Studyof DS-CDMA wireless communication over a Nakagami-m multipath fading channel in presence of imperfect power control

The reverse link performance of direct sequence code division multiple access (DS-CDMA) system in wireless communication over a frequency selective multipath fading channel has been investigated in this paper. The channel has been modeled as Nakagami-m distributed frequency selective multipath fading channel. A conventional correlator type receiver has been considered for the analysis. Noise is taken as additive white Gaussian noise (AWGN) with two sided power spectral density N₀/2 . To model multiple access interference (MAI), standard Gaussian approximation (SGA) has been considered in this paper. To mitigate the near-far problem, a power control scheme, but imperfect has been assumed in this paper. The bit error rate (BER) expression for the system has been derived and simulated by varying number of users, number of fading path, processing gain, fading parameter, SNR per bit E_b/N₀ and variation in the amplitude of the received signal. The analysis shows that as the number of simultaneous active user, the number of fading path and the variation in the power of the received signal increases, the BER of the system increases indicating the performance degradation. As the value of the processing gain, the ratio E_b/N₀ and the fading parameter increases, the BER performance of the system improves.