The future wireless communication systems require an intelligent and service adaptive network selection to perform vertical handover (HO) in heterogeneous environments. Since multiple parameters are considered to select the best suitable network, reducing the complexity in multi-attribute decision making algorithm becomes apparent. In the proposed scheme, fuzzy logic controllers are used to estimate the necessity of HO and to determine the user satisfaction degree based on the critical parameters, such as mobile terminal speed, network load and service cost. Fuzzy analytic hierarchy process is used to calculate the weights of each attribute according to the traffic. Since it handles the uncertainty and vagueness in mapping the user preference to the priority scales, consistency level of network selection can be improved. Quality of service factor is calculated for each network by processing the weighted decision matrix using principal component analysis. Simulation results show that proposed scheme can ensure the best network selection by providing trade-off between complexity and consistency.

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Next generation wireless networks are expected to include heterogeneous wireless networks to offer a diverse range of multimedia services to mobile users. Due to the heterogeneity and the diversity of access networks, various user applications with different Quality of Service (QoS) requirements pose new challenges on multi-interface Mobile Terminal (MT) in designing optimal network selection algorithm for guaranteeing seamless QoS support to the users. Thus, vertical hand off (VHO) is necessary to provide uninterrupted services to mobile users anywhere and anytime in 4G Networks. In this paper, a Modified Weight Function based Network Selection Algorithm (MWF-NSA) that considers user preference and application profile is proposed. It considers the characteristics of both network conditions and connection performance in deciding the weight functions of the network parameters in order to reflect the importance of each metric in network selection algorithm. Our Matlab simulation results show that the proposed algorithm selects the best suitable network among UMTS, WiMAX and WLAN networks, while achieving balance between user preference and QoS requirements of running applications.