，提供一种通信方法，该方法可适用于PSSCH资源有关联PUCCH资源的情况下，也可适用于PSSCH资源没有关联PUCCH资源的情况下。该方法的执行主体为第一终端设备和第二终端设备。可以理解的是，第一终端设备和第二终端设备可以为终端设备，也可以为配置于终端设备中的部件(例如，芯片、电路或其它等)。该方法包括：
第一终端设备接收来自网络设备的第一DCI，第一DCI用于调度Sidelink HARQ进程的第i次传输。所述Sidelink HARQ进程维护或关联两个计时器，分别为第一计时器和第二计时器。所述第一终端设备可根据第一DCI的调度，利用Sidelink HARQ进程向第二终端设备发送Sidelink数据。第一终端设备可根据Sidelink HARQ进程的HARQ反馈以及接收HARQ反馈的PSFCH资源的时域位置，开启或不开启第一计时器。例如，当所述Sidelink HARQ进程的HARQ反馈为NACK时，可根据PSFCH资源的时域位置，开启第一计时器。而当Sidelink HARQ进程的HARQ反馈为ACK时，则不再开启第一计时器。在开启第一计时器的情况下，当第一计时器超时时，可直接开启第二计时器。第一终端设备在第二计时器的运行期间，监听PDCCH。
通过上述方法，第一终端设备可根据PSFCH资源的时域位置，开启第一计时器和第二计时器。因此，在没有配置PUCCH资源的情况下，也能成功开启第一计时器和第二计时器，满足第一终端设备监听PDCCH的需求。进一步，在第二计时器的运行期间，可监听用于调度Sidelink HARQ进程的第i+1次传输，可降低Sidelink的通信时延，满足Sidelink的QoS需求。
在一种可能的设计中，第一终端设备根据所述第一PSFCH资源的时域资源位置和第二时域偏移，确定第二时域位置；或者，所述第一终端设备将所述第一PSFCH资源的时域资源的结束位置后的第一个时间单元，作为所述第二时域位置。
上述第二时域偏移可为协议规定的，或者，网络设备配置的，或者，终端设备内部实现的，不作限定。通过灵活的设置第二时域偏移，可灵活的设置开启第一计时器的时域单元。
在一种可能的设计中，所述第一终端设备根据所述HARQ反馈，在所述第二时域位置，开启或不开启所述第一计时器。例如，所述第一终端设备在确定所述Sidelink HARQ进程的HARQ反馈为NACK时，则所述第一终端设备在所述第二时域位置，开启所述第一计时器；否则所述第一终端设备在所述第二时域位置，不再开启所述第一计时器。
通过上述方法，第一终端设备根据Sidelink HARQ进程的HARQ反馈，决定是否开启第一计时器。相对于，第一终端设备无论何种情况，均在第二时域位置，开启第一计时器，可降低终端设备的功耗。
在一种可能的设计中，所述第一终端设备在所述第二时域位置，开启所述第一计时器，包括:所述第一终端设备确定所述Sidelink HARQ进程关联的Sidelink数据的传输次数；若所述Sidelink HARQ进程关联的Sidelink数据的传输次数小于或等于最大传输次数或预设传输次数，则所述第一终端设备在所述第二时域位置，开启所述第一计时器。否则，则所述第一终端设备在所述第二时域位置，不再开启所述第一计时器。
在上述方法中，最大传输次数或预设传输次数可以为协议规定的，或者，网络设备配置的，或者，终端设备内部实现的。当Sidelink数据的传输次数达到最大传输次数或预设传输次数时，网络设备不再调度Sidelink HARQ进程的第i+1次传输，而此时设置第一终端设备不再开启第一计时器，降低第一终端设备的功耗。
在一种可能的设计中，在所述第一终端设备开启所述第二计时器的情况下，所述方法还包括：在所述第二计时器的运行期间，若所述第一终端设备监听到用于调度所述第一终端设备Sidelink数据重传的PDCCH，则所述第一终端设备停止所述第二计时器。
第三方面，本申请实施例还提供一种装置，有益效果可参见第一方面的描述。所述装 置具有实现上述第一方面的方法实施例中行为的功能。所述功能可以通过执行相应的硬件或软件实现。所述硬件或软件可包括一个或多个上述功能相对应的模块。在一种可能的设计中，该装置可包括：收发单元，用于接收来自网络设备的第一下行控制信息DCI，所述第一DCI用于调度侧行链路Sidelink数据的初传或重传，所述Sidelink数据关联的Sidelink混合自动重传请求HARQ进程关联两个计时器，分别为第一计时器和第二计时器；处理单元，用于根据所述第一DCI的调度，利用物理侧行链路共享信道PSSCH资源向第二终端设备发送Sidelink数据；处理单元，还用于根据所述PSSCH资源的时域位置，开启第一计时器；处理单元，还用于根据所述第一计时器，开启或不开启第二计时器；其中，在开启第二计时器的情况下，在所述第二计时器的运行期间，所述第一终端设备监听物理下行控制信道PDCCH。这些单元可以执行上述第一方面方法示例中的相应功能，具体参见方法示例中的详细描述，此处不做赘述。
第四方面，本申请实施例还提供一种装置，有益效果可参见第二方面的描述。所述装置具有实现上述第二方面的方法实施例中行为的功能。所述功能可以通过执行相应的硬件或软件。所述硬件或软件可包括一个或多个上述功能相对应的模块。在一种可能的设计中，该装置包括：收发单元，用于接收来自网络设备的第一下行控制信息DCI，所述第一DCI用于调度侧行链路Sidelink数据的初传或重传，所述Sidelink数据关联的Sidelink混合自动重传请求HARQ进程关联两个计时器，分别为第一计时器和第二计时器；处理单元，用于根据所述第一DCI的调度，利用物理侧行链路共享信道PSSCH资源向第二终端设备发送Sidelink数据；处理单元，还用于利用物理侧行反馈信道PSFCH资源，接收来自所述第二终端设备对所述Sidelink HARQ进程的HARQ反馈，所述HARQ反馈为肯定性确认ACK或否定性确认NACK；处理单元，还用于根据所述HARQ反馈以及所述PSFCH资源的时域位置，开启或不开启第一计时器；其中，在开启所述第一计时器的情况下，当所述第一计时器超时时，所述第一终端设备开启第二计时器，在所述第二计时器的运行期间，所述第一终端设备监听物理下行控制信道PDCCH。这些单元可以执行上述第二方面方法示例中的相应功能，具体参见方法示例中的详细描述，此处不做赘述。
第五方面，提供了一种装置，该装置可以为上述第一方面方法实施例中的终端设备，或者为设置在终端设备中的芯片。该装置包括通信接口以及处理器，可选的，还包括存储器。其中，该存储器用于存储计算机程序或指令，处理器与存储器、通信接口耦合，当处理器执行所述计算机程序或指令时，使装置执行上述第一方面方法实施例中由终端设备所执行的方法。
第六方面，提供了一种装置，该装置可以为上述第二方面方法实施例中的终端设备，或者为设置在终端设备中的芯片。该装置包括通信接口以及处理器，可选的，还包括存储器。其中，该存储器用于存储计算机程序或指令，处理器与存储器、通信接口耦合，当处理器执行所述计算机程序或指令时，使装置执行上述第二方面方法实施例中由终端设备所执行的方法。
第七方面，提供了一种计算机程序产品，所述计算机程序产品包括：计算机程序代码，当所述计算机程序代码并运行时，使得上述第一方面中由终端设备执行的方法被执行。
第八方面，提供了一种计算机程序产品，所述计算机程序产品包括：计算机程序代码，当所述计算机程序代码被运行时，使得上述第二方面中由终端设备执行的方法被执行。
第九方面，本申请提供了一种芯片系统，该芯片系统包括处理器，用于实现上述第一 方面的方法中终端设备的功能。在一种可能的设计中，所述芯片系统还包括存储器，用于保存程序指令和/或数据。该芯片系统，可以由芯片构成，也可以包括芯片和其他分立器件。
第十方面，本申请提供了一种芯片系统，该芯片系统包括处理器，用于实现上述第二方面的方法中终端设备的功能。在一种可能的设计中，所述芯片系统还包括存储器，用于保存程序指令和/或数据。该芯片系统，可以由芯片构成，也可以包括芯片和其他分立器件。
第十一方面，本申请提供了一种计算机可读存储介质，该计算机可读存储介质存储有计算机程序，当该计算机程序被运行时，实现上述第一方面中由终端设备执行的方法。
第十二方面，本申请提供了一种计算机可读存储介质，该计算机可读存储介质存储有计算机程序，当该计算机程序被运行时，实现上述第二方面中由终端设备执行的方法。
附图说明
图1为本申请实施例提供的网络架构的一示意图；
图2A、图2B和图2C为本申请实施例提供的DRX的一示意图；
图3为本申请实施例提供的通信方法的一流程图；
图4为本申请实施例提供的通信方法的一流程图；
图5为本申请实施例提供的通信方法的一流程图；
图6为本申请实施例提供的通信方法的一流程图；
图7为本申请实施例提供的通信方法的一流程图；
图8为本申请实施例提供的通信装置的一结构示意图；
图9为本申请实施例提供的通信装置的一结构示意图。
具体实施方式
本申请的实施方式部分使用的术语仅用于对本申请的具体实施例进行解释，而非旨在限定本申请。
图1示出了本申请涉及的无线通信系统100。无线通信系统100可以是长期演进(long term evolution，LTE)系统、第五代移动通信(5 th generation，5G)系统、新空口(new radio，NR)系统，还可以是机器与机器通信(machine to machine，M2M)系统、未来演进的第六代通信系统等。如图1所示，无线通信系统100可包括：一个或多个网络设备101，两个或两个以上终端设备103以及核心网(未示出)。其中：
网络设备101可用于在网络设备控制器(未示出)，如基站控制器(base station controller，BSC)的控制下，通过Uu接口105与终端设备103通信。在Uu接口105上，终端设备103向网络设备101发送数据的链路称为上行链路(Uplink，UL)，而终端设备103接收网络设备101发送的数据的链路称为下行链路(Downlink，DL)。在一些实施例中，网络设备控制器可以是核心网的一部分，也可以集成到网络设备101中。
网络设备101还可用于通过回程(blackhaul)接口，如S1接口，向核心网传输控制信息或者用户数据。
网络设备101与网络设备101之间也可以通过回程(blackhaul)接口，如X2接口，直接地或者间接地相互通信。
终端设备103与终端设备103之间的通信接口107称为PC5接口。在PC5接口107 上，终端设备103和终端设备103之间传输数据的链路称为侧行链路(Sidelink，SL)。终端设备103处于演进的通用陆地无线接入网(evolved universal terrestrial radio access network，E-UTRAN)覆盖区内时，可以在蜂窝网络的控制下使用Uu接口105。无论是否处于E-UTRAN覆盖区内，终端设备103都可以采用PC5接口107进行Sidelink通信。Sidelink通信可以是两个终端设备103之间的点对点通信，也可以是一组两个以上的终端设备103进行的组播通信。
网络设备101可以是时分同步码分多址(time division synchronous code division multiple access，TD-SCDMA)系统中的基站收发台(base transceiver station，BTS)，也可以是LTE系统中的演进型基站(evolutional node B，eNB)，以及5G系统、新空口(NR)系统中的基站等。另外，基站也可以为接入点(access point，AP)、传输节点(transmission and reception point，TRP)、中心单元(central unit，CU)或其他网络实体，并且可以包括以上网络实体的功能中的一些或所有功能。
终端设备103可以是车载终端、智能手机、路边单元(road side unit，RSU)、物联网终端设备，机器类型通信(machine type communication，MTC)终端等无线通信设备。终端设备还可以包括一个或多个具有部分UE功能的基站，如微基站。终端设备可以分布在整个无线通信系统100中，可以是静止的，也可以是移动的。
需要说明的，图1示出的无线通信系统100仅仅是为了更加清楚的说明本申请的技术方案，并不构成对本申请的限定，本领域普通技术人员可知，随着网络架构的演变和新业务场景的出现，本申请提供的技术方案对于类似的技术问题，同样适用。
Sidelink通信一般可用于V2X等设备间直联通信的场景。V2X是指把车联到网或者把车联成网，共有4种不同类型的应用，分别是汽车对汽车(vehicle to vehicle，V2V)、汽车对基础设施(vehicle to infrastructure，V2I)、汽车对网络(vehicle to network，V2N)、汽车对行人(vehicle to pedestrian，V2P)。通过这4种应用，车辆、路边的基础设施、应用服务器和行人收集、处理和分享周边车辆和环境的状态信息，以提供更智能化的服务，如无人驾驶(unmanned driving)、自动驾驶(automated driving/ADS)、辅助驾驶(driver assistance/ADAS)、智能驾驶(intelligent driving)、网联驾驶(connected driving)、智能网联驾驶(intelligent network driving)、汽车共享(car sharing)等。
如图1所示，在V2V场景中，终端设备103可以是车载终端。在PC5接口107上，车载终端与车载终端之间可以通过Sidelink交互数据，如车辆位置、车辆速度、行驶方向等等指示车辆动态的数据。例如，车载终端A可以通过Sidelink向另一个车载终端B发送数据，该数据用于指示车载终端A所处的车辆的驾驶动态。在这次Sidelink通信中，车载终端A是TX UE，车载终端B是RX UE。接收到该数据后，车载终端B可以显示用户界面20。用户界面20中可以显示该数据所表达的内容21，如后方车辆的车牌号码(“FAF787”)、后方车辆正在执行的驾驶操作(“后方车辆FAF787正在执行超车操作”)、后方车辆的当前车速(“80km/h”)，等等。这样，可以降低交通事故发生率，增强驾驶安全。
目前，Sidelink通信的一种主要资源分配方式为基于基站调度的资源分配方式。在这种Sidelink的资源分配方式中，基站在PDCCH下发下行控制信息DCI来动态的分配资源，TXUE需要监听PDCCH以获得基站下发的Sidelink授权(grant)。
在Uu接口105上，为了降低UE一直监听PDCCH所造成的功率消耗，目前3GPP所采用的一种解决方式为非连续接收(discontinuous reception，DRX)机制。下面说明现有 的DRX机制。
(1)DRX机制的基本工作原理
如图2A所示，在LTE或NR系统中，DRX机制是网络设备为处于无线资源控制(radio control resource，RRC)连接态的UE配置的一个DRX周期(DRX cycle)。DRX cycle由“On Duration”和“Opportunity for DRX”这两个时间段组成。“On Duration”可称为持续期，“Opportunity for DRX”可称为DRX机会。在“On Duration”内，UE监听并接收PDCCH。在“Opportunity for DRX”内，UE不监听PDCCH以减少功耗。“On Duration”的值(如10ms)指定了，从DRX Cycle的起始位置开始，UE需要监听PDCCH的时间。“On Duration”可以大于1ms，也可以小于1ms。在“On Duration”内，UE处于激活态，即UE监听PDCCH。在“Opportunity for DRX”内，UE处于休眠态，即UE不监听PDCCH。这里，休眠态仅是针对监听PDCCH而言，表示UE不监听PDCCH。处于休眠态的UE依然处于RRC连接态，能够在Uu接口105上通过物理上行控制信道(physical uplink control channel，PUCCH)、物理上行共享信道(physical uplink shared channel，PUSCH)等传输上行数据或通过物理下行共享信道(physicaldownlink shared channel，PDSCH)接收基站发送的下行数据，还能够在PC5接口107上通过物理侧行链路共享信道(physicalSidelink shared channel，PSSCH)、物理侧行链路控制信道(physicalSidelink control channel，PSCCH)等传输Sidelink数据。
