Investigation on joint optimization for user association and inter-cell interference coordination based on proportional fair criteria

Abstract

In order to support the continuous growth in the amount of mobile traffic, small cell deployments, that increase the base station (BS) density, are promising. In small cell deployments, combined usage of user association and inter-cell interference coordination (ICIC) is inevitable. This paper investigates the joint optimization of user association and ICIC in the downlink. We first formulate the joint optimization problem as a utility maximization problem. We then employ the logarithmic utility function known as the proportional fair criteria. The optimum user association and the ICIC are derived by solving a convex optimization problem based on the average spectral efficiencies of all users. We propose an iterative algorithm to obtain the optimum solution to this problem. We evaluate the performance of the proposed algorithm in the small cell deployments and shows that the proposed algorithm works well. Furthermore, we show that the combined usage of the inter-tier ICIC and intra-tier ICIC enhances the throughput performance compared to schemes employing either the inter-or intra-tier ICIC scheme.