Performance analysis of link going down threshold for Media Independent Handovers

The emerging IEEE 802.21 Media Independent Handover (MIH) is a framework proposed to support vertical handover between heterogeneous networks. The framework provides link layer intelligence and static information of nearby networks to the upper layers in order to optimize handovers between heterogeneous networks. The link layer intelligence service provided by MIH, to an MIH user results in low-latency handovers. It provides service through the MIH events, command and information. The Link Going Down (LGD) event defined in MIH helps to timely initiate the handover procedure resulting in low handover latency and low packet loss during handovers. LGD is defined as a predictive event in MIH draft. However key action lies in setting a threshold value for LGD trigger. Therefore, for proper handover, the threshold value must be fixed at an optimum value. A high threshold value will result in increase of packet loss before handover. Similarly a low threshold value will lead to unnecessary handovers. In this paper we have presented the simulation results of effect of node velocity in setting threshold value. It is seen that node velocity has effects on setting up of effective threshold value. The simulation is carried out using NIST mobility add-on for NS2 simulator developed by NIST.