A novel vertical handover scheme for integrated WLAN and cellular wireless networks

The integration of wireless local area network (WLAN) and cellular wireless network is capable of providing ubiquitous data service, ranging from low to high speed in strategic locations. The commercial benefit of using WLAN in hot spots to relieve congestion in a cellular network is another motivation for the integration. For the integrated WLAN and cellular network, this paper proposes a novel vertical handover scheme to achieve better system utilization without compromising the quality of service (QoS) in terms of packet delay violation ratio. The handover scheme suggests performing an unconditional handover from WLAN to cellular network as long as it is needed. On the other hand, the handover from cellular network to WLAN will be conditional and depending on user's traveling speed and cellular network's load. The proposed handover scheme has been evaluated using OPNET random event simulator. Simulation results show that, given a target user violation ratio, the proposed scheme can support a larger user arrival rate without compromising packet delay violation ratio. Also, the results show that the proposed scheme can reduce the number of toggling at the heterogeneous network boundary by 10% while maintaining the same user arrival rate.