Abstract

In this paper, the frame-error-rate (FER) performance of full-diversity high-rate space-time block-coded (STBC) system is presented for quadrature phase-shift keying (QPSK) digital modulation technique, which is using the numeric-variable-forgetting-factor (NVFF) least-squares (LS) algorithm based channel estimator. The STBC transmission data-rates  with two-transmitter antennas and  with four-transmitter antennas are achieved by maximizing the coding gain and by minimizing the peak-to-minimum-power-ratio while using the selective power scaling of the information symbols, which also guarantees full-diversity in case of the two-transmitter antennas. The imperfect channel estimation leads to degradation in the FER performance of the low complexity maximum likelihood decoding algorithms, though the optimum power scaling factor is incorporated along with the constellation rotation scheme. Simulation results are presented to demonstrate that the FER performance of high-rate STBC system under idealistic conditions is quite different from its performance under realistic wireless environment due to the channel estimation errors. Therefore, the tracking performance of the pilot channel estimator is found to play significant role in the overall performance evaluation of the proposed wireless systems under slowly time-varying channels also in case of the general M-ary phase-shift keying (M-PSK) constellations.

Key words: Space-time block-code, coding gain, peak-to-minimum-power-ratio, numeric-variable-forgetting-factor, variable-forgetting-factor, least-squares algorithm.