Pilot-assisted decision feedback channel estimation for STTD in OFDM mobile radio

In this paper, we propose pilot-assisted decision feedback channel estimation (PA-DFCE) for space-time coded transmit diversity (STTD) in orthogonal frequency division multiplexing (OFDM). Two transmit channels are simultaneously estimated by transmitting the STTD encoded pilot. To improve the tracking ability of the channel estimation against fast fading, decision feedback is also used in addition to pilot. For noise reduction and preventing the error propagation, windowing of the estimated channel impulse response in the time-delay domain is applied. The average bit error rate (BER) performance of OFDM with STTD is evaluated by computer simulation. It is found that the use of PA-DFCE can achieve a degradation in the required E_b/N₀ from ideal CE of as small as 0.6 dB for an average BER = 10^-3 and requires about 2.4 dB less E_b/N₀ compared to differential STTD that requires no CE.