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arXiv 2012.05667cs.ITeess.SPmath.IT
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MIMO窃听信道的秘密容量:凸变换和有效数值方法

On the Secrecy Capacity of MIMO Wiretap Channels: Convex Reformulation and Efficient Numerical Methods

Anshu Mukherjee, Björn Ottersten, Le-Nam Tran

摘要:

本文提出了一种新的数值计算方法来计算多输入多输出(MIMO)窃听信道在多个线性发射协方差约束(包括和功率约束、每天线功率约束和干扰功率约束)下的保密容量。这个问题的解析解是未知的,现有的数值解收敛速度慢和/或每次迭代的复杂性高。推导计算有效的解决方案的保密容量问题是具有挑战性的,因为保密率表示为一个差异的凸函数(DC)的传输协方差矩阵,其凸性只知道在某些特殊情况下。在本文中,我们提出了两个低复杂度的方法来计算的保密能力,随着退化信道的凸重构。在第一种方法中,我们利用加速DC算法,这需要解决一系列的凸子问题,为此,我们提出了一个有效的迭代算法,每次迭代承认一个封闭形式的解决方案。在第二种方法中,我们依赖于凹凸等效的保密容量问题,使我们能够推导出所谓的部分最佳对策算法,以获得最优解的重新制定。值得注意的是,第二种方法的每次迭代也可以以封闭形式进行。仿真结果表明,与其他已知的解决方案相比,我们的方法具有更快的收敛速度。我们进行了广泛的数值实验,以评估各种参数对实现的保密能力的影响。

英文摘要:

This paper presents novel numerical approaches to finding the secrecy capacity of the multiple-input multiple-output (MIMO) wiretap channel subject to multiple linear transmit covariance constraints, including sum power constraint, per antenna power constraints and interference power constraint. An analytical solution to this problem is not known and existing numerical solutions suffer from slow convergence rate and/or high per-iteration complexity. Deriving computationally efficient solutions to the secrecy capacity problem is challenging since the secrecy rate is expressed as a difference of convex functions (DC) of the transmit covariance matrix, for which its convexity is only known for some special cases. In this paper we propose two low-complexity methods to compute the secrecy capacity along with a convex reformulation for degraded channels. In the first method we capitalize on the accelerated DC algorithm which requires solving a sequence of convex subproblems, for which we propose an efficient iterative algorithm where each iteration admits a closed-form solution. In the second method, we rely on the concave-convex equivalent reformulation of the secrecy capacity problem which allows us to derive the so-called partial best response algorithm to obtain an optimal solution. Notably, each iteration of the second method can also be done in closed form. The simulation results demonstrate a faster convergence rate of our methods compared to other known solutions. We carry out extensive numerical experiments to evaluate the impact of various parameters on the achieved secrecy capacity.

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