On EXIT-charts for space-time block codes

In this work, we consider the application of the well-known space-time block code (STBC), the Alamouti-scheme, as inner code within a "turbo" coding scheme for the multiple-input-multiple-output (MIMO) Rayleigh fading channel. We analyze therefore the applicability of the Alamouti-scheme for iterative space-time detection and decoding applied at the receiver. To this end, we use extrinsic information transfer characteristics (EXIT-charts) in order to predict the performance of the Alamouti-scheme. Furthermore, we analyze the impact of different mapping strategies on the information transfer of the soft-input-soft-output (SISO) space-time detector and show analytically that it is possible to improve the performance by employing other mapping schemes than Gray mapping.