物理层安全的随机波束成型传输算法

针对传统信息论物理层安全研究中，对合法用户信道质量要求较高的问题，文中提出随机波束成型的物理层安全传输方法。该方法通过在主信道特征向量的垂直方向构造人工随机波束成型信道，使得合法用户与窃听方信道传输特征的差异性转化为信道质量的差异，最终得到正的保密容量。为保证算法的完备性，文章解决了三方面问题:1）给出随机波束成型的空间构造方法；2）随机波束成型方法的保密容量和最佳信源分布；3）人工随机信道的构造方法。最后针对采用随机波束成型算法的发送分集系统，通过设计、仿真其噪声发生和功率分配方案，进一步说明即使在合法用户信道质量差的情况下，随机波束成型传输算法也可获得保密传输容量。 

The Random Beamforming Security Scheme of Physical Layer

In conventional information theory research on physical layer security, to lower the requirement of the main channel quality, the random beamforming security scheme (RBS) is presented in this paper. This method sends the information data on the direction of the main channel, and adds multiplicative interference on the vertical direction. As a result, this scheme converts the channel characteristic (such as channel states vector) difference between the main channel and the wiretap channel to the channel quality difference, and makes the secrecy capacity positive. For the completeness of RBS, we solved three problems: 1) Presenting the construction method of RBS in vector space; 2) Calculating the secrecy capacity and optimum source distribution; 3) Constructing the artificial noise. Finally, with the RBS in transmitting diversity system, after designing and simulating the noise generating, power allocation scheme, we illustrate that RBS can get a positive secrecy capacity, even the main channel is worse than the wiretap channel.