Handover mechanisms in next generation heterogeneous wireless ...

MULTI-INTERFACE MOBILE MODEL FOR MEDIA INDEPENDENT HANDOVER
ADF is set to be 3 times the ADI. The setting means that the MH is allowed to miss
three consecutive advertisements before the attachment with the current agent is
regarded as being invalid by the MH. The AP that the MH attaches to is referred to as
the old AP, in contrast to the new AP that the MH would switch to in a handover. The
ADI of the old AP is fixed to 1s. The ADI of the new AP was varied in the simulation,
and thus the ratio of ADI old _ AP to ADI new _ AP may change accordingly. When the cross-layer
trigger of Figure 7.2) is enabled through the HOMgr, the handover delay can keep a
constant value at around 40ms as illustrated Figure 7.11. However, when the cross-layer
trigger is not applied, the handover delay fluctuates at 3s. The corresponding results can
be found in Figure 7.12. In both cases, the handover delay appears not to be influenced
by the difference of the ADI between heterogeneous wireless networks. The
introduction of the cross-layer trigger mechanism in the proposed multi-interface model
can effectively reduce handover delay down to 40ms.
Figure 7.11 Heterogeneity of ADI vs. Handover delay (with cross-layer trigger
mechanism)
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