Multiple-Symbol Differential Sphere Decoding Aided Amplify-and-Forward Differential Space-Time Modulation

Differential Space-Time Modulation (DSTM) employing multiple antennas provides a diversity advantage in rich scattering environments, whilst the excessive complexity of MIMO channel estimation is avoided. However, due to size, cost or other hardware limitations, the multiple antennas may be in deep fade simultaneously and hence experience spatially correlated fading, which leads to a loss of diversity gain. Hence in this paper, we design an Amplify-and-Forward (AF) relaying aided DSTM scheme, which is capable of attaining a diversity gain even when the source node is in deep fade. Furthermore, Multiple-Symbol Differential Sphere Decoding (MSDSD) is developed for the proposed scheme to avoid the potential performance degradation of the noncoherent receiver in fast fading channels.