On the impact of mobility and soft vertical handoff on voice admission control in loosely coupled 3G/WLAN networks

Loose coupling between 3G and WLAN ensures flexibility and openness. However, providing an ubiquitous mobile voice service in a loosely coupled 3G/WLAN network requires both packet-level and call-level quality of service (QoS) guarantees using soft vertical handoff (SVHO) and call admission control (CAC). In this paper, we evaluate the impact of both SVHO and WLAN mobility on call blocking and dropping probabilities rederived for the integrated network. For this purpose, we propose a new multi-region mobility model that accurately estimate these probabilities under a resource-efficient dynamic threshold SVHO compared to a standard static-threshold SVHO. Results show us that the resource-efficient SVHO blocks and drops much less voice calls than the static one when very low mean and high variability of multi-mode mobile station velocities are noticed. Therefore, resource-efficient SVHO implementations are highly recommended in these mobility environments.