Unequal Secrecy Protection for Untrusted Two-Way Relaying Systems: Constellation Overlapping and Noise Aggregation
Unequal Secrecy Protection for Untrusted Two-Way Relaying Systems: Constellation Overlapping and Noise Aggregation
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DOI：
10.1109/tvt.2018.2861836
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发表时间：
2018-07
影响因子：
6.8
通讯作者：
Li Sun;Hongbin Xu
中科院分区：
文献类型：
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作者：
Li Sun;Hongbin Xu
本文研究了双向中继系统中的安全信息交换问题，其中两个终端用户借助一个不可信的中继进行双向通信。假设每个用户具有两个具有不同优先级的消息：高优先级和低优先级。首先传输高优先级消息(HPM)，为此，我们提出了一种星座重叠方案，使得在中继处接收的信号彼此重叠，并创建高差错平台以防止不可信的中继器破译信息。在完成HPM交换后，每个用户通过将其低优先级消息(LPM)叠加到来自另一用户的先前解码的HPM来发送其低优先级消息(LPM)。通过利用终端用户和中继处HPM的差错模式之间的差异，可以在中继处聚集不同时隙中的信道噪声，以确保LPM传输。分析了终端用户和非可信中继的误码概率，证明了HPM比LPM具有更高的可靠性和更高的保密性。然而，LPM的传输具有较低的实现复杂度和较低的系统开销，这充分说明了基于消息优先级的不等保密保护框架可以实现良好的性能-复杂度折衷。仿真结果表明，与现有的竞争解决方案相比，提出的设计方案具有一定的优越性。
This paper studies the secure information exchange of two-way relaying systems, where two terminal users communicate bi-directionally with the assistance of an untrusted relay. Each user is assumed to have two messages with distinct priorities: high priority and low priority. The high-priority messages (HPM) are first transmitted, for which we propose a constellation overlapping scheme such that the received signals at the relay overlap with each other and a high error floor is created to prevent the untrusted relay from deciphering the information. Upon the completion of HPM exchange, each user sends its low-priority message (LPM) by superposing it onto the previously decoded HPM from the other user. By exploiting the difference between the error patterns for HPM at the terminal users and the relay, channel noises in various time slots can be aggregated at the relay to secure the LPM transmission. The symbol error probability (SEP) at the terminal users as well as the untrusted relay is analyzed, from which it is shown that HPM is guaranteed to have greater reliability and higher secrecy level than that of LPM. However, the transmission of LPM enjoys lower implementation complexity and reduced system overhead, which fully demonstrates that the message-prioritization-based unequal secrecy protection framework can realize a good performance-complexity tradeoff. Simulation results exhibit the superiority of the proposed design compared to the existing competing solutions.