Differential Space-time Coding with Multiple Amplitudes Modulation in the Case of Non-square Code Matrix

By introducing multiple levels quadrature amplitude modulation and matrix transform method; we develop a multiple amplitudes differential space-time coding (DSTC) scheme in the case of non-square code matrix. The scheme can avoid the performance loss of conventional DSTC schemes based on MPSK modulation in high spectrum efficiency, and it can be applied to non-square code matrix, thus it overcomes the shortcoming that some DSTC schemes only suit square code matrix. Compared with MPSK based single amplitude DSTC schemes, the developed scheme have higher spectrum efficiency by carrying information not only on phases but also on amplitudes. Moreover, the scheme has linear decoding complexity, and higher code rate in the case of more than two transmit antennas. The simulation results show that our scheme has lower BER when compared with the existing single amplitude differential space-time block coding schemes.