A beacon-based handover scanning mechanism with QoS support in WiMAX FemtoCell architecture

Deploying FemtoCells in WiMAX network, also called WiMAX FemtoCell architecture, gains a lot of attention due to better indoor services can be provided and WiMAX network traffic can be shared by the FemtoCell. However, since the signal of WiMAX base station (BS) is stronger than FemtoCell Base Station (fBS), the handover procedure may not be triggered even though fBS is within the BS coverage. Besides, since the coverage of FemtoCell is small, it is possible that a huge number of fBSs are deployed in a WiMAX BS coverage, which causes a large volume of power consumption to scan all indoor fBSs for a handover. In this paper, we propose a beacon-based handover scanning mechanism with Quality of Service (QoS) support. In the proposed mechanism, through the beacon and modified MOB_NBR-ADV messages, a neighbor cell list with QoS parameters is generated automatically at mobile station (MS). The decision criteria for triggering the handover procedure and selecting an appropriate target indoor cell from many candidate fBSs are developed. Through the adoption of the proposed mechanism, the system throughput can be improved and the traffic load through the WiMAX BS can be reduced effectively. A simulation was conducted using QualNet simulator. The simulation results demonstrate that along with the number of FemtoCells increases, both the system throughput and the utilization of FemtoCells increase significantly, as compared with conventional handover mechanisms.