Patent Description:
In a new radio (new radio, NR) system, communication of a terminal device is classified into Uu air-interface communication and sidelink (sidelink, SL) communication. The Uu air-interface communication is communication that is between the terminal device and a base station and that is on an air interface resource. The sidelink communication is communication that is between terminal devices and that is on a sidelink resource.

The terminal device needs to obtain a resource before the sidelink communication. Currently, a sidelink resource allocation manner mainly includes the following two modes: One is a network device allocation mode, to be specific, a network device allocates, to the terminal device by using downlink control information, a resource required for communication on the sidelink resource. The other is a terminal device self-selection mode, to be specific, the terminal device selects a resource required for communication on the sidelink resource.

In the foregoing two modes, the resource allocated by the network device may be a licensed spectrum resource, or may be an unlicensed spectrum resource. Currently, there is no solution for how the network device allocates the unlicensed spectrum resource.

<NPL>, discusses mechanisms for recovery from consistent LBT failure. If a serving cell with LBT issues is not an SpCell, then the UE sends a secondary cell failure report on the PCell of the SCell's MAC entity.

<NPL>, proposes performing separate monitoring of consitent UL LBT failures on PRACH and other UL PHY resources.

<NPL>, discusses recovery actions upon detection of UL LBT failures.

<NPL>, introcudes a new cause value to inciate a LBT failure in RLF report, SCG failure report and establishment failure report.

<NPL> discusses BSR/SR for retransmisison. It is proposed that separate SR resources and configurations are supported for SL new transmission and SL retranmission, and a new NR sidelink BSR is introduced to carry retransmission information, i.e., HARQ process ID, destination ID for target UE/Group, and associated TB size level.

<NPL>, observes that the transmitter UE indicates the need for retransmission of a TB in the form of SR or BSR according to RAN1 agreement. It is proposed that RAN2 selects a method from the two options: Option <NUM>: Tx UE inciates need for retransmission in the form of SR, and Option <NUM>: Tx UE indicates need for retransmission in the form of BSR.

An objective of implementations of this application is to provide two communication methods and corresponding apparatuses and computer-readable storage mediums, to resolve a problem of how a network device allocates an unlicensed spectrum resource on a sidelink.

According to a first aspect, an embodiment of this application provides a communication method, including: A first terminal device determines first information, where the first information includes a result of a channel access process performed on a first resource, and the first resource is used for sidelink communication between the first terminal device and a second terminal device, or is used for communication between the first terminal device and a network device; or the first information includes a resource request message, and the resource request message is used to request a resource for retransmission on a sidelink between the first terminal device and a second terminal device; and the first terminal device sends the first information to the network device.

According to the foregoing method, the first terminal indicates the first information to the network device, so that the network device determines, based on the first information, the result of the channel access process performed on the first resource, or determines the resource requested by the first device for retransmission. In this way, the network device may determine, based on the first information, whether to allocate a resource to the first device, so that resource allocation effectiveness is improved.

In a possible implementation, that a first terminal device determines first information includes: When receiving second information from the network device, the first terminal device determines the first information, where the second information is used to indicate the first terminal device to send the first information; when receiving third information or the second information from the network device, the first terminal device starts or restarts a first timer, and when the first timer expires, the first terminal device determines the first information, where the third information is used to indicate a part or all of resources in the first resource; or when determining that a quantity of times for which the channel access process fails on the first resource is equal to a preset quantity, the first terminal device determines the first information.

In a possible implementation, the quantity of times for which the channel access process fails on the first resource is a quantity of times for which the first terminal device fails to perform the channel access process on a unicast resource in the first resource; is a quantity of times for which the first terminal device fails to perform the channel access process on a multicast resource in the first resource; is a quantity of times for which the first terminal device fails to perform the channel access process on a broadcast resource in the first resource; is a quantity of times for which the first terminal device fails to perform the channel access process on a multicast resource and a broadcast resource in the first resource; is a quantity of times for which the first terminal device fails to perform the channel access process on a unicast resource and a broadcast resource in the first resource; is a quantity of times for which the first terminal device fails to perform the channel access process on a multicast resource and a unicast resource in the first resource; is a quantity of times for which the first terminal device fails to perform the channel access process on a resource that is a part of a preset channel and that is in the first resource; is a quantity of times for which the first terminal device fails to perform the channel access process on a resource that is a part of a preset subband and that is in the first resource; or is a total quantity of times for which the first terminal device fails to perform the channel access process on the first resource.

