A new differential unitary space-time modulation scheme with reduced receiver complexity

The differential unitary space-time modulation (DUSTM) scheme provides full diversity without channel knowledge at either the transmitter or the receiver. However, the complexity of maximum-likelihood decoding is exponential in the number of transmit antennas and the data rate. For the case where the number of transmit antennas is even, we propose a new DUSTM scheme which preserves full diversity while reducing the decoding complexity. Moreover, our scheme simplifies the constellation design. Theoretical analysis and simulation results show that for some typical scenarios, the proposed scheme achieves better bit-error-rate performance than the original DUSTM scheme.