Research On Vertical Handoff Decision Algorithm Based On User Assisted Information For Heterogeneous Wireless Networks

Seamless mobility is that the missing ingredient required dealing with theinefficient communication issues faced by the field workforces of servicecompanies. The key enabling function for achieving seamless mobility and seamlessservice continuity is seamless handoffs across heterogeneous wireless accessnetworks. As the satellite communications technology developing towardsbroadband and all-IP based, this technology trying to design integrated withterrestrial cellular networks to combine their most favorable part. A challengingissue within the integrated satellite and terrestrial network is to design intelligentand optimal vertical handoff decision algorithms. Therefore, the effective handoffmechanism with multi-attribute decision making ability is a considerable researchhotspot in the field of ISTN.All of traditional MADM algorithms are depend on set a weighting functionfor an optimal handoff target with entering the decision-making factors associatedwith the objective conditions, meanwhile are based on only signal strength, todetermine when to perform a handoff and to provide optimal choice of accessnetwork technology among all available access networks. For users of sameweighting function and candidate network, the normal algorithm can offer virtuallyidentical target network, leading to network congestion and an enhanced failureprobability of handoff and new call request. Furthermore, it will always select thenetwork with large service radius as handoff target when users have a high-speedmobility, this still resulting in the handoff performance. The objective of thedissertation is to solve the problems above; this thesis firstly proposed a novelhandoff decision methodology towards user experience and designs its module byselecting the network with the lowest user experience difference to perform handoff.This thesis adopted fuzzy logic and fuzzy inference systems to design a suitablehandoff initiation algorithm to design a module and can handle handoff request ofthe mobile terminal in high speed, also proposed a handoff decision method bycombining the speed perception with user experience and A method severally.Eventually, simulation performance verified the validity of the proposed algorithmand the preponderance in reducing the probability of handoff failure and new callblocking. In addition, the system will maintain a higher network load, whichindicates the preponderance of resource allocation among the entire network.