Joint User Association and Interference Coordination in Heterogeneous Cellular Networks

In this letter, the user association problem in conjunction with almost blank subframe (ABSF) based interference coordination (IC) technique is considered in heterogeneous cellular networks. First, we formulate the combinatorial optimization problem as a network-wide utility maximization problem, whose solution is NP-hard. Fortunately, we reveal that the optimal ABSF density is the ratio of the number of vulnerable users and total users. Based on this relationship, the original problem is reduced to a pure optimal user association problem. Then, we propose a marginal utility based user association algorithm for the reformulated problem. Simulation results show the efficiency of our proposed scheme.