In a possible implementation, the first information further includes any one or more of the following:.

In a possible implementation, the method further includes: When determining that the quantity of times for which the channel access process fails on the first resource is equal to the preset quantity, the first terminal device starts a second timer, and performs a radio link restoration process during running of the second timer.

In a possible implementation, the method further includes: When the second timer expires, if the radio link restoration process fails, the first terminal device triggers a radio link re-establishment process.

According to a second aspect, a communication method is provided, including: A network device obtains first information from a first terminal device, where the first information includes a result of a channel access process performed on a first resource, and the first resource is used for sidelink communication between the first terminal device and a second terminal device, or is used for communication between the first terminal device and the network device; or the first information includes a resource request message, and the resource request message is used to request a resource for retransmission on a sidelink between the first terminal device and a second terminal device; and the network device allocates a second resource to the first terminal device based on the first information.

According to the foregoing method, the network device determines, based on the first information, the result of the channel access process performed on the first resource, or determines the resource requested by the first device for retransmission, and allocates the second resource to the first terminal device. Because the second resource allocated by the network device is targeted, resource allocation effectiveness can be improved.

In a possible implementation, the second resource is used for the sidelink communication between the first terminal device and the second terminal device, or is used for the communication between the first terminal device and the network device.

According to a third aspect, this application further provides a communication apparatus. The communication apparatus has a function of implementing any method provided in the first aspect or the second aspect. The communication apparatus may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or the software includes one or more units or units corresponding to the foregoing function.

In a possible implementation, the communication apparatus includes a processor, and the processor is configured to support the communication apparatus in performing a corresponding function of the first terminal device or the network device in the foregoing method. The communication apparatus may further include a memory, and the memory may be coupled to the processor, and stores program instructions and data that are necessary for the communication apparatus. Optionally, the communication apparatus further includes a communication interface, and the communication interface is configured to support communication between the communication apparatus and a device such as the first terminal device or the network device.

In a possible implementation, the communication apparatus includes corresponding functional units, respectively configured to implement the steps in the foregoing method. The function may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or the software includes one or more units corresponding to the foregoing function.

In a possible implementation, a structure of the communication apparatus includes a processing unit and a communication unit. These units may perform corresponding functions in the foregoing method examples. For details, refer to the descriptions in the method provided in the first aspect or the second aspect.

According to a fourth aspect, this application provides a communication apparatus, including a processor and a memory. The memory is configured to store computer-executable instructions, and when the apparatus runs, the processor executes the computer-executable instructions stored in the memory, to enable the apparatus to perform the methods described in the foregoing aspects.

According to a fifth aspect, this application provides a communication apparatus, including a unit or a means (means) configured to perform the steps in the foregoing aspects.

According to a sixth aspect, this application provides a communication apparatus, including a processor and a communication interface. The processor is configured to communicate with another apparatus through the communication interface, and perform the methods described in the foregoing aspects. There are one or more processors.

According to a seventh aspect, this application provides a communication apparatus, including a processor, configured to connect to at least one memory, and invoke a program stored in the at least one memory, to perform the methods described in the foregoing aspects. The at least one memory may be located inside the apparatus, or may be located outside the apparatus. In addition, there are one or more processors.

According to an eighth aspect, this application further provides a computer-readable storage medium. The computer-readable storage medium stores instructions. When the instructions are run on a computer, the computer is enabled to perform the methods described in the foregoing aspects.

According to a ninth aspect, this application further provides a computer program product including instructions. When the computer program product is run on a computer, the computer is enabled to perform the methods described in the foregoing aspects.

According to a tenth aspect, this application further provides a chip system, including a processor, configured to perform the methods described in the foregoing aspects.

According to an eleventh aspect, this application further provides a chip system, including the foregoing provided first terminal device and/or the network device.

According to a twelfth aspect, this application further provides a communication system, including the foregoing provided first terminal device and/or the network device. Optionally, the communication system further includes a core network device.

The present invention is best understood with reference to <FIG>.

The following further describes in detail embodiments of this application with reference to the accompanying drawings.

The following explains and describes some communication nouns or terms used in this application. The communication nouns or the terms are also used as a part of the invention content of this application.

