Study On The Security Of Spectrum Sensing In Cognitive Radio

Due to the rapid development of wireless communication business and technology,the limited wireless spectrum resources becomes more scarce,which largely restricts the healthy development of the wireless technology.But the actual situation of spectrum using is that certain frequency bands have carried on too many wireless service and even been saturated,while the usage rate of some other frequency bands is seriously low.Therefore,the wireless service can not be carried out in a high-efficiency way,as well as the limited spectrum resource will be badly wasted in that mode of occupation.To make the scarce spectrum resource be used reasonably and fully,the “Cognitive Radio” technology was proposed at the historic moment.In the Cognitive Radio technology,the secondary users are allowed to use the authorized spectrum which is assigned to the primary user in a dynamic way after they sense and find a free authorized frequency band,and the important premise is that the movement of secondary users must not disturb the primary users to use their bands,so that the usage rate of spectrum resource can be increased and the above mentioned problem can be solved as well.However,there exists some secure problems that can't be ignore in the spectrum sensing phase which is one of the important components of the Cognitive Radio,they are “Primary User Emulation(PUE) attack” and “Spectrum Sensing Data Falsification(SSDF) attack”.In this paper,we mainly study the PUE attack and SSDF attack in the spectrum sensing phase,and two effective schemes were proposed to defend the attacks respectively.In order to avoid the adverse effects of the PUE attack in spectrum sensing phase,an authentication scheme based on Hash-Chain was proposed.Two occasions are considered in this scheme,one is PUEA between primary users and primary user base station,the other is between primary user base station and secondary users.In the view of the former,we adopt the self-updating HASH values to realize the signal verification,while dealing with the latter by issuing the Hash-Chain in a reversed way.This scheme made the best of HASH characteristics of the irreversible and the forgery prevention to ensure the security, while the properties of self-updating reduced the storage content and simplified the validation process, so that the overhead of system could be reduced and the efficiency of the scheme could be guaranteed.Analysis shows that this scheme can solve the PUEA in cognitive radio networks effectively.To defense the SSDF attack, a modified reputation value updated mechanism for weighted sequential probability ratio test is proposed. Firstly, the actual circumstance is taken into consideration, where the Signal Noise Ratio(SNR) of each secondary user is different,and the updated-step of reputation values are weighted by a corresponding proportion,then the correctness of secondary users' history sensing results is used as the basis of the reputation value's updating, and a coefficient is set up to make the updated-step change with the incorrect sensing times in a progressive way, so that the noncontinuous attack can be defended effectively. The simulation result shows that, the proposed method obtains a better detection performance than the original one under different kinds of attack modes.