Iterative channel estimation and decoding in turbo coded space-time systems

A noncoherent multiple antenna coded communication system over both block fading and time-selective flat fading Rayleigh channel is considered. Several iterative decoding strategies consisting of pilot symbol assisted demodulation and turbo decoding are proposed. It is shown that, at a system rate of 0.9 bits per channel use, the SNR required to achieve a BER of 10^-4 is only about 2 dB from the imperfect CSI capacity lower bound. The channel estimation error variance is demonstrated to be close to the theoretical limit set by the Modified Cramér-Rao bound. The simulation results coincide with the trends dictated by recent information-theoretic analysis and demonstrate the effect that inaccuracy of the channel estimation has on the performance of the iterative decoding scheme.