Dynamic Role-Switching for Cooperative Covert Communication

The goal of covert communication is to make Alice’s transmissions to Bob indistinguishable from background noise and interference, thereby preventing Eve from detecting the presence of the communication. For effective covert communication, Eve’s detection error should be close to random guessing, while Bob’s error in message recovery should be minimal. The performance of covert communication is limited by the Square Root Law (SRL), which constrains Alice’s per-symbol power and transmission capacity. One solution to increase covertness while keeping the communication reliable is to employ a friendly jammer, however, this is not a feasible solution to every scenario. We therefore explore a cooperative jamming strategy instead of relying on a friendly jammer. In our proposed network scenario, two transmitters, Alice-A and Alice-B, alternate between transmitting to Bob and jamming to confuse Eve. We model the interaction between Alice-A and Alice-B using the Alternating Prisoner’s Dilemma game. This model serves as a framework to determine the conditions under which they are incentivized to cooperate. Our findings suggest that rational cooperation can offer a viable alternative to the traditional use of friendly jammers.