Research Of Blind Signal Processing Technology In The RFID System

Radio Frequency Identification (RFID) is a kind of automatic identification technology at the beginning of 1990s. Blind Signal Processing technology which belongs to RFID is a research hotspot in recent years. Blind signal separation, blind equalization and blind multiuser detection are mainly studied in this paper. Blind Signal Processing technology is a signal processing method which draw or restore the original signal from receiving mixed signal within the situations that the source signal and transmission channels are unknown. Blind Signal Processing technology which involves the artificial neural network, signal processing, optimizing information theory etc earns widespread respect by research institutions in recent years.By analyzing the communication between tags and readers, the problem that aliasing signals emerge when multi-signals communicate with a single reader is pointed out in this paper. The independent component analysis (ICA) algorithm is put forward in this paper, in order to deal with the problem that the mixed signals are separated difficultly. To verify the ICA algorithm availably, simulations based on matlab simulation platform are made in this paper. Simulation results show that the relative error between the source signal and the signal which is separated through ICA algorithm. It indicates that the ICA algorithm is effective. The uncertainty in this simulation is studied as well. The conclusion indicates that the influence on tag modulation signal caused by the uncertainty of signal amplitude is acceptable. Simulation results of the research have certain reference value to the research of the reader with multi-protocol. It can also be used as a new method to solve the problem of tag collision.As the communication between the tag and reader is non-contact, the tag is interfered by other tags when it communicates with the reader. Therefore, channel equalization, inter-symbol interference and the multiple access interference of the reader's signal exit in the RFID system. The constant modulus blind equalization algorithm (CMA) is suggested in this paper to deal with inter-symbol interference. From the curve of MSE, ISI and the error rate, it can be seen that bit error rate and inter-symbol interference between the tags is reduced after the convergence of the algorithm. The aim of channels equalization is achieved as well. The multiple access interference is one of technical difficulties of multiple access technology. The traditional constant modulus algorithm for blind multiuser detection is improved and a new signal processing methods based on LS-CMA blind multiuser detection is put forward in this paper. By analyzing the matlab simulation and BER, the result shows that compared with the traditional signal processing method, the improved one has more excellent performance which include convergence speed, bit error rate and practicality.