Wireless Location Technology Research Based On TDOA And TOA In The NLOS Environment

Wireless communication technology is developing rapidly. With the development of3G and4G,people are no longer satisfied with the services of telephone and message about wirelesscommunications. In this context, wireless location technology has got widely attention. The comingof internet of things also promote the development of wireless location technology. This paperstudies algorithms based on TDOA and TOA in NLOS environments to eliminate the effect ofNLOS propagation. Paper includes the following aspects:(1)The basic cellular wireless location technologies，sources of error and related models areintroduced. Three common algorithms based on TDOA, including FANG algorithm, CHANalgorithm, Taylor series expansion are introduced. The performances of three methods are comparedby simulation. In the LOS environment CHAN algorithm has the best performance. However, In theNLOS environment, Taylor series expansion has better performance.(2)The principle, including Kalman filtering iterative method and two improved Kalmanfiltering methods, is introduced. The latter two methods eliminate NLOS error by discarding largemeasurement errors or overall curve offset. The performances of three methods are compared bysimulation. In less NLOS environment, offset algorithm has better performance. Then, in the seriousNLOS environment, drop algorithm is better.(3) In order to eliminate severe NLOS error, this paper studies three geometric centeringoptimization methods, including Chebyshev center, analytic center and improved analytic center.Improved analytic center has the best performance in any case. The distribution model ofexponential distributions is preferred by comparing.