TECHNICAL FIELD

Embodiments of the present disclosure relate to the field of communications technologies, and in particular, to a signal transmission method, network device, and terminal device.

BACKGROUND

In wireless communications, in a scenario of using a low-frequency carrier, a wireless signal has a relatively small path loss, and a beam formed at each antenna port is a wide beam; and therefore, users of an entire cell can be covered. For example, as shown inFIG. 1, a broadcast channel, a system message, paging, and the like of a network device may be transmitted by using a wide beam, to better cover a terminal device1and a terminal device2.

However, in a high-frequency scenario, as shown inFIG. 2, a path loss of a wireless signal increases. If a wide beam is still used for transmission, cell coverage becomes very small and cannot cover a relatively remote terminal device3and terminal device4.

An antenna distance may become smaller in high frequency, so that a unit area can accommodate more antennas. Therefore, a large antenna gain may be obtained by using a massive multiple-input multiple-output (massive MIMO) beamforming technology, to compensate for the path loss. There may be a large quantity of antennas even hundreds of antennas in massive MIMO. When a large antenna gain is obtained, a formed beam is very narrow in width. One narrow beam can cover only a part of an area, but cannot cover all users in a cell. For example, as shown inFIG. 3, a beam B2can cover only a terminal device5, but cannot cover a terminal device6.

In a high-frequency multi-beam transmission scenario, to serve the users in the cell, different beams may need to serve the users in the cell in a time division manner, and the beams need common channels such as a broadcast channel, a synchronization channel, and a control channel to cover all the users in the cell, so that the users in the cell are synchronized and obtain a necessary system message to access the cell.

A beamformed control channel is sent by using an existing method for sending a control channel. For example, an existing control channel is a physical downlink control channel (PDCCH), and a beamformed control channel is a beamformed PDCCH. In this case, in one subframe, there may be both the PDCCH with large coverage used to serve an old terminal device, and the beamformed PDCCH used to serve a terminal device in enlarged coverage. The PDCCH with wide coverage is demodulated by using a common reference signal (CRS) with wide coverage. However, the beamformed PDCCH cannot be demodulated by using the existing CRS, and needs to be demodulated by using a beamformed reference signal. Therefore, when the beamformed PDCCH is used, a UE cannot correctly receive the beamformed PDCCH if there is no corresponding beamformed reference signal.

Therefore, how to transmit a beamformed control channel and a reference signal of the beamformed control channel becomes a problem that urgently needs to be resolved.

SUMMARY

Embodiments of the present disclosure provide a signal transmission method, network device, and terminal device. In this method, a beamformed control channel and a reference signal of the beamformed control channel can be transmitted.

According to a first aspect, a signal transmission method is provided, and the method includes:

determining a first time-frequency resource, where the first time-frequency resource is a first candidate resource in a plurality of candidate resources;

obtaining a second time-frequency resource and a third time-frequency resource based on the first time-frequency resource and a preset rule, where the third time-frequency resource includes at least one resource element RE at a predefined location in the first time-frequency resource, the second time-frequency resource includes a resource other than the third time-frequency resource in the first time-frequency resource, the preset rule indicates the predefined location, the second time-frequency resource is used to carry a beamformed control channel, and the third time-frequency resource is used to carry a reference signal of the beamformed control channel; and

respectively transmitting the beamformed control channel and the reference signal of the beamformed control channel to a terminal device by using the second time-frequency resource and the third time-frequency resource.

Therefore, in this embodiment of the present disclosure, resources carrying the beamformed control channel and the reference signal of the beamformed control channel are determined, to transmit the beamformed control channel and the reference signal of the beamformed control channel. In this way, it becomes possible to improve coverage of a control channel through beamforming in an existing system.

In addition, a design of the beamformed control channel and the reference signal used for demodulating the beamformed control channel is used in this embodiment of the present disclosure, to improve coverage and performance of the control channel in comparison with a conventional control channel, and especially, to improve coverage of a cell using a high-frequency carrier. In addition, introduction of the beamformed control channel has no impact on or has slight impact on compatibility of a conventional terminal device.

It should be noted that the term “candidate resource” according to this embodiment of the present disclosure is defined as follows:

One time-frequency resource set may be divided into a plurality of time-frequency resource subsets, and the candidate resource is a resource that includes one or more time-frequency resource subsets selected based on a specific rule.

