Integration of GPS and Cellular Networks to Improve Wireless Location Performance

Wireless location is important because of the E-911 application. Both network-based solutions and GPS-based solutions have been proposed for this application. However, neither of them can handle the issues well because both approaches suffer from poor signal availability and low measurement accuracy problems in serious fading environments such as, urban canyons or inside buildings. In this paper, the poor signal availability of cellular networks is first discussed. To improve location performance, GPS and cellular networks are suggested to be used simultaneously. Three integration architectures are proposed. They are the epoch-by-epoch Least-Squares (LS)-based integration, the position domain Kalman filterbased integration, and the measurement domain Kalman filter-based integration. Simulated results demonstrate the effectiveness of these three integration schemes.