Differential modulation diversity

In this paper, differential modulation diversity (DMD) is introduced. This diversity scheme is based on diagonal signal constellations which have been previously proposed for differential space-time modulation (DSTM). DMD can exploit both space and time diversity and DSTM, which is a pure space-diversity scheme, results as a special case. Low-complexity noncoherent receivers originally designed for DSTM are adapted to DMD and the power efficiency of DMD for Ricean fading with spatial correlation and imperfect interleaving is investigated. Based on analytical expressions for the pairwise error probability it is shown that space diversity increases the effective fading bandwidth, which has a negative influence on performance. Time diversity does not have this disadvantage and is preferable especially for fast fading channels. If space and time diversity are combined, a robust receiver results that yields high performance for a wide range of fading velocities.