Performance of fast cell selection in two-tier OFDMA networks with small cells

If large amount of small cells, i.e., femtocells, picocells or microcells, is deployed, users perform handover among small cells and macrocells very often. In OFDMA networks, only hard handover is usually supported as this type can be implemented easily. On the other hand, frequent hard handover negatively influence a quality of service experienced by users. The degradation of the quality is a consequence of a short interruption in communication during hard handover and due to redundant overhead generated for controlling and managing the handover procedure. This paper investigates performance of a fast cell selection applied in two-tier networks with small cells and compares it with the hard handover. We focus on the impact of a backhaul capacity limitation on the performance of both hard handover and fast cell selection. As our results indicate, there is a gain in throughput introduced by the fast cell selection if the backhaul of the small cells is not a bottleneck in term of capacity. Nevertheless, if the backhaul capacity is limited, the fast cell selection is profitable only for low bitrates. This observation indicates a need for mandatory consideration of the backhaul capacity for the fast cell selection in the networks with small cells.