For example, in a Long Term Evolution (LTE) system, the time-frequency resource set may be time-frequency resources corresponding to first three orthogonal frequency division multiplexing (OFDM) symbols in a subframe. The time-frequency resource subset may be a control channel element (CCE) or an enhanced control channel element (ECCE). The candidate resource is one or more subsets selected based on the specific rule. For example, the candidate resource includes one CCE, two CCEs, four CCEs, or eight CCEs, and a corresponding aggregation level is respectively 1, 2, 4, or 8.

For example, a network device may determine the first time-frequency resource based on an existing method for determining a PDCCH resource in LTE.

Optionally, the determining a first time-frequency resource includes:

determining an aggregation level, where the aggregation level is used to indicate a size of the candidate resource; and

selecting one candidate resource from a set of the plurality of candidate resources corresponding to the aggregation level, and using the candidate resource as the first time-frequency resource.

Specifically, the network device may first determine the aggregation level. The aggregation level is used to indicate the size of the candidate resource. For example, the network device may first determine a PDCCH format. A PDCCH format corresponds to a specific aggregation level, the aggregation level corresponds to a quantity of CCEs carrying a PDCCH, and the quantity of CCEs corresponds to a size of a candidate resource in the PDCCH format.

Then, the candidate resource is selected from the set of the plurality of candidate resources corresponding to the aggregation level, and the candidate resource is used as the first time-frequency resource.

It should be understood that the aggregation level may include 4 and 8; 1, 2, 4, and 8; or the like. For detailed description of the aggregation level, refer to a definition in an existing standard. Details are not described herein.

It should be understood that the first time-frequency resource may include a plurality of (a quantity corresponds to an aggregation level) resource element (RE) sets, and each of the plurality of RE sets includes a same fixed quantity of REs.

For example, in LTE, an RE set is a control channel element CCE, a PDCCH is carried by at least one CCE, and a quantity of CCEs carrying the PDCCH is determined by an aggregation level. For example, a quantity of CCEs may be 1, 2, 4, or 8. One CCE includes nine resource element groups (REGs), and one REG includes four REs. In other words, one RE set may include 36 REs. Only LTE is used as an example herein for description. In different systems, one RE set may include another quantity of REs. This embodiment of the present disclosure is not limited thereto.

In the LTE system, the first time-frequency resource may be obtained through respectively aggregating one control channel element CCE, two consecutive CCEs, four consecutive CCEs, or eight consecutive CCEs in first three orthogonal frequency division multiplexing OFDM symbols in a subframe for an aggregation level 1, 2, 4, or 8. For example, as shown inFIG. 5, the first time-frequency resource includes eight CCEs, respectively CCE0to CCE7.

In other words, the candidate resource set herein may correspond to an existing resource set carrying an existing PDCCH.

In this embodiment of the present disclosure, the first time-frequency resource may be used to carry a beamformed PDCCH, and may be used to carry a reference signal of the beamformed PDCCH.

It should be understood that the plurality of candidate resources in this embodiment of the present disclosure may include candidate resources corresponding to all aggregation levels, or may include candidate resources corresponding to one aggregation level. This is not limited in this embodiment of the present disclosure.

It should be understood that the foregoing describes a process of determining the first time-frequency resource based on the existing method for determining a PDCCH resource in LTE, and describes an example in which the first time-frequency resource may include a plurality of CCEs. In this embodiment of the present disclosure, alternatively, the first time-frequency resource may be the first time-frequency resource that is determined by the network device based on an existing method for determining an enhanced physical downlink control channel (EPDCCH) resource in LTE. The EPDCCH is carried by at least one ECCE. A quantity of ECCEs carrying the EPDCCH is determined based on an EPDCCH format. Each EPDCCH format corresponds to a specific aggregation level, and the aggregation level corresponds to a specific quantity of ECCEs. An EPDCCH candidate resource set may correspond to a resource set that includes a specific quantity of ECCEs corresponding to an EPDCCH format. Each ECCE may include four or eight EREGs. The aggregation level corresponding to the EPDCCH format includes 1, 2, 4, 8, 16, and 32. In other words, a corresponding first time-frequency resource may include 1, 2, 4, 8, 16, and 32 ECCEs.

It should be understood that the preset rule in this embodiment of the present disclosure may be a rule preset in the system. In other words, the preset rule may be a rule on which the network device and the terminal device preagree. After the first resource is determined, the network device and the terminal device may obtain the second resource and the third resource based on the preset rule.

