Research Of Wireless Localization Methods In DS-CDMA System Based On Two-dimensional DOA Estimation

This thesis considers the wireless localization methods in DS-CDMA system based on two-dimensional DOA estimation. In the thesis, the geometry principle and the method of DOA-based mobile station localization are analyzed. By combining higher order cumulant with the array antenna-based DS-CDMA system, the two-dimensional DOA estimation problem in the DS-CDMA system under multi-user and multi-path is studied using uniform planar array and uniform circular array. The new estimation algorithms are proposed, which can suppress the Gaussian colored noise. The main research work of the thesis is as follows:The thesis expatiate the geometry principle of DOA-based mobile station localization and the network structure of CDMA location service. The influence factors of location precise in CDMA network are analyzed. The conventional DOA estimation models and methods are introduced from both one-dimensional estimation and two-dimensional estimation, based on uniform planar array and uniform circular array, respectively. Array geometries are analyzed.By developing the formerly proposed higher order cumulant-based VESPA algorithm to two-dimension and applying it in the array antenna DS-CDMA system, we proposed a new higher order cumulant-based two-dimensional VESPA algorithm in DS-CDMA system. Through simulation and contrast using two kind of array geometries (plane square array and three-dimensional array), this algorithm is confirmed to be able to improve the two-dimensional DOA estimation precision in multi-user and multi-path situation of DS-CDMA system, increase array aperture, and effectively suppress multiple access interference (MAI) and Gaussian colored noise.Based on the research of the method of conventional second orderstatistics-based two-dimensional DOA estimation using uniform circular array, we apply it in the array antenna DS-CDMA system. Using higher order cumulant, we propose a new higher order cumulant-based two-dimensional MUSIC algorithm using uniform circular array in DS-CDMA system. Through the simulation of the proposed algorithm, it is confirmed that the azimuth angle estimation range of uniform circle array is larger than that of plane square array. In a way, it can also improve the two-dimensional DOA estimation precision in multi-user and multi-path situation of DS-CDMA system, and effectively suppress multiple access interference (MAI) and Gaussian colored noise.This thesis is divided into six chapters, the concrete arrangement is as follows:First chapter, the introduction, elaborated the topic research background, the development history, present research situation and problems in the CDMA wireless localization and the DOA estimation.Second chapter introduced the DS-CDMA system principle, the elementary knowledge of higher order cumulant and the matrix algebra, which are the theory preparation for the algorithm proposition in the following chapter.Third chapter elaborated the geometry principle of DOA-based mobile station localization, and analyzed the influence factors of location precise in CDMA network. The conventional one-dimensional DOA estimation and two-dimensional DOA estimation models and methods are introduced.Fourth chapter proposed a new higher order cumulant-based two-dimensional VESPA algorithm in DS-CDMA system. The validity of the proposed method is confirmed through the simulation experiment;Fifth chapter proposed a new higher order cumulant-based two-dimensional MUSIC algorithm using uniform circular array in DS-CDMA system. The validityof the proposed method is confirmed through the simulation experiment.Sixth chapter summarized this thesis and pointed out the problems to be further studied.