On the optimal base-station density for CDMA cellular networks

In this paper, the minimal base-station density for a code-division multiple-access (CDMA) cellular radio network is determined such that the outage probability does not exceed a certain threshold. Base stations are assumed to be located on a regular triangular grid of minimum distance d, while mobiles are randomly distributed according to a two-dimensional Poisson point pattern. Each mobile may be connected to, at most, one of four surrounding base stations, effectively connecting and applying power control to the one with least attenuation. Thus, we model the use of macroscopic selection diversity. We obtain a normal approximation to the total interference power at a reference base station for a correlated log-normal shadowing law. The base station distance we obtain is proportional to the inverse of the square root of the traffic intensity, and we obtain the constant of proportionality, which is itself a function of the minimum acceptable carrier-to-interference (C/I) ratio and the maximum tolerable outage probability. Our formula for this distance can be used in network planning and design.