The performance of the M-ary DS/CDMA cellular system over Rayleigh-fading channel with hybrid EGC-SC scheme

The BER performance of M-ary DS/CDMA communication systems armed with hybrid EGC-SC scheme of which the N-th order multipath selection combining in combination with the 2-nd order equal gain diversity combining scheme over a Rayleigh-fading channel has been investigated. The results were compared with that of multipath equal gain combining (EGG) diversity and multipath selection combining diversity (SC). The fading channel is a frequency selective discrete independent slowly fading channel having L number of resolvable paths. The RAKE receiver structure with square law demodulation is used. The system is operated in an asynchronous mode and perfect power control is assumed. The multiple access interference is modeled as Gaussian. Three close form expressions to evaluate the BER performance for the three diversity schemes have been respectively derived. Furthermore, the three close form expressions can also be applied to other similar DS/CDMA systems with M-ary orthogonal modulation at higher transmission chip rate.