Fade-resistant CDMA transmission and reception over time-varying wireless channels

Physical limitations due to fading and interference in wireless channels pose technical challenges in achieving reliable communication. To adapt to this adverse radio environment efficiently, we propose a fade-resistant transmission system based on code division multiple access (CDMA) technology. In this system, all the symbols of a user are transmitted simultaneously using parallel sequences over a time-varying wireless channel. We derive the relationship between the self-interference and the multiple-access interference in such a system. We prove that instantaneous signal-to-interference-plus-noise ratio (SINR) at the matched filter output of a system with parallel sequences is statistically higher than that of the conventional CDMA system. Numerical results demonstrate that the parallel sequence transmission scheme can provide capacity improvement over the conventional CDMA system depending on variations in the channel.