Precoding for Security Gap Physical Layer Security in Multiuser MIMO Satellite Systems

For military and governmental communications, physical layer security (PLS) is beneficial to resist cryptanalysis and brute-force attacks with powerful computers. However, due to their Line-of-Sight channels, PLS is even more challenging to achieve in satellite communication (SATCOM) downlinks. In multibeam multiuser multiple-input multiple-output (MU-MIMO) satellite systems, the spatial degrees of freedom allow the use of special precoding algorithms to improve the security. The security gap of error correcting channel codes achieves a practical PLS based on the bit-error rate of users and eavesdroppers. We propose MU-MIMO SATCOM precoding algorithms with and without artificial noise for reliable user communications and security against eavesdropping.