On the Gaussian Multiple Access Wiretap Channel and the Gaussian Wiretap Channel With a Helper: Achievable Schemes and Upper Bounds

Abstract

We study deterministic approximations of the Gaussian two-user multiple access wiretap channel (G-MAC-WT) and the Gaussian wiretap channel with a helper (G-WT-H). These approximations enable results beyond the recently shown 2/3 and 1/2 secure degrees of freedom (s.d.o.f.) for the G-MAC-WT and the G-WT-H, respectively. While the s.d.o.f. were obtained by real interference alignment, our approach uses signal-scale alignment. We show achievable schemes which are independent of the rationality of the channel gains. Moreover, our results can differentiate between channel strengths, in particular between both users, and will establish secrecy rates dependent on this difference. We can show that the resulting achievable secrecy rates tend to the s.d.o.f. for vanishing channel gain differences. Moreover, we extend previous and develop new techniques to prove generalized s.d.o.f. bounds for varying channel strengths and show that our achievable schemes reach the bounds for certain channel gain parameters. We believe that our analysis is the next step towards a constant-gap analysis of the G-MAC-WT and the G-WT-H.

Self-Secure Capacity-Achieving Feedback Schemes of Gaussian Multiple-Access Wiretap Channels With Degraded Message Sets

“…[15] investigated arbitrarily varying MAC with strong secrecy constraint, and provided bounds on its secrecy capacity region. [16]- [18] studied variations of the MAC with secrecy constraint, and proposed bounds on the corresponding secrecy capacity regions. [19] proposed cooperative jamming schemes for the multiple-access wiretap channel (MAC-WT), which enhance the secrecy capacity region.…”