Secure Transmission in Multiple Access Wiretap Channel: Cooperative Jamming Without Sharing CSI

This paper investigates the secure transmission in multiple access wiretap channels, where multiple legitimate users transmit private information to an intended receiver in the presence of multiple eavesdroppers. In order to improve security, we propose a novel cooperative jamming scheme, in which users do not share channel state information (CSI) but the legitimate channels will not be degraded by the artificial noise. The basic idea is to make each user exploit its own CSI in two slots to design artificial noise, so that the intended receiver can eliminate all the artificial noise but the eavesdroppers cannot. In this process, the interference between users plays a key role to achieve security, because it guarantees that the artificial noise from different users helps each other. We consider the non-collusion and collusion of eavesdroppers and analyze the secrecy performance for both scenarios. We adopt the secrecy sum-rate as the main metric, and show that positive secrecy sum-rate can be achieved by using the proposed scheme. Especially, we observe that when eavesdroppers collude and their additive white Gaussian noise (AWGN) close to zero, the number of users must not be less than twice the number of eavesdroppers to ensure positive secrecy sum-rate. Finally, simulation results are provided to corroborate our theoretical findings.

Automated summary

This paper proposes a novel cooperative jamming scheme to improve security in multiple access wiretap channels, where users use their own CSI to design artificial noise to eliminate eavesdroppers' ability to intercept legitimate information. The interference between users plays a key role in achieving security by ensuring that artificial noise from different users helps each other. The study considers both non-collusion and collusion scenarios of eavesdroppers, and shows that positive secrecy sum-rate can be achieved by the proposed scheme.