Partial Equalization for MC-CDMA Systems in Non-Ideally Estimated Correlated Fading

Multi-carrier code division multiple access (MC- CDMA) is capable of supporting high data rates in next generation multiuser wireless communication systems. Partial equalization (PE) is a low complexity receiver technique to combine the signals of subcarriers for improving the achievable performance of MC-CDMA systems in terms of their bit error probability (BEP) and bit error outage (BEO) in comparison to maximal ratio combining, orthogonality restoring combining and equal gain combining techniques. We analyze the performance of multiuser MC-CDMA downlink and derive the optimal PE parameter expression, which minimizes the BEP. Realistic imper- fect channel estimation and frequency-domain (FD) block fading channels are considered. More explicitly, the analytical expression of the optimum PE parameter is derived as a function of number of subcarriers, number of active users (i.e., the system load), mean signal-to-noise ratio, variance of the channel estimation errors for the above-mentioned FD block fading channel. The choice of the optimal PE technique significantly increases the achievable system load for given target BEP and BEO.