Investigation into the performance of EOTD for GSM users in Telematics applications

Location-based services have been standardized for incorporation into 3 generation wireless communications as a result of the Federal Communications Commission’s (FCC) mandate on wireless carriers to provide automatic location information (ALI) during emergency 911 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 accuracy of 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 study assumes 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 accuracy of 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 technology enabler in telematics applications.