Disclosed are a method and an apparatus for a node used for wireless communication. The method includes: receiving, by a first node, a first information block, where the first information block is used to indicate a first time-frequency resource block; performing first access detection in a first sub-band, where the first access detection includes more than one time of first type monitoring; and sending 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 abstaining 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.