The uplink transmission means that the terminal device sends information to the access network device, and the information in the uplink transmission may be referred to as uplink information or an uplink signal. The uplink information or the uplink signal may include one or more of a PUSCH, a PUCCH, and a sounding reference signal (sounding reference signal, SRS). A channel used to transmit the uplink information or the uplink signal is referred to as an uplink channel, and the uplink channel may include one or more of a physical uplink data channel (physical uplink shared channel, PUSCH) and a physical uplink control channel (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 uplink control information (uplink control information, UCI) fed back by the terminal device. For example, the UCI may include one or more of channel state information (channel state information, CSI), an ACK, a NACK, and the like that are fed back by the terminal device.

The downlink transmission means that the access network sends information to the terminal device, and the information in the downlink transmission may be downlink information or a downlink signal. The downlink information or the downlink signal may include at least one of a PDSCH, a PDCCH, a channel state information reference signal (channel state information reference signal, CSI-RS), and a phase tracking reference signal (phase tracking reference signal, PTRS). A channel used to transmit downlink information or a downlink signal is referred to as a downlink channel, and the downlink channel may include one or more of a physical downlink data channel (physical downlink shared channel, PDSCH) and a physical downlink control channel (physical downlink control channel, PDCCH). The PDCCH is used to carry downlink control information (downlink control information, DCI), and the PDSCH is used to carry downlink data (data). The downlink data may also be referred to as downlink data information.

Channel access process. The channel access process may also be referred to as a listen before talk (listen before talk, LBT) process, and is uniformly referred to as the channel access process below. The channel access process includes two types. Type <NUM>: In a channel access process based on fixed duration, a communication device detects the fixed duration, and if energy of a signal that is detected in a channel within the fixed duration is less than a preset threshold, it is considered that the channel is in an idle state. Therefore, the communication device may occupy the channel. Otherwise, the communication device needs to contend for a channel again.

Type <NUM>: In a backoff-based channel access process, a communication device randomly selects a value A in a contention window, and it may be determined, only after at least A idle slots are detected, that a channel is in the idle state. Therefore, the communication device may occupy the channel. Otherwise, the communication device needs to contend for a channel again. The idle slot means that energy of a signal detected in the channel in the slot is less than a preset threshold. In this type of channel access process, four channel access priority classes (channel access priority classes, CAPCs) are introduced. Different CAPCs correspond to different channel access parameters. The channel access parameter includes a size of a contention window, a corresponding service status, channel occupancy time (channel occupancy time, COT) information, and the like. The COT is duration for which a channel can be used after a channel access process succeeds.

<FIG> is a schematic diagram of a network architecture of a communication system to which an embodiment of this application is applicable. The communication system includes a first terminal device and a second terminal device, and may certainly further include another terminal device. For ease of description, the another terminal device is not shown herein. A direct communication link between the first terminal device and the second terminal device is a sidelink.

The communication system further includes a network device, and the network device may communicate with at least one terminal device (for example, the first terminal device shown in <FIG>) through a Uu interface.

The network device in <FIG> may be an access network device, for example, a base station. The access network device corresponds to different devices in different systems. For example, in a <NUM> system, the access network device corresponds to an access network device in <NUM>, for example, a gNB. The network device in <FIG> may be an evolved NodeB (evolved NodeB, eNB) in an LTE system, a base transceiver station (base transceiver station, BTS) in a global system for mobile communications (global system for mobile communications, GSM) system or code division multiple access (code division multiple access, CDMA), or a NodeB (NodeB, NB) in a wideband code division multiple access (wideband code division multiple access, WCDMA) system. Although only the first terminal device and the second terminal device are shown in <FIG>, it should be understood that the network device may serve more terminal devices, and a quantity of network devices and a quantity of terminal devices in the communication system are not limited in this embodiment of this application.

The terminal device in <FIG> may be a device having a wireless transceiver function or a chip that can be disposed in any device, or may be referred to as user equipment (user equipment, UE), an access terminal, a subscriber unit, a subscriber station, a mobile station, a remote station, a remote terminal, a mobile device, a user terminal, a wireless communication device, a user agent, or a user apparatus. The terminal device in embodiments of this application may be a mobile phone (mobile phone), a tablet computer (Pad), a computer having a wireless transceiver function, a virtual reality (virtual reality, VR) terminal, an augmented reality (augmented reality, AR) terminal, a wireless terminal in industrial control (industrial control), a wireless terminal in self driving (self driving), a wireless terminal in remote medical (remote medical), a wireless terminal in a smart grid (smart grid), a wireless terminal in transportation safety (transportation safety), a wireless terminal in a smart city (smart city), a wireless terminal in a smart home (smart home), or the like.

