Mobile Positioning Technique Based on Timing Advance and Microcell Zone Concept for GSM Systems

Abstract

This paper aims to present an approximate location of a Mobile Station (MS) in Microcell zone concept in GSM system based on retrieving the Timing Advance (TA) from the Base Station (BS). In microcell concept, three or more zone sites are connected to a single BS and share the same radio equipment. Therefore, a MS travels within the cell uses the same frequency band assigned to the cell and served by the zone site with the strongest signal. Unlike sectoring, this method requires no additional hardware and a handoff procedure is not required at the Mobile Station Controller (MSC) when the MS travels between different zones within the same cell. The base station switches the channel to the next zone site. This algorithm is very useful for measuring the TA by the MSC while the MS is at the idle mode, since the BS can switch the channel to a different zone. By doing so and measuring the TA at each time the channel is switched to the next zone, a promising mobile positioning technique can be determined. Matlab simulation based location results and measurements statistics are also provided as MS coordinates, distances from the zone sites and the angles between the MS position and the zone site. These results using the direct solution approximated the error in calculating the distances between the MS and the zone sites to values between 100 – 133 meters.