Study On Suppression Techniques For UHF RFID Reader Baseband Self-Interference Signal

In recent years,related products of Radio Frequency Identification(RFID)technology have been widely used in military and civilian fields such as intelligent production lines,intelligent logistics,and intelligent traffic management.Recognition distance of UHF RFID systems is easily reaching several meters,making applications of the system highly expandable.In RFID backscatter communication,due to the same frequency and simultaneous full-duplex communication mode,the receiver sensitivity of the reader is directly related to the transmitter-to-receiver isolation.The signals transmitted by readers in RFID backscatter communication are unmodulated continuous wave(CW).After down-convert to DC,the signal energy concentrated on DC portion can be removed effectively by using the capacitor.However,the phase noise carried by the CW will be converted into low-frequency amplitude noise,and it will directly affect the reader's receiving sensitivity.Decreasing the strength of the self-jammer in the receiving link of the UHF RFID reader and thus improving its receiving sensitivity and communication distance is one of the key technologies for UHF RFID system research.Cancellation scheme of self-jammer in the digital baseband domain can effectively reduce the adverse effects of carrier phase noise.Based on the self-jammer of RF carrier generated in UHF RFID system,this paper designs a digital baseband self-jammer signal suppression scheme,and analyzes,simulates and tests its performance.The main content of this article is shown as following:The principle of UHF RFID system is briefly described.By analyzing the working principle of the reader,the mechanism of the self-jammer signal in backscatter communication is introduced.Furthermore,impact to the performance of the receiver is further analyzed.A self-jammer signal suppression scheme based on adaptive filter is designed to solve self-jammer signal suppression problem.This scheme can be used in conjunction with the suppression technology of the antenna and the RF side,and can effectively suppress the residual self-jammer signal that reached the digital side,thereby improving the UHF RFID reader receiving sensitivity.A digital self-jammer signal suppression algorithm based on adaptive filter is designed to making use of the correlation between self-jammer signal and reference signal.Its theoretical suppression effect is analyzed and calculated.This paper simulates and tests self-jammer signal strength,performance of digital suppression scheme and its influencing factors under different parameters by constructing signals in UHF RFID receiver.