Enhanced Alamouti space-time block-coding transmission based on a developed OFDM system

This paper presents a new Alamouti space-timeblock coding (STBC) orthogonal frequency division multiplexing (ST-OFDM) system. The transmitter of the proposed scheme is based on a low complexity X-transform that is developed in [1] as a modulation scheme instead of the inverse fast Fourier transform (IFFT). The proposed ST-X-OFDM scheme massively reduces the transmitter complexity, the effects of multipath channels, and the peak-to-average power ratio (PAPR). The complexity of the proposed scheme is evaluated and compared with the conventional ST-OFDM, showing that the proposed scheme is efficient, fast, and simple in implementation. An exact closed-form bit-error rate (BER) is derived for the proposed scheme over multipath channels and different kinds of modulation formats. Computer simulations corroborated by mathematical results prove that, over frequency-selective multipath channels and different mapping schemes, the proposed approach achieves significant signal-to-noise ratio (SNR) gain in comparison to the ST-OFDM system. The proposed ST-X-OFDM system adopts only a single, low complexity transform at the transmitter without precoding and achieves significant BER improvement over the conventional ST-OFDM system.