Performability Model of Vertical Handoff in Wireless Data Network

The integration of different wireless technologies is the emerging trend in providing ubiquitous access to the high data rate wireless network. In such system user will be roaming among different radio access technologies (RATs) and this is known as vertical handover/handoff. In order to understand the practical behavior of the system, the Performability model is found to be essential. In wireless network the available bandwidth (ABW) of network is divided into set of logical channels[1] and these set of channels are shared among a set of network users. The network users are divided into new users and handoff users. The handoff users are further classified into vertical handoff users and horizontal handoff users. In a wireless network, the priority is given to handoff users. In order to provide better service to the wireless users the quality of service (QoS) parameters were defined[2]. One of the QoS parameter for the wireless network is handoff dropping probability. For better QoS it is desirable to reduce the handoff dropping probability hence separate set of guard channels were reserved for handoff[3][4]. In this prevailing scenario it is highly desirable to obtain analytic performability model. The stochastic Petri net (SPN) based performability model has been developed to verify the efficiency and accuracy of analytic performability model. The results obtained from both the performability models are promising.