Jamming-aided secure communication in ultra-dense LEO integrated satellite-terrestrial networks

The ultra-dense low earth orbit (LEO) integrated satellite-terrestrial networks (UDLEO-ISTN) can bring lots of benefits in terms of wide coverage, high capacity, and strong robustness. Meanwhile, the broadcasting and open natures of satellite links also reveal many challenges for transmission security protection, especially for eavesdropping defence. How to efficiently take advantage of the LEO satellite's density and ensure the secure communication by leveraging physical layer security with the cooperation of jammers deserves further investigation. To our knowledge, using satellites as jammers in UDLEO-ISTN is still a new problem since existing works mainly focused on this issue only from the aspect of terrestrial networks. To this end, we study in this paper the cooperative secrecy communication problem in UDLEO-ISTN by utilizing several satellites to send jamming signal to the eavesdroppers. An iterative scheme is proposed as our solution to maximize the system secrecy energy efficiency (SEE) via jointly optimizing transmit power allocation and user association. Extensive experiment results verify that our designed optimization scheme can significantly enhance the system SEE and achieve the optimal power allocation and user association strategies.