移动通信FDD信道密钥生成方法研究

This project focuses on secret key generation from frequency division duplex (FDD) channels for mobile communications. Taking advantage of high similarity between the uplink and downlink wave propagation paths in FDD channels, extract or construct the reciprocal channel parameters from the received signals on both communication sides, and then convert the channel parameters to symmetric keys. The data via the wireless channel are encrypted/decrypted using the symmetric key. Thus the aim to protect the wireless air interface can be achieved. The proposed scheme has the advantage of high security performance and needless of key distribution. It is more appropriate for securing communication for large scale mobile users...Combining the requirement of security key distribution for mobile communications, this project builds up a multipath model of the FDD wireless channel and studys the secret key generation methods based on FDD channels. A novel approach is proposed to extract symmetric channel parameter based on the combination of multipath separation and frequency adjustment. A multiple round transmission protocal is designed to construct reciprocal composite channel parameters. To gain maximal secret key rate, the optimization key generation methods are proposed. This project will also combine the theoretical methods with experiments, and build up an OFDM FDD prototype system for point to point secure communications. It will form the theory of secret key generation from wireless channel in systems using FDD, and will obtain some invention patents. It will make contributions to the formation of Chinese original technology for future mobile communications.

本项目研究移动通信中FDD信道密钥生成方法，利用FDD信道中上下行传播路径的高度相似性，提取或构建互易的信道特征参数，将之转换为通信双方所需的对称密钥，加解密经过该无线信道的数据，达到保护空口安全传输的目的。该方案具有高安全性及无需密钥分配的优点，更适合大规模移动通信用户的保密通信应用。.本项目结合移动通信中安全密钥分发的需求，建立FDD无线信道多径传输模型，研究FDD信道密钥生成方法。开创性地提出了基于多径分离和频率修正相结合的对称信道参数提取方法，基于多轮传输协议的互易复合信道参数构建方法以及最大化生成速率的优化密钥生成方法。将理论研究与系统实验相结合，构建基于无线信道特性密钥的OFDM FDD点到点保密通信原型系统，形成FDD模式系统中无线信道密钥生成理论体系，取得一些专利成果，为我国未来移动通信原创技术的形成添砖加瓦。

基于无线信道特征的物理层安全技术已成为近期通信与安全交叉领域研究热点。本项目研究了频分双工（FDD）模式下的密钥生成速率的理论、互易信道特征构造方法、多用户密钥生成方法及信道密钥生成演示系统。取得具有代表性的成果如下：（1）提出基于路径分离及频带映射两种互易特征构建方法，生成高度相似的信道特征参数，产生具备高一致性的密钥；（2）提出基于双频带回传的共享符合信道特征构建机制，降低了设备硬件不匹配对信道互易性的影响，密钥速率有了量级提升；（3）提出一种前向纠错的保密通信方法，在不增加密钥泄露率的同时有效降低了通信开销以及计算复杂度；（4）提出基于波束域信道的多用户密钥生成方法，降低用户间的干扰及窃听风险，获得接近于单用户的平均密钥生成速率；（5）搭建FDD信道密钥生成演示验证系统，密钥生成的速率达到3~4bit/pkt。依托上述研究，在项目执行期间，共发表学术论文27篇，其中在《IEEE Transactions on Information Forensics and Security》, 《IEEE Transactions on Communications》, 《IEEE Internet of Things Journal》等顶级SCI检索源期刊上发表论文18篇；在IEEE INFOCOM等顶级会议上发表论文8篇。申请国家发明专利10项，PCT专利2项。同时，在项目执行期间，组织国际顶级会议研讨会1项，参与多个国内外重要的学术会议；培养了博士研究生4名，硕士研究生8名。本项目的研究成果为FDD系统中上下行信道预测、物理层密钥生成技术、移动通信系统中高效、安全和可靠传输等相关的理论和应用研究提供了重要的参考。