Whisper when under Attack: Delay Tolerant Fast-Forward Relays against Full-Duplex Jamming

In this work, we synthesise a cooperative strategy to mitigate jamming attacks by a full-duplex cognitive adversary. The full-duplex adversary is such that it jams a specific frequency band and measures the average energy level of the jammed band. We first analyse the state-of-art cooperative strategy to mitigate full-duplex cognitive adversary, wherein a full-duplex single-antenna helper node fast-forwards the victim's symbols to the base station. We then point out that these schemes are not robust when the helper node introduces processing delays. To circumvent this problem, we propose a relaying scheme, namely, the Semi-Coherent Delay Tolerant Fast-Forward Full-Duplex relaying scheme, wherein the full-duplex helper node uses multiple receive-antennas to listen to the victim's symbols, thereby reducing the dependency on the direct link to decode symbols. Through analytical and simulation results, we show that our scheme outperforms the state-of-art scheme and provides reliable communication between the victim and the base station even if the helper node introduces processing delays. Further, we also show that the victim completely engages the adversary to the jammed frequency band.