Research On Secret Key Generation Based On The Physical Layer Characteristics Of Multi-Antenna Channel

With the development of wireless communications,it is of great value to ensure the security of wireless communications.Compared to wired networks,the openness and instability of wireless networks make them more vulnerable.At the same time,the traditional key distribution scheme is not suitable for wireless communication due to the limitation of the mobility,computing ability,endurance and storage space of the wireless network terminal.The technology of key extraction based on the characteristics of wireless channel physical layer has the features of low computational complexity and high security.However,most of the techniques have the problems of low efficiency,low key generation rate and lack of experiments.Multi-antenna system can provide more randomness and improve the key generation efficiency.Therefore,this paper studies the key extraction technology based on the characteristics of multi-antenna channel and proposes channel frequency response calibration(CFRC)algorithm to improve the key agreement.Finally,this paper verifies the algorithm in the actual measurement environment.The innovative achievements of the thesis include:1.We design and implemented a secret key generation system based on the physical layer characteristics of single-antenna channel in OFDM system.The simulation result shows that the mean square error(MSE)of channel state information(CSI)measured by this system is 3.4 × 10-4 and the key generation rate(KGR)is 656bit/packet.2.In order to improve the efficiency of key generation,this paper designs secret key generation system based on the physical layer characteristics of multi-antenna channel in OFDM system.Based on the research of single-antenna key extraction system,the 1 × 2 single input multiple output key extraction system is designed.The simulation result shows that the KGR of Multi-antenna key generation system is doubled to that of single-antenna key extraction system.3.To solve the problem of low key generation rate,the reciprocity enhancement scheme of the wireless channel is studied.The CFRC preprocessing algorithm is put forward to eliminate the deviations of hardware devices.Furthermore,the pre-processing method based on principal component analysis(PCA)is used to reduce the redundancy of the channel measurements.The results show that the MSE of CSI decreases about 36%in simulation and 75%in the measured environment after PCA preprocessing.4.In view of the lack of the experiment in real environment,a multi-antenna key extraction system is built to analyze the performance of CFRC.The experimental results show that the CFRC makes the cross-correlation coefficient of the two CSIs reaching 0.9895 in the multi-antenna key extraction system,which is 41.4%higher than the traditional single-antenna key extraction scheme without CFRC.In addition,the KGR of CFRK preprocessed multi-antenna key extraction system is about 1.5 times that of the original single-antenna key extraction system.The average KGR increases by 5 times compared with theexisting key extraction scheme using channel gain compensation(CGC)preprocessing.