Signal transmission method and apparatus

A signal transmission apparatus, comprising:

• at least one processor;
• a non-transitory computer-readable storage medium coupled to the at least one processor and storing programming instructions for execution by the at least one processor, wherein the programming instructions instruct the at least one processor to:
• filter a first time domain OFDM signal at each of M spatial transmission layers, wherein M is an integer greater than or equal to 1;
• perform spatial precoding on the first time domain OFDM signal that is filtered and that is at each of the M spatial transmission layers, and map the filtered first time domain OFDM signal at each of the M spatial transmission layers to each of Nt transmit antenna ports, wherein Nt is an integer greater than or equal to M;
• and
• a transceiver, configured to superpose and transmit the first time domain OFDM signals that are at the M spatial transmission layers and that are mapped to all the Nt transmit antenna ports.