Enhancing Cybersecurity of Satellites at Sub-THz Bands

In this work, we present a novel idea to enhance the cybersecurity of a low earth orbit (LEO) satellite link assuming that the communication between the satellite (Alice) to the ground station receiver (Bob) is done at sub-THz frequency bands. Such short wavelength creates highly directional antenna beam with very small spot on the ground and thus making it difficult for eavesdropping. However, the satellite transmitter power can be further tuned close to the noise floor so as to make the eavesdropping even more practically difficult. In order to augment the security of the link further, we communicate only within a very specific and designated angle of arrivals of the satellite signal with transmitter power tuned close to the noise floor. The lowering of transmitter power will lead to a lower signal-to-noise ratio (SNR) at the ground station receiver and will thus cause a very high probability of eavesdropper (Eve) outages. In order to improve the SNR of Bob’s receiver, we derive an optimization algorithm considering the impact of thermal noises from the sky, the ground and the receiver circuit. The algorithm adapts the inter-element spacing between the phased array elements to shape the gain pattern so as to minimize the required transmitter power for a given SNR at the receiver of Bob.