Power allocation to noise-generating nodes for cooperative secrecy in the wireless environment

The wireless transmission environment opens up opportunities for an eavesdropper to intercept a secret message from the source to the legitimate destination, particularly in the case when the eavesdropper is close to the source. Cooperative jamming, where nodes that are inactive serve as noise-generating nodes to disrupt an eavesdropper, has recently been considered in wireless communication networks to improve secrecy in such scenarios. Here we consider optimal power allocation to these jamming nodes (termed “chatterers”) in the case of an eavesdropper of known location. The optimal power allocation to the chatterer nodes is achieved via water-filling that, as one would expect, favors nodes that are close to the eavesdropper but will not impact the message to the destination significantly, either because the chatterer is located at a large distance from the destination or because the chatterer´s signal is significantly faded at the destination. Numerical results compare the performance of the system employing the optimal power allocation to the performance of lower overhead schemes that employ only a single jamming node.