Abstract In the latest semicentennial,with the rapid development of munication technology,the location-based service has e increasingly important, and there are growing demand in timeliness and accuracy,especially in military,medical and other emergency scenarios。Therefore,various location-based services have mushroomed。GPS and work based positioning systems are mon localization system。GPS with at least four satellites can achieve global location positioning in unobstructed environment。For strong sheltered indoor environment,GPS e useless。The cellular network based positioning system make the use of the time information of the base station to obtain the location of the mobile device。Generally synchronization between base stations is very poor,thus such kind of localization system will achieve very poor accuracy。 In recent years,with the rapid development of WLAN technology,WLAN devices have been widely deployment in densely populated areas,and WLAN devices is cheap and easy to deploy,so a lot of WLAN-based localization techniques have been developed。 Though many achievements have gained ,there are some drawbacks those technique had emerged,such as poor accuracy and heavy labor cost ,especially in large scale environment ,workload will be significantly increased as the scene size increases. Main content of this paper is to discuss the problems emerged in large scale environment, main content is as following: This paper first gives a brief introduction to the research background and summed up the inadequacies of some typical positioning technology and some of the advantages of WLAN-based positioning system. Then introduce two kinds of topologies in WLAN and channel characteristics in WLAN. A detailed prehensive introduction on the principals and positioning technology of WLAN positioning are also provided and then leads to the discussing on fingerprinting based technology in large scale environment. Workload and fingerprinting matching number will increase sign
