Innovative Performance Evaluation of Unnecessary Handoffs and Handoff Failures during Access Network Selection between WLAN and Cellular Networks

Received Signal Strength based (RSS) horizontal handoff algorithms have been most commonly used by nearly all second generation and third generation wireless networks in a homogeneous environment. Vertical handoffs or network selection algorithms are the terms coined due to integration and interoperability of existing wired and wireless access networks under the umbrella called as 4G. This work takes a thorough review of existing variations of RSS based network selection through vertical handoff between WLAN and Cellular Networks. It further presents innovative performance analysis of these algorithms in terms of number of handoffs by varying velocity of the Mobile Terminal (MT). Unnecessary handoffs results when the MT traveling at a higher velocity close to the WLAN coverage initiates a handoff to WLAN network resulting in connection breakdown and resource wastage. A handoff failure occurs when the traveling duration inside the WLAN cell is less than the handoff latency from the cellular network to the WLAN. Hence this work further suggests an innovative approach to evaluate the probability of handoff failures and unnecessary handoffs by considering radius of WLAN, velocity of MT and Handoff latencies from Cellular-WLAN.