Vertical Handover Analysis for Voice over WLAN/Cellular Network

The development of handheld mobile terminals (MT) capable of operating over both cellular networks and Wireless Local Area Networks (WLAN) is an important step towards the evolution of next-generation integrated networks. For real-time applications, maintaining a seamless connectivity and an acceptable level of quality is essential, and efficient vertical handover (VH) algorithms are required. This paper proposes an analytical framework of evaluating the performance of VH algorithms for the voice application over a WLAN/cellular inter-working environment. The performance of a generic algorithm that uses the Received Signal Strength Indicator samples to estimate the WLAN usability is evaluated for an MT roaming in and out of the WLAN coverage area under the random waypoint model. The analytical procedure is utilized in deriving the required signal strength thresholds upon which an MT bases its handover decisions, and validated through Monte Carlo simulation.