Nullification of Multiple Correlated Jammers

Effective suppression of the intentional jamming signals is crucial to ensure reliable wireless communication. However, as demonstrated in this paper, when the transmitted jamming signals are highly correlated, and especially when the correlations between transmitted jamming signals are deliberately varied over time, nullifying the jamming signals can be challenging. Unlike existing studies assuming uncorrelated jamming signals or non-zero but constant correlations, we evaluate the impact of the non-zero and varying correlations on the suppression of the jamming signals. We discover that by varying the correlations between transmitted jamming signals, jammers can “virtually change” the jamming channels hence their nullspace, even when these channels do not physically change. That makes most jamming suppression techniques that rely on steering receiving beams towards the nullspace of jamming channels no longer applicable. To tackle the problem, we develop techniques to effectively track the jamming nullspace and update the receiving beams accordingly. It is demonstrated by Monte Carlo simulations that our proposed techniques can suppress/nullify jamming signals for all considered scenarios with non-zero and varying correlations amongst jamming signals.