Research On Indoor And Outdoor Seamless Positioning Technology Based On CMMB And WiFi

In recent years, seamless positioning technology has been widely developed in social life.Its application involves security service, location management, and navigation etc. It is greatsignificant to meet the demand of mobile users’ global positioning navigation and thedevelopment of the navigation and positioning technology. OFDM modulation technology isadopted in mobile broadcasting signal, and it is able to weaken the multipath effect effectively,and have a good ranging accuracy of time synchronization. WiFi technology has manyadvantages such as high speed in transmitting information, high positioning accuracy and lowcost. The indoor and outdoor seamless positioning can be achieved by combining theadvantages of CMMB and WiFi. In this paper, the indoor and outdoor seamless positioningtechnology is studied, and the main works of three aspects is as follows.Firstly, the theoretical knowledge related to WiFi, CMMB and TDOA are introduced,including the indoor positioning principle and positioning method based on WiFi positioningtechnology, the outdoor channel transmission model based on CMMB positioning technology,and basic localization algorithm based on TDOA location model. A fusion location algorithmof TOA/TDOA based on CMMB is proposed. It makes use of centroid method to twoestimations of TOA by improved Taylor algorithm and a estimation of TDOA by Chanalgorithm, and gets the final positioning estimation. The simulation results show that thealgorithm can improve the positioning accuracy and restrain the NLOS error effectively,besides, it is simple easy for implementation of project.Secondly, the WiFi radio propagation path loss model is analyzed in this paper, mainlyincluding the free space propagation model, logarithm normal distribution model andsimplified model. A regional decision method of seamless positioning area is proposed,which is based on WiFi received signal strength. The central part of this method lies inestablishing a function based on path loss factor, then confirms the mobile station’s areaunder any environment and chooses a proper algorithm to locate effectively.Finally, the implementation of seamless positioning scheme and the key technology oflocation for indoor and outdoor seamless interaction area are analyzed. A seamless fusionpositioning algorithm between CMMB and WiFi is proposed in this paper. This algorithmintegrates the observation data of TDOA in CMMB and the measurement of RSSI in WiFi,then gets a estimation for the mobile station under the interaction area. A lot of simulationsare carried on in this paper, and the simulation results show that the algorithm can locatewhen the target lies in indoor and outdoor interactive area. Besides, the fusion algorithm canget a better localization accuracy than a single positioning technology.