Research On Satellite Covert Overlap Communication Method Based On Carrier Aggregation

Because of the characteristic of wide coverage,satellite communication has became the main solution for long-distance wireless communication in remote geographical environments such as oceans,deserts,and mountains.But at the same time,satellite communication technology has security problems when it is used as a special long-distance communication method.The third party can intercept the information of the wireless satellite communication system using the electronic reconnaissance equipment within the satellite downlink beam range,which seriously affects the security performance of the terminal wireless communication.With the development of electronic detection technology and the raise of security performance requirements,traditional techniques such as spread spectrum communication and overlap communication are hard to meet the needs of satellite covert communication,especially when the bandwidth and interference tolerance of a single cover signal are insufficient.In view of the above problems,a satellite overlap communication strategy based on carrier aggregation is proposed.The segmentation and aggregation methods of communication signals in the frequency domain is studied.The segmentation scheme,power allocation strategy and distribution of multiple cover signals are explored.The probability of the communication signals being detected by the third part is reduced as much as possible while the communication performance of the terminal is ensured,and the performance of transmission was improved at the physical layer.The main contributions of this thesis are as follows:(1)Aiming at the problem of realize the secure transmission of communication information at the physical layer due to the wide coverage of satellite communication system,a satellite overlapping covert communication method based on carrier aggregation is proposed.The terminal side explores the frequency domain segmentation method of the communication signal,and designs the corresponding segmentation filter bank parameters under different segmentation methods;The gateway side studies two different carrier aggregation methods based on pilot frequency and blind phase estimation.Using the covert communication method proposed in this paper,the communication signal can be hidden in the current electromagnetic spectrum environment of satellite transponders.Even if the electronic reconnaissance equipment of the third party finds part of divided sub-spectrum signals,it cannot demodulate useful communication information from it.(2)Aiming at the problem of insufficient bandwidth and power tolerance of a single cover signal in the traditional satellite overlapping communication,a multi-cover signal overlapping communication method with frequency domain division and sub-spectrum power control joint optimization is proposed by using multiple cover signals in the satellite transponder spectrum environment.A bi-objective optimization problem of signal transmission performance and stealth performance for covert communication is established.The gateway side uses the perceived historical spectrum data to train and generate the SVM regression prediction model,which is used to predict the communication performance and stealth performance of covert signals in different transponder spectrum environments,and download the trained prediction model to the communication terminal.The terminal side uses the dual-target knapsack algorithm to select cover signals in the transponder spectrum environment by taking the communication performance and covert performance of the covert signal predicted by the SVM regression prediction model as value factors,and the number of cover signals as the backpack weight,and solve the frequency domain division of the concealed signal and the power control parameters of the sub-spectrum,so as to realize the purpose of hiding the terminal communication signal in the frequency spectrum environment of the satellite transponder.