Mobility load balancing over intra-frequency heterogeneous networks using handover adaptation

Abstract

Heterogeneous Networks (HetNet) present a straightforward and effective key factor for enhancing performance of next generation cellular networks. Since outdoor macro-cells are often likely to be affected by heavy loaded situations, a major issue in HetNet planning is to ensure that small-cells actually serve enough user equipments (UE). A scenario to consider is the traffic offloading from macro-cells to small-cells. The concept of Mobility Load Balancing (MLB) which had arisen with the 3rd Generation Partnership Project (3GPP) Release 8 [1, 2] to maximize the whole capacity of the system by optimally distributing traffic among neighbouring cells, may play a key role in such a situation. In this paper, we present a review of MLB algorithms proposed in the literature and designed for HetNets by classifying these algorithms based on the UE state (i.e. UE in idle or connected mode). In fact the adopted MLB technique is closely related to the mode of the UE (idle or connected mode). We also present a technique for MLB based on optimizing handover (HO) by adapting hysteresis values based on cells’ loads.