Secrecy Rate Maximization for Untrusted Relay Networks With Nonorthogonal Cooperative Transmission Protocols
Secrecy Rate Maximization for Untrusted Relay Networks With Nonorthogonal Cooperative Transmission Protocols
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DOI：
10.1109/tvt.2018.2819245
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发表时间：
2018-03
影响因子：
6.8
通讯作者：
Weiheng Jiang;Yi Gong;Qian Xiao;Yong Liao
中科院分区：
文献类型：
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作者：
Weiheng Jiang;Yi Gong;Qian Xiao;Yong Liao
在这篇文章中，考虑了一个基于中继的网络，其中信源通过一个非再生的中继将机密消息传输到目的地。这是因为该中继是未识别的，因此可以窃听从源到目的地的中继消息。在这方面，提出了两种新的半双工非正交放大转发(NAF)安全通信协议，它们对目的地的传输能力有不同的假设，即NAF-I用于没有传输能力的目的地，NAF-II用于有传输能力的目的地。我们分别推导了在固定的源/目的传输功率下，这两种协议产生正保密率的充要条件，并讨论了它们的联合功率分配使系统保密率最大化。尽管所考虑的功率分配问题是非凸性的，但另一种优化方法被证明是处理这些问题的有效方法，并提出了相应的算法。我们进一步证明了所提算法的收敛性质，并分析了它们的复杂性。出于比较的目的，还将讨论扩展到基于正交放大转发(OAF)的协议，即OAF-1或OAF-II。数值结果表明，所提出的NAF协议的保密率性能优于现有的传输协议，同时也验证了所设计的备选优化算法的有效性。
In this paper, a relay based network is considered where the source transmits confidential message to the destination via a nonregenerative relay. Due to the fact that the relay is unidentified, and thus may wiretap the relayed message from source to destination. In this regard, two new half-duplex nonorthogonal amplify-and-forward (NAF) secure communication protocols are proposed, with different assumptions on the transmission ability of the destination, i.e., NAF-I for destination without transmission ability and NAF-II for destination with transmission ability. We separately derive the sufficient and necessary conditions to yield positive secrecy rate for these protocols under fixed source/destination transmission power, and discuss their joint power allocation that maximizes the system secrecy rate. Despite the nonconvexity of the considered power allocation problems, alternative optimization approach is proved useful in dealing with these problems, and the corresponding algorithms are proposed. We further prove the convergence of the proposed algorithms and analyze their complexity. The discussion is also extended to the orthogonal amplify-and-forward (OAF) based protocols, i.e., OAF-I or OAF-II, for comparison purpose. Our numerical results demonstrate the gain of the secrecy rate performance of the proposed NAF protocols over existing transmission protocols, and also verify the effectiveness of the designed alternative optimization algorithms.