Covert Communication Under Public Satellite Signals: System Modeling and Performance Analysis with Finite-Length Coding

Covert communication has emerged as an promising scheme to protect the communication process from being detected by Willie with arbitrarily small probability. In this paper, we study the problem of hiding private messages under public signals in a satellite system, by exploiting the uncertainty of public signals' decoding errors. To this end, we firstly propose a theoretical model for such a covert transmission system, where the covertness condition of transmission power is established for the private message. Then, under such conditions, performance of the effective covert capacity for Bob is analyzed for transmitting finite-length private messages, by ensuring reliability of the inter-fered public signals at legitimate users. Finally, numerical results demonstrate that the effective capacity of covert communication can be improved by 11.7% under traditional schemes without the exploitation of the public signals.