Randomized OFDM Waveforms for Simultaneous Radar Operation and Asynchronous Covert Communications

Scattering-based communications are defined for this work as asynchronous, non-LOS ad-hoc data transfer between friendly autonomous sensors and in presence of a possible interceptor, enabled by high-power radar pulse reflections from same target scene. We consider orthogonal frequency division multiplexing (OFDM) signaling for this purpose, deriving a frequency-domain, magnitude-based reception scheme. Additionally, we introduce a randomization approach in which OFDM sub-carrier coefficients are used to encode both data and the random mask. Simulation study is performed to infer method's performance in interceptor/ eavesdropper penalization, as well as radar signal performance via the wideband ambiguity function (WAF) analysis. Finally, experimental study of scatter-based communication is carried out and WAF-based radar signal performance is analyzed to test the implementation.