(2)引入drx-InactivityTimer
在大多数情况下，UE在某个PDCCH时机(Occasion)被调度来接收或发送数据后，很可能在接下来的几个子帧(subframe)内也被继续调度，以完成一份较大字节的数据的接收或发送。如果该UE已经进入休眠态，则该UE要等到下一个DRX cycle再监听PDCCH获取资源调度来接收或发送后续数据。这会增加数据传输的时延。为了降低这类延迟，DRX机制引入了一个计时器：drx-InactivityTimer。如图2B所示，当UE监听并接收到一个用于调度新数据的PDCCH时，UE会开启(或重启)计时器drx-InactivityTimer。UE会在drx-InactivityTimer运行期间的每一个子帧都监听PDCCH，直到该计时器超时。新数据的指示信息会携带在PDCCH中，占1bit。可以看出，drx-InactivityTimer的引入，可确保UE在drx-InactivityTimer运行期间处于激活态，接收接下来基站的调度，相当于对“On Duration”进行了扩展。如果UE连续接收到用于调度不同新数据的PDCCH，则UE会相继开启(或重启)多个drx-InactivityTimer，可能会使得UE在整个DRX cycle都处于激活态，即“On Duration”可能扩展至整个DRX cycle。
(3)DRX
在NR系统中，如果基站为TXUE配置了基于Sidelink的混合自动重传请求(hybrid automatic repeat request，HARQ)反馈的重传机制后，那么对于基于基站调度的资源分配方式，一种可能的HARQ工作方式是：基站根据Sidelink数据传输的HARQ反馈(feedback)来为TXUE调度重传资源。HARQ反馈可以是否定性确认(negtive acknowledgment，NACK)或肯定性确认(acknowledgment，ACK)。如图2C所示，如果数据a的HARQ反馈为NACK，则基站在接收到NACK之后，为数据a的重传调度资源，并在PDCCH下发用于数据a的重传的Sidelink授权(grant)。
但是，如图2C所示，当Tx UE向基站发送的数据a的HARQ确认为NACK时，Tx UE之后需要接收基站下发的用于调度数据a重传的PDCCH，以进行数据a的重传。但是，基 于目前的DRX机制，在基站下发该PDCCH时，TX UE可能已经进入“opportunity for DRX”状态，不再监听PDCCH。TX UE需要等到下一个DRX cycle的“On Duration”才会监听PDCCH，才能接收到基站下发的用于调度数据a重传的PDCCH，然后进行数据a的重传。这会导致TxUE在Sidelink上的数据重传被延迟，导致Sidelink上传输的业务的QoS要求无法被满足。
为了解决现有的技术问题，基于基站调度的Sidelink资源分配方式，提供一种有利于降低Sidelink数据的传输时延的方案，该方案包括：TX UE在利用PUCCH资源，向基站发送HARQ反馈时，即开启第一计时器，所述第一计时器可以是drx-HARQ-RTT-TimerSL且第一计时器超时时，开启第二计时器，所述第二计时器可为drx-RetransmissionTimerSL。TX UE在第二计时器的运行期间内，监听PDCCH，从而可避免TX UE在下一个DRX cycle的“On Duration”内才可监听PDCCH，降低Sidelink数据的传输时延。通过上述可以看出，在上述方案中，TX UE是在利用PUCCH资源，向基站反馈HARQ时，才开启第一计时器和第二计时器的。在一种场景中，若基站没有给TX UE配置PUCCH资源，此时TX UE无法向基站发送HARQ反馈，进而也无法开启第一计时器和第二计时器。在该场景下，如何降低Sidelink数据的传输时延，是本申请实施例待解决的技术问题。
基于上述，本申请实施例提供一种通信方法及装置，可在TX UE未配置PUCCH资源的情况下，开启第一计时器和第二计时器，降低Sidelink数据的传输时延。该方法可包括两种方案：第一种方案为：TX UE在PSSCH资源上发送Sidelink数据之后，根据PSSCH资源的时域位置，开启第一计时器，之后，开启第二计时器。具体可参见下述实施例一和实施例二中的记载。第二种方案为：TX UE在PSFCH资源上接收到HARQ反馈之后，根据PSFCH资源的时域位置，开启第一计时器，之后，开启第二计时器。具体可参见下述实施例三中的记载。
除此之外，本申请实施例还提供并不涉及第一计时器和第二计时器两种方案：第三种方案，TX UE在PSSCH资源上发送Sidelink数据之后，根据PSSCH资源的时域位置，监听PDCCH。具体可参见下述实施例四中的记载。第四种方案，TX UE在PSFCH资源上接收到HARQ反馈之后，根据PSFCH资源的时域位置，监听PDCCH。具体可参见了下述实施例五中的记载。
为了便于理解，首先介绍本申请实施例所涉及的名词或术语，该名词或术语也作为本申请实施例发明内容的一部分。
一、终端设备
终端设备可以简称为终端，是一种具有无线收发功能的设备。终端设备可以部署在陆地上，包括室内或室外、手持或车载；也可以部署在水面上(如轮船等)；还可以部署在空中(例如飞机、气球和卫星上等)。所述终端设备可以是手机(mobile phone)、平板电脑(pad)、带无线收发功能的电脑、虚拟现实(virtual reality，VR)终端设备、增强现实(augmented reality，AR)终端设备、工业控制(industrial control)中的无线终端设备、无人驾驶(self driving)中的无线终端设备、远程医疗(remote medical)中的无线终端设备、智能电网(smart grid)中的无线终端设备、运输安全(transportation safety)中的无线终端设备、智慧城市(smart city)中的无线终端设备、智慧家庭(smart home)中的无线终端设备，以及还可以包括用户设备(user equipment，UE)等。终端设备还可以是蜂窝电话、无绳电话、会话启动协议(session initiation protocol，SIP)电话、无线本地环路(wireless  local loop，WLL)站、个人数字助理(personal digital assistant，PDA)、具有无线通信功能的手持设备、计算设备或连接到无线调制解调器的其它处理设备、车载设备、可穿戴设备，未来第五代(5th generation，5G)网络中的终端设备或者未来演进的公用陆地移动通信网络(public land mobile network，PLMN)中的终端设备等。终端设备有时也可以称为终端、接入终端设备、车载终端设备、工业控制终端设备、UE单元、UE站、移动站、移动台、远方站、远程终端设备、移动设备、UE终端设备、终端设备、无线通信设备、UE代理或UE装置等。终端设备也可以是固定的或者移动的。本申请实施例对此并不限定。
本申请实施例中，用于实现终端的功能的装置可以是终端；也可以是能够支持终端实现该功能的装置，例如芯片系统，该装置可以被安装在终端中。本申请实施例中，芯片系统可以由芯片构成，也可以包括芯片和其他分立器件。本申请实施例提供的技术方案中，以用于实现终端的功能的装置是终端，以终端是UE为例，描述本申请实施例提供的技术方案。
二、网络设备
网络设备可以是接入网设备，接入网设备也可以称为无线接入网(radio access network，RAN)设备，是一种为终端设备提供无线通信功能的设备。接入网设备例如包括但不限于：5G中的下一代基站(generation nodeB，gNB)、演进型节点B(evolved node B，eNB)、无线网络控制器(radio network controller，RNC)、节点B(node B，NB)、基站控制器(base station controller，BSC)、基站收发台(base transceiver station，BTS)、家庭基站(例如，home evolved nodeB，或home node B，HNB)、基带单元(baseband unit，BBU)、收发点(transmitting and receiving point，TRP)、发射点(transmitting point，TP)、移动交换中心等。接入网设备还可以是云无线接入网络(cloud radio access network，CRAN)场景下的无线控制器、集中单元(centralized unit，CU)，和/或分布单元(distributed unit,DU)，或者网络设备可以为中继站、接入点、车载设备、可穿戴设备以及未来5G网络中的网络设备或者未来演进的PLMN网络中的网络设备等。终端设备可以与不同技术的多个接入网设备进行通信，例如，终端设备可以与支持长期演进(long term evolution，LTE)的接入网设备通信，也可以与支持5G的接入网设备通信，还可以与支持LTE的接入网设备以及支持5G的接入网设备的双连接。本申请实施例并不限定。
本申请实施例中，用于实现网络设备的功能的装置可以是网络设备；也可以是能够支持网络设备实现该功能的装置，例如芯片系统，该装置可以被安装在网络设备中。在本申请实施例提供的技术方案中，以用于实现网络设备的功能的装置是网络设备，以网络设备是基站为例，描述本申请实施例提供的技术方案。
三、边链路(sidelink，SL)
边链路用于终端设备和终端设备之间的通信，终端设备和终端设备之间的通信接口可为PC5接口。边链路通信中涉及的信道可以包括物理边链路共享信道(physical sidelink shared channel,PSSCH)、物理边链路控制信道(physical sidelink control channel,PSCCH)和物理边链路反馈信道(physical sidelink feedback channel，PSFCH)。
其中，PSSCH用于承载边链路数据(SL data)，PSCCH用于承载边链路控制信息(sidelinkcontrolinformation，SCI)，所述SCI也可以称为边链路调度分配(sidelink schedulingassigment，SL SA)。SL SA是用于数据调度相关的信息，比如，用于承载PSSCH的资源分配和/或调制编码机制(modulation and coding scheme，MCS)等信息。PSFCH可 以用于传输边链路反馈控制信息(sidelink feedback control information，SFCI)。边链路反馈控制信息可以包括信道状态信息(channel state information，CSI)和HARQ等信息中的一个或多个。其中，HARQ信息中可以包括ACK或NACK等。
四、Uu空口
Uu空口可以简称为Uu，Uu空口用于终端设备与网络设备之间的通信。Uu空口的传输可以包括上行传输和下行传输。
其中，上行传输是指终端设备向网络设备发送信息，上行传输的信息可以称为上行信息或上行信号。上行信息或上行信号中可以包括上行数据信,上行控制信号,探测参考信号(sounding reference signal，SRS)中的一种或多种。用于传输上行信息或上行信号的信道称为上行信道，上行信道可以包括物理上行数据信道(physical uplink shared channel，PUSCH)和物理上行控制信道(physical uplink controlchannel，PUCCH)中的一种或多种。PUSCH用于承载上行数据，上行数据也可以称为上行数据信息。PUCCH用于承载终端设备反馈的上行控制信息(uplink control information，UCI)。示例的，UCI中可以包括终端设备反馈的信道状态信息(channel state information，CSI)、ACK和NACK等中的一个或多个。
下行传输是指网络设备向终端设备发送信息，下行传输的信息可以为下行信息或下行信号。下行信息或下行信号可以包括下行数据信号，下行控制信号,信道状态信息参考信号(channel state information reference signal，CSI-RS)，相位跟踪参考信号(phase tracking reference signal，PTRS)中的一种或多种。用于传输下行信息或下行信号的信道称为下行信道，下行信道可以包括物理下行数据信道(physical downlink shared channel，PDSCH)和物理下行控制信道(physical downlink control channel，PDCCH)中的一种或多种。所述PDCCH用于承载下行控制信息(downlink control information，DCI)，PDSCH用于承载下行数据(data)，下行数据也可称为下行数据信息。
五、Sidelink HARQ进程
在本申请实施例中，TX UE可以针对每一个Sidelink数据，如TX UE向RX UE传输的MAC PDU，设置一个Sidelink HARQ进程。即一个Sidelink HARQ进程关联一个Sidelink数据，该Sidelink数据可存储在该Sidelink HARQ进程关联的Sidelink HARQ buffer中。一个Sidelink HARQ进程可维护一个状态变量CURRENT_SL_TX_NB，该状态变量用于指示该Sidelink HARQ进程关联的Sidelink数据的传输次数。CURRENT_SL_TX_NB可以被初始化为0。
其中，一个Sidelink数据关联的Sidelink HARQ进程的HARQ反馈资源，可用于RX UE向TX UE发送Sidelink HARQ进程的HARQ反馈。该HARQ反馈资源为PSFCH资源，可用于承载RX UE向TX UE发送HARQ反馈。该HARQ反馈可用于指示该Sidelink HARQ进程的前一次传输的接收成功与否，即该Sidelink HARQ进程关联的Sidelink数据的前一次传输的接收成功与否。如果HARQ反馈为ACK，则可指示该Sidelink HARQ进程的前一次传输的接收成功；如果HARQ反馈为NACK，则可指示该Sidelink HARQ进程的前一次传输的接收未成功。
其中，TX UE处于RRC连接态，并被配置了DRX cycle。从DRX cycle的起始时间开始的一段时间内，TX UE处于激活态，可监听并接收到一个PDCCH。该PDCCH用于调度该Sidelink数据的一次传输。该一次传输可以是该Sidelink数据的初始传输(initial  transmission)，也可以是该Sidelink数据的重传输，例如第二次、第三次传输等等。
这里，从DRX cycle的起始时间开始的一段时间，可以是指DRX cycle的“On Duration”，也可以为开启drx-InactivityTimer后形成的扩展的“On Duration”。关于“On Duration”的扩展，可参考前面图2B的相关描述。即，该一段时间的起始时间为DRX cycle的起始时间，该一段时间的持续时长等于或大于“On Duration”的持续时长。
本申请中实施例中所涉及的Sidelink数据可以是媒体接入控制(media access control，MAC)层的数据，例如MAC协议数据单元(protocol data unit，PDU)等不作限定。本申请实施例提供的通信方法中，TX UE可以称为第一终端设备，RX UE可以称为第二终端设备。所述TX UE和RX UE可以采用单播传输方式，或者组播传输方式等，不作限定。当采用组播传输方式时，RX UE的数量可以为一个或多个。
需要说明的是，在本申请的描述中，除非另有说明，“/”表示前后关联的对象是一种“或”的关系，例如，A/B可以表示A或B；本申请中的“和/或”仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况，其中A，B可以是单数或者复数。并且，在本申请的描述中，除非另有说明，“多个”是指两个或多于两个。“以下至少一项(个)”或其类似表达，是指的这些项中的任意组合，包括单项(个)或复数项(个)的任意组合。例如，a，b，或c中的至少一项(个)，可以表示：a，b，c，a-b，a-c，b-c，或a-b-c，其中a，b，c可以是单个，也可以是多个。另外，为了便于清楚描述本申请实施例的技术方案，在本申请的实施例中，采用了“第一”、“第二”等字样对功能和作用基本相同的相同项或相似项进行区分。本领域技术人员可以理解“第一”、“第二”等字样并不对数量和执行次序进行限定，并且“第一”、“第二”等字样也并不限定一定不同。
