The importance of MIH derives from the fact that a diverse range of broadband wireless access technologies is available and in course of development, including GSM, UMTS, CDMA2000, WiMAX, Mobile-Fi and WPANs.
Mobile devices and access points clearly need to implement MIHF in order to communicate in a standard way between each other and between the wireless and IP layers.
Such servers allow a wireless network operator to balance the traffic load so as to alleviate congestion on specific access points, and deliver sufficient QoS to all users.
Before a handover is required, the MIHFs communicate to identify which access points using which wireless technologies are within range and what QoS is available from them.
MIH can also be used to pre-authenticate the mobile device with alternative potential access points and to reserve capacity prior to handover.
Some technologies divide traffic into “Service Classes”, e.g. streaming, while others allow users to specify quantitative “QoS Parameters”, e.g. transfer delay.
MIH can be used to exchange information about service class and QoS parameter availability from one wireless technology to another and to the IP layer.
To illustrate the operation of MIH, let us take an example of a real-time gaming application, using DiffServ at the IP layer, being handed over from Mobile-Fi to WiMAX.
Since the MIH standard is not yet finalized, this example is illustrative of the type of functionality that may be provided, as opposed to a firm guarantee of what will become available.
The MIHF in the mobile device determines that the best signal strength comes from a WiMAX access point, and passes that information to its IP layer, using the Event Notification Service.
DiffServ selects the WiMAX UGS, and uses the MIH Command Service to tell the mobile device to commit to handover.
It was originally developed by an independent industry consortium and was incorporated into the 3GPP standards in 2005 under the name GAN (Generic Access Network).
David J Wright; Maintaining QoS During Handover Among Multiple Wireless Access Technologies, International Conference on Mobile Commerce, Toronto, July 2007.
Al Mosawi, T.; Wisely, D.; Aghvami, H.; A Novel Micro Mobility Solution Based on Media Independent Handover and SIP, Vehicular Technology Conference, 2006.