The Design and Implementation of a Dual-Channel Location Estimation System for providing Location Services in Metropolitan Areas

A dual channel system, which is based on the GPS and the GSM Network, is being developed to compensate the problem of the lost of GPS signals in providing location services to mobile users in metropolitan areas. It is well-known that GPS can provide accurate location estimation in a range of 5-15 meters. But it is also a known fact that GPS does not perform well in urban areas like downtown New York and cities like Hong Kong. In our design, when GPS signals are being blocked in blind spot areas, GSM positioning algorithms would be used as an alternative method to provide location estimations for the location based services. This paper is a report of our investigation in search of a set of location estimation algorithms based on signal attenuation from the base-stations of the GSM network, and our research on an algorithm/channel selector to integrate the GSM and GPS together, so as to develop a dual channel positioning system for providing continuous support for location estimation in metropolitan areas. With the technical support from a local mobile operator, we have constructed and conducted several real world experiments for our investigation and results are promising.