Performance of a direct-sequence code division multiple access cellular network

Spread spectrum direct-sequence code division multiple access (DS/CDMA) is being touted by some as the solution to the capacity problem for cellular networks. Some engineers estimate that a forty-five-fold increase in capacity over analog networks can be realized with DS/CDMA. The capacity relies on the amount of interference inflicted on a user by random noise and, more importantly, co-channel users. A precise equation relating the interference to the noise and number of users has yet to be developed. A Gaussian approximation however, for the interference inflicted by users is gaining acceptance. In this paper, a DS/CDMA system using Binary Phase Shift Keying (BPSK) modulation and a processing gain close to that of a cellular network will be simulated on a computer to determine bit error probabilities for various numbers of users. The results will then be compared to results obtained using the Gaussian approximation. This paper represents the culmination of seven months of research and experimentation via computer simulation.