A method includes: mapping, by a base station, N reference signals to a specified time-frequency resource; and transmitting, by the base station, a reference signal on the specified time-frequency resource to user equipment, where for any PRB, the specified time-frequency resource includes a first OFDM symbol in a data region in time domain; where the PRB includes a type-1 control channel and the data region, the data region includes a type-2 control channel and a data channel, the type-1 control channel includes first m OFDM symbols of the PRB in time domain, and the data region includes OFDM symbols other than the type-1 control channel in the PRB in time domain; and the type-2 control channel includes first n OFDM symbols in the data region in time domain, and the data channel includes OFDM symbols other than the type-2 control channel in the data region in time domain.