Joint User Association and Resource Allocation for Interference Mitigation and Load Balancing in HCNs

—The deployment of Heterogeneous Cellular Networks (HCNs) can acquire high system capacity and spectrum efficiency through spatial reuse, compared with the conventional cellular networks. Nevertheless, the co-channel deployment of HCNs and ultra-high connection density bring severe downlink and uplink interference. In addition, the traditional user association schemes, which mainly take downlink power into account, may result in an imbalanced distribution of load because of the massive disparities in cell sizes in HCNs. To solve the aforementioned challenges, we present a QoS-aware user association scheme with resource allocation for load balancing and inference mitigation, which includes both uplink and downlink channels, and formulate it as a network-wide utility maximization problem. A lowcomplexity distributed algorithm is also proposed via the dual decomposition method to obtain a near-optimal solution. Numerical results demonstrate that compared with the traditional association schemes, the proposed association scheme has some significant advantages in the mass.