The Design And Implementation Of The Smart Jamming For Spread Spectrum Communication

The spread spectrum communication technologies are widely used because of its well performance of anti-jamming,anti-multipath fading,lowly capture probability and multiple access.CDMA(Code Division Multiple Access)system is a typical direct sequence spread spectrum communication system.As the earliest commercial CDMA system,IS-95 system still plays an important role in mobile communication.However,with the wide application of mobile terminals,various social problems arise,which makes the researching of the jamming of IS-95 system significant.This thesis firstly introduces the background of the research and the research status of jamming technologies for spread spectrum communication.Then analysis the defects of the existing jamming methods and the characteristics of the spread spectrum sequences that used in IS-95 system.on this basis,two smart jamming schemes for IS-95 system are proposed,which are pilot channel jamming and pilot channel and synchronous channel jamming.The principle of the two jamming scheme in multipath fading channel is described in detail.Finally,this thesis introduces the synchronization algorithm of jammer and deduces the threshold formula.On the basis of the overall scheme design,this thesis using MATLAB to set up the simulation link for the smart jamming of IS-95 system.Firstly,the system bit error rate performance without jamming is verified by simulation.And then a simulation is made to get the system bit error rate performance with the pilot channel jamming,comparing the performance differences between pilot channel jamming with different offset.Next,the system bit error rate performance with the pilot channel and synchronous channel jamming is simulated,and the performance differences between the jamming with different offset and different power ratio are compared.Then,the performance comparison between the smart jamming and the traditional oppressive jamming is carried out.It can be concluded that both kind of smart jamming result in obvious increase of the error rate of the system,and the power of the smart jamming is far less than that of the oppressive jamming.Finally,the synchronization probability of the jammer is obtained by simulation,and the proper length of correlation is selected based on the amount of hardware resource and the algorithm complexity.On the last of the thesis,The FPGA implementation scheme for the smart jamming of IS-95 system is designed,and the overall architecture of the implementation scheme is introduced,which can be divided into two parts: jamming unit and peripheral module.The jamming unit,which is the core of the scheme,includes the preprocess module,the synchronization module and the jamming transmission module.The peripheral module mainly includes the AD9361 data interface module,clock and reset module and AD9361 management module,the function of this part is to complete the configuration and calibration of AD9361,make data format conversion,generate the global clock and reset signal,guarantee the proper functioning of the system.Finally,the function of each module has been verified by simulation.