It should be understood that the preset rule may be a rule on which the network device and the terminal device preagree. After the first resource is determined, the network device and the terminal device may obtain the second resource and the third resource based on the preset rule. Alternatively, the preset rule may be notified by the network device to the terminal device by using signaling. To be specific, the network device sends a message in advance to agree on the preset rule with the terminal device.

Correspondingly, in another embodiment, before410, the method may further include: sending an indication message to the terminal device, where the indication message indicates the predefined location.

For example, the indication message may be a radio resource control (RRC) signaling message. This embodiment of the present disclosure is not limited thereto.

Optionally, the first time-frequency resource includes a plurality of resource element RE sets, each of the plurality of RE sets includes a same fixed quantity of REs, and the third time-frequency resource includes an RE at a preset location in each of the plurality of RE sets.

Optionally, the first time-frequency resource includes a plurality of resource element RE sets, each of the plurality of RE sets includes a same fixed quantity of REs, and the third time-frequency resource includes all REs in at least one of the plurality of RE sets.

According to a second aspect, a signal transmission method is provided, and the method includes:

detecting a first time-frequency resource, where the first time-frequency resource is a first candidate resource in a plurality of candidate resources;

obtaining a second time-frequency resource and a third time-frequency resource based on the first time-frequency resource and a preset rule, where the third time-frequency resource includes at least one resource element RE at a predefined location in the first time-frequency resource, the second time-frequency resource includes a resource other than the third time-frequency resource in the first time-frequency resource, the preset rule indicates the predefined location, the second time-frequency resource is used to carry a beamformed control channel, and the third time-frequency resource is used to carry a reference signal of the beamformed control channel; and

demodulating, based on the reference signal that is of the beamformed control channel and that is carried in the third time-frequency resource, the beamformed control channel carried in the second time-frequency resource.

Therefore, in this embodiment of the present disclosure, resources carrying the beamformed control channel and the reference signal of the beamformed control channel are determined, to transmit the beamformed control channel and the reference signal of the beamformed control channel. In this way, it becomes possible to improve coverage of a control channel through beamforming in an existing system.

It should be understood that the second aspect corresponds to the foregoing first aspect, the first aspect is performed by a network device, and the second aspect may be performed by a terminal device. For corresponding features of the method on a terminal side, refer to the foregoing description of the first aspect. Therefore, for brevity, detailed description is omitted.

Optionally, the first time-frequency resource includes a plurality of resource element RE sets, each of the plurality of RE sets includes a same fixed quantity of REs, and the third time-frequency resource includes an RE at a preset location in each of the plurality of RE sets.

Optionally, the first time-frequency resource includes a plurality of resource element RE sets, each of the plurality of RE sets includes a same fixed quantity of REs, and the third time-frequency resource includes all REs in at least one of the plurality of RE sets.

Optionally, before the detecting a first time-frequency resource, the method further includes:

receiving an indication message, where the indication message indicates the preset rule.

According to a third aspect, a signal transmission method is provided, including:

determining a first time-frequency resource, where the first time-frequency resource is a first candidate resource in a plurality of candidate resources, and the first time-frequency resource is used to carry a beamformed control channel;

determining a second time-frequency resource, where the second time-frequency resource is a second candidate resource in the plurality of candidate resources, or the second time-frequency resource is a resource other than the plurality of candidate resources configured for a terminal device, and the second time-frequency resource is used to carry a reference signal of the beamformed control channel; and

respectively transmitting the beamformed control channel and the reference signal of the beamformed control channel to the terminal device by using the first time-frequency resource and the second time-frequency resource.

Therefore, in this embodiment of the present disclosure, resources carrying the beamformed control channel and the reference signal of the beamformed control channel are determined, to transmit the beamformed control channel and the reference signal of the beamformed control channel. In this way, it becomes possible to improve coverage of a control channel through beamforming in an existing system.

In addition, a design of the beamformed control channel and the reference signal used for demodulating the beamformed control channel is used in this embodiment of the present disclosure, to improve coverage and performance of the control channel in comparison with a conventional control channel, and especially, to improve coverage of a cell using a high-frequency carrier. In addition, introduction of the beamformed control channel has no impact on or has slight impact on compatibility of a conventional terminal device.

It should be noted that the term “candidate resource” according to this embodiment of the present disclosure is defined as follows:

One time-frequency resource set may be divided into a plurality of time-frequency resource subsets, and the candidate resource is a resource that includes one or more time-frequency resource subsets selected based on a specific rule.

