Overview on technology of vertical handover and MIH architecture

Communicate anywhere and at any time is a requirement of great importance for mobile users. Future mobile networks will consist of a set of heterogeneous systems where the user can access multiple networks at the same time and be able to enjoy a seamless transfer between multiple access network technologies. Fundamentally, the vertical handover (VHO) will be the essential part in a heterogeneous network for future generations. In this article, we propose an overview on the process, types and bases of a vertical handover. We also present a summary of the criteria for choosing a vertical handover. We focus on the description of the standard IEEE 802.21, to highlight the services and the basic functions to ensure the management of vertical handover process.