WiFi and Cell-ID based positioning - Protocols, Standards and Solutions

The localization of handset devices gains more and more importance in various fields, such as advertisement, navigation, safety and also observation and tracking. The accuracy of localization improves by the years and offers more use to mobile applications, which make use of the knowledge of a user’s position. A well-known example of the apply of localization is the E911 mandate in the USA. It demands that that the GSM network providers must be able to locate a 911-caller within a radius of 300m in network based locating solutions, and 150m in handsetassisted solutions in 95% of all cases. [1] Further, localization heritages a big potential for commercial location based services. Matching a current location, services can be provided to users. Location-Based Services are expected to generate billions of dollars in annual revenue within the next few years. [2] Generally Location Based Services (LBS) can be classified into Commercial LBS, Internal LBS, Emergency LBS and Lawful Intercept LBS [3], so they are the base of a high percentage of today’s and tomorrow’s applications and market possibilities. There are different ways how information about the location of a mobile device is generated. This paper explains the state of the art technology of WiFi and Cell-ID based positioning and describes some of its applications. The exchange of information for the positioning is realized via standardized protocols. The Secure User Plane Location Protocol (SUPL protocol) is the most common protocol in GSM networks, but can also be used over WiFi connections. Therefore this paper discusses SUPL in detail. By knowing how location data is collected and processed the reader understands how location-based solutions work. Some examples are given at the end of the paper.