本申请实施例提供一种通信方法，该方法可对于上述第一种方案。可以理解的是，该方法中的第一终端设备和第二终端设备可以为终端设备，也可以为终端设备中的部件(例如，芯片、电路或其它等)。网络设备可为接入网设备，例如基站等。该方法具体可为：
网络设备向第一终端设备发送第一DCI，所述第一DCI用于调度第一终端设备Sidelink数据的初传或重传。第一终端设备根据第一DCI的调度，利用PSSCH资源向第二终端设备发送Sidelink数据。第一终端设备根据PSSCH资源的时域位置，确定第一时域位置，且在第一时域位置开启第一计时器。之后当第一计时器超时时，开启第二计时器。
(一)实施例一
本申请实施例中，针对每个被配置为基于侧行链路的HARQ反馈的HARQ重传机制的SidelinkHARQ process，第一终端设备为每个Sidelink HARQ进程维护两个计时器：第一计时器和第二计时器。可替代的，上述过程还可描述为，第一终端设备为每个Sidelink HARQ进程关联两个计时器，分别为第一计时器和第二计时器。示例性的，第一计时器可以命名为：drx-HARQ-RTT-TimerSL；第二计时器可以命名为drx-RetransmissionTimerSL。在第二计时器运行期间，第一终端设备监听PDCCH。第一计时器、第二计时器的命名还可以为其他，本申请实施例对此不做限制。
图3示出了实施例一提供的通信方法的具体流程。
S301,第一终端设备和网络设备之间建立RRC连接。
RRC连接建立后，第一终端设备进入RRC连接态。
S302，第一终端设备与第二终端设备之间建立Sidelink。
该Sidelink建立后，第一终端设备通过该Sidelink向第二终端设备传输数据。
S303，网络设备为处于RRC连接态的第一终端设备配置DRX cycle。
DRX cycle由“On Duration”和“Opportunity for DRX”组成：在“On Duration”内，第一终端设备监听并接收PDCCH(激活态)；在“Opportunityfor DRX”内，第一终端设备不监听PDCCH(休眠态)。
S304，网络设备为处于RRC连接态的第一终端设备配置计时器：drx-InactivityTimer、drx-HARQ-RTT-TimerSL、drx-RetransmissionTimerSL。本申请实施例中，drx-HARQ-RTT-TimerSL可称为第一计时器，drx-RetransmissionTimerSL可称为第二计时器。
不限于图3所示，S302也可以在S301之前被执行。关于S302与S301、S303、S304的时序，本申请不做限制。
第一终端设备还可以向网络设备发送资源调度请求，以请求网络设备为Sidelink数据传输调度传输资源。通常，资源调度请求可携带缓存状态报告(buffer status report)，以指示第一终端设备在Sidelink上有多少Sidelink数据待发送。相应的，网络设备在接收到该资源调度请求之后，网络设备可以为Sidelink传输调度资源，并在PDCCH中下发所调度的Sidelink资源。第一终端设备可以通过监听PDCCH来获知网络设备调度的Sidelink资源。
S305，第一终端设备可监听并接收到网络设备下发的PDCCH 1。PDCCH 1可指示网络设备为某个Sidelink HARQ进程(如Sidelink HARQ进程a)的第i次传输所调度的Sidelink资源，即PDCCH 1可用于调度Sidelink HARQ进程a的第i次传输。
Sidelink HARQ进程a可关联数据a。Sidelink HARQ进程a可用于第一终端设备在S302建立的Sidelink上向第二终端设备传输数据a。Sidelink HARQ进程a可维护一个状态变量：CURRENT_SL_TX_NB。其中，CURRENT_SL_TX_NB可指示数据a的传输次数，CURRENT_SL_TX_NB可以被初始化为0。
Sidelink HARQ进程a关联的状态变量CURRENT_SL_TX_NB的初始值可设为0。每当第一终端设备监听并接收到用于调度Sidelink HARQ进程a的传输(包括初传、重传)的PDCCH时，第一终端设备可以将Sidelink HARQ进程a关联的CURRENT_SL_TX_NB加1。用于调度Sidelink HARQ进程a的传输的PDCCH可指示网络设备分配给Sidelink HARQ进程a的传输资源。
PDCCH 1可携带以下信息：SL grant 1、NDI、Sidelink HARQ进程a的ID。其中，SL grant 1可指示网络设备为Sidelink HARQ进程a的第i次传输所调度的资源。NDI可指示PDCCH 1所调度的Sidelink HARQ进程a的第i次传输是初传(initial transmission)还是重传(retransmission)。可选的，在一种更具体的实现方式中，PDCCH1中可携带DCI1，DCI1中可携带上述SL grant1、ND1、Sidelink HARQ进程a的ID等信息。
具体的，第一终端设备可以通过PDCCH 1中的NDI是否发生反转(toggled)来判断Sidelink HARQ进程a的第i次传输是初传还是重传：如果PDCCH 1中的NDI的值，与上一次调度给的Sidelink HARQ进程a的PDCCH中的NDI相比发生了反转，则表示Sidelink HARQ进程a的第i次传输为初传；否则，表示Sidelink HARQ进程a的第i次传输为重传。所谓NDI反转，可以是指NDI的值从0变成1，或者从1变成0。
S306，在接收到PDCCH 1之后，第一终端设备可以在PDCCH 1指示的PSSCH资源上通过Sidelink HARQ进程a向第二终端设备传输数据a，即进行数据a的第i次传输。相 应的，第二终端设备可以在PDCCH 1指示的PSSCH资源上接收第一终端设备发送的数据a。
具体的，第二终端设备可以通过监听PSCCH来获知第一终端设备会在哪些PSSCH资源上传输数据a。因为，在接收到PDCCH 1之后，第一终端设备可以在PSCCH上发送侧行链路控制信息(sidelink control information，SCI)。第二终端设备可以通过监听PSCCH来接收该SCI。该SCI用于指示第一终端设备传输数据a的资源。
S307，第一终端设备根据进行数据a的第i次传输的PSSCH资源的时域位置，开启第一计时器。
PSSCH资源包括时域资源和频域资源。所述进行数据a的第i次传输的PSSCH的时域资源可占用一个或多个时间单元。上述开启第一计时器的第一时域位置，可为进行数据a的第i次传输的PSSCH的时域资源中的最后一个时间单元之后的第一个时间单元。或者，上述开启第一计时器的第一时域位置，可为与第i次传输的PSSCH的时域资源中的最后一个时域单元距离第一时域偏移的一个时间单元。第一时域偏移可包括一个或多个时间单元。
示例性的，时间单元可以是符号、时隙等。这两个计时器以及第一时域偏移的计时单位可以是符号、时隙或者绝对时间单位(如毫秒)。符号、时隙的长度可以取决于用于传输第一数据的Sidelink的带宽部分(bandwidthpart，BWP)的参数集Numerology，如子载波间隔(subcarrier space，SCS)。不限于此，符号、时隙的长度也可以取决于第一终端设备向网络设备发送HARQ反馈的上行链路带宽部分BWP的参数集Numerology，如SCS等。
在一种可能的实现方式中，第一终端设备可根据进行数据a的第i次传输的PSSCH资源的时域资源位置和第一时域偏移，确定第一时域位置。在第一时域位置，开启第一计时器。第一时域偏移可以是协议规定的，或者，网络设备配置的，或者，第一终端设备内部实现的，不作限定。例如，一种可能的实现方式是网络设备可通过SL-PSSCH-Config信令携带上述第一时域偏移的配置等。本申请实施例，对第一时域偏移的配置方式、配置信令以及第一时域偏移的命名，不作限定。第一时域位置可为距离进行数据a的第i次传输的PSSCH资源的时域资源结束位置的一个时域偏移。当该第一时域偏移为0时，第一终端设备可在PSSCH资源上发送完数据a的第i次传输后的第一个时间单元上，即开启第一计时器。
在另一种可能的实现方式中，不定义第一时域偏移的概念，第一终端设备将进行数据a的第i次传输的PSSCH资源的时域资源结束位置后的第一个时间单元，作为第一时域位置，且在第一时域位置，开启第一计时器。
可选的，除上述情形外，第一终端设备开启第一计时器时，还可在满足以下条件：第一终端设备确定Sidelink HARQ进程a关联的状态变量CURRENT_SL_TX_NB指示Sidelink HARQ进程a的传输次数是否超过最大传输次数或预设传输次数。
当所述Sidelink HARQ进程a关联的状态变量CURRENT_SL_TX_NB小于最大传输次数或预设传输次数时，第一终端设备在第一时域位置，开启第一计时器；否则，在第一时域位置，不再开启第一计时器。需要说明的是，当所述Sidelink HARQ进程a关联的状态变量CURRENT_SL_TX_NB等于最大传输次数或预设传输次数时，可开启第一计时器，或者，也可不开启第一计时器，不作限定。所述最大传输次数和预设传输次数可为协议规定的，或者，网络设备配置的，或者第一终端设备内部实现的，不作限定。可以理解的是， 上述Sidelink HARQ进程a的传输次数，包括Sidelink HARQ进程a的初始和重传次数。例如，Sidelink HARQ进程a初传1次，重传2次，可认为该Sidelink HARQ进程a的传输次数为3次。若上述最大传输次数为5次，可以为上述Sidelink HARQ进程a的传输次数小于最大传输次数。此时，在第一时域位置，可开启第一计时器。
S308，第一终端设备根据第一计时器，开启第二计时器。
具体的，当第一计时器超时时，第一终端设备可开启第二计时器。在第二计时器运行期间，第一终端设备监听PDCCH。
S309，在监听并接收到PDCCH 2时，第一终端设备可停止第二计时器。
在一种可能的实现方式中，PDCCH 2指示的资源可以是网络设备为Sidelink HARQ进程a的第i+1次传输所调度的资源，即PDCCH 2可用于调度Sidelink HARQ进程a的数据a的第i+1次传输。PDCCH 2可携带以下信息：SL grant 2、NDI、Sidelink HARQ进程a的ID。示例性的，SL grant 2即网络设备为Sidelink HARQ进程a的第i+1次传输所调度的资源。NDI可指示PDCCH 2所调度的Sidelink HARQ进程a的第i+1次传输是初传(initial transmission)还是重传(retransmission)。第i+1次传输相对于第i次传输为重传，第i次传输为第i+1次传输的前一次传输。
在另一种可能的实现方式中，PDCCH 2指示的资源可以是网络设备为Sidelink HARQ进程a的初始传输所调度的资源。此时，Sidelink HARQ进程a关联新的数据，如数据b。即Sidelink HARQ进程a已用于第一终端设备传输新的数据，而不再是数据a。通常，这种可能的情况可发生在数据a的传输已达到最大传输次数(如5次)时。此该情况下，在后续S310中，第一终端设备也可停止第二计时器。
S310，在接收到PDCCH 2之后，第一终端设备可以在PDCCH 2指示的资源上通过Sidelink HARQ进程a向第二终端设备传输数据a，即进行数据a的第i+1次传输。相应的，第二终端设备可以在PDCCH 2指示的资源上接收第一终端设备发送的数据a。
可以看出，实施例一中，在第一时域位置，第一终端设备可开启第一计时器，并在第一计时器超时时，开启第二计时器。也即是说，在Sidelink HARQ进程a的数据发送后，在第二计时器运行期间，第一终端设备处于active态，能够监听并接收到网络设备在此期间下发的用于调度Sidelink HARQ进程a的重传的PDCCH。这样，可提高Sidelink HARQ进程a的重传的效率，避免增加Sidelink数据重传的延迟。
需要说明的是，上述方案既可应用于点对点的单播传输，也可应用于点对多点的多播传输，既可应用于配置PSFCH资源的情况，也可适用于没有配置PSFCH资源的情况。
针对没有配置PSFCH资源的情况下，本申请实施例还提供另一种可能的实现方式。与上述方法相似，不同的是，第一终端设备可默认数据a的第i次传输的HARQ反馈为ACK。上述S307的流程可替换为：第一终端设备在第一时域位置，不再开启第一计时器。关于第一终端设备确定第一时域位置的方式，可参见上述记载，不再说明。
针对配置PSFCH资源的情况，本申请实施例(二)提供另一种可能的实现方式，该方式可对应于上述第一种方案，与上述实施例(一)的区别在于：当第一计时器超时时，第一终端设备不再直接开启第二计时器。第一终端设备是否开启第二计时器还需要考虑第二终端设备通过PSFCH资源所反馈的HARQ反馈。
(二)实施例二
本实施例中，针对每个被配置为基于侧行链路的HARQ反馈的HARQ重传机制的 SidelinkHARQ process，第一终端设备为每个Sidelink HARQ进程维护两个计时器：第一计时器和第二计时器。可替代的，上述过程还可描述为，第一终端设备为每个Sidelink HARQ进程关联两个计时器，分别为第一计时器和第二计时器。示例性的，第一计时器可以命名为：drx-HARQ-RTT-TimerSL；第二计时器可以命名为drx-RetransmissionTimerSL。在第二计时器运行期间，第一终端设备监听PDCCH。第一计时器、第二计时器的命名还可以为其他，本申请对此不做限制。
图4示出了实施例二提供的通信方法的具体流程。
S401,第一终端设备和网络设备之间建立RRC连接。
RRC连接建立后，第一终端设备进入RRC连接态。
S402，第一终端设备与第二终端设备之间建立Sidelink。
该Sidelink建立后，第一终端设备通过该Sidelink向第二终端设备传输数据。
S403，网络设备为处于RRC连接态的第一终端设备配置DRX cycle。
DRX cycle由“On Duration”和“Opportunity for DRX”组成：在“On Duration”内，第一终端设备监听并接收PDCCH(激活态)；在“Opportunityfor DRX”内，第一终端设备不再监听PDCCH(休眠态)。
S404，网络设备为处于RRC连接态的第一终端设备配置计时器：drx-InactivityTimer、drx-HARQ-RTT-TimerSL、drx-RetransmissionTimerSL。本申请实施例中，drx-HARQ-RTT-TimerSL可称为第一计时器，drx-RetransmissionTimerSL可称为第二计时器。
不限于图4所示，S402也可以在S401之前被执行。关于S402与S401、S403、S404的时序，本申请不做限制。
可选的，第一终端设备还可以向网络设备发送资源调度请求，以请求网络设备为Sidelink数据传输调度传输资源。通常，资源调度请求可携带缓存状态报告(buffer status report)，以指示第一终端设备在Sidelink上有多少Sidelink数据要发送。相应的，在接收到该资源调度请求之后，网络设备可以为Sidelink传输调度资源，并在PDCCH中下发所调度的资源。第一终端设备可以通过监听PDCCH来获知网络设备调度的资源。
S405，第一终端设备可监听并接收到网络设备下发的PDCCH 1。PDCCH 1可指示网络设备为某个Sidelink HARQ进程(如Sidelink HARQ进程a)的第i次传输所调度的资源，即PDCCH 1可用于调度Sidelink HARQ进程a的第i次传输。
可选的，Sidelink HARQ进程a可关联数据a。Sidelink HARQ进程a可用于第一终端设备在S402建立的Sidelink上向第二终端设备传输数据a。Sidelink HARQ进程a可维护一个状态变量：CURRENT_SL_TX_NB。示例性的，CURRENT_SL_TX_NB可指示数据a的传输次数，CURRENT_SL_TX_NB可以被初始化为0。
