Efficient spread space-time block coding scheme in multiple antenna systems

Space-time coding is an important technique t ha t can improve transmission performance at fading environments in mobile communic ation systems. In this paper, we propose a novel diversity scheme using spread s pace-time block coding (SSTBC) in multiple antenna systems. At the transmitter, the primitive data are serial to parallel converted to multiple data streams, a nd each stream is rotated in constellation. Then Walsh codes are used to spread each symbol to all antenna space in a space-time block. The signals received fr om all receiver antennas are combined with the maximum ratio combining (MRC), eq ualized with linear equalizer to eliminate the inter-code interference and fina lly demodulated to recover to transmit data by using the one-symbol maximum lik elihood detector. The proposed scheme does not sacrifice the spectrum efficiency meanwhile maintains the transceiver with low complexity. Owing to the transmiss ion symbols of different transmit antennas passing through all the spatial sub- channels between transceiver antenna pairs, the system obtains the partial addit ional space diversity gain of all spatial paths. It is also shown that the diver sity gain is better than the previous space-time block coding (STBC) schemes wi th full transmission rate.