Performance Evaluation of SFBC MIMO–OFDM Using FrFT Under TWDP Fading Channel

Abstract

Multiple-input–multiple-output orthogonal frequency division multiplexing (MIMO–OFDM) is a promising 4G technology to increase data rate and capacity of a system. Further, the space–frequency-block-coding (SFBC) technique in MIMO–OFDM system has increased reliability of system in high mobility channels. Fourier transform in conventional OFDM system can obtain either in time or frequency domain, hence it can be acceptable to reduce inter-carrier-interference while it fails for doubly dispersive channels where both the domain are changing simultaneously. Another mathematical tool named as fractional Fourier transform (FrFT) cancels the effect of rapidly varying time–frequency-distortions by considering new rotating axis \(\left( {u,v} \right)\) at an angle \(\alpha\) from conventional time–frequency plane. In this paper, the performance of SFBC encoded MIMO OFDM system using FrFT in place of FFT has been analyzed under two-wave-diffused-power (TWDP) frequency selective fading channel. In this paper, the novel closed form expression for average bit-error-rate (BER) for coded and un-coded FrFT based MIMO–OFDM system under TWDP has also been presented in this paper. The results carried out using simulation shows that the proposed model achieves BER of 10−2 at 5 dB SNR whereas conventional achieves the same at 14 dB hence, concluded that the novel system performance improved by nearly 9 dB.