安全空间感知的物理层协作保密通信：系统设计和优化

Information security is of paramount importance in the design of wireless communications. Traditional information security utilizes key-based cryptography, which relies on extremely high computational complexity in the decryption process to guarantee security. As the computing power of end devices continuously increases, the security of key-based cryptography will be threatened in future communication systems. Physical-layer security, using proper source and channel encoding, guarantees perfect secrecy of communication links in the information theoretical sense. The current physical-layer security techniques are subject to relatively low secrecy rate and/or high secrecy outage probability. The proposed project aims to provide spectral-efficient and robust secure communications by leveraging cooperative communication devices, densely distributed within certain safe space. Focusing on the high-velocity Unmanned Aerial Vehicles (UAV) system, where UAVs are densely clustered inside a dynamically-changing safe space, we design relevant cooperative secure communication scheme feasible for mobile networks. First, implement virtual antenna array using multiple cooperative mobile devices, and investigate ubiquitously secure space-time channel encoding, which fulfills the secrecy constraint for any arbitrary eavesdropper. Leveraging the possible locations of eavesdroppers, the system secrecy rate is further improved by using the safe-space awared system optimization framework. Then, the fast-converging optimization algorithm is investigated. In order to combat the eavesdroppers located within the safe space, the artificial noise injection by the cooperative devices is configured via the packing theory, and the distributed injection algorithm is studied. This proposed project lays the groundwork for highly spectral-efficient and highly robust physical-layer security, and provide technical support for implementing practical secure communication systems.

信息安全是无线通信中的突出问题。传统信息安全技术利用秘钥加密，提高信息破解的计算复杂度保证信息安全。随着终端设备计算能力不断提高，秘钥加密在未来通信系统中的安全性受到挑战。物理层安全利用信源、信道编码，从信息论的角度保证通信链路完全保密。本课题针对现有物理层安全技术中安全速率较低、安全中断概率较高等问题，利用安全空间中聚集分布的协作通信设备实现高速率、高可靠性协作保密通信。针对高速移动的无人机集群，设计移动网络中切实可行的保密通信方案。首先，利用协作设备实现分布式虚拟天线阵信号传输，并提出空时信道普适保密编码，对任意窃听者满足安全约束。针对窃听者空间分布特征，设计安全空间感知的系统优化框架，改善保密通信性能并研究快速收敛算法。通过密堆积理论优化协作设备人工噪声注入，提出分布式人工噪声配置算法。本课题为实现高速率、高可靠性物理层保密通信奠定了理论基础，并为保密通信实用化提供重要技术支撑。

本项目针对轻量化、小型化移动通信设备的功率、信号处理与计算等平台资源受限，导致单一设备无线通信性能和安全传输能力不足等问题展开研究。在物理层安全的理论框架下，同时利用小尺度信道衰落特征和大尺度网络节点分布特征，设计安全空间感知的多点协同传输方法、合法协同设备选择和用户关联方法、动态网络的协同设备重构方法。相比单一通信设备，提高协同收发集群之间信息传输速率和信息安全性。..本项目针对安全空间感知的物理层协作保密通信关键技术进行了研究，取得的研究进展和成果包括：1. 根据安全空间构造并求解安全速率优化问题，提出了安全空间感知的多天线预编码优化框架；2. 在安全预编码优化框架中，提出了分布式保密信号传输和人工噪声注入联合设计方法；3. 针对大规模协同网络，设计了分布式合法协作节点选择和用户关联方法；4. 在动态协同网络中，研究了针对拓扑结构动态变化的分布式协同网络重构技术；5. 针对非授权频谱工业物联网，研究立体空间中的物理层协作保密通信及其性能评估。..经过项目组的努力，已在IEEE Transactions on Wireless Communications， IEEE Transactions on Vehicular Technology， IEEE Internet of Things Journal， IEEE Wireless Communications Letters等国际著名期刊和ICC等著名国际会议上共发表论文12篇，申请专利4项，超额完成原定计划。本项目取得的研究成果表明在安全空间感知的条件下，分布式多点联合信号处理和协同传输技术可有效提升合法通信系统安全速率，保证传输信息频谱效率和信息安全性。