A sending-end apparatus determines N.sub.1 first sequences, where an n.sup.th first sequence is determined based on an n.sup.th first base sequence, n=0, 1, . . . , N.sub.11, and each first base sequence is a sequence in a GCP. The sending-end apparatus sequentially sends the N.sub.1 first sequences, where an equal time interval exists between time domain positions of any two adjacent first sequences, and N.sub.1 first base sequences are related to a prime factor of N.sub.1, or N.sub.1 first base sequences are predefined sequences.