Study Of The Short-Range Positioning Based On IR-UWB

In February2002FCC approves UWB for commercialized use. Because of its special technical advantages, UWB has attracted wide attention, along with its research more and more. Ultra-wideband positioning technology with low emission power, low power, low cost, simple transceiver hardware structure, and high multipath resolution capability, especially to achieve centimeter-level positioning accuracy advantages in wireless location technology is very promising. In terms of intrusion alarms, supervision, command and control, logistics, and emergency search and rescue, has broad application prospects.This paper focuses on time difference of arrival measurements in UWB positioning, introduces ultra-wideband wireless communication theory, analyzes the characteristics of Gaussian pulse waveform and channels using in UWB localization, the mathematical model of wireless location parameters and positioning were studied, focuses on the high-precision time interval measurement methods, and finished UWB positioning simulation with Chan algorithm.This article analyzes the advantages and disadvantages of various wireless location technologies and theoretically proved which one is able to take full advantage of UWB technology. RSSI has no direct relationship with bandwidth; AOA is not suitable in multipath channel conditions, and it needs the antenna array which increasing the cost; the TOA method can use full advantages of UWB signals with high temporal resolution, and provides a very high positioning accuracy.In UWB positioning based on TOA, the positioning accuracy is limited by the precision of time interval measurement. The basic time measurement method is coarse counter, the accuracy is determined by frequency of the reference clock; the way to improve the accuracy of time measurement methods are time-stretch, the Vernier method, tapped delay line method. The methods to detect the UWB pulse are correlation and non-correlation. The correlation based on matched filtering(MF) can achieve good accuracy, but requires local template waveform; while non-correlation based energy detection does not require a local reference waveform and reduces sampling rate as well as complexity, but the accuracy is not limited. This thesis maintains correlating detection and sets a little frequency difference between the receiver and transmitter, so the receiver is equivalent to the Vernier time measurement model which can obtain high precision of time measurement, but sampling rate is only MHz level.Finally, we get a lot of experimental data to prove the effectiveness of the proposed method. First, the performance of the time measurement is verified by simulation; then UWB positioning has been simulated under IEEE802.15.4a channel model. In this paper, the experiment proved to achieve a high positioning accuracy which is less than20cm.