Mobile location estimation based on differences of signal attenuations for GSM systems

GSM system provides measurements regarding the signal attenuations from serving and neighboring base stations for managing radio resources. This paper proposes a mobile location estimation based on differences of downlink signal attenuations, which yield circles along which the mobile may lie. Then, the curves intersect at the estimated mobile position. The proposed method does not require a known and accurate path loss modeling, reduces the impact of shadowing on location, and is capable of being applied in existing systems without hardware development. Performance simulations include environments involving different standard deviation and cross-correlation of shadowings, and different abilities to detect base stations. Simulations demonstrate encouraging performance with only three base stations being available in severe shadowing environments. Additionally, the results of driving measurement show that the proposed method outperforms the cell-ID method in a real GSM in urban Taipei.