Research Of TOA/TDOA Techniques For Position Location In Mobile Communication Network

Cellular wireless location service is a new mobile value-added service with a good market future. Its basic principle is to implement mobile user location through estimating charactistics parameters relative to position, including time-of-arrival, time-difference-of-arrival, direction-of-arrival, ect. An average people usually notice the location technology in 3G. Though TOA location method has higher accurate, it request higher to the time synchronization of mobile station and basestation also(the error of 1us will produce the location error of 300m) .Because TDOA location method meature the time diffence in which the signal arrives different basestation ,it is not to ask the accurate time synchronization between MS and BS .So we can reduce cost and still prove location accurition in some extent.In theory ,though 3Gbroad band system can improve location accurition,the location acctrition of TDOA technology is challenged because there are multiaddress interfere, far and near effection, power cotrolling .In conclusion ,at present there is not a location technology which can realize the requestion of F-911 by oneself. So, now what is being noticed broadly and lucubrated is Data Fusion technology based on multisensor and the combination location technology assistanted by sample database. In 3G, the location of cellular network location system will be realized by one or a few combination what have been introduced. The factors that affects location accurition are still multipath spread, NLOS, multiaddress, power controlling, far and near effect, the numble limit of BS and so on. First, we analyze the location service requirements and location technology in the 3G mobile communication system, propose an open location services architecture and structure model which provides end-to-end location service, and point out the design idea that location service and access network should be separated between each other, which also provides a system background for location algorithms design. then we present a TOA/TDOA data fusion model based on mathematical statistics for radiolocation in cellular network, and fuse TOA/TDOA measurement shrough a best linear fusion method and a mobile position based dynamic location algorithm, which shows good performance of robustness and accuracy. In order to improve adaptability and robustness of algorithms, we present another TOA/TDOA data fusion algorithm based on Support Vector Machine Regression for radiolocation. Then we test the capability of location estimation algorithm in distinct channel environments, the results suggest that the location precision within 125m is accessed with 70% probability by this method. At the same time, we analyze the key factors related to algorithm behavior. Then work content: Chapter one,we have introduced the background of cellular network location briefly and summed up various kinds of orient technology existingly. Among them the localization way of measure and calculating network based on TOA/TDOA have outstanding advantage and appeal because it can modify the network facility in minimum limit . So, we will study the location system of cellular network based on measuring time especially Chapter two, We discuss cellular network location system based on TOA/TDOA in an all-round way .We put forward a kind of system structure and letter way with good opening and compatibillity at first; then according to relevant documents, provide relevant measurement technology of TOA and TDOA; Because the non-eyesight-distance-spreading(NLOS) is the main source of measuring error of TOA and TDOA, the next part provides many kinds of methods of suppressing and differentiation NLOS errors. There have Wylie-Holtzman algorithm based on time sequence measuring mainly, the method of supposing and examining, weighting improved LS algorithm ,etc.. And then, according to the different designing idea of the algorithm, we divide the estimate algorithms into two big classes mainly, one is a traditional multilateral geometry model, the other is a localization model based on estimation theory. Among them, the multilateral geometry algorithm ,on condition that it is conformed with the prerequisite that 3 visual base stations limit is satisfied, has good performance . In a situation that NLOS is serious and the channel environment is changeable, the latter demonstrates very strong intelligence because of having its adaptive capacity and learning ability by oneself. But there often need channel environmental information of priori, especially suitable for the micro cellular or the room .We discuss main factor of influencing location and evaluating the designing index of location systematic function finally. Chapter three ,The method of localization based on signal arrival time can get better performance [1 ]. High-accuracy spread time delays estimates is the key to improve the radio orienting precision. The real-time time delay estimate algorithm is the prerequisite of mobile terminal location business practicality. This chapter probe into adaptive parametric multipath time difference of arrival (APMTDOA) algorithms based on least mean square error(LMS). The main content has basic APMTDOA method , method based on relevant APMTDOA. In these methods , the multipath time delay estimate method based on quadrature and cumulation...