Research And Implementation On Key Technologies Of Physical Layer Security Based On Channel Characteristics

Due to the open nature of the channel,wireless communications are vulnerable to eavesdropping and deception attacks.However,traditional authentication and encryption schemes,often built on a network protocol stack,encounter challenges in the face of increasing quantum computing power and emerging business scenarios such as largescale machine connectivity.For this problem,based on the natural randomness and uniqueness of the wireless channel,this thesis studies the lightweight and reliable physical layer authentication and encryption technology as a supplement to the traditional security scheme.The main work of this paper includes:The thesis studies three channel-based physical layer authentication algorithms under single-hop network.In a typical communication system based on multi-carrier,channel frequency response has strong randomness,large amount of data and is easy to extract,so it is selected as the basic channel characteristics.Firstly,the classical authentication scheme based on likelihood ratio test is studied.Considering that its performance is easily affected by the speed of channel change,the relatively stable multipath delay is introduced as the second channel characteristic,and the joint authentication scheme based on two-dimensional channel quantization is studied.Taking into account the limitations of channel characteristics,the thesis extracts the carrier frequency offset as the characteristics of the sender's equipment,and constructs the joint test statistics together with the channel frequency response to achieve joint authentication of channel and device.Digital simulation and analysis verify that with the introduction of multi-dimensional features,the performance of joint authentication can be improved and guaranteed.The thesis studies the channel-based physical layer authentication algorithm under dual-hop network and its power allocation optimization scheme.Firstly,the likelihood ratio test is extended to the dual-hop network,but its theoretical expressions for constant false alarm threshold and detection probability cannot be deduced.In order to solve this problem,the thesis adopts the method of majority voting to simplify the authentication decision rules,and deduces and analyzes the theoretical performance of the simplified system.By quantifying the upper bound for the sum of FAR and MDR,the thesis proposes an optimal power allocation which takes advantage of the difference in noise power between the relay and the receiver to jointly adjust the transmit power,so as to improve the authentication performance on condition of fixed total power.The thesis studies the channel-based key generation and designs a lightweight encryption scheme.Starting from the general process of the key generation mechanism,the thesis studies the classical algorithms in channel detection,preprocessing,quantization and agreement,carring out simulation and comparative analysis under typical channel conditions.Analysis shows that the effective path extraction and wavelet transform reconstruction can effectively reduce the influence of noise on the initial key inconsistency rate;As for the quantization algorithm,the equal-probability quantization does not need feedback,and the generated key has strong randomness,so it is more practical;In the selection of agreement scheme,the scheme based on error-correction code can reduce the inconsistency rate with less information interaction times,which is easy to implement in engineering.Starting from the general process of the key generation mechanism,the thesis studies the classical algorithms in channel detection,preprocessing,quantization and agreement.A secure communication system including physical layer authentication and encryption is implemented based on the software radio platform USRP.For key modules such as the construction of the test platform,system link design,identity authentication and key generation.,the thesis gives specific implementation schemes,and tests each module in a simulated channel and a real wireless environment.The test results show that the authentication and encryption mechanism based on channel characteristics can effectively resist the attack of eavesdropping and spoofing.