Sidelink HARQ进程a关联的状态变量CURRENT_SL_TX_NB的初始值可设为0。每当第一终端设备监听并接收到用于调度Sidelink HARQ进程a的传输(包括初传、重传)的PDCCH时，第一终端设备可以将Sidelink HARQ进程a关联的CURRENT_SL_TX_NB加1。用于调度Sidelink HARQ进程a的传输的PDCCH可指示网络设备分配给Sidelink HARQ进程a的传输资源。
PDCCH 1可携带以下信息：SL grant 1、NDI、Sidelink HARQ进程a的ID。示例性的，SL grant 1可指示网络设备为Sidelink HARQ进程a的第i次传输所调度的资源。NDI可指示PDCCH 1所调度的Sidelink HARQ进程a的第i次传输是初传(initial transmission)还 是重传(retransmission)。
具体的，第一终端设备可以通过PDCCH 1中的NDI是否发生反转(toggled)来判断Sidelink HARQ进程a的第i次传输是初传还是重传：如果PDCCH 1中的NDI的值，与上一次调度给的Sidelink HARQ进程a的PDCCH中的NDI相比发生了反转，则表示Sidelink HARQ进程a的第i次传输为初传；否则，表示Sidelink HARQ进程a的第i次传输为重传。所谓NDI反转，可以是指NDI的值从0变成1，或者从1变成0。
S406，在接收到PDCCH 1之后，第一终端设备可以在PDCCH 1指示的PSSCH资源上通过Sidelink HARQ进程a向第二终端设备传输数据a，即进行数据a的第i次传输。相应的，第二终端设备可以在PDCCH 1指示的PSSCH资源上接收第一终端设备发送的数据a。
具体的，第二终端设备可以通过监听PSCCH来获知第一终端设备会在哪些PSSCH资源上传输数据a。因为，在接收到PDCCH 1之后，第一终端设备可以在PSCCH上发送侧行链路控制信息(sidelink control information，SCI)。第二终端设备可以通过监听PSCCH来接收该SCI。该SCI用于指示第一终端设备传输数据a的资源。
S407，第一终端设备根据进行数据a的第i次传输的PSSCH资源的时域位置，开启第一计时器。关于第一终端设备开启第一计时器的方式，可参见上述图3中的记载，在此不再说明。
S408，第一终端设备在PSFCH资源上接收Sidelink HARQ进程a的第i次传输的HARQ反馈，所述PSFCH资源可用于承载第二终端设备向第一终端设备发送Sidelink HARQ进程a的第i次传输的HARQ反馈。
S409，第一终端设备确定Sidelink HARQ进程a的第i次传输的HARQ反馈。Sidelink HARQ进程a的第i次传输的HARQ反馈用于指示数据a的第i次传输的接收成功与否。关于如何确定数据a的第i次传输的接收成功与否，后面内容会介绍。
S410，第一终端设备根据Sidelink HARQ进程a的第i次传输的HARQ反馈，开启或者不开启或者停止第二计时器。
具体的，一种可能的情况，在第一计时器超时之前，第一终端设备可以确定Sidelink HARQ进程a的第i次传输的HARQ反馈。如果第一终端设备确定Sidelink HARQ进程a的第i次传输的HARQ反馈为NACK，即确定Sidelink HARQ进程a的第i次传输的接收未成功，则当第一计时器超时时，第一终端设备可开启第二计时器。在第二计时器运行期间，第一终端设备监听PDCCH。如果第一终端设备确定Sidelink HARQ进程a的第i次传输的HARQ反馈为ACK，即确定Sidelink HARQ进程a的第i次传输的接收成功，则第一终端设备直接停止第一计时器，且也不再存在第一计时器超时的情况，也不再开启第二计时器或者第一终端设备也可不停止第一计时器，只是在第一计时器超时时，不再开启第二计时器。
另外一种可能的情况，在第一计时器超时之前，第一终端设备不可以确定Sidelink HARQ进程a的第i次传输的HARQ反馈。由于第一计时器超时，第二计时器已经启动，在第二计时器运行期间，如果第一终端设备确定Sidelink HARQ进程a的第i次传输的HARQ反馈为NACK，即确定Sidelink HARQ进程a的第i次传输的接收未成功，第一终端设备不停止第二计时器。在第二计时器运行期间，第一终端设备监听PDCCH。在第二计时器运行期间，如果第一终端设备确定Sidelink HARQ进程a的第i次传输的HARQ反 馈为ACK，即确定Sidelink HARQ进程a的第i次传输的接收成功，则第一终端设备直接停止第二计时器，不再监听PDCCH。
S411，在监听并接收到PDCCH 2时，第一终端设备可停止第二计时器。
在一种可能的实现方式中，PDCCH 2指示的资源可以是网络设备为Sidelink HARQ进程a的第i+1次传输所调度的资源，即PDCCH 2可用于调度Sidelink HARQ进程a的第i+1次传输。PDCCH 2可携带以下信息：SL grant 2、NDI、Sidelink HARQ进程a的ID。示例性的，SL grant 2即网络设备为Sidelink HARQ进程a的第i+1次传输所调度的资源。NDI可指示PDCCH 2所调度的Sidelink HARQ进程a的第i+1次传输是初传(initial transmission)还是重传(retransmission)。第i+1次传输相对于第i次传输为重传，第i次传输为第i+1次传输的前一次传输。当第一终端设备监听并接收到PDCCH2时，可停止第二计时器。
在另一种可能的实现方式中，PDCCH 2指示的资源可以是网络设备为Sidelink HARQ进程a的初始传输所调度的资源。此时，Sidelink HARQ进程a关联新的数据，如数据b。即Sidelink HARQ进程a已用于第一终端设备传输新的数据，而不再是数据a。通常，这种可能的情况可发生在数据a的传输已达到最大传输次数(如5次)时。此该情况下，第一终端设备也可停止第二计时器。
S412，在接收到PDCCH 2之后，第一终端设备可以在PDCCH 2指示的资源上通过Sidelink HARQ进程a向第二终端设备传输数据a，即进行数据a的第i+1次传输。相应的，第二终端设备可以在PDCCH 2指示的资源上接收第一终端设备发送的数据a。
可以看出，实施例二中，在第一时域位置，第一终端设备可开启第一计时器，并根据Sidelink HARQ进程a的第i次传输的HARQ反馈，开启第二定时器，或者，不开启或者停止第二定时器。具体的，在第一计时器超时之前，第一终端设备可以确定Sidelink HARQ进程a的第i次传输的HARQ反馈。如果第一终端设备确定Sidelink HARQ进程a的第i次传输的HARQ反馈为NACK，则当第一计时器超时时，第一终端设备可开启第二计时器。如果第一终端设备确定Sidelink HARQ进程a的第i次传输的HARQ反馈为ACK，则第一终端设备不再开启第二计时器。在第一计时器超时之前，第一终端设备不可以确定Sidelink HARQ进程a的第i次传输的HARQ反馈，在第二计时器运行期间，如果第一终端设备确定Sidelink HARQ进程a的第i次传输的HARQ反馈为NACK，第一终端设备不停止第二计时器。在第二计时器运行期间，如果第一终端设备确定Sidelink HARQ进程a的第i次传输的HARQ反馈为ACK，则第一终端设备直接停止第二计时器。相对于，上述在第一定时器超时时，直接开启第二定时器的方案，可减少第一终端设备的功耗。
需要说明的是，在上述实施例一和实施例二中，是以一个PDCCH调度一次Sidelink的数据传输为例进行说明的。在本申请实施例中，一个PDCCH也可以调度一个Sidelink数据的多次传输，例如，可以为2次或3次等。当一个PDCCH调度一个Sidelink的数据的多次传输时，一个PDCCH可指示多个PSSCH资源。在本申请实施例中，当一个PDCCH调度一个Sidelink数据的多次传输时，上述S307或S407中，根据PSSCH资源的时域位置，确定第一时域位置，开启第一计时器。可具体为：根据传输第一个重复(repetition)的PSSCH资源的时域位置，确定第一时域位置，开启第一定时器，具体如何确定第一时域位置，参考S307或S407中的描述，不再赘述。当然，上述仅为示意性说明，也可根据最后一个重复的PSSCH资源的时域位置，确定第一时域位置，开启第一定时器，甚至任一个重复的PSSCH资源的时域位置，确定第一时域位置，开启第一定时器等，不作限定。 所述第一个重复(repetition)是指所述PDCCH调度的一个Sidelink数据的多次传输中的第一次传输。
针对配置PSFCH资源的情况，本申请实施例(三)提供另一种可能的实现方式，该方式可对应于上述第二种方案，该方案可为：网络设备向第一终端设备发送第一DCI，第一DCI用于调度第一终端设备进行Sidelink数据的初传或重传。第一终端设备根据第一DCI的调度，利用PSSCH资源向第二终端设备发送Sidelink数据。第二终端设备在接收到所述Sidelink数据后，向第一终端设备发送HARQ反馈。第一终端设备利用PSFCH资源，接收上述HARQ反馈。且根据上述HARQ反馈以及PSFCH资源的时域位置，开启或不开启第一计时器。进一步的，在开启第一计时器的情况下，当第一计时器超时时，开启第二计时器。且在第二计时器的运行期间，第一终端设备处于active态，监听PDCCH。
(三)实施例三
本实施例中，针对每个被配置为基于侧行链路的HARQ反馈的HARQ重传机制的SidelinkHARQ process，第一终端设备为每个Sidelink HARQ进程维护两个计时器：第一计时器和第二计时器。可替代的，上述过程还可描述为，第一终端设备为每个Sidelink HARQ进程关联两个计时器，分别为第一计时器和第二计时器。示例性的，第一计时器可以命名为：drx-HARQ-RTT-TimerSL；第二计时器可以命名为drx-RetransmissionTimerSL。在第二计时器运行期间，第一终端设备监听PDCCH。第一计时器、第二计时器的命名还可以为其他，本申请对此不做限制。
图5示出了实施例三提供的通信方法的具体流程。
S501，第一终端设备和网络设备之间建立RRC连接。
RRC连接建立后，第一终端设备进入RRC连接态。
S502，第一终端设备与第二终端设备之间建立Sidelink。
该Sidelink建立后，第一终端设备通过该Sidelink向第二终端设备传输数据。
S503，网络设备为处于RRC连接态的第一终端设备配置DRX cycle。
DRX cycle由“On Duration”和“Opportunity for DRX”组成：在“On Duration”内，第一终端设备监听并接收PDCCH(激活态)；在“Opportunityfor DRX”内，第一终端设备不接收PDCCH以节省功耗(休眠态)。
S504，网络设备为处于RRC连接态的第一终端设备配置计时器：drx-InactivityTimer、drx-HARQ-RTT-TimerSL、drx-RetransmissionTimerSL。在本申请实施例中，drx-HARQ-RTT-TimerSL可称为第一计时器，drx-RetransmissionTimerSL可称为第二计时器。
不限于图5所示，S502也可以在S501之前被执行。关于S502与S501、S503、S504的时序，本申请不做限制。
可选的，第一终端设备还可以向网络设备发送资源调度请求，以请求网络设备为Sidelink数据传输调度传输资源。通常，资源调度请求可携带缓存状态报告(buffer status report)，以指示第一终端设备在Sidelink上有多少Sidelink数据要发送。相应的，在接收到该资源调度请求之后，网络设备可以为Sidelink传输调度资源，并在PDCCH中下发所调度的资源。第一终端设备可以通过监听PDCCH来获知网络设备调度的资源。
S505，第一终端设备可监听并接收到网络设备下发的PDCCH 1。PDCCH 1可指示网络设备为某个Sidelink HARQ进程(如Sidelink HARQ进程a)的第i次传输所调度的资源，即PDCCH 1可用于调度Sidelink HARQ进程a的第i次传输。
可选的，Sidelink HARQ进程a可关联数据a。Sidelink HARQ进程a可用于第一终端设备在S502建立的Sidelink上向第二终端设备传输数据a。Sidelink HARQ进程a可维护一个状态变量：CURRENT_SL_TX_NB。示例性的，CURRENT_SL_TX_NB可指示数据a的传输次数，CURRENT_SL_TX_NB可以被初始化为0。
进一步的，Sidelink HARQ进程a关联的状态变量CURRENT_SL_TX_NB的初始值可设为0。每当第一终端设备监听并接收到用于调度Sidelink HARQ进程a的传输(包括初传、重传)的PDCCH时，第一终端设备可以将Sidelink HARQ进程a关联的CURRENT_SL_TX_NB加1。用于调度Sidelink HARQ进程a的传输的PDCCH可指示网络设备分配给Sidelink HARQ进程a的传输资源。
S506，在接收到PDCCH 1之后，第一终端设备可以在PDCCH 1指示的PSSCH资源上通过Sidelink HARQ进程a向第二终端设备传输数据a，即进行数据a的第i次传输。相应的，第二终端设备可以在PDCCH 1指示的PSSCH资源上接收第一终端设备发送的数据a。
具体的，第二终端设备可以通过监听PSCCH来获知第一终端设备会在哪些PSSCH资源上传输数据a。因为，在接收到PDCCH 1之后，第一终端设备可以在PSCCH上发送SCI。第二终端设备可以通过监听PSCCH来接收该SCI。该SCI用于指示第一终端设备传输数据a的资源。
S507，第一终端设备在PSFCH资源上接收Sidelink HARQ进程a的第i次传输的HARQ反馈，所述PSFCH资源可用于承载第二终端设备向第一终端设备发送Sidelink HARQ进程a的第i次传输的HARQ反馈。
S508，第一终端设备确定Sidelink HARQ进程a的第i次传输HARQ反馈。Sidelink HARQ进程a的第i次传输HARQ反馈用于指示数据a的第i次传输的接收成功与否。关于如何确定数据a的第i次传输的接收成功与否，后面内容会介绍。
S509，第一终端设备根据Sidelink HARQ进程a的第i次传输HARQ反馈以及接收Sidelink HARQ进程a的第i次传输的HARQ反馈的PSFCH资源的时域位置，开启或者不开启第一计时器。
具体的，一种可能的情况，如果第一终端设备确定Sidelink HARQ进程a的第i次传输的HARQ反馈为NACK，即确定Sidelink HARQ进程a的第i次传输的接收未成功，则第一终端设备在第二时域位置，开启第一计时器；如果第一终端设备确定Sidelink HARQ进程a的第i次传输的HARQ反馈为ACK，即确定Sidelink HARQ进程a的第i次传输的接收成功，则第一终端设备在第二时域位置，不开启第一计时器。如何确定第二时域位置，有如下可能的实现方式：
PSFCH资源包括时域资源和频域资源。所述接收Sidelink HARQ进程a的第i次传输的HARQ反馈的PSFCH的时域资源可占用一个或多个时间单元。上述开启第一计时器的第二时域位置，可为接收Sidelink HARQ进程a的第i次传输的HARQ反馈的PSFCH资源的时域资源中最后一个时间单元之后的第一个时间单元。或者，可以为距离接收Sidelink HARQ进程a的第i次传输的HARQ反馈的PSFCH资源的时域资源中最后一个时间单元第二时域偏移的时间单元。第二时域偏移可以包括一个或多个时间单元。
在一种可能的实现方式中，第一终端设备可根据接收Sidelink HARQ进程a的第i次传输的HARQ反馈的PSFCH资源的时域资源位置和第二时域偏移，确定第二时域位置。 在第二时域位置，开启第一计时器。第二时域偏移可以为协议预定义的，或者，网络设备配置的，或者，第一终端设备内部实现的等，例如一种可能的实现方式是，网络设备通过SL-PSFCH-Config信令携带第二时域偏移的配置，第二时域偏移的具体配置方式、配置信令以及对第二时域偏移的命名不作限定。第二时域位置可为距离接收Sidelink HARQ进程a的第i次传输的HARQ反馈的PSFCH资源的时域资源结束位置的一个时域偏移。当该第二时域偏移为0时，第一终端设备在PSFCH资源上接收完数据a的第i次传输的HARQ反馈后的第一个时间单元上，即开启第一计时器。或者，可描述为第一终端设备在接收Sidelink HARQ进程a的第i次传输的HARQ反馈的PSFCH资源结束位置后的第一个时间单元上，即开启第一计时器。
