On the interference of surrounding cells in a DS-CDMA system

It is well known that the capacity of a cellular CDMA system is limited by the interuser interference. This effect is often computed using a Gaussian approximation or a lognormal approximation. In this paper, we study the effect of surrounding layers of cells on the reverse link by adding one layer at a time. This approach shows us the relationship among the bit error rate, the path loss exponent and the number of layers that need to be considered. A large number of integrals are incurred in the computation process and we demonstrate two efficient approaches, namely, the mean method and Monte Carlo integration, to obtain the bit error rate. For a typical valve of the path loss exponent r=2.5, at least 3 or 4 layers are required to capture most of the interuser-interference effect.