Research Of Handover Algorithm Based On Fuzzy Logic Control For Seamless Navigation System

With the increasing demand for Location-Based Services (LBS), the issue of“seamless navigation” between indoor and outdoor has been paid more attention. Aswell-known, Global Positioning System (GPS) has provided position accuratelyoutdoor, but has the weak signals for indoor environment. Of course, a lot oftechnologies to solve this problem have emerged, such as High-Sensitivity GPS(HSGPS) technology by specific algorithms of acquiring and tracking for GPS weaksignals. However until recently, Wireless Local Area Network (WLAN) still hasbeen the most developed and accurate indoor positioning system. Therefore thevertical handover between the two different positioning systems has been thepivotal issue for seamless navigation.Firstly, this paper introduces the positioning principles and algorithms, and theanalysis of Dilution of Precision (DOP) of GPS, and then describes the WLANindoor positioning technology and its methods. After that, the WLAN signalscoverage model indoor is obtained, through the analysis for the rules of radiopropagation. Furthermore, the main technical specifications of WLAN architectureare briefly demonstrated for realization.Secondly, the main concepts and points of handover in wirelesscommunication have been presented. This paper utilizes appropriately the fuzzylogic theory and the idea of cost function with simple additive weighting methodfrom existing algorithms of wireless communication.Given the coverage of GPS and the estimation of indoor channel, this paperproposes a vertical handover algorithm based on fuzzy additive weighting methodfor seamless navigation. The simulation results clearly show the differentpositioning areas using GPS or WLAN, under different handover strategies andvalues of various parameters respectively. Proved by the simulation, the verticalhandover between different positioning systems for seamless navigation could berealized with the proposed algorithm.At last, the issue of deployment of APs for seamless LBS is discussed, basedon the existed APs deployment strategy for WLAN indoor positioning system. Thedifference between two circumstances mainly exists in the coverage of APs to be considered. Therefore according to the improved APs deployment strategyconsidering the handover issue, the number and position of APs for optimization areobtained.