Research And Implementation Of Key Generation Technology Based On Physical Layer In Wireless Communication System

In the era of rapid communications development,wireless networks are widely found in individuals or public areas.However,due to the natural broadcast characteristics of wireless networks,the security issues become more and more important.To deal with security problems in wireless communication systems,the traditional classical encryption and security methods are facing many challenges.Key generation technologies that exploit the natural random nature of wireless channels from the physical layer have received widespread attention.Physical layer key-based security at the physical layer is a lightweight key generation.For the future D2 D communication mode,it is conducive to the future trend that the terminal equipment,especially the mobile terminal,will be faster,smaller and more convenient.As MIMO and OFDM technologies are key technologies for future 5G,key generation technologies based on MIMO-OFDM systems are worthy of attention and research.This thesis first designs a key generation scheme based on MIMO-OFDM system.The scheme includes processes such as channel detection,normalization processing,smoothing filter processing to reduce noise,equal quantization enhancement key security,information reconciliation technique based on BCH code,exploit double hash function to generate confirmation information and privacy amplification.Secondly,this thesis proposes a key generation scheme combining unconditional secure transmission mode from the perspective of physical layer security for passive eavesdropping attack scenarios.And the unconditional secure transmission mode is mainly used in the information reconciliation phase.The unconditional transmission mode can effectively target passive eavesdropping so that eavesdroppers is not able to obtain information of the key.By selecting the appropriate parameters,the eavesdropper's bit error rate can be kept between 0.45 and 0.5,while the legal person's bit error rate can keep its bit error rate at 0 by cascading channel coding.Through the simulation results,it can be seen that the security and reliability of the key generation can be ensured through the unconditional secure transmission mode.Finally,this thesis describes in detail the process of implementing a key generation scheme on the USRP,and added eavesdroppers to verify the security of key generation.In the case of binary,the inconsistency rate between the eavesdropper's acquired key and the legitimate person's key is distributed between 42% and 57%,as the number of key distributions tends to be infinite,the key inconsistency rate approaches 0.5,ie the eavesdropper obtains the key and the legal person's key mutual information is zero,which indicates that the program can guarantee security in the case of passive eavesdropping.At the same time,legal users can achieve high KGR,low complexity key distribution process.This article also makes innovative improvements to the original scheme.After the analysis of the continuous channel response of the same device,the channel response is denoised to reduce the inconsistency of the initial key by about 30%.Through the experimental data,it can be seen that the scheme has an objective improvement in the key generation rate and security compared with the original scheme,and the new scheme does not require additional information exchange,and does not increase the complexity of the key generation while improving the performance.