Abstract：Differential Unitary Space-Time Modulation (DUSTM) based on diagonal signals achieves full antenna diversity without requiring channel estimation. However, its receiver has a computational complexity that grows exponentially with the number of transmit antennas and the data rate. To reduce receiver complexity, a new DUSTM scheme is proposed for systems where the number of transmit antennas is even. The scheme partitions transmit antennas into two groups with equal number of antennas, and diagonal unitary space-time modulation is applied on each group. The differential encoding matrix is constructed so that maximum-likelihood detection of the two diagonal signals can be decoupled, thereby reducing receiver complexity significantly. Theoretical analysis and simulation results show that the proposed scheme preserves full antenna diversity and provides better bit-error rate performance than diagonal signals in some scenarios.
2006, Vol. 28 
