Example MIH Scenario
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. The application is currently using the Assured Forwarding Class 1, AF1, DiffServ service, and the Class 2 Real-Time Interactive Mobile-Fi service.
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. Also the standard specifies the MIH messages. The use of those messages in any particular application is implementation dependent. The example below is for illustrative purposes only.
1. The mobile device notices a degradation in the Mobile-Fi wireless signal strength and uses the MIH Event Notification Service to inform the MIHF layer in the mobile device. This information is passed to the MIHF in the access point.
2. The access point uses the MIH Command Service to tell the mobile device to initiate handover and includes a list of potential access points.
3. The mobile device MIHF passes this list to its various wireless layers and, using the MIH Information Service, requests them to determine the signal strength of each access point and report back to the MIHF.
4. 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.
5. DiffServ at the IP layer in the mobile device uses the Information Service to request performance information from the WiMAX access point. This request is passed through the mobile device MIHF, via the WiMAX access point MIHF, to the WiMAX access point wireless layer.
6. The WiMAX layer in the access point uses IEEE 802.16f to obtain the performance information and reports back that it can schedule the session using its Unsolicited Grant Service, UGS, with a link delay of 5 msecs, or on its Real-Time Polling Service with a link delay of 18 msecs.
7. DiffServ selects the WiMAX UGS, and uses the MIH Command Service to tell the mobile device to commit to handover. It may also use Mobile IP if a change in the mobile device IP address is required.
Read more about this topic: Media-independent Handover
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