A communications method includes a first communications device that communicates a first signal on a first time domain resource in a first time unit, communicates a second signal on a third time domain resource in a second time unit, communicates a fourth signal on a second time domain resource in the first time unit, and communicates a third signal on a fourth time domain resource in the second time unit. The first time unit successively includes, in time domain, the first time domain resource, a first guard period, the second time domain resource, and a second guard period that are consecutive in time domain, and the second time unit successively includes, in time domain, the third time domain resource, a third guard period, the fourth time domain resource, and a fourth guard period that are consecutive in time domain.