Research And Performance Analysis Of UWB Positioning Algorithm On Single-base Station And Multi-base Station

In wireless positioning environment based on Ultra Wideband Radio (UWB), asa result of the integrated influence of several disadvantages including multipath、non-line-of-sight (NLOS) propagation、 interference and channel frequencycharacteristics, the measurements of the features in TDOA, TOA, AOA inevitably getsome errors, leading to the performance of all sorts of positioning algorithm droppingsignificantly. What’s worse, greater deviation of positioning estimation emerges.Centered on the core issue–improving the positioning accuracy, on the basis ofmulti-base station positioning algorithm as well as the advanced single basepositioning algorithm, this paper conduct a deep research of UWB wirelesspositioning technology from four main aspects: analysis of the multi-base stationTDOA positioning algorithm, anti-NLOS high-accuracy positioning technology,hybrid positioning algorithm, single base station positioning algorithm based onantenna array.First of all, a brief description of the definition, characteristics as well as theadvantages of IR-UWB is presented. Besides, it describes fundamentals of severalwireless positioning methods, including TOA, TDOA, AOA, etc. Also, the accuracyevaluation index and the cause of the position precision effect are presented.Secondly, this paper puts forward a Chan algorithm based on a3D model ofUWB signal positioning. IEEE802.15.4a channel of UWB model joined the smallscale fading model and extend the distance, making it practically significant to workon UWB positioning technology. In this paper, the performance of the mentionedpositioning algorithm in2-10GHz indoor office environment in4a channel isanalyzed. With the purpose of further improvement of the positioning accuracy, wefiltering the TOA value of Chan algorithm by moving average algorithm.Then, this paper proposes two positioning algorithm, namely, Minimum ErrorPositioning and Biased Kalman Filter Positioning algorithm, to reduce the effect onpositioning accuracy caused by the error of NLOS. This paper introduces thefundamentals of Minimum Error Positioning algorithm, and the Cramer-Rao lowerbound (CRLB) theoretical value of the range of measurements in TDOA accordingwith Gauss distribution. In addition, this paper performs MATLAB simulation ofMinimum Error Positioning algorithm in the environment of same quantities ofreference node as well as same propagation conditions. The simulation results show that no matter in line-of-sight (LOS) or non-line-of-sight (NLOS) cases, thepositioning accuracy of the Minimum Error Positioning algorithm is greatly improvedcompared with Chan algorithm. In order to conduct positioning estimation in non-lineof sight (NLOS) propagation case, a biased Kalman Filter positioning model is built.Simulation results show that the positioning accuracy is improved obviously with thisBiased Kalman filtering.Next, this paper analyzes the limitations of single positioning technology.Knowing that Kalman Filter has an excellent tracking performance, the paper comeup with a hybrid positioning algorithm of TDOA/AOA combined with thecharacteristics of AOA algorithm, along with the performance motion trail of thisalgorithm as well as the theoretical boundary. Simulation of the performance of thisnew algorithm presents that it provides better performance with this hybrid algorithmas long as the AOA measurement in service base station is precisely enough. A3Dpositioning system is built in laboratory to verify this hybrid algorithm, receiving aresult that the positioning accuracy is Cm level with an accuracy of1centimeter inthe best situation.At last, this paper provides a single base station UWB positioning system withhigh accuracy based on the antenna array. In this system, the amplitude of thereceived pulse signal on the antenna array of the reference base station is measuredinstead of previously measuring the tiny time differences. Combined with the beampattern of the antennas, it is easy to precisely calculate the arrival angle of the signal.Thus, it is convenient to safely obtain the accurate location of the positioning label. Inexperiment, some improvements of the ultra-wideband pulse generator are taken,resolving the severe trailing problem of the output signals. In the end, function is set up to dispel the influence that the attenuation of the signal amplitude has on thepositioning accuracy. In this way, we finally obtain a TOA positioning accuracy of2centimeters, as well as a AOA accuracy of1centigrade.