  Two mechanisms have been proposed independently by IEEE and 3GPP; namely,
Media Independent Handover (MIH) and Access Network Discovery and Selection
Function (ANDSF), respectively. These mechanisms enable a seamless Vertical
Handover (VHO) between the different types of technologies (3GPP and non-3GPP),
such as GSM (Global System for Mobile Communication), Wireless Fidelity (Wi-
Fi), Worldwide Interoperability for Microwave Access (WiMAX), Universal Mobile
Telecommunications System (UMTS) and Long Term Evolution (LTE). In this paper,
we overview these mechanisms and show their components, benefits and drawbacks.
Then we present our Imperative Alternative MIH for Vertical Handover (I AM 4
VHO) approach based on the approaches that have been studied in the literature
with better performance (packet loss and latency), less connection failure
(probability of reject sessions), less complexity and more exhaustive for
enhancing VHO heterogeneous wireless networks environment.
