Zone-based load balancing in two-tier heterogeneous cellular networks: a game theoretic approach

In this paper, load balancing in two-tier cellular networks is investigated. The network under-study is divided into several zones. The first tier of each zone includes a heavy-loaded Macrocell (i.e., the central cell) and its neighboring cells. The second tier includes Picocells in the area of the zone. We model the load balancing problem in each zone as a Cournot game where the optimal load distribution of each cell is the Nash Equilibrium Solution (NES) of the game. Since the actual load of each cell depends on the initial placement of users and their mobility pattern, a load balancing algorithm called Weighted Distributed Heterogeneous Zone based Load Balancing (W-DHZLB) is proposed which transfers loads between over-loaded and under-loaded cells aiming at approximating the obtained NES. In order to avoid ping-pong effect during hand-overs, inner users are given a higher priority to join a Macrocell compared to the users locating on the edge of the same Macrocell. Therefore, when loads are transferred to a Picocell, it is more likely one of the internal users of the corresponding Macrocell rather than users residing in the neighboring Macrocell. The proposed algorithm reduces the risk of epidemic unbalanced load distribution in heterogeneous networks. Simulation results show that W-DHZLB outperforms a previous load balancing algorithm in the literature.