Design Of Anti-interception Baseband Mixed Signal And Separation Algorithm

As one of the main battlefields in modern military confrontation,electronic countermeasure battlefield is one of the most important subjects for military experts from all over the world to study.As one of the important parts of electronic countermeasures,the main challenge for military communications is how to improve the Anti-interception and efficiency of the wireless communication is to protect the communication information from the enemy's interference and detection,and to give instructions to the battlefield actually.Therefore,this dissertation proposes a baseband mixed signal design scheme,which can effectively protect the signal from detection and interference by the enemy.At the same time,in order to improve the transmission efficiency,we also design a mixed signal multi-channel transmission scheme,which combined with the multi-channel transmission detection method to ensure its reception performance.The design of mixed synchronization scheme to prevent the acquisition and interference of the synchronization signal by the enemy is provided to improve the overall security of the communication system.Firstly,we proposr a specific design scheme of baseband mixed signal waveform,which combines high spectral efficiency and good anti-interception.We alse propose a blind mixed signal separation algorithm,which uses the Gibbs sampling algorithm and QRD-M decomposition algorithm,to separate the mixed signal.We introduce the fundamental principle of Gibbs sampling algorithm,and deduce the preprocessing process and separation algorithm for the mixed signals.Using QRD-M algorithm,we can reduce the computational complexity of the system as much as possible on the premise of the acceptable performance loss.By designing the parameters of different mixed signals and the parameters of the separation algorithm,we can find the appropriate combination of parameters,and improve the security of signal as much as possible without affecting the communication.Secondly,based on the designed baseband mixed signal waveform,we introduce the multi-input multi-output(MIMO)technology to improve the spectral efficiency and reliability of the system.Then,several minimum mean square error(MMSE)detection algorithms for MIMO channel are discussed.In this dissertation,one of the detection algorithms is selected to prove that MIMO technology can be combined with mixed signal waveform transmission,and the subsequent separation work is completed.Different detection algorithms can be selected to achieve the tradeoff between complexity and performance.We also discuss the advantages of the baseband mixed signal multi-channel transmission over the traditional multi-channel mixed signal transmission in anti-interception.We introduce a synchronization scheme to help the receiver to obtain channel parameters.Finally,we propose a new hybrid synchronization scheme,which mixes two different synchronization sequences in the way of mixed signals,and estimates the channel delay by sliding sampling capture at the receiving end.The simulation results show that the separation results are not satisfactory when the sampling point does not fall within a code length range near the optimal sampling point.The separation bit error rate is lower than the threshold value when sliding to the optimal sampling area,which can be used as a rough estimation of channel delay.The estimated channel delay is used in signal preprocessing to reduce the performance loss caused by channel delay.