Rapid growth of demand for various wireless communication services has led the industry and the researches to investigate on a new generation of telecommunication systems .One of the main objectives in designing and developing these systems is to provide the mobile user with a robust connection to different networks so that the users can move freely between heterogeneous networks while running their computing applications. Handoff is a process, which maintains a mobile user’s active connection as it moves within wireless networks and vertical handoff considers handoff between different types of networks or otherwise stated between different network layers
