  This work addresses a strategy to mitigate jamming attack on low-latency
communication by a Full-Duplex (FD) adversary in fast-fading channel
conditions. The threat model is such that the FD adversary can jam a frequency
band and measure the jammed band's power level. We first point out that due to
the presence of this FD adversary, Frequency Hopping (FH) fails. We then
propose a fast-forward cooperative relaying scheme, wherein the victim node
hops to the frequency band of a nearby FD helper node that fast-forwards the
victim's symbol along with its symbol. At the same time, the victim and the
helper cooperatively pour some fraction of their power on the jammed band to
engage the adversary. Due to fast-fading channel conditions, the victim and the
helper use amplitude based non-coherent signalling referred to as Non-Coherent
Fast-Forward Full-Duplex (NC-F2FD) relaying. To minimize the error-rate of this
strategy, we jointly design the constellations at the helper node and the
victim node by formulating an optimization problem. Using non-trivial results,
we first analyse the objective function and then, based on the analytical
results, propose a low-complexity algorithm to synthesize the fast-forwarded
constellations. Through simulations, we show that the error performance of the
victim improves after employing our countermeasure.
