Fuzzy MADM based vertical handover algorithm for enhancing network performances

One of the most challenging topics for next generation wireless networks is vertical handoff concept since several wireless technologies are assumed to cooperate in a single heterogeneous environment. Several parameters must be considered in vertical handoff process along with traditional received signal strength (RSS) information, they are related to user preferences, terminal capabilities and QoS, such as data rate, tolerated delay. In this context, Classical Multiple Attribute Decision Making (MADM) methods, like the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) were used to make suitable handover decisions. Our approach called Fuzzy TOPSIS, is based on the combination of TOPSIS method with fuzzy logic in order to reduce the decision delays, blocking probability and the number of executed handoffs. Performance results of the proposed system are also compared with those of the classical TOPSIS method. The proposed algorithm is able to determine properly whether a handoff is necessary or not, and selects the best candidate radio access technology (RAT) considering the input parameters and fuzzy inference rules. Simulation results show an improvement of decision time by 40 % comparing to classical approach.