For example, in an LTE system, the time-frequency resource set may be time-frequency resources corresponding to first three OFDM symbols in a subframe. The time-frequency resource subset may be a CCE or an ECCE. The candidate resource is one or more subsets selected based on the specific rule. The candidate resource includes one CCE, two CCEs, four CCEs, or eight CCEs, and a corresponding aggregation level is respectively 1, 2, 4, or 8.

For example, a network device may determine the first time-frequency resource based on an existing method for determining a PDCCH resource in LTE.

Specifically, the network device may first determine an aggregation level. The aggregation level is used to indicate a size of the candidate resource. For example, the network device may first determine a PDCCH format. A PDCCH format corresponds to a specific aggregation level, the aggregation level corresponds to a quantity of CCEs carrying a PDCCH, and the quantity of CCEs corresponds to a size of a candidate resource in the PDCCH format.

Then, the candidate resource is selected from a set of the plurality of candidate resources corresponding to the aggregation level, and the candidate resource is used as the first time-frequency resource.

It should be understood that the aggregation level may include 4 and 8; 1, 2, 4, and 8; or the like. For detailed description of the aggregation level, refer to a definition in an existing standard. Details are not described herein.

It should be understood that the first time-frequency resource may include a plurality of (a quantity corresponds to an aggregation level) resource element RE sets, and each of the plurality of RE sets includes a same fixed quantity of REs.

For example, in LTE, an RE set is a control channel element CCE, a PDCCH is carried by at least one CCE, and a quantity of CCEs carrying the PDCCH is determined by an aggregation level. For example, a quantity of CCEs may be 1, 2, 4, or 8. One CCE includes nine resource element groups (REGs), and one REG includes four REs. In other words, one RE set may include 36 REs. Only LTE is used as an example herein for description. In different systems, one RE set may include another quantity of REs. This embodiment of the present disclosure is not limited thereto.

In the LTE system, the first time-frequency resource may be obtained through respectively aggregating one control channel element CCE, two consecutive CCEs, four consecutive CCEs, or eight consecutive CCEs in first three orthogonal frequency division multiplexing OFDM symbols in a subframe for an aggregation level 1, 2, 4, or 8. For example, as shown inFIG. 5, the first time-frequency resource includes eight CCEs, respectively CCE0to CCE7.

In other words, the candidate resource set herein may correspond to an existing resource set carrying an existing PDCCH.

In this embodiment of the present disclosure, the first time-frequency resource may be used to carry a beamformed PDCCH.

It should be understood that the plurality of candidate resources in this embodiment of the present disclosure may include candidate resources corresponding to all aggregation levels, or may include candidate resources corresponding to one aggregation level. This is not limited in this embodiment of the present disclosure.

It should be understood that the foregoing describes a process of determining the first time-frequency resource based on the existing method for determining a PDCCH resource in LTE, and describes an example in which the first time-frequency resource may include a plurality of CCEs. In this embodiment of the present disclosure, alternatively, the first time-frequency resource may be the first time-frequency resource that is determined by the network device based on an existing method for determining an EPDCCH resource in LTE. The EPDCCH is carried by at least one ECCE. A quantity of ECCEs carrying the EPDCCH is determined based on an EPDCCH format. Each EPDCCH format corresponds to a specific aggregation level, and the aggregation level corresponds to a specific quantity of ECCEs. An EPDCCH candidate resource set may correspond to a resource set that includes a specific quantity of ECCEs corresponding to an EPDCCH format. Each ECCE may include four or eight EREGs. The aggregation level corresponding to the EPDCCH format includes 1, 2, 4, 8, 16, and 32. In other words, a corresponding first time-frequency resource may include 1, 2, 4, 8, 16, and 32 ECCEs.

Specifically, the second time-frequency resource is a resource other than the first time-frequency resource, and the second time-frequency resource is used to carry the reference signal of the beamformed control channel.

It should be understood that the second time-frequency resource in this embodiment of the present disclosure has a plurality of feasible manners. The following separately describes in detail a case in which the second time-frequency resource is the second candidate resource and a case in which the second time-frequency resource is the resource other than the plurality of candidate resources configured for the terminal device.

When the second time-frequency resource is the second candidate resource in the plurality of candidate resources, the second time-frequency resource may be the second candidate resource predefined in the plurality of candidate resources.

In other words, the second time-frequency resource is a predefined resource, and the predefined resource is one of the plurality of candidate resources, namely, the second candidate resource.

In other words, the second resource is a predefined resource, to be specific, a resource predefined in the system or a resource on which the network device and the terminal device preagree. Both the network device and the terminal device learn of a location of the second resource in advance, and the second resource carries the reference signal of the beamformed control channel.

