Analysis of mapping strategies for turbo-coded space-time block codes

We propose a “turbo” coding scheme for the multiple-input multiple-output (MIMO) Rayleigh fading channel consisting of the serially concatenation of a block code as the outer code and different orthogonal space-time block codes (STBC) for more than two transmit antennas as the inner code. Here, we consider the orthogonal STBC as a mapping scheme in space and time. At the receiver, we apply iterative space-time detection and decoding. We analyze the impact of different mapping strategies on the information transfer of the soft-input-soft-output (SISO) space-time detector. Moreover, we analytically show that additional performance gains over Gray mapping can be obtained by different mapping strategies. Furthermore, we use extrinsic information transfer characteristics (EXITcharts) in order to predict the performance and the behavior of the system.