Research On Anti-interference Strategy Of UHF RFID System

The UHF RFID system has the advantage of farther identification distance, faster data rate etc, which make it be the current focus of application and research. However, the interference from the real application environment increases the bit error rate (BER), reduce the identification rate and space of the UHF RFID system, and makes it fail to satisfy the capability requirement of the internet of things. So the research on anti-interference strategy of UHF RFID system has great theoretical significance and practical value. In this paper, we chose the UHF RFID system as study object, and classified and analyzed the interference, based on which corresponding anti-interference strategy was put forward.First, the interference to UHF RFID system was analyzed detailedly. According to the occur principle, interference was divided into four categories, security and privacy, multipath interference, collision interference and the interference from ISM device. Besides, the anti-interference method in existence was researched.Second, the hash lock-based strengthen synchronization RFID authentication protocol was put forward for the security and pricacy problem of UHF RFID system. The RFID authentication protocol based on one-way hash lock and key updating mechanism realized two-way authentication and dynamic key update. Furthermore, the protocol satisfied the anti-desynchronization requestment by adding anti-desynchronization key K p into the database. Analysis and simulation shows that the new scheme realizes the requestment of anti-information leakage, intractability and synchronization with a low computer load.Third, the constant modulus algorithm(CMA)as one of Bussgang blind equalization algorithm was introduced into UHF RFID systems to solve multipath interference problem. The constant modulus algorithm is low in computational load, fit for real-time signal processing, fast in convergence rate and the cost function is just relared with the amplitude of received signal not its phase, which adapt it to the UHF RFID system. Computer simulation illustrates that constant modulus blind equalization algorithm can reduce the BER of UHF RFID system effectively.Finally, we put forward three RFID reader anti-collision algorithms, namely the RFID anti-collision algorithm based on distributed power control, the anti-collision algorithm based on neural network graph coloring and the anti-collision algorithm based on simulated annealing Q-learning. These algorithms are based on space division multiple access(SDMA), time division multiple access(TDMA)and frequency division multiple access(FDMA)separately, so these algorithm can apply flexiblely to diverse occasion.The protocol and algorithms given forms an integrated anti-interference strategy, solves the problem that interference deteriorate system performance. By different combinations, these algorithms are extremely flexible in practical applications.