Interference Mitigation and Dynamic User Association for Load Balancing in Heterogeneous Networks

Viewing the communication system as three-dimensional (3-D) with various tiers cooperating among each other is a new trend to present 5G heterogeneous networks (HetNets). Base stations (BS) in each tier operate with different power levels, access methods, and unique topologies. A proper user (UE) association algorithm for HetNets is a great challenge. We develop a new real-time dynamic user (UE) association algorithm for multi-tier cooperating systems that considers users' mobility and traffic dynamics considering both overall network load and received signal to interference and noise ratio (SINR). Despite that our proposed UE association algorithm does not depend on an interference mitigation algorithm to improve its performance, we develop a location-based interference mitigation algorithm to mitigate co-tier and cross-tier interferences in the worst case scenario of spectrum sharing among various tier BSs to overcome some of the drawbacks of spectrum partitioning algorithms. Our new algorithms are studied and analyzed through simulation and they are proved to provide the best performance compared to other algorithms.