A Study On Localization Theories And Algorithms For Tdma Target Using Multiple Stations

Time division multiple access (TDMA) system plays an important role in wireless communication which has the advantages of flexible of networking architecture and multi-service support.Passive location technology is widely used in modern information warfare because of its strong hidden ability and long operation distance.Based on the study of the features of the TDMA system, this dissertation investigates target location estimation algorithms and provides methods for improving the estimation accuracy. Location systems with single-sensor time of arrival (TOA), single-sensor TOA and direction of arrival (DOA), bi-sensor TOA and tri-sensor TOA are considered.This dissertation focuses on localization algorithms for moving TDMA targets, and for fixed TDMA targets in multi-sensor localization systems.The contributions of this dissertation are as follows:1. The features of the TDMA system are employed in the target location algorithms. Firstly, the TDMA system is time synchronized. The time difference between the transmission of signals at different slots is an integer multiple of the slot signal cycle. Hence, the slot signal can be considered as quasi-periodic. The synchronization of the TDMA system makes it possible for single and multiple station TOA-only target motion analysis. Secondly, the TDMA system has multiple targets which are synchronous in time. The target location accuracy can be improved by the use of multi-target synchronization.2. For the TOA-only target motion analysis (TMA) in a single-sensor system, the closed-form algorithm of range-velocity estimation is proposed which is suitable for any number of snapshots of TOAs. The estimation accuracies are analyzed for targets that move towards or away from the localization system. The forward and the backward estimation algorithms for range-velocity estimation are presented. In order to fully utilize the data information of the entire snapshot, the globally-weighted least-square range estimation algorithm is proposed which leads to an overall optimal range estimation.3. In the single-sensor TOA and DOA target motion analysis, the parametric TMA method is used in analyzing the observability condition of the target position, which deduces the theoretic analysis algorithm of location accuracy. The single-sensor location of the TDMA target can be realized using measurements of more than two target positions without the linearization of nonlinear observation equation.4. For the dual-sensor system, algorithms for the estimation of range, velocity, velocity components and position coordinates are proposed, and respective observabilities for the above target motion parameters are analyzed. In addition to the situation of target motion on the sensor axis, these algorithms can estimate the range and velocity of moving target in three-dimensional space, and make two-valued estimations of velocity components and position coordinates for two-dimensional target and then obtain two upper and lower trajectories symmetrical to the connecting line of the two sensors. The false trajectory can be excluded by the information of the region or bearing of moving target and then the target can be located.5. In the three-sensor time different of arrival (TDOA) location system, the algorithms to estimate its range, velocity, velocity components and position coordinates are presented. Unique solutions of velocity components and position coordinates of two-dimensional target can be obtained by using the TMA method. For the target moving with a constant speed in a three-dimensional space, the two-valued estimations of its velocity components and position coordinates can be obtained. Since the height of a flying target cannot be negative, the false position can be excluded.6. In the traditional TDOA localization system, if the base station position of the TDMA system is known, the target range will be calculated according to the TOA of a slot. Two kinds of joint localization algorithms of TDOA and TOA for TDMA target are proposed. Two weighed least square algorithms for multi-target ranging and locating are presented in order to improve the localization precision. For TDMA moving target, three location algorithms are proposed based on the measurements of TOA. The TMA method is used to analyze the observability condition of target position, and realize the TMA TDOA localization of moving target (TDOA-M). Two joint algorithms of conventional TDOA location (TDOA-C) and TDOA-M with TMA ranging algorithm are proposed to improve the localization precision by making full use of the target motion property. The ambiguity and non-solution problems in the traditional TDOA location algorithm are avoided in these algorithms. In contrast with the existing bearing-only TMA and multi-station TDOA localization approaches, the TOA-only TMAs of single, bi- and tri-station are lucubrated. The closed-form algorithm of range-velocity estimation and its improved algorithms are proposed. Several TDOA location algorithms of single and multi-target are realized by the use of the synchronization characteristic of the TDMA system. The results of this work are instructional for the actual passive location of the TDMA targets. Some parts of these algorithms have been applied to the actual single and multi-station location systems.