Predictive Reservation for Handover Optimization in Two-Tier Heterogeneous Cellular Networks

The mobile network operators seek ways to increase their capacity and coverage in order to be able to deliver high quality services even under surging mobile broadband demand. The deployment of femtocells is the most efficient, economical and technically feasible approach to achieve this goal. However, a two-layered femtocell/macrocell heterogeneous networks where users can handover from a femtocell to the overlaid macrocell requires innovative traffic management techniques. While call handover from a femtocell to a macrocell can be easily implemented based on already known procedures, on the other hand, the handover towards a femtocell is more challenging. More specifically, due to the limited bandwidth available at each femtocell, it is not spectrally efficient to use a typical guard channel scheme in order to prioritize handover calls over new calls. Therefore, in this paper we introduce a dynamic pre-reservation scheme, which is based on the predictive channel reservation concept and adjusts dynamically the reserved resources. We show both analytically and by simulation that the proposed scheme can be efficiently applied to a two-layered femtocell/macrocell heterogeneous mobile network.