Wavelet-time diversity transmission in wireless systems: Performance results

This paper presents the fundamentals of wavelet-time diversity transmission, which is proposed to be used in M-ary digital communication systems, and investigates the performance of a novel 4-QAM system with wavelet-time diversity transmission and MMSE equalization over flat Rayleigh fading channels. This transmit diversity scheme exploits the orthogonality properties between rows of a wavelet matrix to disseminate the information of modulation symbols prior transmission. Consequently, our focus here is to experimentally investigate the performance gains over fading channels only with a diversity scheme, without adding redundancy to the information bits. Several simulation experiments varying the genus of wavelet matrix are carried out to demonstrate the potential benefits of this diversity scheme. Our numerical results show that the bit error rate (BER) performance of this novel 4-QAM system can be significantly improved with this approach. In fact, when compared with a space-time coded system our diversity system can easily achieve much higher performance under flat-fading conditions, while remains unaffected the spectral efficiency of the original modulation scheme.