The terms "system" and "network" may be used interchangeably in embodiments of this application. "A plurality of" means two or more. In view of this, "a plurality of" may also be understood as "at least two" in embodiments of this application. "At least one" may be understood as one or more, for example, one, two, or more. For example, "including at least one" means including one, two, or more, and does not limit which items are included. For example, if at least one of A, B, and C is included, A, B, C, A and B, A and C, B and C, or A, B, and C may be included. Similarly, understanding of descriptions such as "at least one type" is similar. "And/or" describes an association relationship between associated objects and represents that three relationships may exist. For example, A and/or B may represent three cases: There is only A, there are both A and B, and there is only B. In addition, the character "/" usually indicates an "or" relationship between the associated objects unless otherwise stated.

Ordinal numbers such as "first" and "second" in embodiments of this application are used to distinguish between a plurality of objects, but are not intended to limit a sequence, a time sequence, priorities, or importance of the plurality of objects. In addition, descriptions of "first" and "second" do not necessarily indicate that objects are different.

With reference to the foregoing descriptions, <FIG> is a schematic flowchart of a communication method according to an embodiment of this application. Refer to <FIG>.

Step <NUM>: A first terminal device obtains a first resource.

The first resource is used for sidelink communication between the first terminal device and a second terminal device, or is used for communication between the first terminal device and a network device. The first resource may include a plurality of resources, and a specific quantity of included resources is not limited in this embodiment of this application.

It should be noted that the first resource may be a resource allocated by the network device to the first terminal device, or may be a resource selected by the first terminal device. The first terminal device may obtain resources for a plurality of times, and a setof the resources obtained for the plurality of times is referred to as the first resource. For example, the first resource may be resources allocated by the network device for a plurality of times, or may be resources selected by the first terminal device for a plurality of times.

The first resource may be an unlicensed (unlicensed) spectrum resource. To be specific, before the first terminal device performs data transmission by using a resource in the first resource, the first terminal device needs to perform a channel access process. If the channel access process succeeds, the first terminal device can perform data transmission by using the resource. If the channel access process fails, the first terminal device cannot perform data transmission by using the resource.

For any resource, when the first terminal device does not complete the channel access process before a transmission start point of the resource, it is determined that the channel access process fails. In this case, the first terminal device cannot perform data transmission by using the resource. When the first terminal device completes the channel access process before the transmission start point of the resource, it is determined that the channel access process succeeds. In this case, the first terminal device can perform data transmission by using the resource.

It should be noted that a specific process in which the first terminal device performs the channel access process is not limited in this embodiment of this application. For details, refer to descriptions of the channel access process in a conventional technology.

In this embodiment of this application, in a process of using the first resource, the first terminal device may count a quantity of times for which the channel access process fails. The first terminal device may perform counting in any one of the following manners when performing counting.

Manner <NUM>: A quantity of times for which the first terminal device fails to perform the channel access process on a unicast resource in the first resource is counted.

Manner <NUM>: A quantity of times for which the first terminal device fails to perform the channel access process on a multicast resource in the first resource is counted.

Manner <NUM>: A quantity of times for which the first terminal device fails to perform the channel access process on a broadcast resource in the first resource is counted.

Manner <NUM>: A quantity of times for which the first terminal device fails to perform the channel access process on a multicast resource and a broadcast resource in the first resource is counted.

Manner <NUM>: A quantity of times for which the first terminal device fails to perform the channel access process on a unicast resource and a broadcast resource in the first resource is counted.

Manner <NUM>: A quantity of times for which the first terminal device fails to perform the channel access process on a multicast resource and a unicast resource in the first resource is counted.

Manner <NUM>: A quantity of times for which the first terminal device fails to perform the channel access process on a resource that is a part of a preset channel (channel) and that is in the first resource is counted.

Manner <NUM>: A quantity of times for which the first terminal device fails to perform the channel access process on a resource that is a part of a preset subband (subband) and that is in the first resource is counted.

Manner <NUM>: A total quantity of times for which the first terminal device fails to perform the channel access process on the first resource is counted without distinguishing between types of the first resource.

When performing counting, if the first terminal device determines that the channel access process fails for a preset quantity of times, the first terminal device may determine that a radio link failure (radio link failure, RLF) occurs. The preset quantity is a preset value, may be a value configured by the network device, or may be a value determined in another manner. This is not limited herein. For example, the preset quantity is five, and the first terminal device counts, in Manner <NUM>, the quantity of times for which the channel access process fails. When the first terminal device determines that the quantity of times for which the channel access process fails is five, the first terminal device may determine that a radio link failure occurs.

