In this letter, we establish the secure degrees-of-freedom of the Gaussian diamond-wiretap channel with rate-limited relay cooperation, where the eavesdropper not only observes the relay transmission through another multiple access channel but also wiretaps some of communication links among relays. The legitimate parties do not know the location of wiretapped relay links nor the eavesdropper’s channel state information. As an optimal relay cooperation strategy, a noise-forwarding scheme that does not incorporate secure network coding is adopted. Furthermore, we briefly outline how the scheme can be extended to incorporate the case when the source-relay links are also wiretapped.
['Si-Hyeon Lee', 'Ashish Khisti']
The Gaussian Diamond-Wiretap Channel With Rate-Limited Relay Cooperation