Signal processing method and apparatus

A communication apparatus, wherein the communication apparatus comprises:

• a processing unit, configured to generate a physical layer protocol data unit (PPDU), wherein the PPDU comprises a first field, the first field is usable for carrying M sequences, the M sequences correspond to M space-time streams, one sequence corresponds to one space-time stream, M is a positive integer greater than 4, the M sequences comprise a first sequence, wherein cross-correlation energy between the first sequence and at least three of the M sequences within a length range of the Golay complementary sequence is zero, and an autocorrelation side lobe energy of the first sequence within the length range of the Golay complementary sequence is zero, the first sequence is based on a channel estimation (CE) sequence, and the Golay complementary sequence is usable for constructing the CE sequence;
• and
• a transceiver unit, configured to send the PPDU.