在另一种可能的实现方式中，不定义第二时域偏移的概念，第一终端设备将接收Sidelink HARQ进程a的第i次传输的HARQ反馈的PSFCH资源的时域资源结束位置后的第一个时间单元，作为第二时域位置，且在第二时域位置，开启第一计时器。
可选的，除上述情形外，第一终端设备开启第一计时器时，还可在满足以下条件：第一终端设备确定Sidelink HARQ进程a关联的状态变量CURRENT_SL_TX_NB指示Sidelink HARQ进程a的传输次数；是否超过最大传输次数或预设传输次数。
当所述Sidelink HARQ进程a关联的状态变量CURRENT_SL_TX_NB小于最大传输次数或预设传输次数时，第一终端设备根据Sidelink HARQ进程a的第i次传输HARQ反馈在第二时域位置，开启或者不开启第一计时器；比如，若Sidelink HARQ进程a的第i次传输的HARQ反馈为ACK，即确定Sidelink HARQ进程a的第i次传输接收成功，则第一终端设备在第二时域位置不开启第一定时器。而若Sidelink HARQ进程a的第i次传输的HARQ反馈为NACK，即确定Sidelink HARQ进程a的第i次传输失败，则第一终端设备在第二时域位置开启第一定时器。而当所述Sidelink HARQ进程a关联的状态变量CURRENT_SL_TX_NB大于最大传输次数或预设传输次数时，则第一终端设备在第二时域位置，不再开启第一计时器。需要说明的是，当所述Sidelink HARQ进程a关联的状态变量CURRENT_SL_TX_NB等于最大传输次数或预设传输次数时，可开启第一计时器，或者，也可不开启第一计时器，不作限定。所述最大传输次数和预设传输次数可为协议规定的，或者，网络设备配置的，或者第一终端设备内部实现的，不作限定。
S510，如果第一计时器开启时，当第一计时器超时时，第一终端设备可开启第二计时器。在第二计时器运行期间，第一终端设备监听PDCCH。
S511，在监听并接收到PDCCH 2时，第一终端设备可停止第二计时器。
在一种可能的实现方式中，PDCCH 2指示的资源可以是网络设备为Sidelink HARQ进程a的第i+1次传输所调度的资源，即PDCCH 2可用于调度Sidelink HARQ进程a的第i+1次传输。第i+1次传输相对于第i次传输为重传，第i次传输为第i+1次传输的前一次传输。当第一终端设备监听到PDCCH2时，可停止第二计时器。
在另一种可能的实现方式中，PDCCH 2指示的资源可以是网络设备为Sidelink HARQ进程a的初始传输所调度的资源。此时，Sidelink HARQ进程a关联新的数据，如数据b。即Sidelink HARQ进程a已用于第一终端设备传输新的数据，而不再是数据a。通常，这种可能的情况可发生在数据a的传输已达到最大传输次数(如5次)时。此该情况下，第一终端设备也可停止第二计时器。
S512，在接收到PDCCH 2之后，第一终端设备可以在PDCCH 2指示的资源上通过 Sidelink HARQ进程a向第二终端设备传输数据a，即进行数据a的第i+1次传输。相应的，第二终端设备可以在PDCCH 2指示的资源上接收第一终端设备发送的数据a。
可以看出，实施例三中，第一终端设备根据Sidelink HARQ进程a的第i次传输HARQ反馈以及接收Sidelink HARQ进程a的第i次传输的HARQ反馈的PSFCH资源的时域位置，开启或者不开启第一计时器。例如，当Sidelink HARQ进程a的第i次传输HARQ反馈为ACK时，则第一终端设备可不再开启第一计时器。而当Sidelink HARQ进程a的第i次传输HARQ反馈为NACK，则第一终端设备开启第一计器，且当第一计时器超时时，开启第二定时器。在第二定时器运行期间，第一终端设备处于active态，能够监听并接收网络设备在此期间下发的用于调度Sidelink进程a的重传的PDCCH。这样，不但可提高Sidelink进程a的重传的效率，避免增加Sidelink数据重传的延迟。进一步，可降低第一终端设备的功耗。
在以下描述中，将继续论述第一终端设备确定Sidelink HARQ进程a的HARQ反馈是ACK或NACK的过程：为了便于理解，首先介绍以下几种通信方式的HAQR反馈。
1、点对点的单播通信方式
针对点对点的单播通信方式，RX UE可能每接收到TX UE发送的一个数据包，即向TX UE反馈HARQ。示例性的，若RX UE成功接收到数据包，且解码无误，则向TX UE反馈ACK，否则反馈NACK。
2、点对多点的组播通信方式
针对点对多点的组播通信方式，HARQ反馈的方式分为两种。第一种是NACK-only的反馈方式。一个组内的RX UE仅向TX UE反馈NACK，并不反馈ACK。当TX UE接收到至少一个NACK的时候，就认为这个数据包的HARQ反馈是NACK。如果TX没有收到HARQ反馈，则认为这个数据包的HARQ反馈是ACK。第二种是ACK-NACK的HARQ反馈方式，一个组内的RX UE既可以向TXUE反馈ACK也可以反馈NACK。只有当TX UE收到组内的所有RX UE的HARQ反馈并且全部都是ACK时，才认为这个数据包的HARQ反馈是ACK，否则就认为这个数据包的HARQ反馈是NACK。具体地，NACK-only反馈方式可以指基于位置(distance-based)的NACK-only反馈，也可以指不基于位置(non-distance based)的NACK-only反馈。示例性的，基于位置的NACK-only反馈是指当TX UE可以获得位置信息的时候，通过SCI指示一个位置范围内的RX UE才可以做NACK-only反馈，这样可以避免接收到远距离RX UE发送的NACK造成不必要的重传。
3、SL MAC PDU的HARQ反馈属性
目前支持通过SL-HARQ-Feedback-Enabled参数对测行链路逻辑信道(sidelinklogical channel，SL LCH)的HARQ属性进行配置。如果一个SL LCH的SL-HARQ-Feedback-Enabled参数被配置为Enable，表示该SL LCH是支持HARQ反馈的。如果一个SL LCH的SL-HARQ-Feedback-Enabled参数被配置为Disable，表示该SL LCH是不支持HARQ反馈的。
TX UE在组包时，逻辑信道复用(logical channel prioritization)过程不能将具有不同HARQ属性的SL LCH复用到一个媒体接入控制(media access control，MAC)协议数据单元(protol data unit，PDU)里面。当一个MAC PDU的HARQ属性是enable的时候，TX UE可以在SCI里将HARQ反馈比特位设置为enable，请求RX UE对该MAC PDU进 行HARQ反馈。而当一个MAC PDU的HARQ属性是disable时，TX UE可以在SCI里将HARQ反馈比特位设置为disable，请求RX UE不对该MAC PDU进行HARQ反馈。
(1)在以下任一情况下，第一终端设备可确定Sidelink HARQ进程a的第i次传输的HARQ反馈为NACK，即可确定Sidelink HARQ进程a的第i次传输的接收未成功：
情况1：在单播通信方式下，第一终端设备接收到第二终端设备发送的HARQ反馈为NACK。
具体地，该HARQ反馈用于指示Sidelink HARQ进程a关联的数据a的第i次传输是否被第二终端设备成功接收。HARQ反馈为NACK时，可指示第二终端设备未成功接收Sidelink HARQ进程a关联的数据a的第i次传输。第二终端设备未成功接收Sidelink HARQ进程a关联的数据a的第i次传输，其原因可包括但不限于：第二终端设备未成功解码该数据a。
情况2：在单播通信方式，或者组播通信方式的ACK-NACK反馈方式下，第一终端设备没有接收到第二终端设备发送的HARQ反馈。
具体地，第一终端设备没有接收到第二终端设备发送的Sidelink HARQ进程a关联的数据a的第i次传输的HARQ反馈，具体可以是指，第一终端设备在Sidelink HARQ进程a关联的PSFCH资源上没有收到第二终端设备发送的Sidelink HARQ进程a关联的数据a的第i次传输的HARQ反馈。Sidelink HARQ进程a关联的PSFCH资源可由网络设备配置。
情况3：第一终端设备在PSSCH资源上未向第二终端设备传输该Sidelink数据。
具体地，PSSCH资源是网络设备为Sidelink HARQ进程a的第i次传输所调度的资源。情况3出现的原因可以为资源冲突，即第一终端设备在PSSCH资源上传输其他数据，而非数据a。情况3适用于单播通信方式，或组播通信方式中的NACK-only反馈或ACK-NACK反馈。
情况4：在组播通信方式的NACK-only反馈方式下，第一终端设备对Sidelink HARQ进程a的第i次传输接收到至少一个NACK反馈。
具体的，在组播通信方式的NACK-only反馈方式下，第一终端设备可以组播传输方式，向至少一个终端设备(包括第二终端设备)发送数据a。针对上述至少一个终端设备中的任一个终端设备，若接收数据a成功，则不再反馈HARQ。若接收数据a失败，则反馈NACK。第一终端设备接收到任一个终端设备发送的NACK，则认为当前数据a的传输失败。
情况5：在组播传输方式的ACK-NACK反馈方式下，第一终端设备对Sidelink HARQ进程a的第i次传输接收到至少一个NACK反馈和/或至少一个不连续发送(discountiouns transmission，DTX)，所述DTX是指第一终端设备没有接收到组内任一个终端设备发送的HARQ反馈。
具体的，在组播通信方式的ACK-NACK反馈方式下，第一终端设备可以组播传输方式，向至少一个终端设备(包括第二终端设备)发送数据a。上述至少一个终端设备中的任一个终端设备，若成功接收上述数据a，则向第一终端设备反馈ACK，否则向第一终端设备反馈NACK。因此，第一终端设备若接收到任一个终端设备发送的NACK，则认为当前数据a的传输失败。或者，由于上述至少一个终端设备中的任一个终端设备，在接收到数据a之后，均会向第一终端设备反馈ACK或NACK。因此，若第一终端设备没有接收到组内任一个终端设备的HARQ反馈，可认为当前数据a的传输是失败的。
(2)在以下情况下，第一终端设备可确定Sidelink HARQ进程a的第i次传输的HARQ 反馈为ACK，即可确定Sidelink HARQ进程a的第i次传输的接收成功：
情况1：在单播通信方式下，第一终端设备接收到第二终端设备发送的HARQ反馈为ACK。该HARQ反馈为ACK时，可指示第二终端设备成功接收Sidelink HARQ进程a的第i次传输。
情况2：在组播通信方式中的NACK-only反馈方式下，第一终端设备对Sidelink HARQ进程a的第i次传输未接收到NACK反馈。
情况3：在组播通信方式中的ACK-NACK反馈方式下，第一终端设备对Sidelink HARQ进程a的第i次传输，所接收到的HARQ反馈都是ACK反馈，即组播组内的所有接收端终端设备反馈的均为ACK。
除此之外，在一种可能的实现方式中。在单播通信方式，或组播通信方式的NACK-only反馈或组播通信方式的ACK-NACK反馈下，若Sidelink HARQ进程a关联的数据a的HARQ属性是去使能(disable)，第一终端设备将SCI中的HARQ反馈比特位去使能，即第一终端设备指示第二终端设备对Sidelink HARQ进程a的第i次传输不进行HARQ反馈。因此第一终端设备不能接收到来自第二终端设备对Sidelink HARQ进程a的第i次传输的HARQ反馈。在这种情况下，第一终端设备可确定Sidelink HARQ进程a的第i次传输的HARQ反馈为NACK，或者确定Sidelink HARQ进程a的第i次传输的HARQ反馈为ACK，不作限定。具体确定Sidelink HARQ进程a的第i次传输的HARQ反馈为NACK或者ACK，取决于第一终端设备的内部实现。
本申请实施例还提供一种通信方法，该通信方法可对应于上述第三种方案，该方案中，不再引入计时器，第一终端设备可根据发送Sidelink数据的PSSCH资源的时域位置，直接监听网络设备的PDCCH。
(四)实施例四
图6示出了实施例四的通信方法的具体流程。
S601，第一终端设备和网络设备之间建立RRC连接。RRX连接建立后，第一终端设备可进入RRC连接态。
S602，第一终端设备与第二终端设备之间建立Sidelink。该Sidelink建立后，第一终端设备可通过该Sidelink向第二终端设备传输数据。
S603，网络设备为处于RRC连接态的第一终端设备配置DRX cycle。
DRX cycle由“On Duration”和“Opportunity for DRX”组成：在“On Duration”内，第一终端设备监听并接收PDCCH(激活态)；在“Opportunity for DRX”内，第一终端设备不监听PDCCH以节省功耗(休眠态)。
可选的，第一终端设备还可向网络设备发送资源调度请求，以请求网络设备为Sidelink数据传输调度传输资源。通常，资源调度请求可携带缓存状态报告(buffer status report)，以指示第一终端设备在Sidelink上有多少Sidelink数据要发送。相应的，在接收到该资源调度请求之后，网络设备可以为Sidelink传输调度资源，并在PDCCH中下发所调度的资源。第一终端设备可通过监听PDCCH来获知网络设备调度的资源。
S604，第一终端设备可监听并接收网络设备下发的PDCCH1。PDCCH1可指示网络设备为某个Sidelink HARQ进程(如Sidelink HARQ进程a)的第i次传输所调度的资源，即PDCCH1可用于调度Sidelink HARQ进程a的第i次传输。
可选的，Sidelink HARQ进程a可关联数据a。Sidelink HARQ进程a可用于第一终端设备在S602建立的Sidelink上向第二终端设备传输数据a。Sidelink HARQ进程a可维护一个状态变量：CURRENT_SL_TX_NB。示例性的，CURRENT_SL_TX_NB可指示数据a的传输次数，CURRENT_SL_TX_NB可以被初始化为0。
Sidelink HARQ进程a关联的状态变量CURRENT_SL_TX_NB的初始值可设为0。每当第一终端设备监听并接收到用于调度Sidelink HARQ进程a的传输(包括初传、重传)的PDCCH时，第一终端设备可以将Sidelink HARQ进程a关联的CURRENT_SL_TX_NB加1。用于调度Sidelink HARQ进程a的传输的PDCCH可指示网络设备分配给Sidelink HARQ进程a的传输资源。
S605，在接收到PDCCH1之后，第一终端设备可以在PDCCH1指示的PSSCH资源上通过Sidelink HARQ进程a向第二终端设备传输数据a，即进行数据a的第i次传输。相应的，第二终端设备可以在PDCCH1指示的PSSCH资源上接收第一终端设备发送的数据a。
S606，第一终端设备根据进行数据a的第i次传输的PSSCH资源的时域位置，开始监听PDCCH。
PSSCH资源包括时域资源和频域资源。所述进行数据a的第i次传输的PSSCH的时域资源可占用一个或多个时间单元。第一终端设备监听PDCCH的第三时域位置，可为进行数据a的第i次传输的PSSCH的时域资源中的最后一个时间单元之后的第一个时间单元。或者，上述监听PDCCH的第三时域位置，可为与第i次传输的PSSCH的时域资源中的最后一个时域单元距离第三时域偏移的一个时间单元。第三时域偏移可包括一个或多个时间单元。
在一种可能的实现方式中，第一终端设备可根据进行数据a的第i次传输的PSSCH资源的时域资源位置和第三时域偏移，确定第三时域位置。在第三时域位置，开始监听PDCCH。第三时域偏移可以是协议规定的，或者，网络设备配置的，或者，第一终端设备内部实现的，不作限定。例如，一种可能的实现方式是网络设备可通过SL-PSSCH-Config信令携带上述第三时域偏移的配置信息等。本申请实施例，对第三时域偏移的配置方式、配置信令以及第三时域偏移的命名，不作限定。第三时域偏移可为距离进行数据a的第i次传输的PSSCH资源的时域资源结束位置的一个时域偏移。当该第三时域偏移为0时，第一终端设备可在PSSCH资源上发送完数据a的第i次传输后的第一个时间单元上，即监听PDCCH。
