A simple diversity technique using spread space-time block coding in MIMO systems

In this paper, we propose a simple diversity technique using spread space-time block coding in multiple input multiple output (MIMO) systems. It spreads the transmission data into multiple sub-streams on different antennas by using Walsh codes. The proposed scheme does not sacrifice the spectrum efficiency meanwhile maintain the receiver with low complexity. Owing to the transmission symbols of different transmit antennas passing through all the sub-channels between transmit-receive antenna pairs, the system obtains the partial additional space diversity gain of all paths. It is also shown that the diversity gain will not be affected by the order of receive diversity and maintain linear improvement with the increase of transmit antennas.