Linear precoding for cognitive multiple access wiretap channel with finite-alphabet inputs

• Published in: IEEE International Conference on Communications (2003) pp. 1 - 6
• Main Authors: Jin, Juening, Xiao, Chengshan, Tao, Meixia, Chen, Wen
• Format: Conference Proceeding Journal Article
• Language: English
• Published: IEEE 01.05.2016
• Subjects: Algorithms; Antennas; Approximation; Approximation algorithms; Channels; Design engineering; Ergodic processes; Interference; Mathematical analysis; Mathematical models; Mutual information; Precoding; Receivers; Security
• ISSN: 1938-1883
• DOI: 10.1109/ICC.2016.7511335

This paper investigates the linear precoder design for cognitive multiple-access wiretap channel (CMAC-WT), where two secondary-user transmitters (STs) communicate with one secondary-user receiver (SR) in the presence of an eavesdropper and subject to interference threshold constraints at primary-user receivers (PRs). It designs linear precoders to maximize the ergodic secrecy sum rate for multiple-input multiple-output (MIMO) CMAC-WT under finite-alphabet inputs and statistical channel state information (CSI). For this non-convex problem, a two-layer algorithm is proposed by embedding the convex-concave procedure into an outer approximation framework. The key idea of this algorithm is to reformulate the approximated ergodic secrecy sum rate as a difference of convex (DC) functions, and then generate a sequence of simpler relaxed sets to approach the non-convex feasible set. In this way, near optimal precoding matrices are obtained by maximizing the approximated ergodic secrecy sum rate over a sequence of relaxed sets. Numerical results show that the proposed precoder design provides a significant performance gain over the Gaussian precoding method in the medium and high SNR regimes.