Achievable secrecy rates in physical layer secure systems with a helping interferer

Various physical-layer techniques have so far been proposed to achieve perfect secrecy in wireless communication systems. In this framework, an approach is investigated to enhance secrecy using a helping interferer transmitted by a friendly node in the network, aiming at confusing a passive eavesdropper. Commonly, such physical layer security approaches rely on the injection of a noise-like signal to intentionally degrade the eavesdropper capacity. Instead, the use of a jamming signal with the same probability mass function as that of the actual data is proposed here. The gains of this approach are investigated via extensive symbol error rate measurements and evaluations of the achievable secrecy rates.