It should be noted that, when the first terminal device performs counting, in a possible implementation, the first terminal device may count a quantity of times for which the channel access process continuously fails. In this manner, the first terminal device may start a counter. Each time the channel access process fails, the first terminal device increases a value of the counter by <NUM>; and each time the channel access process succeeds or a third timer expires, the first terminal device resets the value of the counter to <NUM>. Each time the channel access process fails, the third timer is started or restarted. When the value of the counter is equal to the preset quantity, the first terminal device determines that a radio link fail occurs. It should be noted that a maximum quantity of times of the counter and duration of the third timer may be configured by the network device.

In another possible implementation, the first terminal device may count the total quantity of times for which the channel access process fails. In this manner, the first terminal device may start a counter, and increase a value of the counter by <NUM> each time the channel access process fails. The first terminal device uses a finally counted value of the counter as the quantity of times for which the channel access process fails. When the value of the counter is greater than or equal to the preset quantity, the first terminal device may determine that radio link fail occurs.

It should be noted that step <NUM> and step <NUM> to step <NUM> may be mutually independent procedures, or may be mutually cooperative. This is not limited in this embodiment of this application.

Step <NUM>: The first terminal device determines first information.

In this embodiment of this application, the first information includes one or more of the following:.

Optionally, the result of the channel access process may further be used to indicate resources on which the channel access process fails and/or resources on which the channel access process succeeds in the first resource.

When obtaining the result of the channel access process performed on the first resource, the network device may determine, based on the result of the channel access process performed on the first resource, the resources on which the channel access process fails and the resources on which the channel access process succeeds in the first resource, to determine whether to allocate, to the first terminal device, a resource for retransmission and a quantity of resources for retransmission.

Resource request message. The resource request message is used to request a resource for retransmission on a sidelink between the first terminal device and a second terminal device.

Correspondingly, when obtaining the resource request message, the network device may determine, based on the resource request message, whether to allocate, to the first terminal device, the resource for retransmission.

Further, optionally, the first information may further include one or more of the following:
<NUM>. At least one sidelink carrier identifier. The at least one sidelink carrier identifier is an identifier of a sidelink carrier corresponding to a resource that is in the first resource and on which the channel access process fails, or the at least one sidelink carrier identifier is an identifier of a sidelink carrier corresponding to a resource that is in the first resource and on which the channel access process succeeds.

When the at least one sidelink carrier identifier is the identifier of the sidelink carrier corresponding to the resource on which the channel access process fails, the network device may determine, based on the at least one sidelink carrier identifier, the carrier corresponding to the resource on which the channel access process fails, to exclude the carrier corresponding to the at least one sidelink carrier identifier when re-allocating a resource to the first terminal device.

Correspondingly, when the at least one sidelink carrier identifier is the identifier of the sidelink carrier corresponding to the resource on which the channel access process succeeds, the network device may determine the carrier corresponding to the resource on which the channel access process succeeds, to preferentially allocate, to the first terminal device when re-allocating a resource to the first terminal device, a resource in the carrier corresponding to the at least one sidelink carrier identifier.

At least one sidelink hybrid automatic repeat request (hybrid automatic repeat request, HARQ) identifier. The at least one sidelink HARQ identifier is a sidelink HARQ identifier corresponding to a transport block that is in the first resource and on which the first terminal device fails to perform the channel access process, or the at least one sidelink HARQ identifier is a sidelink HARQ identifier corresponding to a resource that is in the first resource and on which the first terminal device successfully sends a transport block.

When performing sidelink communication, the first terminal device maintains at least one HARQ process (process), where each HARQ process has one HARQ identifier, and each HARQ process is used to transmit a different transport block. The network device may determine, based on the at least one sidelink HARQ identifier, a transport blocks that fails to be sent.

When allocating a retransmission resource to the first terminal device, the network device may indicate, to the first terminal device, a sidelink HARQ identifier corresponding to the retransmission resource. The first terminal device may determine the retransmission resource based on the sidelink HARQ identifier indicated by the network device, where the retransmission resource is used to retransmit a transport block corresponding to the sidelink HARQ identifier.

Channel access process type information. The channel access process type information is used to indicate a type of the channel access process performed by the first terminal device on the first resource.

