Abstract: With technological advances in the telecommunications
sector, everyone around the world would like to be connected seamlessly anytime
anywhere through the best network. Making a transition from one network to
another and moving between heterogeneous networks is not the only problem that
worried specialists, scientific and mobile operators; the concern of QoS is as important as the handoff, The requirements like
capability of the network, network conditions, handoff latency, power
consumption, network cost, and user preferences must be taken into
consideration during vertical handoff. Importance of inter working between
architecture requires adaptive approaches to implement the vertical handoff
mechanism in 4G wireless networks and produce an effective service for the user
by considering handover parameters.
this paper, we analyzed the main approaches for vertical handoff to offer a
systematic comparison for new researchers. The survey revealed the need for new
approach which satisfy the most important requirements and reduce the HO
failure probability and the number of unnecessary handover.
Keywords: Wireless networks; 4G; vertical handoff, horizontal handoff, QOS (Quality of Service), Next Generation Network (NGN).