Research On Physical Layer Security Technology Based On Device-environment Physical Characteristics

With the commercial development of the 5th generation wireless systems(5G)and its integration in the Internet of things,vehicle road cooperation and other fields,wireless communication carries more and more user information and more important confidential information.Due to the characteristics of wireless communication broadcasting,the risk of these information being eavesdropped and interfered is greatly increased,and the problem of information security is becoming more and more prominent.Information security technology based on encryption and decryption protocol relies on computational complexity.With the exponential increase of the number of communication terminals,the complexity of key management and distribution is also increasing rapidly.Traditional information security technology is increasingly difficult to meet the current security needs in the future.Based on time division duplex orthogonal frequency division multiplexing(TDD-OFDM),this paper studies the physical layer security technology based on channel characteristics from the point of view of single user single antenna and multi-user multi antenna and build a hardware test platform to verify the feasibility of the physical layer encryption system by using universal software radio peripheral(USRP).Firstly,based on the single user key generation model of single antenna TDD-OFDM system,an improved joint phase and amplitude quantization interval design and adaptive parameter optimization algorithm are proposed.Simulation results show that the improved quantization interval design and adaptive algorithm proposed in this paper can improve the key length performance effectively.The increase of doppler frequency shift will reduce the secret key length and will enhance the secret key bit rate.The increase of pilot interpolation interval will slightly increase the key length performance.The phase information loss ratio has a great influence on the performance,which highlights the necessity of adaptive algorithm.From the simulation of the attack scenario,it can be seen that the key generation algorithm in this paper can protect confidential communication from the eavesdropping attack at the cost of BER decrease of 0.4d B,in exchange for 0.5BER performance of the eavesdropper;in the attack scenario where the power of the replay attack is the same as the power of the transmitted signal,compared with the lowpower replay attack of-10 d B,the average key length performance is reduced by nearly50%,which can be under the high power replay attack easily.Secondly,this paper studies the multi-antenna multi-user key generation model and deduces the security capacity of the system under the multi antenna model.The simulation results show that increasing the number of transmit and receive antennas at the same time can significantly improve the security capacity of the system.Based on the traditional multi antenna multi-user key generation model,this paper proposes a key generation model based on channel dimension reduction of multi antenna system.The precoding and receiving matrix based on beam space channel are designed.The key generation rate of different pilot multiplexing schemes and beam overlapping schemes are simulated and analyzed.When the number of users is 4 and the number of transmitted beam and received beam of base station is 4,the scheme of multiplexing pilot and nonoverlapping beam can obtain the highest secret key rate.Finally,this paper builds a hardware test platform by using Simulink to drive USRP equipment and verifies the single user key generation model in single antenna TDDOFDM system.This platform designs two kinds of eavesdroppers with different eavesdropping ability,the one is the decryption Eve with key generation module,the other one is the non-decryption Eve without key generation module.The test results show that the key generation algorithm proposed in this paper can significantly improve the security of the legitimate channel communication at the slight sacrifice of the BER performance of the legitimate channel.However,when the eavesdropper is close to the legitimate user,the eavesdropper can generate the same key as the legitimate user through the same key generation algorithm,and the eavesdropper can eavesdrop information of legitimate users perfectly.