BER Performance of Pre-Coded Space-Time Conjugate Two-Path OFDM Systems

It’s critical to design a robust wireless communication system that achieves an improved bit error rate (BER) in mobile channels. In this paper, a 2x2 space-time (ST) orthogonal frequency division multiplexing (OFDM) system is proposed with conjugate cancellation (CC) two-path transmission scheme. The 2x2 STCC-OFDM system features in the excellent inter-carrier interference (ICI) mitigation in the mobile channels with a better BER than that of a conventional 2x2 ST-OFDM system. Five orthogonal transforms are employed as the precoder to enhance the BER further, such as Zadoff-Chu transform (ZCT), slant transform (ST), discrete Hartley transform (DHT), Haar transform (HT), and Walsh–Hadamard transform (WHT). ZCT row wise precoder provide the lowest peak-to-average power ratio and good BER performance. Simulations demonstrate that the proposed STCC-OFDM systems are robust to various channel environments Although the STCC-OFDM systems improve BER with the cost of reducing bandwidth efficiency when compared to a ST-OFDM, they can be compensated by a higher QAM constellation size.