在另一种可能的实现方式中，不定义第三时域偏移的概念，第一终端设备将进行数据a的第i次传输的PSSCH资源的时域资源结束位置后的第一个时间单元，作为第三时域位置，且在第三时域位置，开始监听PDCCH。
除上述情形外，第一终端设备监听PDCCH，还可在满足以下条件：第一终端设备确定Sidelink HARQ进程a关联的状态变量CURRENT_SL_TX_NB指示Sidelink HARQ进程a的传输次数；是否超过最大传输次数或预设传输次数。
当所述Sidelink HARQ进程a关联的状态变量CURRENT_SL_TX_NB小于最大传输次数或预设传输次数时，第一终端设备根据Sidelink HARQ进程a的第i次传输HARQ反馈在第三时域位置，监听PDCCH；否则，在第三时域位置，不再监听PDCCH。需要说明的是，当所述Sidelink HARQ进程a关联的状态变量CURRENT_SL_TX_NB等于最大传输次数或预设传输次数时，第一终端设备可监听PDCCH，或者，第一终端设备也可不监听PDCCH，不作限定。所述最大传输次数和预设传输次数可为协议规定的，或者，网络设备 配置的，或者第一终端设备内部实现的，不作限定。
S607，第一终端设备接收到PDCCH2。
在一种可能的实现方式中，PDCCH2指示的资源可以是网络设备为Sidelink HARQ进程a的第i+1次传输所调度的资源，即PDCCH2可用于调度Sidelink HARQ进程a的第i+1次传输。第i+1次传输相对于第i次传输为重传，第i次传输相对于第i+1次传输的前一次传输。
在另一种可能的实现方式中，PDCCH2指示的资源可以是网络设备为Sidelink HARQ进程a的初始传输所调度的资源。此时，Sidelink HARQ进程a关联新的数据，如数据b。即Sidelink HARQ进程a已用于第一终端设备传输新的数据，而不再是数据a。在该情况下，在后续S608中，第一终端设备也可以停止第二计时器。
S608，在监听并接收到PDCCH2时，第一终端设备可停止对PDCCH的监听。之后，第一终端设备可根据PDCCH2的调度，向第二终端设备进行Sidelink HARQ进程a的第i+1次传输。
或者，第一终端设备可在预设时刻，停止对PDCCH的监听。所述预设时刻可以为协议规定的，或者，网络设备配置的，或者，基于第一终端设备内部实现的，不作限定。
需要说明的是，上述方案既可应用于点对点的单播传输，也可应用于点对多点的多播传输，既可应用于配置PSFCH资源的情况，也可适用于没有配置PSFCH资源的情况，不作限定。
在实施例四的方案中，不再引入计时器，第一终端设备根据PSSCH资源的时域位置，直接监听网络设备的PDCCH。该方法也可降低Sidelink数据的传输时延，满足Sidelink业务的QoS要求。
需要说明的是，在本申请实施例四中，是以一个PDCCH调度一次Sidelink的数据传输为例进行说明的。当然，一个PDCCH也可以调度一个Sidelink数据的多次传输。此时，一个PDCCH可指示多个PSSCH资源。在上述S606中，第一终端设备PSSCH资源的时域位置，确定第三时域位置，开始监听PDCCH，可具体为：第一终端设备可根据传输第一个重复(repetition)的PSSCH资源的时域位置，确定第三时域位置，开始监听PDCCH，具体如何确定第三时域位置，可参考S606中的描述，不再赘述。当然，上述仅为示意性说明，也可根据最后一个重复的PSSCH资源的时域位置，确定第三时域位置，开始监听PDCCH，甚至任一个重复的PSSCH资源的时域位置，确定第三时域位置，开始监听PDCCH等，不作限定。所述第一个重复是指所述PDCCH调度的一个Sidelink数据的多次传输中的第一次传输。本申请实施例还提供一种通信方法，该通信方法可对应于上述第四种方案，该方案中，不再引入计时器，第一终端设备可在PSFCH资源上接收到HARQ反馈时，根据PSFCH资源的时域位置，直接监听PDCCH。
(五)实施例五
针对配置PSFCH资源的情况，提供一种实施例。
如图7所示，实施例五提供的通信方法的具体流程。
S701，第一终端设备和网络设备之间建立RRC连接。
RRC连接建立后，第一终端设备进入RRC连接态。
S702，第一终端设备与第二终端设备之间建立Sidelink。
该Sidelink建立后，第一终端设备可通过该Sidelink向第二终端设备传输数据。
S703，网络设备为处于RRC连接态的第一终端设备配置DRX cycle。
示例性的，DRX cycle由“On Duration”和“Opportunity for DRX”组成：在“On Duration”内，第一终端设备监听并接收PDCCH(激活态)；在“Opportunityfor DRX”内，第一终端设备不监听PDCCH(休眠态)。
可选的，第一终端设备还可向网络设备发送资源调度请求，以请求网络设备为Sidelink数据传输调度传输资源。通常，资源调度请求可携带缓存状态报告，以指示第一终端设备在Sidelink上有多少Sidelink数据要发送。相应的，在接收到该资源调度请求之后，网络设备可以为Sidelink传输调度资源，并在PDCCH中下发所调度的资源。第一终端设备可通过监听PDCCH来获知网络设备调度的资源。
S704，第一终端设备可监听并接收网络设备下发的PDCCH1。PDCCH1可指示网络设备为某个Sidelink HARQ进程(如Sidelink HARQ进程a)的第i次传输所调度的资源，即PDCCH1可用于调度Sidelink HARQ进程a的第i次传输。
可选的，Sidelink HARQ进程a可关联数据a。Sidelink HARQ进程a可用于第一终端设备在S702建立的Sidelink上向第二终端设备传输数据a。Sidelink HARQ进程a可维护一个状态变量：CURRENT_SL_TX_NB。示例性的，CURRENT_SL_TX_NB可指示数据a的传输次数，CURRENT_SL_TX_NB可以被初始化为0。
Sidelink HARQ进程a关联的状态变量CURRENT_SL_TX_NB的初始值可设为0。每当第一终端设备监听并接收到用于调度Sidelink HARQ进程a的传输(包括初传、重传)的PDCCH时，第一终端设备可以将Sidelink HARQ进程a关联的CURRENT_SL_TX_NB加1。用于调度Sidelink HARQ进程a的传输的PDCCH可指示网络设备分配给Sidelink HARQ进程a的传输资源。
S705，在接收到PDCCH1之后，第一终端设备可以在PDCCH1指示的PSSCH资源上通过Sidelink HARQ进程a向第二终端设备传输数据a，即进行数据a的第i次传输。相应的，第二终端设备可以在PDCCH1指示的PSSCH资源上接收第一终端设备发送的数据a。
具体的，第二终端设备可以通过监听PSCCH来获知第一终端设备会在哪些PSSCH资源上传输数据a。因此，在接收到PDCCH1之后，第一终端设备可以在PSCCH上发送SCI。第二终端设备可以通过监听PSCCH来接收该SCI。该SCI用于指示第一终端设备传输数据a的资源。
S706，第一终端设备在PSFCH资源上接收Sidelink HARQ进程a的第i次传输的HARQ反馈，所述PSFCH资源可用于承载第二终端设备向第一终端设备发送Sidelink HARQ进程a的第i次传输的HARQ反馈。
S707，第一终端设备确定Sidelink HARQ进程a的第i次传输HARQ反馈。Sidelink HARQ进程a的第i次传输HARQ反馈用于指示数据a的第i次传输的接收成功与否。关于第一终端设备确定Sidelink HARQ进程a的第i次传输的HARQ反馈是否成功的过程，可参见上述描述，在此不再说明。
S708，第一终端设备根据Sidelink HARQ进程a的第i次传输HARQ反馈以及接收Sidelink HARQ进程a的第i次传输的HARQ反馈的PSFCH资源的时域位置，监听或不监听PDCCH。第一终端设备在监听并接收到PDCCH2时，PDCCH2可用于调度Sidelink HARQ进程a的第i+1次传输。第一设备可以在PDCCH2指示的PSSCH资源上通过Sidelink HARQ进程a向第二终端设备传输数据a，即进行数据a的第i+1次传输。
在一种可能的实现方式中，如果第一终端设备确定Sidelink HARQ进程a的第i次传输的HARQ反馈为NACK，即确定Sidelink HARQ进程a的第i次传输的接收未成功，则第一终端设备可根据接收Sidelink HARQ进程a的第i次传输的HARQ反馈的PSFCH资源的时域位置，确定第四时域位置；第一终端设备在第四时域位置，监听PDCCH。之后，第一终端设备在监听并接收到PDCCH2时，则第一终端设备停止监听PDCCH。或者，第一终端设备可在预设时刻，停止监听PDCCH。所述预设时刻可为协议规定的，或者，网络设备配置，或者为第一终端设备内部实现的等，不作限定。
可选的，第一终端设备可根据接收Sidelink HARQ进程a的第i次传输的HARQ反馈的PSFCH资源的时域资源位置和第四时域偏移，确定第四时域位置。在第四时域位置，监听PDCCH。第四时域偏移可以为协议预定义的，或者，网络设备配置的，或者，第一终端设备内部实现的等，不作限定。例如在一种可能的实现方式中，网络设备通过SL-PSFCH-Config信令携带第四时域偏移的配置，第四时域偏移的具体配置方式、配置信令以及对第四时域偏移的命名不作限定。第四时域位置可为距离接收Sidelink HARQ进程a的第i次传输的HARQ反馈的PSFCH资源的时域资源结束位置的一个时域偏移。当该第四时域偏移为0时，第一终端设备在PSFCH资源上接收完数据a的第i次传输的HARQ反馈后的第一个时间单元上，即监听PDCCH。或者，可描述为第一终端设备在接收Sidelink HARQ进程a的第i次传输的HARQ反馈的PSFCH资源结束位置后的第一个时间单元上，即监听PDCCH。
在另一种可能的实现方式中，不定义第四时域偏移的概念，第一终端设备将接收Sidelink HARQ进程a的第i次传输的HARQ反馈的PSFCH资源的时域资源结束位置后的第一个时间单元，作为第四时域位置，且在第四时域位置，监听PDCCH。
在另一种可能的实现方式中，如果第一终端设备确定Sidelink HARQ进程a的第i次传输的HARQ反馈为ACK，即确定Sidelink HARQ进程a的第i次传输的接收成功，则第一终端设备在第四时域位置不再监听PDCCH。
除上述情形外，第一终端设备监听PDCCH，还可在满足以下条件：第一终端设备确定Sidelink HARQ进程a关联的状态变量CURRENT_SL_TX_NB指示Sidelink HARQ进程a的传输次数；是否超过最大传输次数或预设传输次数。
当所述Sidelink HARQ进程a关联的状态变量CURRENT_SL_TX_NB小于最大传输次数或预设传输次数时，第一终端设备可根据Sidelink HARQ进程a的第i次传输的HARQ反馈，在第四时域位置，监听或者不监听PDCCH；比如，若Sidelink HARQ进程a的第i次传输的HARQ反馈为ACK，即确定Sidelink HARQ进程a的第i次传输接收成功，则第一终端设备可不监听PDCCH。而若Sidelink HARQ进程a的第i次传输的HARQ反馈为NACK，即确定Sidelink HARQ进程a的第i次传输失败，则第一终端设备监听PDCCH。而当所述Sidelink HARQ进程a关联的状态变量CURRENT_SL_TX_NB大于最大传输次数或预设传输次数时，则第一终端设备在第四时域位置，不再监听PDCCH。
需要说明的是，当所述Sidelink HARQ进程a关联的状态变量CURRENT_SL_TX_NB等于最大传输次数或预设传输次数时，第一终端设备可监听PDCCH，或者，第一终端设备也可不监听PDCCH，不作限定。所述最大传输次数和预设传输次数可为协议规定的，或者，网络设备配置的，或者第一终端设备内部实现的，不作限定。
在该通信方法中，不再引入计时器，第一终端设备可根据PSFCH资源的时域位置， 直接监听网络设备的PDCCH。该方法也可降低Sidelink数据的传输时延，满足Sidelink业务的QoS要求。
需要说明的是，上述实施例一至实施例五，可应用于配置有PUCCH资源的情况下，也可应用于没有配置PUCCH资源的情况下，不作限定。其中，配置PUCCH资源还可称为所述PSSCH资源(数据a的第i次传输的PSSCH资源)有关联的PUCCH资源，没有配置PUCCH资源还可称为所述PSSCH资源(数据a的第i次传输的PSSCH资源)没有关联的PUCCH资源。示例性的，PUCCH资源可以为所述第一终端设备向所述网络设备发送所述数据a的第i次传输的HARQ反馈的资源。
或者，上述实施例一至实施例五，可应用于动态DCI调度的Sidelink传输的情况下，即数据a的第i次传输是PDCCH动态调度的Sidelink传输，也可应用于预配置的Sidelink授权(configured Sidelink grant)的情况下，即数据a的第i次传输是在预配置的Sidelink授权上的Sidelink传输。可选的，在预配置的Sidelink授权中，该预配置的Sidelink授权可没有关联的PUCCH资源，示例性的，PUSCCH资源可以为所述第一终端设备给所述网络设备发送所述数据a的第i次传输的HARQ反馈的资源。
所述预配置的Sidelink授权可以指在NR Sidelink中网络设备为终端预配置的Sidelink传输所需的资源。示例性的，将预配置的Sidelink传输所需的资源可以称为Sidelink CG配置，或预配置Sidelink授权配置。终端无需网络设备的动态调度，就可以在Sidelink CG配置上进行Sidelink传输。Sidelink CG配置包括但不限于第五代移动通信技术(5th-Generation，5G)所采用的两种预配置授权资源。5G所采用的两种预配置授权资源分别是通过两种授权方式得到，该两种授权方式包括配置授权方式1(configured grant type1)和配置授权方式2(configured grant type2)。
示例性的，配置授权方式1是指网络设备通过半静态配置方式为终端预配置上行传输所需的资源(CG配置)，即按周期配置激活的CG配置，不需要终端每次发送上行数据前都向网络设备获取该CG配置的上行授权。例如，网络设备可以通过RRC信令为终端配置用于上行传输的CG配置，该RRC信令还可以包括该CG配置的周期。对于Sidelink CG配置，就是指网络设备通过半静态配置方式为终端预配置Sidelink传输所需的资源(Sidelink CG配置)，即按周期配置激活的Sidelink CG配置，不需要终端每次发送Sidelink数据前都向网络设备获取该Sidelink CG配置的Sidelink授权。例如，网络设备可以通过RRC信令为终端配置用于Sidelink传输的Sidelink CG配置，该RRC信令还可以包括该Sidelink_CG配置的周期。
配置授权方式2是指网络设备可以通过RRC信令为终端配置用于上行传输的部分信息，例如，用于上行传输的CG配置的周期等。然后，网络设备通过携带有用于上行传输的CG配置的物理层信令，激活该CG配置，从而终端可以在该CG配置进行上行传输。其中，物理层信令包括DCI。对于Sidelink配置，就是指网络设备可以通过RRC信令为终端配置用于Sidelink传输的部分信息，例如，用于Sidelink传输的Sidelink_CG配置的周期等。然后，网络设备通过携带有用于Sidelink传输的CG配置的物理层信令，激活该Sidelink CG配置，从而终端可以在该Sidelink CG配置进行Sidelink传输。其中，物理层信令包括DCI。
需要说明的是，上述两种授权方式的命名不仅仅局限于配置授权方式1和配置授权方式2，还可以有其他命名，本申请实施例对这两种授权方式的命名不做限制。上述两种授 权方式适用的通信系统除了5G通信系统，也可以是LTE通信系统，或者其他通信系统，本申请实施例对这两种授权方式适用的通信系统也不做限制。
以上结合图1、图2A至图2C、图3至图7详细说明了本申请实施提供的方法。以下结合图8和图9详细说明本申请实施例提供的装置。应理解，装置实施例的描述与方法实施例的描述相互对应。因此，未详细描述的内容可参见上文方法实施例中的描述。
