Vertical Handover Decision Policy Based on the End User´s Perceived Quality of Service

The integration of heterogeneous wireless networks allows the users to benefit simultaneously from these radio access technology (RAT) and they can also use an important number of applications. New applications constraints are more complex and may be change dynamically and rapidly under time. The handover mechanism is responsible to guarantee the required quality of service when users roam across different RAT in order to provide an ubiquitous environment. With the diversification of the context metrics allowed by these networks, the level of computationally and complexity has a direct impact on the perceived quality of service especially of the network selection process on application performance. The present work addresses the network selection process, which is probably the most important key of the vertical handover decision mechanism. It proposes a modification of the Simple Additive Weighting called Enhanced-Simple Additive Weighting (E-SAW) for ranking networks that avoid computational cheaper by eliminating network access which does not satisfy a minimum required context. After ranking, in order to avoid bad network selection which does not respond to user requirement, we define handover decision scheme that improves network performances perceived by end users and avoid the processing delay caused by unnecessary handover.