Fuzzy Logic Based Adaptive Handoff Algorithm for Heterogeneous Network

Abstract

Different handoff (HO) algorithms are currently available in cellular call transfer. All these algorithms take decision based on
Received Signal Strength Indicator (RSSI). These algorithms failed to mitigate the requirement of a heterogeneous network consisting
of Wireless Local Area Network (WLAN), Worldwide Interoperability for Microwave Access (WiMAX), Wireless Fidelity (Wi-Fi)
and General Packet Radio Service (GPRS) Networks. Because in such a network much more design issues like cell coverage area,
velocity of the Mobile Station (MS) and traffic density in WLAN are to be considered at a time. In this work an adaptive handoff
algorithm based on fuzzy logic has been simulated. Fuzzy logic is employed as it is well known for its simplicity and ability to solve
conflicting parameters. This work is focused to select a best candidate cell for handoff. Hysteresis level which is kept constant in the
conventional handoff algorithms is made adaptive with distance, velocity and traffic. A fuzzy rule base is constructed to make the
decision precise. Results show that this algorithm is able to make a distinct decision regarding the handoff- a fast moving user or a
user in long distance is always handed to GPRS (macro cell) while an immobile or slow user in the short or medium distance is able
to be connected with WLANs. Thus unnecessary handoff is neglected and the number of handoff is reduced.