Physical layer security is a useful tool to prevent confidential information from wiretapping. In this paper, we consider a generalized model of conventional physical layer security, referred to as hierarchical information accessibility (HIA). A main feature of the HIA model is that a network has a hierarchy in information accessibility, wherein decoding feasibility is determined by a priority of users. Under this HIA model, we formulate a sum secrecy rate maximization problem with regard to precoding vectors. This problem is challenging since multiple non-smooth functions are involved into the secrecy rate to fulfill the HIA conditions and also the problem is non-convex. To address the challenges, we approximate the minimum function by using the LogSumExp technique, thereafter obtain the first-order optimality condition. One key observation is that the derived condition is cast as a functional eigenvalue problem, where the eigenvalue is equivalent to the approximated objective function of the formulated problem. Accordingly, we show that finding a principal eigenvector is equivalent to finding a local optimal solution. To this end, we develop a novel method called generalized power iteration for HIA (GPI-HIA). Simulations demonstrate that the GPI-HIA significantly outperforms other baseline methods in terms of the secrecy rate.
翻译:物理层安全是防止保密信息被窃听的有用工具。 在本文中,我们认为常规物理层安全的普遍模式,称为等级信息无障碍(HIA)。 HIA模式的一个主要特点是,网络在信息无障碍性方面有等级分级,其中解码的可行性由用户优先决定。根据HIA模式,我们针对预先编码的矢量制定了总保密率最大化问题。这个问题具有挑战性,因为要满足 HIA 条件的保密率涉及多种非移动功能,而且问题也是非凝固。为了应对挑战,我们通过使用LogSumExplate 技术来接近最低功能,然后获得一阶的最佳性条件。一个关键的观察是,由此产生的条件被描绘成一个功能性电子价值问题,在这种情况下,egen值相当于所拟订的问题的近似客观功能。因此,我们表明,找到一个主导体相当于找到一种地方最佳解决办法。为此,我们开发了一种新型方法,称为HIA(GI-HI-HIA)的通用能力,在GIA-HIPA 的基数中,以大大超低的GIIS-HIPA方法。