IEEE 802.21: Media independent handover services

The IEEE 802.21 working group (see www.ieee802.org/21) recently finalized the first standard for dealing with handovers in heterogeneous networks, also referred to as media-independent handovers (MIH). The standard is expected to allow mobile users (and operators) to take full advantage of overlapping and diverse access networks. It provides a framework for efficiently discovering networks in range and executing intelligent heterogeneous handovers, based on their respective capabilities and current link conditions. This article aims to serve as a primer for those interested in the IEEE 802.21 standard. After introducing the IEEE 802.21 reference model, we present the MIH services and provide illustrative use cases that highlight the benefits of employing the Media Independent Handover Services standard in heterogeneous networks.