A Time-Threshold-Based Priority Hopping Scheme for Vertical Handoff in Cellular/WLAN Interworking

This paper proposes a novel Time-threshold-based Priority Hopping Scheme (TPHS) for vertical handoff in WLAN-embedded cellular networks. In order to further improve the Upward Vertical Handoff (UVH) call dropping probabilities and newly blocking probability of cellular calls, proposed scheme designs a newly priority hopping scheme by adjusting priority of prioritized UVH calls in different circumstances and revising Downward Vertical Handoff (DVH) decision algorithm of cellular ongoing voice calls to modify the Time-threshold-based Upward Priority Scheme (TUPS). Simulation results show that the proposed scheme remarkably improves the UVH call dropping probabilities and newly cellular call blocking probability at the cost of slight sacrificing quality of service (QoS) of insensitive voice calls in cellular zone while ensuring high cellular bandwidth utilization compared with TUPS. The proposed scheme can offer preferable QoS than TUPS in WLAN-embedded cellular networks.