As described above, in this embodiment of this application, the channel access process includes two types: Type <NUM>: a channel access process based on fixed duration; and Type <NUM>: a backoff-based channel access process.

The network device may determine, based on the channel access process type information, a type of the channel access process used when the first terminal device performs the channel access process. When the network device re-allocates a resource to the first terminal device, the network device may indicate the type of the channel access process to the first terminal device. The type that is indicated by the network device and that is of the channel access process may be determined based on the channel access process type information.

For example, when the network device determines, based on the result of the channel access process performed on the first resource, that a ratio of a quantity of resources that is in the first resource and on which the channel access process succeeds to a total quantity of resources included in the first resource is greater than a threshold, and the network device determines, based on the channel access process type information, that the type of the channel access process used by the first terminal device is Type <NUM>, the network device may indicate the first terminal device to continue to use the Type-<NUM> channel access process to perform the channel access process on the resource allocated by the network device. Another case is not described.

Channel access priority class information. The channel access priority class information is used to indicate a channel access priority class used by the first terminal device to perform the channel access process on the first resource.

As described above, different channel access priority classes correspond to different channel access parameters. The channel access parameter includes a size of a contention window, channel occupancy time (channel occupancy time, COT) information, and the like. The network device may determine, based on the channel access priority class information, information such as COT of the first terminal device in a resource on which the channel access process succeeds.

Information about a quantity of times for which the channel access process fails. The information about the quantity of times for which the channel access process fails is used to indicate a quantity of times for which the channel access process is performed, where the quantity corresponds to each resource that is in the first resource and on which the channel access process fails.

With reference to the foregoing at least one sidelink carrier identifier, the network device may determine, based on the information about the quantity of times for which the channel access process fails and the at least one sidelink carrier identifier, a carrier with a large quantity of times for which the first terminal device fails to perform the channel access process. When the network device allocates a resource to the first terminal device, the network device can avoid allocating, to the first terminal device, a resource in the carrier with the large quantity of times for which the channel access process fails.

Sidelink type information. The sidelink type information is used to indicate a resource type corresponding to a resource that is in the first resource and on which the channel access process fails.

As described in step <NUM>, when the first terminal device counts the quantity of times for which the channel access process fails on the first resource, the first terminal device performs counting based on a resource type corresponding to the first resource. The sidelink type information herein is a resource type corresponding to a counted resource when the first device counts the resource on which the channel access process fails. As described above, the resource type may include any one of the following:.

Step <NUM>: The first terminal device sends the first information to the network device.

It should be noted that the first information may be transmitted by using physical layer signaling, a media access control (media access control, MAC) control element (control element, CE), or the like. This is not limited in this embodiment of this application.

Step <NUM>: The network device obtains the first information from the first terminal device.

Step <NUM>: The network device allocates a second resource to the first terminal device based on the first information.

The second resource is used for the sidelink communication between the first terminal device and the second terminal device, or is used for the communication between the first terminal device and the network device.

For example, in step <NUM>, when determining that a radio link failure occurs, or determining that the quantity of times for which the channel access process fails is greater than or equal to the preset quantity, the first terminal device starts a second timer. Timing duration of the second timer is preset, or is configured by the network device. This is not limited in this embodiment of this application. The first terminal device performs a radio link restoration process during running of the second timer.

When the second timer expires, if the radio link restoration process fails, the first terminal device triggers a radio link re-establishment process.

During running of the second timer, the first terminal device is allowed to perform bandwidth part (bandwidth part, BWP) switching. Specifically, during running of the second timer, the first terminal device may be switched from a first BWP to which the first resource belongs to a second BWP. The second BWP may be any BWP configured by the network device for the first terminal device.

When the second timer expires, and the first terminal device fails to perform radio link restoration for a cell, the first terminal device may perform a cell selection process to select a cell, perform a random access process by using the cell, and send a re-establishment request to the network device by using the random access process. After receiving the re-establishment request, the network device sends a response message to the first terminal device for re-establishment.

Before step <NUM>, the first terminal device may determine to send the first information to the network device when determining that any one of the following conditions is satisfied.

Condition <NUM>: The first terminal device receives second information from the network device, where the second information is used to indicate the first terminal device to send the first information.

In Condition <NUM>, the network device directly indicates, by using the second information, the first terminal device to send the second information. When receiving the second information, the first terminal device may send the first information to the network device.

