Research On The Mechanism And Influencing Factors Of Radio Frequency Fingerprint Of Wireless Devices

"Radio frequency fingerprint identification" is based on the hardware characteristics of the physical layer of the wireless device to extract unique characteristics of the radio frequency to realize the identification of the wireless device.It is a method that has been widely studied in recent years to improve wireless network security.This paper mainly studies the generation mechanism and influencing factors of radio frequency fingerprint of wireless devices,and evaluates the impact of transmitter hardware damage through simulation and measured dataset.The research contents are as follows:Firstly,the structure and theoretical basic of the radio frequency fingerprint identification system are introduced.The feature extraction methods such as power spectrum feature and permutation entropy feature,feature dimensionality reduction methods and three classifiers are introduced.Then,the mechanism of radio frequency fingerprint is studied.This paper studies the transmitter devices and models the output signal after the communication signal passes through each transmitter component.On this basis,a variety of influencing factors are considered,and the radio frequency fingerprint is mathematically modeled,which lays the foundation for the subsequent radio frequency fingerprint identification research.Secondly,the influencing factors of the radio frequency fingerprint are studied,including modulation methods,digital shaping filters,the carrier frequency offset,phase offset,I/Q imbalance of the mixer,and the nonlinearity of the amplifier.The nonlinear characteristics of each influencing factor are visualized,and the distortion caused by different influencing factors on the signal are studied and evaluated by the error vector magnitude(EVM)and Euclidean distance.Finally,based on the analysis of the influencing factors of the RF fingerprint,amplifiers and mixers are selected as the key research objects.By changing the nonlinearity of the amplifier,the frequency offset and the phase offset of the mixer,the radio frequency damage is caused by the artificial introduction to simulate the hardware defects of the transmitter in the actual environment and study the impact of transmitter hardware damage on signal.A simulation dataset containing different radio frequency impairments is generated.Since different influencing factors will affect the signal waveform,and the difference in signal waveform is difficult to distinguish intuitively,the paper proposes a "damage score" evaluation model to quantitatively evaluate the influence of different influencing factors.What's more,a communication link in the actual environment is built and an actual dataset is collected to verify the evaluation model proposed in this paper and the results of simulation data sets.The experimental results show that the proposed method of artificially introducing RF impairments to study the nonlinearity of transmitter devices is feasible,and the "damage score" evaluation model proposed in this paper can accurately evaluate the influencing factors.And it is concluded that the influence of the local oscillator on the radio frequency fingerprint is stronger than that of the amplifier,and the amplifier has a certain weakening effect on the nonlinearity of the local oscillator and the filter.