Wireless Positioning: Fundamentals, Systems and State of the Art Signal Processing Techniques

Abstract

With the astonishing growth of wireless technologies, the requirement of providing universal location services by wireless technologies is growing. The process of obtaining a terminal’s location by exploiting wireless network infrastructure and utilizing wireless communication technologies is called wireless positioning (Rappaport, 1996). Location information can be used to enhance public safety and revolutionary products and services. In 1996, the U.S. federal communications commission (FCC) passed a mandate requiring wireless service providers to provide the location of a wireless 911 caller to the nearest public safety answering point (PSAP) (Zagami et al., 1998). The wireless E911 program is divided into two partsPhase I and Phase II, carriers were required to report the phone number of the wireless E911 caller and the location (Reed, 1998). The accuracy demands of Phase II are rather stringent. Separate accuracy requirements were set forth for network-based and handset-based technologies: For networkbased solution: within 100m for 67% of calls, and within 300m for 95% of the calls. For handset-based solutions: within 50m for 67% of calls and within 150m for 95% of calls. Now E911 is widely used in U.S. for providing national security, publish safety and personal emergency location service. Wireless positioning has also been found useful for other applications, such as mobility management, security, asset tracking, intelligent transportation system, radio resource management, etc. As far as the mobile industry is concerned, location based service (LBS) is of utmost importance as it is the key feature that differentiates a mobile device from traditional fixed devices (Vaughan-Nichols, 2009). With this in mind, telecommunications, devices, and software companies throughout the world have invested large amounts of money in developing technologies and acquiring businesses that would let them provide LBS. Numerous companies-such as Garmin, Magellan, and TomTom international-sell dedicated GPS devices, principally for navigation. Several manufacturesincluding Nokia and Research in Motion-sell mobile phones that provide LBS. Google’s My Location service for mobile devices, currently in beta, uses the company’s database of cell tower positions to triangulate locations and helps point out the current location on Google map. Various chip makers manufacture processors that provide devices with LBS functionality. These companies’ products and services work together to provide location-based services, as Fig. 1. Shows (Vaughan-Nichols, 2009).