It should be noted that the second information may further be used to schedule an uplink resource, and the uplink resource scheduled by using the second information is used by the first terminal device to send the first information. The uplink resource scheduled by using the second information may be located on a licensed spectrum, or may be located on an unlicensed spectrum. This is not limited in this embodiment of this application.

Condition <NUM>: When receiving third information or the second information from the network device, the first terminal device starts or restarts a first timer. Timing duration of the first timer may be preset duration, or may be duration configured by the network device.

During running of the first timer, the first terminal device may restart the first timer when receiving the third information or the second information. When the first timer expires, if the first terminal device does not receive the third information or the second information during running of the first timer, the first terminal device determines that the first information needs to be sent to the network device.

A meaning of the second information is the same as the meaning of the second information in Condition <NUM>, and details are not described herein again. Before the first terminal device determines to send the first information to the network device, the network device has allocated a resource to the first terminal device. The third information is used to indicate a part or all of resources in the first resource. That is, the third information is information about the resource allocated by the network device to the first terminal device.

In Condition <NUM>, the first timer is set, so that the first terminal device sends the first information to the network device at intervals of a time period, and this avoids a case in which the network device cannot determine resource utilization of the first terminal device because the first terminal device does not report a resource usage result for a long time.

Condition <NUM>: The first terminal device determines that a quantity of times for which the channel access process fails on the first resource is equal to a preset quantity.

For how the first terminal device specifically determines the quantity of times for which the channel access process fails, refer to the descriptions in step <NUM>.

It should be noted that the foregoing conditions are merely examples, and there may be other conditions, which are not described herein by using examples one by one.

Finally, in step <NUM>, the network device allocates the second resource to the first terminal device based on the first information. For how the network device specifically allocates the second resource, refer to the foregoing descriptions. It should be noted that when allocating the second resource, the network device may only refer to the first information, and does not necessarily allocate the second resource based on the first information. For example, the first information requests to allocate a resource. If the network device determines that there is no resource that can be allocated currently, the network device may skip allocating the second resource to the first terminal device. Another case is not described.

Embodiments described in this specification may be independent solutions, or may be combined based on internal logic.

It may be understood that, in the foregoing method embodiment the methods and the operations implemented by the terminal device may alternatively be implemented by a component (for example, a chip or a circuit) used in the terminal device, and the methods and the operations implemented by the network device may alternatively be implemented by a component (for example, a chip or a circuit) used in the network device.

The foregoing mainly describes, from a perspective of interaction between network elements, solutions provided in this application. It may be understood that, to implement the foregoing functions, each network element includes a corresponding hardware structure and/or software module for implementing each function. A person skilled in the art should be easily aware that units, algorithms, and steps in the examples described with reference to embodiments disclosed in this specification can be implemented by hardware or a combination of hardware and computer software in the present invention. Whether a function is performed by hardware or hardware driven by computer software depends on particular applications and design constraints of the technical solutions. A person skilled in the art may use different methods to implement the described functions for each particular application, provided they do not depart from the scope of the claims.

<FIG> is a possible example block diagram of a communication apparatus300 according to this application. The apparatus <NUM> may exist in a form of software or hardware. The apparatus <NUM> may include a processing unit <NUM> and a communication unit <NUM>. In an implementation, the communication unit <NUM> may include a receiving unit and a sending unit. The processing unit <NUM> is configured to control and manage an action of the apparatus <NUM>. The communication unit <NUM> is configured to support the apparatus <NUM> in communicating with another network entity.

When the apparatus <NUM> is configured to implement a function of the first terminal device in the foregoing method embodiment,.

In a possible implementation, the processing unit <NUM> is specifically configured to:.

In a possible implementation, the quantity of times for which the channel access process fails on the first resource is a quantity of times for which the channel access process fails on a unicast resource in the first resource;.

In a possible implementation, the processing unit <NUM> is further configured to:
when determining that the quantity of times for which the channel access process fails on the first resource is equal to the preset quantity, start a second timer, and perform a radio link restoration process during running of the second timer.

In a possible implementation, the processing unit <NUM> is further configured to:
when the second timer expires, if the radio link restoration process fails, trigger a radio link re-establishment process.

When the apparatus <NUM> is configured to implement a function of network device in the foregoing method embodiment,.

<FIG> shows an apparatus <NUM> according to an embodiment of this application. The apparatus shown in <FIG> may be an implementation of a hardware circuit of the apparatus shown in <FIG>. The communication apparatus is applicable to the flowchart shown above, and performs the function of the first terminal device or the network device in the foregoing method embodiment. For ease of description, <FIG> shows only main components of the communication apparatus.

