MC-CDMA Systems with Uplink and Downlink Receivers over Fading Channels

Bit error rates of uplink and downlink Multicarrier Code Division Multiple Access (MC-CDMA) system using coherent Maximal-Ratio Combing (MRC) and Equal Gain Combining (EGC) receivers are estimated over Rayleigh fading channels. The analysis assumes that different subcarriers experience independent fading channels, but not necessary identically distributed. The analysis is based on Gaussian approximation of the multiple access interference. Generalized bit error rate (BER) expressions for both uplink and downlink with MRC and EGC receivers were derived. The analytical results are supported with computer simulation results. The effect of fading parameters, number of users, and number of subcarriers were presented. The BER performance of the EGC receiver in the uplink is highly influenced by the fading parameter compared with the MRC receiver. The EGC receiver achieves advantages compared to the MRC receiver in the downlink, the MRC receiver obtains small improvement compared to the EGC in the uplink. Key-Words: Multicarrier Code Division Multiple Access, Maximal Ratio Combining, Equal Gain Combining, Uplink MC-CDMA Receiver, Downlink MC-CDMA Receiver.