It should be understood that the second time-frequency resource and the first time-frequency resource may have a same size (for example, a same aggregation level) or may have different sizes. This is not limited in this embodiment of the present disclosure.

For example, the second time-frequency resource and the first time-frequency resource may have a same size (for example, a same aggregation level). In other words, the second time-frequency resource is a candidate resource other than the first time-frequency resource in the set of the plurality of candidate resources corresponding to the first time-frequency resource. For example, in the LTE system, each of aggregation levels of the first time-frequency resource and the second time-frequency resource is 1, 2, 4, 8, or the like.

For another example, a size of the second time-frequency resource is different from a size of the second time-frequency resource. In other words, the second time-frequency resource is a candidate resource in another set of candidate resources. For example, in the LTE system, an aggregation level of the first time-frequency resource is 2, and an aggregation level of the second candidate resource is 4 or the like.

In addition, when the second time-frequency resource is the second candidate resource in the plurality of candidate resources, the second time-frequency resource is the second candidate resource configured for the terminal device.

For example, the network device may send, to the terminal device, a message that is used to configure the second resource as the second candidate resource. For example, the message may be an RRC signaling message. However, this embodiment of the present disclosure is not limited thereto.

In addition, when the second time-frequency resource is the second candidate resource in the plurality of candidate resources, the network device may determine the second candidate time-frequency resource based on a preset mapping relationship between the first time-frequency resource and the second time-frequency resource.

In a case, the second candidate time-frequency resource may be one of candidate resources that have a same size as the first time-frequency resource and that are in the plurality of candidate resources.

For example, the network device may determine the second time-frequency resource based on the preset mapping relationship between the first time-frequency resource and the second time-frequency resource. The second time-frequency resource is another candidate resource other than the first time-frequency resource in the candidate resources that have a same size.

For example, the mapping relationship indicates that the second time-frequency resource may be a candidate resource adjacent to the first time-frequency resource, a time-frequency resource at a fixed distance from the first time-frequency resource, or the like.

It should be understood that the mapping relationship may be preagreed on by the network device and the terminal device, for example, may be sent by the network device to the terminal device in advance. This is not limited in this embodiment of the present disclosure.

In another case, the second candidate time-frequency resource is a candidate resource that is in candidate resources of a specified size in the plurality of candidate resources and that does not overlap with the first time-frequency resource.

For example, the specified size may be an aggregation level 1, 2, 4, 8, or the like. The specified size may be the same as or different from the size of the first time-frequency resource. This is not limited in this embodiment of the present disclosure.

For example, the specified size may be an aggregation level 4, and the second time-frequency resource may be a candidate resource that is in a plurality of candidate resources whose aggregation levels are 4 and that has a smallest or a largest number in candidate resources that do not overlap with the first time-frequency resource. This embodiment of the present disclosure is not limited thereto. However, it should be understood that the network device and the terminal device need to have a consistent rule for determining the second time-frequency resource. For example, both the network device and the terminal device agree that the second time-frequency resource is a candidate resource that has a smallest number in a set of a plurality of candidate resources of a specified size and that does not overlap with the first time-frequency resource.

When the second time-frequency resource is the resource other than the plurality of candidate resources configured for the terminal device, the second time-frequency resource includes a resource other than the first time-frequency resource configured by the network device for the terminal device.

For example, the second time-frequency resource includes a time-frequency resource corresponding to another reference signal other than a common reference signal (CRS), or the second time-frequency resource includes a time-frequency resource corresponding to a data channel.

Specifically, the network device may send an indication message for configuration to the terminal device. The indication message indicates a location of the second time-frequency resource. For example, the indication message may be an RRC signaling message. However, this embodiment of the present disclosure is not limited thereto.

For example, in LTE, the second time-frequency resource may be a time-frequency resource in a fourth to a 14thOFDM symbols in a subframe.

For example, the second time-frequency resource may include a resource that corresponds to a PDSCH and that is in the fourth to the 14thOFDM symbols in the subframe.

Specifically, the second time-frequency resource may include at least one RE in a zero-power user status information-reference signal zero-power CSI-RS resource configured for the user equipment.

Alternatively, the third time-frequency resource may include at least one RE that is in the fourth to the 14thOFDM symbols in the subframe and that is in a non-zero power user status information-reference signal non-zero power CSI-RS resource configured for the user equipment.

