Research On The Positioning Algorithm Under Single Base Station In NLOS Environment

Wireless location techniques estimate the target position through measurement results of signals from the target. Wireless location techniques are divided into two types by the number of observers:single base station positioning techniques and multi-observer positioning techniques. Compared with the location techniques using multi-observer, single base station positioning techniques need less equipment and cost. But realization of single base station positioning techniques is difficult because the information measured by the single base station is much less than the multi-observer. On the other hand, Non-Line of Sight (NLOS) propagation exists in the complicated wireless environment, which attracts the research of mitigating NLOS errors in the field of wireless location research. The maneuvering observer can achieve more information to the positioning system, which also leads to the NLOS effect becoming even worse. This dissertation focuses on the single base station positioning techniques in NLOS environment.The research of this paper is divided into two parts, the first describes the basic knowledge of wireless location and pseudo-target dynamic feasible region constraint method. The second part introduces single station positioning technology research, aiming at building an abstract algorithm model of single base station positioning, which can be applied in the NLOS environment. The proposed model is applicable to different NLOS error distribution models and different guide lines of algorithm. Then the instantiation of concrete NLOS error distribution model and optimization standard is studied in detail in the dissertation.We introduced a novel location method using single base station, which is named by pseudo-target dynamic feasible region constraint (PTDFRC) method. Algorithm models of several key problems are built. PTDFRC method regards the scatters in NLOS environment as pseudo-target, and constructs the dynamic feasible region of real target with maneuvering of the observer utilizing the information of pseudo-target. In the feasible region, the optimization methods are applied to estimate the location of real target. The key issues of PTDFRC method include feasible region construction of the real target, optimal route layout of the maneuvering observer, estimation algorithm of key parameters of NLOS models. In order to mitigate the effect of NLOS propagation impact on the positioning accuracy, base on the geometry based single-bounced circular model statistical model, a new compression and positioning algorithm of feasible region under single location in NLOS environment is proposed. The basic idea is to use smart antenna technology estimated AOA and TOA of the mobile terminal, calculate the position of the scattering object, then use the mean of arrival time to correct the region of GBSBCM model, making the feasibility region as small as possible, and then use the penalty function approach inequality constrained nonlinear least squares problem is solved for precise positioning.