Achieving optimum coded diversity with scalar codes

In this correspondence, we consider the case of multiple-antenna transmission diversity. We outline a recent result on the maximum possible performance (in terms of mutual information) and show that it can be achieved using scalar codes instead of vector codes. The scalar coding schemes we propose are based on space-time block codes and do not involve any reduction in data rate for two transmitter antennas. For the case of three and four transmitter antennas we achieve 3/4 of the rate achieved using vector codes. For more than four transmitter antennas we achieve 1/2 of the maximum possible rate. In all cases, the diversity performance is the same as that corresponding to vector codes. In addition, the receiver has a simple structure which makes implementation easier and keeps down the computational complexity.