The apparatus <NUM> shown in <FIG> includes at least one processor <NUM>. For example, the processor <NUM> may be a general-purpose central processing unit (central processing unit, CPU), a general-purpose processor, a digital signal processor (digital signal processor, DSP), an application-specific integrated circuit (application-specific integrated circuit, ASIC), a field programmable gate array (field programmable gate array, FPGA) or another programmable logic device, a transistor logic device, a hardware component, or any combination thereof. The processing module may implement or execute various example logical blocks, modules, and circuits described with reference to content disclosed in this application. Alternatively, the processor may be a combination of processors implementing a computing function, for example, a combination of one or more microprocessors, or a combination of a DSP and a microprocessor.

The apparatus <NUM> may further include at least one memory <NUM>, configured to store program instructions and/or data. Coupling in embodiments of this application is an indirect coupling or a communication connection between apparatuses, units, or modules, may be in an electrical, a mechanical, or another form, and is used for information exchange between the apparatuses, the units, or the modules. The processor <NUM> may cooperate with the memory <NUM>. The processor <NUM> may execute the program instructions stored in the memory <NUM>. At least one of the at least one memory may be included in the processor.

The apparatus <NUM> may further include a communication interface <NUM>, configured to communicate with another device by using a transmission medium, so that the apparatus in the apparatus <NUM> may communicate with the another device. In this embodiment of this application, the communication interface may be a transceiver, a circuit, a bus, a module, or a communication interface of another type. In this embodiment of this application, the transceiver may be an independent receiver, an independent transmitter, a transceiver with an integrated receiving and transmitting function, or an interface circuit.

The apparatus <NUM> may further include a communication line <NUM>. The communication interface <NUM>, the processor <NUM>, and the memory <NUM> may be connected to each other through the communication line <NUM>. The communication line <NUM> may be a peripheral component interconnect (peripheral component interconnect, PCI for short) bus, an extended industry standard architecture (extended industry standard architecture, EISA for short) bus, or the like. The communication line <NUM> may be classified into an address bus, a data bus, a control bus, and the like. For ease of representation, only one thick line is used to represent the bus in <FIG>, but this does not mean that there is only one bus or only one type of bus.

In a possible implementation, the processor <NUM> is specifically configured to:.

In a possible implementation, the processor <NUM> is further configured to:
when determining that the quantity of times for which the channel access process fails on the first resource is equal to the preset quantity, start a second timer, and perform a radio link restoration process during running of the second timer.

In a possible implementation, the processor <NUM> is further configured to:
when the second timer expires, if the radio link restoration process fails, trigger a radio link re-establishment process.

A person skilled in the art should understand that embodiments of this application may be provided as a method, a system, or a computer program product. Moreover, this application may use a form of a computer program product that is implemented on one or more computer-usable storage media (including but not limited to a disk memory, an optical memory, and the like) that include computer-usable program code.

This application is described with reference to the flowcharts and/or block diagrams of the method, the device (system), and the computer program product according to this application. It should be understood that computer program instructions may be used to implement each process and/or each block in the flowcharts and/or the block diagrams and a combination of a process and/or a block in the flowcharts and/or the block diagrams. These computer program instructions may be provided for a general-purpose computer, a dedicated computer, an embedded processor, or a processor of another programmable data processing device to generate a machine, so that the instructions executed by the computer or the processor of the another programmable data processing device generate an apparatus for implementing a specific function in one or more processes in the flowcharts and/or in one or more blocks in the block diagrams.

These computer program instructions may be stored in a computer-readable memory that can indicate the computer or the another programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate an artifact that includes an instruction apparatus. The instruction apparatus implements the specific function in one or more processes in the flowcharts and/or in one or more blocks in the block diagrams.

Claim 1:
A communication method, comprising:
when determining that a quantity of times for which a channel access process fails on a first resource is equal to a preset quantity, determining (<NUM>), by a first terminal device, first information, wherein the first information comprises a result of the channel access process performed on the first resource or comprises a resource request message, the channel access process is a listen before talk process performed by the first terminal device, the resource request message is used to request a resource for retransmission on a sidelink between the first terminal device and a second terminal device, and the first resource is used for sidelink communication between the first terminal device and the second terminal device, ; and
sending (<NUM>), by the first terminal device, the first information to a network device.