Research And Application Of DOA Estimation Method In Wireless Communication System

The main task of this dissertation is DOA estimation in multi-path based on cyclic correlation and high order cyclic statistics (HOCS), completed part of the main technology project supported by Ministry of Education "Location Research and Practice about Mobile Station in the Mobile Communication System". DOA(Direction-Of-Arrival) estimation sometimes called direction discerning (Direction Finding), which originated from the old source location. It studies how to confirm which direction of the receiving signal coming from. DOA estimation is widely used in the field of communication, radar, sonar, earthquake exploring, navigation and physical etc. It has been the emphasized content of communication, radar and sonar research filed all the time.In the smart antenna, in the Time Division Dual (TDD) system, the uplink and downlink have the same frequency, we can estimate the downlink beam form through uplink spatial characteristic of signal directly. But in Frequency Division Dual (FDD) system, the uplink and downlink have the different frequency, DOA estimation is the ligament of the uplink and downlink. It is the only basis that the down beam forms. Limited by the mathematics means, traditional DOA estimation methods can suppress only stationary Gaussian white noises and have no choice in eliminating Gaussian colored noise, non-Gaussian, stationary noise, furthermore the source is supposed as far field narrowband stationary Gaussian sources and independent each other. With the development of high order statistics (HOS), the methods based on HOS can allow stationary Guassian colored noise or symmetry distributing non-Guassian noise. They can enlarge the array aperture and don't need to calculate noise variance. The method based on cyclic correlation and HOCS expand suppressed noise and interference to random distributing stationary noise/interfering or stationary Guassian colored noise and circulation interference with different cyclic frequency. Through studying the theory of HOS and HOCS, we can find the advantage of using HOCS. Therefore the main mathematic method of the DOA estimation solution of the paper is HOCS. However, in multi-path situation, the signals have relevant or coherence characteristic, the method based on high-order cyclic statistics can't estimate the direction of interested source,so the multi-path solution method must be used.. The main research of the thesis focuses on the subscriber estimation in wireless communication system. The new method based on cyclic correlation was proposed and HOCS with multi-path solution method are well combined and can be used to solve the multi-path DOA estimation in Unified Linear Array (ULA) and arbitrary array. At the same time in order to make the algorithm not merely remain at the computer simulation stage, we developed the digital electronic white board. The paper is divided into seven chapters: In chapter one, the dissertation research background, communication oriented method and development and present station of DOA estimation are introduced. The basic theory knowledge of array signal processing is described in chapter two, which lay a strong foundation for the introduction of traditional method and the proposed method of the paper. In chapter three, the DOA estimation model in ULA is introduced first, then the paper give the description of traditional classical method based on correlation, HOS and HOCS. Simulation experiments and analysis are conducted in different noise environment. At last the solution methods in multi-path are given in the chapter three. Based on the study of the traditional method, two new methods: Extended Cyclic Root-MUSIC-Like method and high order cyclic linear prediction (HOCLP) method. based on HOCS in ULA are proposed in chapter four. In chapter five, a new method used in arbitrary array is proposed, which can solve the multi-path DOA estimation in stationary noise environment and enlarge the array aperture. The practical production base on DOA theory: "digital electronic white board"is introduced in chapter six.