Abstract: A communication method includes jointly sending first data to a first communication device in n first time domain resources, where the n first time domain resources respectively belong to n first time units, where relative positions of the n first time domain resources in the n first time units are the same, where n is an integer greater than or equal to 2, where the n first time domain resources are included in a second time domain resource, and where the second time domain resource is a first periodic resource.

Abstract: A method, an apparatus and a system for estimating channels are disclosed. A method for estimating channels includes: receiving downlink signals inclusive of reference signals from two or more Access Points (APs), where the relative frequency shift between reference signals sent by different APs is zero; and performing channel estimation according to the reference signals. Another method for estimating channels includes: receiving downlink signals inclusive of reference signals from two or more APs, where for a first AP and a second AP among the two or more APs, a specific time-frequency lattice in the downlink signals sent by the first AP does not include data signal, and the specific time-frequency lattice corresponds to a time-frequency lattice utilized by the second AP to send a reference signal; and performing channel estimation according to the reference signals.