A distributed muting adaptation solution for a QoS-aware user association and load balancing in HetNets

In Heterogeneous Networks (HetNets), Almost Blank Subframe (ABS) can provide interference free communication to the Cell Range Expansion (CRE) area users. Although the CRE technique is simple and guarantees a better offloading, it might not be the best way for balancing the load. In this paper, we investigate the joint optimization of the user association and the ABS ratio computation. We propose a load-aware and QoS-aware user association that jointly considers the load of each BS and the users' required data rates. Our problem is a combinatorial NP-hard one. The existence of an optimal ABS ratio is proved by simulation. Hence, we choose to discover the candidate ABS ratios iteratively in order to reach this optimal value that minimizes the system blocking. Heuristic distributed and semi-distributed algorithms are proposed for user association and load balancing in two-tier HetNets.