Simple analysis of MRC receivers for MC-CDMA systems in fading channels

Multicarrier code-division multiple-access (MC-CDMA) is a transmission scheme that combines orthogonal frequency division multiplexing (OFDM) signaling with the CDMA technique allowing efficient, utilization of the bandwidth in broadband mobile radio channels. In this paper, a new practical technique based on alternative Gaussian approximation (AGA) for determining the bit error rate (BER) of maximal-ratio combining (MRC) receivers for MC-CDMA systems with multiple active users in frequency selective Rayleigh fading channels is presented. The analysis assumes that different subcarriers experience independent fading channels, which are not necessarily identically distributed. Unlike other existing analysis methods, this new procedure takes advantage of an alternate integral representation of the conditional BER, leading to the final average BER in the form of a single finite range integral and an integrand composed of an elementary function which can be easily computed numerically. The accuracy of the proposed approach based on AGA is demonstrated with computer simulations results in a Rayleigh fading channel.