Study On Time-Difference-of-Arrival-Based Wireless Location Algorithms In Cellular Networks

Cellular wireless location in mobile communication system is a useful and significant technology in future 3G. Its basic principle is to implement mobile user location through estimating characteristic parameters relative to position, including time-of-arrival, time-difference-of-arrival, angle-of-arrival, ect.First of all, the application of radio location technology to cellular subscribers in wireless mobile system is introduced and several widely used wireless location schemes are discussed.Secondly, the mathematical model of TDOA hyperbolic equations is established, two location algorithms based on time-difference-of-arrival (TDOA), Chan and Taylor algorithms, are analyzed in detail, the main technical difficulties and the approaches of improving location accuracy are also analyzed.Thirdly, the constrained weighted least squares algorithm based on TDOA is proposed. Computer simulations are conducted to evaluate the performance of the proposed TDOA-based location algorithm by comparing with the other two algorithms and CRLB. The performance of the CWLS method outperforms the other two algorithms and approaches the CRLB.Fourthly, the data fusion model proposed by Kleine-Ostmann for mobile position estimation is investigated in great detail. Based on this model, a mended data fusion model is proposed. In this model, the second and fourth data fusion obey a best linear fusion method. The fusion rule of the model is analyzed and its effectiveness to improve the location performance is demonstrated by simulation.Finally, we make conclusions for completed work and prospect for directionsof future research.