Simple Decoded OFDM-QOSTBC Wireless System in the Presence of Nakagami Fading and Imperfect Channel Estimation

In this paper, a simple decoded orthogonal frequency division multiplexing (OFDM) quasi orthogonal space time block coding (QOSTBC) wideband wireless system is proposed in the presence of Nakagami-m fading and imperfect channel state information (CSI). The proposed scheme preserves full diversity and full code rate with simple decoding complexity. The use of OFDM is to eliminate the problem of inter-symbol interference (ISI) caused by the frequency selectivity of the channel. Due to practical considerations, imperfect CSI is considered in this work to imitate real transmission scenarios. Simulation results show that in the case of Rayleigh fading and channel estimation error variance of 0, the proposed and the conventional schemes overlap. This shows the good capability of the OFDM technology on repealing the effect of ISI. In addition, it is noted that the performance improves as the Nakagami-m parameter increases. Moreover, it can be observed that as the imperfect estimation error variance increases the performance degrades.