Differential unitary space-time modulation in fast fading channel

A new differential unitary space-time modulation scheme based on a cyclic unitary group code is proposed for systems with multiple transmit antennas in fast fading channels. By changing the sequence of transmitted symbols, this new differential unitary space-time modulation scheme reduces the deteriorating effect of fast fading channels at the cost of larger processing delay and additional transmission power. For a relatively large processing delay, the additional transmission power is negligible. Theoretical analysis and computer simulations are carried out to investigate the performance of the conventional and the proposed differential unitary space-time modulation schemes. It is demonstrated that this new differential unitary space-time modulation scheme can achieve significant gains compared with the conventional differential unitary space-time modulation in fast fading channels with very little cost.