A first node configured to be used for wireless communication, comprising a first receiving set, configured to receive a first information block, wherein the first information block is used to indicate a first time-frequency resource block; and the first receiving set is configured to perform first access detection in a first sub-band, wherein the first access detection comprises more than one time of first type monitoring; and a first transmitting set, configured to: send a first signal in the first time-frequency resource block when a quantity of times of the first type monitoring, in the first access detection, with monitoring results indicating that a channel is idle is not less than Q1; or abstain from sending of a first signal in the first time-frequency resource block when a quantity of times of the first type monitoring, in the first access detection, with monitoring results indicating that a channel is idle is less than Q1, wherein an end time of the first access detection is not later than a start time of the first time-frequency resource block, the monitoring result of one time of the first type monitoring comprises a channel being idle or a channel being busy, and Q1 is a positive integer; the first access detection comprises Q2 times of first type monitoring and Q3 times of first type monitoring, the Q2 times of first type monitoring are earlier than the Q3 times of first type monitoring in time domain, Q2 is a positive integer, and Q3 is a positive integer; a first multi-antenna relevant parameter is used in the Q2 times of first type monitoring, a second multi-antenna relevant parameter is used in the Q3 times of first type monitoring, and the second multi-antenna relevant parameter is different from the first multi-antenna relevant parameter; and a quantity of times of the first type monitoring, in the Q2 times of first type monitoring, with monitoring results indicating that a channel is idle is less than Q1. a first receiving set, configured to receive a first information block, wherein the first information block is used to indicate a first time-frequency resource block; and the first receiving set is configured to perform first access detection in a first sub-band, wherein the first access detection comprises more than one time of first type monitoring; and a first transmitting set, configured to: send a first signal in the first time-frequency resource block when a quantity of times of the first type monitoring, in the first access detection, with monitoring results indicating that a channel is idle is not less than Q1; or abstain from sending of a first signal in the first time-frequency resource block when a quantity of times of the first type monitoring, in the first access detection, with monitoring results indicating that a channel is idle is less than Q1, wherein an end time of the first access detection is not later than a start time of the first time-frequency resource block, the monitoring result of one time of the first type monitoring comprises a channel being idle or a channel being busy, and Q1 is a positive integer; the first access detection comprises Q2 times of first type monitoring and Q3 times of first type monitoring, the Q2 times of first type monitoring are earlier than the Q3 times of first type monitoring in time domain, Q2 is a positive integer, and Q3 is a positive integer; a first multi-antenna relevant parameter is used in the Q2 times of first type monitoring, a second multi-antenna relevant parameter is used in the Q3 times of first type monitoring, and the second multi-antenna relevant parameter is different from the first multi-antenna relevant parameter; and a quantity of times of the first type monitoring, in the Q2 times of first type monitoring, with monitoring results indicating that a channel is idle is less than Q1.