Research On Rfid Time Delay Estimating Algorithm

Radio Frequency Identification (RFID) is a technology, which using radio waves to automatically collect relevant information, and the working of collection can be done without human's intervention, and the relevant equipment can be worked in a variety of harsh environments. The RFID location systems are wildly used in the world. RFID location systems usually use two methods to locate the object; they are Received Signal Strength Indicator (RSSI) and Time Difference of Arrival (TDOA). Estimating the delay time of arrival signal is the premise of using time difference of arrival to locate.To improve the precision of time delay estimation, this dissertation studies time delay estimation algorithm and builds time delay simulating model. The main contents are as follows:This dissertation describes the working principle of RFID location system, and the main application at home and abroad. This dissertation introduces several major wireless location technologies, and analyzes the main factors of affecting the locating accuracy.This dissertation analyzes the principles of basic correlation algorithms, and compares the basic correlation algorithms, Roth Impulse Response Processor (Roth), Phase Transform (PHAT), and Smooth Coherence Transform (SCOT). All of the four algorithms are simulated in Matlab.Using the method of least squares quadratic polynomial fitting improves the accuracy of correlation algorithm. The idea of improving time delay estimation algorithm can be divided into two steps, firstly to get the coarse data using the cross correlation algorithm, then to obtain better results with least squares quadratic polynomial fitting method.