Cell Capacity of CDMA Networks Taking the Effect of Mobile Locations into Consideration

In this paper, we evaluate the cell capacity of CDMA networks more accurately through simulation. Earlier work relating to the computation of Erlang cell capacity, other-cell interference imposed by an inter-cell mobile on the base station receiver is taken as the average with reference to all its possible spatial locations. This conventional approach implicitly is assuming that each inter-cell mobile has the same impact on the receiver performance. However, for interference-limited systems, mobiles located differently over the area will generate different amount of total other-cell interference, and hence, the receiver performance is expected to vary with instantaneous mobile locations. To investigate this effect, we first generate the mobile locations in all co-channel cells according to the known spatial distribution statistics. Perfect power control is applied to obtain the maximum number of mobiles in the referenced cell. By repeating for a large number of snapshots, the probability mass function for the maximum number of mobiles, which can be supported by the referenced cell, can be obtained to derive the Erlang cell capacity. Our results show that the Erlang cell capacity obtained using the conventional approach is smaller than that obtained from simulation, and unable to predict the variation in the maximum number of mobiles that can be supported by the referenced cell. We put forward an approach in quantifying the impact of mobile locations on the cell capacity without affecting the existing analytical approaches used in evaluating the Erlang cell capacity.