Taking N=4 and K=4 as an example, as shown in FIG. 13, the network device configures a control resource on each of the 4 subbands, The set formed by the control resource on each of the 4 subbands is the first control resource set, that is, the first control resource set is located on the 4 subbands. When transmitting a PDCCH, the network device will select a subband where the channel use right is obtained, to transmit the PDCCH to the terminal device. Before a downlink transmission opportunity of the network device starts, the terminal device receives the control channel according to the first control resource set, that is, the terminal device needs to detect the control resources on the 4 subbands to receive the PDCCH. When the downlink transmission opportunity of the network device starts, the terminal device determines the number of subbands for communication in the four subbands. For example, the channel using right is not obtained on subband 0, and communication is not performed on subband 0, and the channel use right is obtained on subband 1, subband 2 and subband 3, so the number of subbands for communication is 3. It can be understood that this is only a illustrative description, and does not limit the number of subbands where the channel use right is obtained. In this case, the number of subbands for communication determined by the terminal device is less than the number of subbands included in the BWP, that is, at least one of the four subbands is not included in the subbands for communication in the BWP. At this time, the terminal device may receive the PDCCH according to the control resources on the subband 1, the subband 2 and the subband 3, and no longer receive the control channel according to the first control resource set. Here the control resource set on subband 1, subband 2 and subband 3 is denoted as a second control resource set. That is, the control resources included in the second control resource set are fewer than the control resources included in the first control resource set.