Design of Space Time Spreading Matrices

In this paper, we study the design of space time spreading matrices that are modulation matrices for communications over multiple-antenna block fading channels. We assume the channel is known to the receiver only and find necessary and sufficient conditions on the space time spreading matrices for the separation of demodulation and decoding at the receivers without loss of optimality. From the perspective of information theory, we design the space time spreading matrices to maximize the mutual information between the transmitted information vector and the channel output. We apply the designed space time spreading code as an inner code in a bit-interleaved serially concatenated coding scheme, and find the connection between the endpoints of the extrinsic information transfer curves and certain mutual information quantities. A design example and simulation results are given.