Effective interference: a novel approach for interference modelling and traffic analysis in CDMA cellular networks

This paper presents an analysis of the reverse link capacity of cellular mobile communication networks operating with direct sequence code division multiple access. The emphasis is on dealing with the variability in user locations and on allowing different numbers of users in each cell. Firstly we calculate the distribution function of the interference at a cell site from a single mobile whose position is a random vector in another cell of the network. Using ideas closely related to the effective bandwidth concept from the analysis of call admission control in ATM networks, a method of handling the sum of the interference from arbitrary numbers of users in each cell is presented. This leads to a set of linear constraints that bounds the capacity region of the network and to the assignment of an effective interference to users. Importantly, the method is readily incorporated into a traffic model which allows the stochastic nature of the call arrival process to be analysed and the Erlang capacity of the network to be calculated.