图8是本申请实施例提供的装置800的示意性框图，用于实现上述方法实施例中的第一终端设备的功能。该装置可以为软件单元或芯片系统。芯片系统可以由芯片构成，也可以包括芯片或其它分立器件。该装置可以包括通信单元801，用于与外部进行通信。该装置还可以包括处理单元802，用于进行处理。
在一种示例中，上述装置800用于实现上述方法实施例一和实施例二中第一终端设备的步骤。装置800可以是终端设备，也可以是配置于终端设备中的芯片或电路。通信单元801用于执行上述实施例一或实施例二中第一终端设备侧的收发相关操作，处理单元802用于执行上述实施例一或实施例二中第一终端设备侧的处理相关操作。
例如，通信单元801，用于接收来自网络设备的第一下行控制信息DCI，所述第一DCI用于调度侧行链路Sidelink数据的初传或重传，所述Sidelink数据关联的Sidelink混合自动重传请求HARQ进程关联两个计时器，分别为第一计时器和第二计时器；处理单元802，用于根据所述第一DCI的调度，利用物理侧行链路共享信道PSSCH资源向第二终端设备发送Sidelink数据；处理单元802，还用于根据所述PSSCH资源的时域位置，开启第一计时器，以及根据所述第一计时器，开启或不开启第二计时器；其中，在开启第二计时器的情况下，在所述第二计时器的运行期间，所述第一终端设备监听物理下行控制信道PDCCH。
可选的，处理单元802根据所述PSSCH资源的时域位置，开启第一计时器，包括：根据所述PSSCH资源的时域资源位置和第一时域偏移，确定第一时域位置；或者，将所述PSSCH资源的时域资源结束位置后的第一个时间单元，作为所述第一时域位置；在所述第一时域位置，开启所述第一计时器。
可选的，处理单元802所述第一时域位置，开启第一计时器，包括：确定所述Sidelink HARQ进程关联的Sidelink数据的传输次数；当所述Sidelink HARQ进程关联的Sidelink数据的传输次数小于或等于最大传输次数或预设传输次数时，在所述第一时域位置，开启所述第一计时器。
可选的，处理单元802，还用于在所述Sidelink HARQ进程关联的Sidelink数据的传输次数大于最大传输次数或预设传输次数时，在所述第一时域位置，不再开启所述第一计时器。
可选的，处理单元802根据所述第一计时器，开启或不开启第二计时器，包括：当所述第一计时器超时时，直接开启所述第二计时器。
可选的，处理单元802根据所述第一计时器，开启或不开启第二计时器，包括:在所述第一计时器超时之前，确定所述Sidelink HARQ进程的HARQ反馈为否定性确认NACK，则当所述第一计时器超时时，开启所述第二计时器；或者，在所述第一计时器超时之前，确定所述Sidelink HARQ进程的HARQ反馈为肯定性确认ACK，则直接停止所述第一计时器，此时不存在所述第一计时器超时的情况，不再开启所述第二计时器，或者，不停止所述第一计时器，但在所述第一计时器超时时，不再开启所述第二计时器。
可选的，处理单元802根据所述第一计时器，开启或不开启第二计时器，包括：在所述第一计时器超时之前，不能确定所述Sidelink HARQ进程的HARQ反馈；在所述第一计时器超时时，开启所述第二计时器。
可选的，处理单元802，还用于：在所述第二计时器的运行期间，确定所述Sidelink HARQ进程的HARQ反馈为NACK的情况下，则不停止所述第二计时器，在所述第二计时器的运行期间，继续监听PDCCH；或者，在所述第二计时器的运行期间，确定所述Sidelink HARQ进程的HARQ反馈为ACK的情况下，则直接停止所述第二计时器，不再监听PDCCH。
可选的，在开启所述第二计时器的情况下，处理单元802，还用于：在所述第二计时器的运行期间，若监听并接收到用于调度所述Sidelink数据重传的PDCCH，则停止所述第二计时器。
在另一种示例中，上述装置800用于实现上文方法实施例三中第一终端设备的步骤。装置800可以是终端设备，也可以是配置于终端设备中的芯片或电路。通信单元801用于执行上述实施例三中第一终端设备侧的收发相关操作，处理单元802用于上述实施例三中第一终端设备侧的处理相关操作。
例如，通信单元801，用于接收来自网络设备的第一下行控制信息DCI，所述第一DCI用于调度侧行链路Sidelink数据的初传或重传，所述Sidelink数据关联的Sidelink混合自动重传请求HARQ进程关联两个计时器，分别为第一计时器和第二计时器；所述第一终端设备根据所述第一DCI的调度，利用物理侧行链路共享信道PSSCH资源向第二终端设备发送Sidelink数据；通信单元801，还用于利用物理侧行反馈信道PSFCH资源，接收来自所述第二终端设备对所述Sidelink HARQ进程的HARQ反馈，所述HARQ反馈为肯定性确认ACK或否定性确认NACK；处理单元802，用于根据所述HARQ反馈以及所述PSFCH资源的时域位置，开启或不开启第一计时器；
其中，在开启所述第一计时器的情况下，当所述第一计时器超时时，所述第一终端设备开启第二计时器，在所述第二计时器的运行期间，所述第一终端设备监听物理下行控制信道PDCCH。
可选的，处理单元802根据所述HARQ反馈以及所述PSFCH资源的时域位置，开启或不开启第一计时器，包括：根据所述第一PSFCH资源的时域资源位置和第二时域偏移，确定第二时域位置；或者，将所述第一PSFCH资源的时域资源的结束位置后的第一个时间单元，作为所述第二时域位置；根据所述HARQ反馈，在所述第二时域位置，开启或不开启所述第一计时器。
可选的，处理单元802根据所述HARQ反馈，在所述第二时域位置，开启或不开启所述第一计时器，包括：确定所述Sidelink HARQ进程的HARQ反馈为ACK的情况下，则在所述第二时域位置，不开启所述第一计时器；或者，确定所述Sidelink HARQ进程的HARQ反馈为NACK的情况下，则在所述第二时域位置，开启所述第一计时器。
可选的，处理单元802在所述第二时域位置，开启所述第一计时器，包括:确定所述Sidelink HARQ进程关联的Sidelink数据的传输次数；若所述Sidelink HARQ进程关联的Sidelink数据的传输次数小于或等于最大传输次数或预设传输次数，则在所述第二时域位置，开启所述第一计时器。
可选的，处理单元802，还用于：在所述Sidelink HARQ进程关联的Sidelink数据的传输次数大于最大传输次数或预设传输次数时，则在所述第二时域位置，不再开启所述第 一计时器。
可选的，在所述第一终端设备开启所述第二计时器的情况下，处理单元802，还用于：
在所述第二计时器的运行期间，若监听到用于调度所述第一终端设备Sidelink数据重传的PDCCH，则所述停止所述第二计时器。
本申请实施例中对单元的划分是示意性的，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，另外，在本申请各个实施例中的各功能单元可以集成在一个处理器中，也可以是单独物理存在，也可以两个或两个以上单元集成在一个单元中。上述集成的单元既可以采用硬件的形式实现，也可以采用软件功能单元的形式实现。
可以理解的是，上述实施例中的通信单元的功能可以由收发器实现，处理单元的功能可以由处理器实现。收发器可以包括发射器和/或接收器等，分别用于实现发送单元和/或接收单元的功能。以下结合图9举例进行说明。
图9所示的通信装置900包括至少一个处理器901。通信装置900还可以包括至少一个存储器902，用于存储程序指令和/或数据。存储器902和处理器901耦合。本申请实施例中的耦合是装置、单元或模块之间的间接耦合或通信连接，可以是电性、机械性或其它的形式，用于装置、单元或模块之间的信息交互。处理器901可以和存储器902协同操作，处理器901可以执行存储器902中存储的程序指令，所述至少一个存储器902中的至少一个可以包括于处理器901中。
装置900还可以包括通信接口903，用于通过传输介质和其它设备进行通信，从而用于通信装置900可以和其它设备进行通信。在本申请实施例中，通信接口可以是收发器、电路、总线、模块或其它类型的通信接口。在本申请实施例中，通信接口为收发器时，收发器可以包括独立的接收器、独立的发射器；也可以集成收发功能的收发器、或者是接口电路。
应理解，本申请实施例中不限定上述处理器901、存储器902以及通信接口903之间的连接介质。本申请实施例在图9中以存储器902、处理器901以及通信接口903之间通过通信总线904连接，总线在图9中以粗线表示，其它部件之间的连接方式，仅是示意性说明，并不作为限定。所述总线可以包括地址总线、数据总线、控制总线等。为了便于表示，图9中仅用一条粗线表示，但并不表示仅有一根总线或一种类型的总线等。
在一种示例中，装置900用于实现上述方法实施例一或实施例二中第一终端设备执行的步骤。通信接口903用于执行上文实施例中第一终端设备侧的收发相关操作，处理器901用于执行上述方法实施例一或实施例二中第一终端设备侧的处理相关操作。
例如，通信接口903，用于接收来自网络设备的第一下行控制信息DCI，所述第一DCI用于调度侧行链路Sidelink数据的初传或重传，所述Sidelink数据关联的Sidelink混合自动重传请求HARQ进程关联两个计时器，分别为第一计时器和第二计时器；处理器901，用于根据所述第一DCI的调度，利用物理侧行链路共享信道PSSCH资源向第二终端设备发送Sidelink数据；处理器901，还用于根据所述PSSCH资源的时域位置，开启第一计时器，以及根据所述第一计时器，开启或不开启第二计时器；其中，在开启第二计时器的情况下，在所述第二计时器的运行期间，所述第一终端设备监听物理下行控制信道PDCCH。
可选的，处理器901根据所述PSSCH资源的时域位置，开启第一计时器，包括：
根据所述PSSCH资源的时域资源位置和第一时域偏移，确定第一时域位置；或者，将所述PSSCH资源的时域资源结束位置后的第一个时间单元，作为所述第一时域位置；在所 述第一时域位置，开启所述第一计时器。
可选的，处理器901在所述第一时域位置，开启第一计时器，包括：确定所述Sidelink HARQ进程关联的Sidelink数据的传输次数；当所述Sidelink HARQ进程关联的Sidelink数据的传输次数小于或等于最大传输次数或预设传输次数时，在所述第一时域位置，开启所述第一计时器。
可选的，处理器901，还用于在所述Sidelink HARQ进程关联的Sidelink数据的传输次数大于最大传输次数或预设传输次数时，在所述第一时域位置，不再开启所述第一计时器。
可选的，处理器901根据所述第一计时器，开启或不开启第二计时器，包括：当所述第一计时器超时时，直接开启所述第二计时器。
可选的，处理器901根据所述第一计时器，开启或不开启第二计时器，包括:在所述第一计时器超时之前，确定所述Sidelink HARQ进程的HARQ反馈为否定性确认NACK的情况下，则当所述第一计时器超时时，开启所述第二计时器；或者，确定所述Sidelink HARQ进程的HARQ反馈为肯定性确认ACK的情况下，则直接停止所述第一计时器，此时不存在所述第一计时器超时的情况，不再开启所述第二计时器，或者，不停止所述第一计时器，但在所述第一计时器超时时，不再开启所述第二计时器。
可选的，处理器901根据所述第一计时器，开启或不开启第二计时器，包括：在所述第一计时器超时之前，不能确定所述Sidelink HARQ进程的HARQ反馈；在所述第一计时器超时时，开启所述第二计时器。
可选的，处理器901，还用于：在所述第二计时器的运行期间，确定所述Sidelink HARQ进程的HARQ反馈为NACK，则不停止所述第二计时器，在所述第二计时器的运行期间，继续监听PDCCH；或者，在所述第二计时器的运行期间，确定所述Sidelink HARQ进程的HARQ反馈为ACK的情况下，则直接停止所述第二计时器，不再监听PDCCH。
可选的，在开启所述第二计时器的情况下，处理器901，还用于：在所述第二计时器的运行期间，若监听并接收到用于调度所述Sidelink数据重传的PDCCH，则停止所述第二计时器。
在一种示例中，装置900用于实现上述方法实施例三中第一终端设备执行的步骤。通信接口903用于执行上文实施例中第一终端设备侧的收发相关操作，处理器901用于执行上述方法实施例三中第一终端设备侧的处理相关操作。
例如，通信接口903，用于接收来自网络设备的第一下行控制信息DCI，所述第一DCI用于调度侧行链路Sidelink数据的初传或重传，所述Sidelink数据关联的Sidelink混合自动重传请求HARQ关联维护两个计时器，分别为第一计时器和第二计时器；所述第一终端设备根据所述第一DCI的调度，利用物理侧行链路共享信道PSSCH资源向第二终端设备发送Sidelink数据；通信接口903，还用于利用物理侧行反馈信道PSFCH资源，接收来自所述第二终端设备对所述Sidelink HARQ进程的HARQ反馈，所述HARQ反馈为肯定性确认ACK或否定性确认NACK；处理器901，用于根据所述HARQ反馈以及所述PSFCH资源的时域位置，开启或不开启第一计时器；
其中，在开启所述第一计时器的情况下，当所述第一计时器超时时，所述第一终端设备开启第二计时器，在所述第二计时器的运行期间，所述第一终端设备监听物理下行控制信道PDCCH。
可选的，处理器901根据所述HARQ反馈以及所述PSFCH资源的时域位置，开启或不开启第一计时器，包括：根据所述第一PSFCH资源的时域资源位置和第二时域偏移，确定第二时域位置；或者，将所述第一PSFCH资源的时域资源的结束位置后的第一个时间单元，作为所述第二时域位置；根据所述HARQ反馈，在所述第二时域位置，开启或不开启所述第一计时器。
可选的，处理器901根据所述HARQ反馈，在所述第二时域位置，开启或不开启所述第一计时器，包括：确定所述Sidelink HARQ进程的HARQ反馈为ACK，则在所述第二时域位置，不开启所述第一计时器；或者，确定所述Sidelink HARQ进程的HARQ反馈为NACK，则在所述第二时域位置，开启所述第一计时器。
可选的，处理器901在所述第二时域位置，开启所述第一计时器，包括:确定所述Sidelink HARQ进程关联的Sidelink数据的传输次数；若所述Sidelink HARQ进程关联的Sidelink数据的传输次数小于或等于最大传输次数或预设传输次数，则在所述第二时域位置，开启所述第一计时器。
可选的，处理器901，还用于：在所述Sidelink HARQ进程关联的Sidelink数据的传输次数大于最大传输次数或预设传输次数时，则在所述第二时域位置，不再开启所述第一计时器。
可选的，在所述第一终端设备开启所述第二计时器的情况下，处理器901，还用于：
在所述第二计时器的运行期间，若监听到用于调度所述第一终端设备Sidelink数据重传的PDCCH，则所述停止所述第二计时器。
进一步的，本申请实施例还提供一种装置，所述装置用于执行上文方法实施例中的方法。一种计算机可读存储介质，包括程序，当所述程序被处理器运行时，上文方法实施例中的方法被执行。一种计算机程序产品，所述计算机程序产品包括计算机程序代码，当所述计算机程序代码在计算机上运行时，使得计算机实现上文方法实施例中的方法。一种芯片，包括：处理器，所述处理器与存储器耦合，所述存储器用于存储程序或指令，当所述程序或指令被所述处理器执行时，使得装置执行上文方法实施例中的方法。
本申请实施例中，处理器可以是通用处理器、数字信号处理器、专用集成电路、现场可编程门阵列或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件，可以实现或者执行本申请实施例中的公开的各方法、步骤及逻辑框图。通用处理器可以是微处理器或者任何常规的处理器等。结合本申请实施例所公开的方法的步骤可以直接体现为硬件处理器执行完成，或者用处理器中的硬件及软件模块组合执行完成。
在本申请实施例中，存储器可以是非易失性存储器，比如硬盘(hard disk drive，HDD)或固态硬盘(solid-state drive，SSD)等，还可以是易失性存储器(volatile memory)，例如随机存取存储器(random-access memory，RAM)。存储器是能够用于携带或存储具有指令或数据结构形式的期望的程序代码并能够由计算机存取的任何其他介质，但不限于此。本申请实施例中的存储器还可以是电路或者其它任意能够实现存储功能的装置，用于存储程序指令和/或数据。
