MAP-PSP for Space-Time Trellis Codes Over Unknown Doppler Channels

This work considers joint channel estimation and data detection of space-time trellis codes (STTCs) over time-varying flat fading channels with unknown normalized Doppler shift, f _dT. An algorithm based on an improved per survivor processing (PSP) technique, where the survivor branch decision is formulated in the symbol by symbol maximum a posteriori probability (MAP) framework, is presented. An adaptive Kalman predictor (AKP) is employed to track the fading channel and f _dT. In the AKP, the sequence of channel estimates produced by the Kalman predictor (KP) is utilized for f _dT estimation. In turn, the estimated f _dT is used in the KP for channel tracking. This coupled process adaptively estimates both the channel coefficients and Doppler shift. The performance of STTC using the proposed receiver is robust against f _dT mismatch, and it is within 0.3 dB from the known f _dT case.