Optimization of Irregular CoMP-Aided OFDMA Networks with SFR: A Multiobjective Approach

Abstract

Coordinated multipoint transmission (CoMP) and soft frequency reuse (SFR) are often combined with the aim of reducing the deleterious effects caused by inter-cell interference in current and envisaged cellular networks (4G/5G). The performance of this combined mechanism has been shown to be strongly influenced by the specific choice of the parameters determining the frequency reuse settings. So far, the optimization of this combined setup has relied on time consuming numerical simulations that make it a challenging issue specially in realistic non-regular network deployments where network symmetry cannot be exploited. In an attempt to revert this situation, this paper introduces a novel analytical framework that, for a specific set of SFR parameters, allows the computation of closed-form approximations to relevant performance metrics such as average total capacity, worst-users rate and backhaul requirements. Remarkably, these approximations exhibit a dependence on the SFR parameters that matches that of the true metrics, hence allowing the optimization of the SFR-related parameters based on the proposed analytical expressions. Furthermore, and very important from a practical perspective, the availability of these closed-form expressions allows the efficient application of multiobjective optimization techniques to realistic scenarios with irregularly-deployed base stations that serve to evaluate the various trade-offs the network designer is facing when optimizing multiple, and often conflictive, performance metrics.