A Rotation-based Method for Precoding in Gaussian MIMOME Channels
share
The problem of maximizing secrecy rate of multiple-input multiple-output multiple-eavesdropper (MIMOME) channels with arbitrary numbers of antennas at each node is studied in this paper. It is proved that linear beamforming is optimum for this problem and optimal signaling to achieve the secrecy capacity is then developed. To this end, it is shown that optimal precoding is a rotation matrix resulted from a set of basic rotations each with one parameter. Next, a gradient-descent based algorithm is developed to find the rotation and power allocation parameters. The proposed rotation-based method can be applied to any MIMOME channels and outperforms state-of-the-art analytical and numerical methods. In particular, the rotation-based precoding achieves higher secrecy rates than the celebrated generalized singular value decomposition (GSVD)-based precoding, with a reasonably higher computational complexity. To further, decrease the computation cost, an algorithm is developed to combine the rotation and GSVD-based precoding. The new rotation-GSVD-based precoding provides an efficient approach to find a near-optimal transmit strategy for the MIMOME channel. Extensive numerical results elaborate on the effectiveness of the rotation-GSVD-based precoding. The new framework developed in this paper can be applied to a verity of similar problems in the context of multi-antenna channels with and without secrecy.
READ FULL TEXT