Full frequency diversity codes for single input single output systems

Due to the severe conditions of wireless channels, it is crucial for wireless systems to accommodate some sort of diversity to achieve reliable communication. Different types of diversity techniques such as temporal, frequency, code, and spatial have been developed in the literature. In addition to the destructive multipath nature of wireless channel frequency selective channels pose intersymbol interference (ISI) while offering frequency diversity for successfully designed systems. Orthogonal frequency division multiplexing (OFDM) has been shown to fight ISI very well by converting the frequency selective channel into parallel flat fading channels. On the other hand, bit interleaved coded modulation (BICM) was shown by Zehavi (IEEE Trans. Comm.. vol. 40, no. 5, pp. 873-884, 1992) and later by Caire et al (IEEE Trans. Inform. Theory vol. 44, no. 3, 1998) to have high performance for flat fading Rayleigh channels. It is natural to combine BICM and OFDM to exploit the common ground of both techniques to improve overall system performance. In this paper we show both analytically and via simulations that for L tap frequency selective fading channels, BICM-OFDM can achieve a diversity order of min(d_free. L), where d_free is the minimum Hamming distance of the convolutional code used for BICM.