MCDM-based Network Access Technology Selection in Heterogeneous Wireless Networks

This thesis aims to provide a seamless mobility approach for users' equipment (UEs) in heterogeneous wireless networks (HWN). With overlapping coverage, UEs now have multiple wireless access networks of different types. To efficiently use these networks, the UE needs to choose the best network for each application and achieve Always Best Connected (ABC) services. This dissertation proposes the UP-MCDM-NS scheme, a user preference-based multi-criteria decision-making method for network selection. It combines fuzzy analytic hierarchy process (FAHP) and TOPSIS to weigh network attributes and calculate scores. User preferences are also considered, and a threshold mechanism is used to reduce unnecessary handovers. The proposed UP-MCDM-NS scheme is evaluated through extensive simulations, which demonstrate its effectiveness in enabling UEs to select the best network while decreasing the number of handovers and unnecessary network switches. The results highlight the scheme's ability to improve the user experience by providing a seamless and efficient network selection process.

In addition to addressing network selection challenges, this thesis also tackles the Rank Reversal Phenomenon (RRP) that occurs in candidate networks. To overcome this issue, a unique hybrid Multi-Criteria Decision Making (MCDM) method is proposed, which combines the Simple Additive Weighting (SAW) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) techniques. This combined approach enhances the efficiency of handovers and reduces the occurrence of RRP. User preferences for networking choices and QoE are also taken into account.

The proposed hybrid MCDM method is also evaluated through extensive simulations, which demonstrate its superiority in terms of handover efficiency and rank reversal reduction compared to existing approaches. The results highlight the method's ability to enable UEs to choose the optimal network interface while decreasing unnecessary handovers and maintaining a high level of service quality.