本申请实施例提供的方法中，可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用软件实现时，可以全部或部分地以计算机程序产品的形式实现。所述计算机程序产品包括一个或多个计算机指令。在计算机上加载和执行所述计算机程序指令时，全部或部分地产生按照本发明实施例所述的流程或功能。所述计算机可以是通用计算机、 专用计算机、计算机网络、网络设备、用户设备或者其他可编程装置。所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如同轴电缆、光纤、数字用户线(digital subscriber line，简称DSL))或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是计算机可以存取的任何可用介质或者是包含一个或多个可用介质集成的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质(例如，软盘、硬盘、磁带)、光介质(例如，数字视频光盘(digital video disc，简称DVD))、或者半导体介质(例如,SSD)等。
显然，本领域的技术人员可以对本申请进行各种改动和变型而不脱离本申请的范围。这样，倘若本申请的这些修改和变型属于本申请权利要求及其等同技术的范围之内，则本申请也意图包含这些改动和变型在内。

Claims (34)

  1. 一种通信方法，其特征在于，包括：
    第一终端设备接收来自网络设备的第一下行控制信息DCI，所述第一DCI用于调度侧行链路Sidelink数据的初传或重传，所述Sidelink数据关联的Sidelink混合自动重传请求HARQ进程关联两个计时器，分别为第一计时器和第二计时器；
    所述第一终端设备根据所述第一DCI的调度，利用物理侧行链路共享信道PSSCH资源向第二终端设备发送Sidelink数据；
    所述第一终端设备根据所述PSSCH资源的时域位置，开启第一计时器；
    所述第一终端设备根据所述第一计时器，开启或不开启第二计时器；
    其中，在开启第二计时器的情况下，在所述第二计时器的运行期间，所述第一终端设备监听物理下行控制信道PDCCH。
  2. 如权利要求1所述的方法，其特征在于，所述第一终端设备根据所述PSSCH资源的时域位置，开启第一计时器，包括：
    所述第一终端设备根据所述PSSCH资源的时域资源位置和第一时域偏移，确定第一时域位置；或者，所述第一终端设备将所述PSSCH资源的时域资源结束位置后的第一个时间单元，作为所述第一时域位置；
    所述第一终端设备在所述第一时域位置，开启所述第一计时器。
  3. 如权利要求1或2所述的方法，其特征在于，所述第一终端设备在所述第一时域位置，开启第一计时器，包括：
    所述第一终端设备确定所述Sidelink HARQ进程关联的Sidelink数据的传输次数；
    当所述Sidelink HARQ进程关联的Sidelink数据的传输次数小于或等于最大传输次数或预设传输次数时，所述第一终端设备在所述第一时域位置，开启所述第一计时器。
  4. 如权利要求3所述的方法，其特征在于，还包括：
    当所述Sidelink HARQ进程关联的Sidelink数据的传输次数大于最大传输次数或预设传输次数时，所述第一终端设备在所述第一时域位置，不开启所述第一计时器。
  5. 如权利要求1至4中任一项所述的方法，其特征在于，所述第一终端设备根据所述第一计时器，开启或不开启第二计时器，包括：
    当所述第一计时器超时时，所述第一终端设备开启所述第二计时器。
  6. 如权利要求1至4中任一项所述的方法，其特征在于，所述第一终端设备根据所述第一计时器，开启或不开启第二计时器，包括:
    在所述第一计时器超时之前，
    所述第一终端设备确定所述Sidelink HARQ进程的HARQ反馈为否定性确认NACK的情况下，则当所述第一计时器超时时，所述第一终端设备开启所述第二计时器；或者，
    在所述第一计时器超时之前，所述第一终端设备确定所述Sidelink HARQ进程的HARQ反馈为肯定性确认ACK的情况下，则所述第一终端设备停止所述第一计时器，此时不存在所述第一计时器超时的情况，不开启所述第二计时器，或者，所述第一终端设备不停止所述第一计时器，但在所述第一计时器超时时，不开启所述第二计时器。
  7. 如权利要求1至4任一项所述的方法，其特征在于，所述第一终端设备根据所述第一计时器，开启或不开启第二计时器，包括：
    在所述第一计时器超时之前，所述第一终端设备不能确定所述Sidelink HARQ进程的HARQ反馈；
    所述第一终端设备在所述第一计时器超时时，开启所述第二计时器。
  8. 如权利要求7所述的方法，其特征在于，所述方法还包括：
    在所述第二计时器的运行期间，所述第一终端设备确定所述Sidelink HARQ进程的HARQ反馈为NACK的情况下，则所述第一终端设备不停止所述第二计时器，在所述第二计时器的运行期间，所述第一终端设备继续监听PDCCH；或者，
    在所述第二计时器的运行期间，所述第一终端设备确定所述Sidelink HARQ进程的HARQ反馈为ACK的情况下，则所述第一终端设备停止所述第二计时器，停止监听PDCCH。
  9. 如权利要求1至8中任一项所述的方法，其特征在于，在所述第一终端设备开启所述第二计时器的情况下，所述方法还包括：
    在所述第二计时器的运行期间，若所述第一终端设备监听并接收到用于调度所述Sidelink数据重传的PDCCH，则所述第一终端设备停止所述第二计时器。
  10. 一种通信方法，其特征在于，包括：
    第一终端设备接收来自网络设备的第一下行控制信息DCI，所述第一DCI用于调度侧行链路Sidelink数据的初传或重传，所述Sidelink数据关联的Sidelink混合自动重传请求HARQ进程关联两个计时器，分别为第一计时器和第二计时器；
    所述第一终端设备根据所述第一DCI的调度，利用物理侧行链路共享信道PSSCH资源向第二终端设备发送Sidelink数据；
    所述第一终端设备利用物理侧行反馈信道PSFCH资源，接收来自所述第二终端设备对所述Sidelink HARQ进程的HARQ反馈，所述HARQ反馈为肯定性确认ACK或否定性确认NACK；
    所述第一终端设备根据所述HARQ反馈以及所述PSFCH资源的时域位置，开启或不开启第一计时器；
    其中，在开启所述第一计时器的情况下，当所述第一计时器超时时，所述第一终端设备开启第二计时器，在所述第二计时器的运行期间，所述第一终端设备监听物理下行控制信道PDCCH。
  11. 如权利要求10所述的方法，其特征在于，所述第一终端设备根据所述HARQ反馈以及所述PSFCH资源的时域位置，开启或不开启第一计时器，包括：
    所述第一终端设备根据所述第一PSFCH资源的时域资源位置和第二时域偏移，确定第二时域位置；或者，所述第一终端设备将所述第一PSFCH资源的时域资源的结束位置后的第一个时间单元，作为所述第二时域位置；
    所述第一终端设备根据所述HARQ反馈，在所述第二时域位置，开启或不开启所述第一计时器。
  12. 如权利要求11所述的方法，其特征在于，所述第一终端设备根据所述HARQ反馈，在所述第二时域位置，开启或不开启所述第一计时器，包括：
    所述第一终端设备确定所述Sidelink HARQ进程的HARQ反馈为ACK的情况下，则所述第一终端设备在所述第二时域位置，不开启所述第一计时器；或者，
    所述第一终端设备确定所述Sidelink HARQ进程的HARQ反馈为NACK的情况下，则所述第一终端设备在所述第二时域位置，开启所述第一计时器。
  13. 如权利要求12所述的方法，其特征在于，所述第一终端设备在所述第二时域位置，开启所述第一计时器，包括:
    所述第一终端设备确定所述Sidelink HARQ进程关联的Sidelink数据的传输次数；
    若所述Sidelink HARQ进程关联的Sidelink数据的传输次数小于或等于最大传输次数或预设传输次数，则所述第一终端设备在所述第二时域位置，开启所述第一计时器。
  14. 如权利要求13所述的方法，其特征在于，还包括：
    若所述Sidelink HARQ进程关联的Sidelink数据的传输次数大于最大传输次数或预设传输次数，则所述第一终端设备在所述第二时域位置，不开启所述第一计时器。
  15. 如权利要求10至14中任一项所述的方法，其特征在于，在所述第一终端设备开启所述第二计时器的情况下，所述方法还包括：
    在所述第二计时器的运行期间，若所述第一终端设备监听到用于调度所述第一终端设备Sidelink数据重传的PDCCH，则所述第一终端设备停止所述第二计时器。
  16. 一种通信装置，其特征在于，包括：
    通信单元，用于接收来自网络设备的第一下行控制信息DCI，所述第一DCI用于调度侧行链路Sidelink数据的初传或重传，所述Sidelink数据关联的Sidelink混合自动重传请求HARQ进程关联两个计时器，分别为第一计时器和第二计时器；
    处理单元，用于根据所述第一DCI的调度，利用物理侧行链路共享信道PSSCH资源向第二终端设备发送Sidelink数据；
    所述处理单元，还用于根据所述PSSCH资源的时域位置，开启第一计时器，以及根据所述第一计时器，开启或不开启第二计时器；
    其中，在开启第二计时器的情况下，在所述第二计时器的运行期间，所述第一终端设备监听物理下行控制信道PDCCH。
  17. 如权利要求16所述的装置，其特征在于，所述处理单元根据所述PSSCH资源的时域位置，开启第一计时器，包括：
    根据所述PSSCH资源的时域资源位置和第一时域偏移，确定第一时域位置；或者，将所述PSSCH资源的时域资源结束位置后的第一个时间单元，作为所述第一时域位置；
    在所述第一时域位置，开启所述第一计时器。
  18. 如权利要求16或17所述的装置，其特征在于，所述处理单元在所述第一时域位置，开启第一计时器，包括：
    确定所述Sidelink HARQ进程关联的Sidelink数据的传输次数；
    当所述Sidelink HARQ进程关联的Sidelink数据的传输次数小于或等于最大传输次数或预设传输次数时，在所述第一时域位置，开启所述第一计时器。
  19. 如权利要求18所述的装置，其特征在于，
    所述处理单元，还用于在所述Sidelink HARQ进程关联的Sidelink数据的传输次数大于最大传输次数或预设传输次数时，在所述第一时域位置，不开启所述第一计时器。
  20. 如权利要求16至19中任一项所述的装置，其特征在于，所述处理单元根据所述第一计时器，开启或不开启第二计时器，包括：
    当所述第一计时器超时时，开启所述第二计时器。
  21. 如权利要求16至19中任一项所述的装置，其特征在于，所述处理单元根据所述第一计时器，开启或不开启第二计时器，包括:
    在所述第一计时器超时之前，所述第一终端设备确定所述Sidelink HARQ进程的HARQ反馈为否定性确认NACK的情况下，则当所述第一计时器超时时，开启所述第二计时器；或者，
    在所述第一计时器超时之前，所述第一终端设备确定所述Sidelink HARQ进程的HARQ反馈为肯定性确认ACK的情况下，则停止所述第一计时器，此时不存在所述第一计时器超时的情况，不开启所述第二计时器，或者，不停止所述第一计时器，但在所述第一计时器超时时，不开启所述第二计时器。
  22. 如权利要求16至20任一项所述的装置，其特征在于，所述处理单元根据所述第一计时器，开启或不开启第二计时器，包括：
    在所述第一计时器超时之前，不能确定所述Sidelink HARQ进程的HARQ反馈；
    在所述第一计时器超时时，开启所述第二计时器。
  23. 如权利要求22所述的装置，其特征在于，所述处理单元，还用于：
    在所述第二计时器的运行期间，所述第一终端设备确定所述Sidelink HARQ进程的HARQ反馈为NACK，则不停止所述第二计时器，在所述第二计时器的运行期间，继续监听PDCCH；或者，
    在所述第二计时器的运行期间，所述第一终端设备确定所述Sidelink HARQ进程的HARQ反馈为ACK，则停止所述第二计时器，停止监听PDCCH。
  24. 如权利要求16至23中任一项所述的装置，其特征在于，在开启所述第二计时器的情况下，所述处理单元，还用于：
    在所述第二计时器的运行期间，若监听并接收到用于调度所述Sidelink数据重传的PDCCH，则停止所述第二计时器。
  25. 一种通信装置，其特征在于，包括：
    通信单元，用于接收来自网络设备的第一下行控制信息DCI，所述第一DCI用于调度侧行链路Sidelink数据的初传或重传，所述Sidelink数据关联的Sidelink混合自动重传请求HARQ进程关联两个计时器，分别为第一计时器和第二计时器；所述第一终端设备根据所述第一DCI的调度，利用物理侧行链路共享信道PSSCH资源向第二终端设备发送Sidelink数据；
    所述通信单元，还用于利用物理侧行反馈信道PSFCH资源，接收来自所述第二终端设备对所述Sidelink HARQ进程的HARQ反馈，所述HARQ反馈为肯定性确认ACK或否定性确认NACK；
    处理单元，用于根据所述HARQ反馈以及所述PSFCH资源的时域位置，开启或不开启第一计时器；
    其中，在开启所述第一计时器的情况下，当所述第一计时器超时时，所述第一终端设备开启第二计时器，在所述第二计时器的运行期间，所述第一终端设备监听物理下行控制信道PDCCH。
  26. 如权利要求25所述的装置，其特征在于，所述处理单元根据所述HARQ反馈以及所述PSFCH资源的时域位置，开启或不开启第一计时器，包括：
    根据所述第一PSFCH资源的时域资源位置和第二时域偏移，确定第二时域位置；或者，将所述第一PSFCH资源的时域资源的结束位置后的第一个时间单元，作为所述第二 时域位置；
    根据所述HARQ反馈，在所述第二时域位置，开启或不开启所述第一计时器。
  27. 如权利要求26所述的装置，其特征在于，所述处理单元根据所述HARQ反馈，在所述第二时域位置，开启或不开启所述第一计时器，包括：
    确定所述Sidelink HARQ进程的HARQ反馈为ACK的情况下，则在所述第二时域位置，不开启所述第一计时器；或者，
    确定所述Sidelink HARQ进程的HARQ反馈为NACK的情况下，则在所述第二时域位置，开启所述第一计时器。
  28. 如权利要求27所述的装置，其特征在于，所述处理单元在所述第二时域位置，开启所述第一计时器，包括:
    确定所述Sidelink HARQ进程关联的Sidelink数据的传输次数；
    若所述Sidelink HARQ进程关联的Sidelink数据的传输次数小于或等于最大传输次数或预设传输次数，则在所述第二时域位置，开启所述第一计时器。
  29. 如权利要求28所述的装置，其特征在于，所述处理单元，还用于：
    在所述Sidelink HARQ进程关联的Sidelink数据的传输次数大于最大传输次数或预设传输次数时，则在所述第二时域位置，不开启所述第一计时器。
  30. 如权利要求25至29中任一项所述的装置，其特征在于，在所述第一终端设备开启所述第二计时器的情况下，所述处理单元，还用于：
    在所述第二计时器的运行期间，若监听到用于调度所述第一终端设备Sidelink数据重传的PDCCH，则所述停止所述第二计时器。
  31. 一种通信装置，其特征在于，包括处理器，所述处理器与至少一个存储器耦合，所述处理器用于读取所述至少一个存储器所存储的计算机程序，以执行如权利要求1至9中任一项所述的方法，或以执行权利要求10至15中任一项所述的方法。
  32. 一种计算机可读存储介质，其特征在于，包括程序，当所述程序被处理器运行时，如权利要求1至9中任一项所述的方法被执行，或如权利要求10至15中任一项所述的方法被执行。
  33. 一种计算机程序产品，其特征在于，包括指令，当所述指令在计算机上运行时，使得计算机执行权利要求1至9中任一项所述的方法，或者权利要求10至15中任一项所述的方法。
  34. 一种通信系统，其特征在于，包括权利求16至24中任一项所述的装置，以及权利要求25至30中任一项所述的装置。
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