关键词: 移动终端定位, 到达时间（TOA）, 最小二乘法, 通信搜寻模型, 克拉美罗下界（CRLB）, 均方误差（MSE）

Abstract: Based on Time of Arrival（TOA） positioning algorithm, Chan algorithm in line of sight propagation environment has high positioning accuracy and faster convergence rate based on time of arrival positioning algorithm. But its function is obviously decreased in non-line of sight propagation environment. Through comparing each positioning algorithm, it uses Taylor series combined with the least square method for positioning. Then, the positioning accuracy and connection ability are introduced to improve the performance of the algorithm. Finally, the positioning accuracy is analyzed by modeling and mathematical simulation, the results show that the improved algorithm has better positioning accuracy.

Key words: mobile terminal positioning, Time of Arrival（TOA）, least-square method, communication search model, Cramer-Rao Low Bound（CRLB）, Mean Square Error（MSE）