Recursive Receivers for Space-Time Trellis Coded OFDM Systems over Time-Varying Block Fading Channels

Space-time trellis coding systems employing orthogonal frequency division multiplexing (OFDM) technique over frequency-selective channels is considered, where the fading gains could vary within a frame interval encompassing a number of OFDM symbol times. The frequency-domain channel time evolution of sub-carriers associated with OFDM symbol is first approximated by a state space model. The per-survivor processing (PSP) incorporated into Kalman filtering (KF) thus enables a recursive receiver for channel tracking along with data decoding. In view of the computational complexity of this PSP-Kalman growing exponentially with the number of sub-carriers, a reduced-complexity alternative by capitalizing on channel cross-correlation on the basis of per- group of neighboring sub-carriers in a sequential order within an OFDM symbol is proposed. Computer simulations are provided to demonstrate the efficacy of the addressed approaches in terms of root mean squared error (RMSE) and frame error rate (FER) in certain different scenarios.