Performance of MC-CDMA vs. OFDM in Rayleigh Fading Channels

Abstract

Multicarrier techniques are of high interest in modem communication systems due to their spectral efficiency and simplicity of channel equalization even in the case of heavily frequency selective channels. Further advantages of MC techniques include, e.g., their insensitivity to timing errors as well as to limited narrowband interference. This paper presents a comparison of MC-CDMA and OFDM with diversity from the spectral efficiency point of view in a Rayleigh fading channel. We come to the general conclusion that MC-CDMA provides best performance with moderate (50 ... 75%) loadings. We also conclude that in the synchronous downlink case, MC-CDMA with moderate loading provides clearly better performance than OFDM with comparable diversity. In the quasi-synchronous uplink case, MCCDMA starts showing better efficiency than OFDM with diversity only in cases with rather low raw bit error rates (10^-3 or lower).