A first communication apparatus obtains K data symbols, where K is a positive integer; based on first configuration information, the first communication apparatus adds a first sequence, a second sequence, and a third sequence to P data symbols to obtain a first set, or adds a first sequence and a second sequence to P data symbols to obtain a first set, or adds a second sequence and a third sequence to P data symbols to obtain a first set, where P is less than or equal to K; and the first communication apparatus modulates the first set to obtain a first waveform symbol. The first configuration information is determined based on a length of a first SCP included in the first waveform symbol and a length of a cyclic prefix CP in the first waveform symbol.