Abstract
In this paper, some new results on the multiple-access wiretap channel (MAC-WT) are provided. Specifically, first, we investigate the degraded MAC-WT, where two users transmit their corresponding confidential messages (no common message) to a legitimate receiver via a multiple-access channel (MAC), while a wiretapper wishes to obtain the messages via a physically degraded wiretap channel. The secrecy capacity region of this model is determined for both the discrete memoryless and Gaussian cases. For the Gaussian case, we find that this secrecy capacity region is exactly the same as the achievable secrecy rate region provided by Tekin and Yener, i.e., Tekin–Yener’s achievable region is exactly the secrecy capacity region of the degraded Gaussian MAC-WT. Second, we study a special Gaussian MAC-WT, and find the power control for two kinds of optimal points (max-min point and single user point) on the secrecy rate region of this special Gaussian model.
Highlights
Transmission of confidential messages has been studied in the literature of several classes of channels.Wyner, in his well-known paper on the wiretap channel [1], studied the problem of how to transmit the confidential messages to a legitimate receiver via a degraded broadcast channel, while keeping the eavesdropper as ignorant of the messages as possible
It is difficult to find a tight outer bound on the secrecy capacity region of the general multiple-access wiretap channel (MAC-WT), and in this paper, we focus on the secrecy capacity region of the degraded multiple-access channel (MAC)-WT
For the Gaussian case, we find that the secrecy capacity region provided in this paper is exactly the same as the achievable secrecy rate region provided by Tekin and Yener [21]
Summary
Transmission of confidential messages has been studied in the literature of several classes of channels. In [22,23], the MAC-WT with partially cooperating encoders (one encoder is allowed to conference and the other does not transmit any message) was studied, and inner and outer bounds on the capacity-equivocation region of this model were provided. The MAC-WT with two conference links between the encoders was investigated in [24], and inner and outer bounds on the secrecy capacity region were established for this model Besides these works on the discrete memoryless and Gaussian cases of MAC-WT, He et al [25] studied the MIMO MAC-WT, where the channel matrices of the legitimate users are fixed and revealed to all of the terminals, whereas the channel matrices of the eavesdropper are arbitrarily varying and only known to the eavesdropper.
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