Therefore, in this embodiment of the present disclosure, the existing first time-frequency resource carrying a control channel carries the beamformed control channel, and another resource (the second time-frequency resource) carries the reference signal of the beamformed control channel, to send the beamformed control channel and the reference signal of the beamformed control channel. In this way, it becomes possible to improve coverage of a control channel through beamforming in the existing system.

In addition, a design of the beamformed control channel and the reference signal used for demodulating the beamformed control channel is used in this embodiment of the present disclosure, to improve coverage and performance of the control channel in comparison with a conventional control channel, and especially, to improve coverage of a cell using a high-frequency carrier. In addition, introduction of the beamformed control channel has no impact on or has slight impact on compatibility of a conventional terminal device.

According to a fourth aspect, a signal transmission method is provided, including:

detecting a first time-frequency resource, where the first time-frequency resource is a first candidate resource in a plurality of candidate resources, and the first time-frequency resource is used to carry a beamformed control channel;

detecting a second time-frequency resource, where the second time-frequency resource is a second candidate resource in the plurality of candidate resources, or the second time-frequency resource is a resource other than the plurality of candidate resources configured for a terminal device, and the second time-frequency resource is used to carry a reference signal of the beamformed control channel; and

demodulating, based on the reference signal that is of the beamformed control channel and that is carried in the second time-frequency resource, the beamformed control channel carried in the first time-frequency resource.

Therefore, in this embodiment of the present disclosure, resources carrying the beamformed control channel and the reference signal of the beamformed control channel are determined, to transmit the beamformed control channel and the reference signal of the beamformed control channel. In this way, it becomes possible to improve coverage of a control channel through beamforming in an existing system.

In addition, a design of the beamformed control channel and the reference signal used for demodulating the beamformed control channel is used in this embodiment of the present disclosure, to improve coverage and performance of the control channel in comparison with a conventional control channel, and especially, to improve coverage of a cell using a high-frequency carrier. In addition, introduction of the beamformed control channel has no impact on or has slight impact on compatibility of a conventional terminal device.

It should be understood that the fourth aspect corresponds to the foregoing third aspect, the third aspect is performed by a network device, and the fourth aspect may be performed by the terminal device. For corresponding features of the method on a terminal side, refer to the foregoing description of the third aspect. Therefore, for brevity, detailed description is omitted.

Optionally, when the second time-frequency resource is the second candidate resource in the plurality of candidate resources,

the second time-frequency resource is the second candidate resource predefined in the plurality of candidate resources.

Optionally, when the second time-frequency resource is the second candidate resource in the plurality of candidate resources,

the second time-frequency resource is the second candidate resource configured for the terminal device.

Optionally, when the second time-frequency resource is the resource other than the plurality of candidate resources configured for the terminal device,

the second time-frequency resource includes a time-frequency resource corresponding to another reference signal other than a common reference signal (CRS), or the second time-frequency resource includes a time-frequency resource corresponding to a data channel.

Optionally, before the detecting a second time-frequency resource, the method further includes:

receiving an indication message sent by the network device, where the indication message indicates a location of the second time-frequency resource.

Optionally, when the second time-frequency resource is the second candidate resource in the plurality of candidate resources,

the second time-frequency resource is the second candidate resource determined based on a preset mapping relationship between the first time-frequency resource and the second time-frequency resource.

Optionally, the second candidate time-frequency resource is one of candidate resources that have a same size as the first time-frequency resource and that are in the plurality of candidate resources.

Optionally, the second candidate time-frequency resource is a candidate resource that is in candidate resources of a specified size in the plurality of candidate resources and that does not overlap with the first time-frequency resource.

According to a fifth aspect, a network device is provided and is configured to perform the method in the first aspect, any possible implementation of the first aspect, the third aspect, or any possible implementation of the third aspect. Specifically, the network device includes a unit configured to perform the foregoing method.

According to a sixth aspect, a terminal device is provided and is configured to perform the method in the second aspect, any possible implementation of the second aspect, the fourth aspect, or any possible implementation of the fourth aspect. Specifically, the terminal device includes a unit configured to perform the foregoing method.

According to a seventh aspect, a computer-readable medium is provided and is configured to store a computer program. The computer program includes an instruction used to perform the method in the first aspect, any possible implementation of the first aspect, the third aspect, or any possible implementation of the third aspect.

According to an eighth aspect, a computer-readable medium is provided and is configured to store a computer program. The computer program includes an instruction used to perform the method in the second aspect, any possible implementation of the second aspect, the fourth aspect, or any possible implementation of the fourth aspect.

