Research On TOA Estimation And NLOS Identification In IR-UWB Positioning System

Ultra Wideband(UWB) communication technology employs very short pulses with low duty-circle to transmit data, has lots of characteristics such as high data rates, wide bandwidth and precise time resolution, etc. When UWB signal is used in system of ranging and location, the ability of location can reach the class of centimeter in theory. This thesis mainly studies the problem of UWB wireless location based on TOA with the characteristics of the UWB signal. Besides with the precision of location higher and higher, the problem of NLOS propagation is become very serious. And the problem of NLOS is studied deeply in this thesis. A method of NLOS identification is proposed based on the theory of Neyman-Pearson with the model of error in location. The main contributions of the thesis are as following:1. The basic theory of UWB is studied deeply and the IEEE802.15.4a channel is studied and the simulation results of the channel pulse response are given.2. The relative theory in location especially the method of location based on time are studied. TOA estimation algorithm based on strongest path(SP) detection by convolution is investigated,and the UWB location method is proposed based on this algorithm. Then the process of formulating is given and the simulation results show that the error of the position is less than one meter even though the range error reach 6 meters.3. The new method of NLOS identification based on theory of Neyman-Pearson is proposed after researching the model of location error and the detection theory of Neyman-Pearson. Then the method is formulated and the simulation results are given. It is demonstrated that the proposed probability of NLOS identification can achieve over 90% in certain false alarm. At last the influencing factor of the NLOS identification probability is analyzed.4. The amending factor of NLOS error is introduced on the use of the pre-information of NLOS identification to mitigate the influence of NLOS propagation during NLOS position. And the simulation indicates that the performance of positioning is improved efficaciously.