Research On Covert Anti-interference Communication In Transform Domain Based On Combined Basis Functions

In recent years,electronic warfare has become a prominent feature of modern warfare,and it has become an important means of combat in military warfare between countries.The concealment,anti interception,and anti-interference capabilities of information transmission have become increasingly important.Based on the research and analysis of existing covert anti-interference communication methods,this article proposes a new type of covert anti-interference communication system-transform domain covert communication based on combined basis functions.This communication system maps part of the Information mapping into frequency point combinations,and the frequency point combinations of the same Information mapping are also different.The frequency point combination is taken as the amplitude spectrum of the basis function,and then the other part of the information is modulated into a time-domain transmission waveform with strong concealment,strong anti interception and strong anti-interference ability,and higher information transmission efficiency through the transform domain modulation technology,which puts forward a new idea for China’s electronic warfare technology.This article focuses on the analysis and research of covert communication in the transformation domain based on composite basis functions.Firstly,a transformation domain covert communication system based on composite basis functions was proposed,and its system receiver transmitter model was given.A simulation model was established to demonstrate the strong concealment and interception resistance of this method.Secondly,the impact of system parameters such as the number of subchannels,available frequency points,and frequency point usage ratio on communication performance was studied through theoretical analysis and simulation verification,and the optimization direction of system performance was clarified.Finally,the differences in spectral efficiency,spread spectrum gain and communication rate between the system and chaotic multitone system,transform domain system and direct sequence spread spectrum system are analyzed.Through theoretical analysis and simulation analysis,conclusions can be drawn:Transform domain covert communication based on combined basis functions utilizes transform domain technology by mapping information into one to many frequency combinations,using basis functions with noise-like characteristics as transmission waveforms,and using different basis functions when sending the same information,making this communication method highly covert and anti interception.The transform domain covert communication based on combined basis functions has strong anti-interference ability.When the interference type is single tone interference,the bit error rate achieved10^-4when the signal-to-interference ratio is-50d B;When the interference type is multi tone interference,the bit error rate that can be achieved10^-4when the signal-to-interference ratio is-45d B;When the interference type is narrowband interference,the bit error rate that can be achieved10^-4when the signal-to-interference ratio is-40d B.Has a certain resistance to sudden interference and can achieve a10^-4bit error rate under various types of interference with a signal-to-interference ratio of-10d B around.It also has a certain resistance to multipath interference and can achieve a10^-4bit error rate under various types of interference with a signal-to-interference ratio of-5d B around.Transform domain covert communication based on combination basis functions has higher information transmission efficiency.When the transform domain modulation is bipolar modulation and the order of frequency point combination coding isM_c（28）2,information can be transmitted at twice the information transmission rate of traditional transform domain communication systems,which islog₂（M _c）times higher than that of traditional transform domain communication systems.