Proc. SPIE. 5084, Location Services and Navigation Technologies
KEYWORDS: Doppler effect, Satellites, Monte Carlo methods, Time metrology, Telecommunications, Wireless communications, Signal detection, Systems modeling, Standards development, Global system for mobile communications
Location-based services have been standardized for incorporation into 3rd generation wireless communications as a result of the Federal Communications Commission’s (FCC) mandate on wireless carriers to provide automatic location information (ALI) during emergency911 calls. This mandate has driven the wireless carriers to explore
terrestrial, satellite, and hybrid based location technology solutions. This paper presents a communications model that investigates the position accuracyof a Global Standard Mobile (GSM) phone employing the enhanced observed time difference (EOTD) location technology. The EOTD positioning technique requires the mobile
station (MS) to detect signals from at least three base stations (BS). This studyassumes the three BSs are synchronized in time. For a given BS geometry with respect to the MS, a Monte Carlo simulation was performed to assess the two-dimensional position accuracyof the MS in Rayleigh and Ricean fading channels. In each channel, a Monte Carlo simulation was performed for a good and a bad BS-to-MS geometry. The paper concludes with a list of pros/cons of implementing EOTD as a location technologyenabler in telematics applications.