Adaptive Time Domain Channel Tracking Algorithm for Space-Time Coded OFDM Systems

In this paper, a least-mean-square (LMS) based adaptive channel tracking scheme for space-time block coded orthogonal frequency division multiplexing (STBC-OFDM) systems is proposed. Based on the recursion of channel impulse response, the proposed channel tracking is essentially carried out in the time domain, which is referred as the time domain LMS scheme (TD-LMS). Since the number of channel taps in the time domain is much smaller than that of the frequency domain in a practical OFDM system, the time domain channel tracking may attain more accurate channel state information than the frequency domain. Moreover, the proposed TD-LMS scheme fully utilizes both the time and frequency domain correlation of the time-variant and frequency-selective channels. Simulation results show that the proposed scheme performs much better than the frequency domain adaptive tracking schemes, which only exploits the time domain correlation. Henceforth, the proposed scheme will approach the performance of the system with perfect channel state information at moderate Doppler frequencies