Research On Location Privacy Protection For Secondary Users In Cooperative Spectrum Sensing

Cognitive radio(CR)technology allows secondary users(SUs)to access the spectrum of primary users(PUs)opportunistically,thus realizing spectrum sharing,which greatly improves the utilization of spectrum and relieves the spectrum tension in the Internet era.Cooperative spectrum sensing(CSS)is the first step of spectrum sharing.However,in CSS,SUs are faced with the leakage of location privacy,which makes SUs reluctant to participate in spectrum sensing and hinders the development of cognitive radio networks.Domestic and foreign researchers have proposed different location privacy protection schemes,but these schemes have high computation and communication costs,and some schemes can not support faulttolerance mechanism well,in addition,the applicable scenarios of these schemes are limited.This thesis considers different CSS and proposes corresponding location privacy protection schemes,as follows:Firstly,we introduce a third party(TP)and propose a location privacy protection scheme based on elliptic curve El Gamal in general CSS,i.e.SUs are semitrusted.We improve the elliptic curve El Gamal cryptosystem so that the sensing report needs to be decrypted twice after it has been encrypted once.We have TP perform the first decryption operation,and after that the obfuscation operation.The obfuscation operation cuts off the relationship between the sensing report and the identity of the SU,and ensures the anonymity of sensing report in the process of fusion,and thus protects the location privacy of SUs.The performance analysis shows that the proposed scheme can effectively reduce SUs' computation cost and the system's communication cost.In addition,the scheme has fault-tolerance and enhances the practicability of the scheme.Secondly,in the CSS where malicious SUs exist,we combine blockchain and propose a scheme to protect SUs' location privacy while resisting tampering attacks.In the CSS after introducing blockchain,every SU is anonymous.Based on this characteristic,we realize the non-association between the sensing report and the SU's identity,thus realizing the location privacy protection of SUs.In addition,we use the elliptic curve digital signature algorithm to realize the integrity of the report in the transmission process and prevent malicious SUs' attacks.Experimental results show that this scheme has some advantages in communication cost and storage cost compared with other schemes,Finally,we propose a location privacy protection scheme that supports data integrity and data source reliability by using elliptic curve cryptography and reputation mechanism in CSS with selfish SUs.This scheme enables reliable SUs to participate in spectrum sensing,and ensures the reliability of sensing report at the source.The results show that,compared with other schemes,this scheme not only protects the location privacy of SUs,but also resists the attack of selfish SUs.Moreover,it improves the communication cost and storage cost obviously.