NLOS error mitigation based on modified Kaiman filter for mobile location in cellular networks

Non-line-of-sight (NLOS) propagation biases Time of Arrival (TOA) and Time Difference of Arrival (TDOA). It causes the principal error for the mobile location in cellular networks. To mitigate the positioning error, a mobile positioning approach based on modified Kalman filter is proposed in this paper. With this approach, the true range is estimated based on the measurements, and the estimated range is utilized to location solution, which can reduce the impact of NLOS effectively. In our approach, the modified Kalman filter adapt its parameters with the estimate of NLOS´s standard deviation, which make the approach remain effective in different environments. Simulation results show that this approach presents a good positioning accuracy even under NLOS propagation environments. The approach can be well applicable to mobile location in cellular networks.