Algorithm Research Of Location Based Service For Mobile Phone Based On Cellular Network

The rapid growth of the mobile communication technology makes people have more demand for location-based services. Location technologies become a very hot research topic among experts and scholars, and the network-based positioning technology develops rapidly. Comparing kinds of algorithms, research results indicate that the location method TDOA can be applied to various types of cellular systems, and it can get high positioning accuracy. One reason is that TDOA requires no strict time synchronization between the mobile station and base station. On the other hand this method can take advantage of existing communications network resources to research wireless location technology, so it may reduce application cost greatly and be more convenient to turn towards the market, the mobile users can enjoy location-based services more comfortably.The main content of this paper is using genetic algorithms to solve nonlinear optimization problems which encountered in estimating the TDOA Location. In order to calculate position coordinates accurately and efficiently, basing on the method TDOA, we propose the hybrid genetic algorithm combined with steepest descent method (HGACSDM). The main work of this thesis is as follows:(1) This paper describes several wireless cellular network positioning methods, evaluation indicators and the channel models.(2) The mathematical model of TDOA is represented, and the hyperbolic equations are established. Three major algorithms based TDOA are analyzed in detail.(3) According to the advantages and disadvantages of the Chan algorithm, analyze and localization algorithm. A hybrid algorithm that combines Chan with HGACSDM is proposed. The simulation result shows its location accuracy is improving.(4) A signal strength weighted average method is using, and tested on the actual phone software development platform.