Multi-User MIMO Satellite Communications with Secrecy Constraints

In satellite communications physical layer security is rather challenging to achieve due to the broadcasting nature of satellite downlinks. We investigate how the advances in multiuser multiple-input multiple-output satellite communications can protect downlinks from eavesdropping. The additional degrees of freedom in multi-antenna systems can not only be utilized for higher spectral efficiency but also to improve the security of the links. Our analysis shows that the area where a hostile interceptor is able to capture the signal is small due to the interference of other user signals. Moreover, the area can be tuned by applying a modified precoding matrix.