Secrecy Performance of Multi-User MISO VLC Broadcast Channels With Confidential Messages

• Published in: IEEE transactions on wireless communications Vol. 17; no. 11; pp. 7789 - 7800
• Main Authors: Arfaoui, Mohamed Amine, Ghrayeb, Ali, Assi, Chadi M.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.11.2018; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Broadcast; Communications systems; Complexity; Fixtures; Light emitting diodes; Mathematical models; Messages; MISO; MISO (control systems); MISO communication; Optical communication; Optical distortion; Optical receivers; Precoding; Secrecy aspects; secrecy performance; VLC; Wireless communication
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2018.2871055

We study, in this paper, the secrecy performance of a multi-user (MU) multiple-input single-output visible light communication broadcast channel with confidential messages. The underlying system model comprises <inline-formula> <tex-math notation="LaTeX">K +1 </tex-math></inline-formula> nodes: a transmitter (Alice) equipped with <inline-formula> <tex-math notation="LaTeX">N </tex-math></inline-formula> fixtures of LEDs and <inline-formula> <tex-math notation="LaTeX">K </tex-math></inline-formula> spatially dispersed users, each equipped with a single photo-diode. The MU channel is modeled as deterministic and real-valued and assumed to be perfectly known to Alice, since all users are assumed to be active. We consider typical secrecy performance measures, namely, the max-min fairness, the harmonic mean, the proportional fairness, and the weighted fairness. For each performance measure, we derive an achievable secrecy rate for the system as a function of the precoding matrix. As such, we propose algorithms that yield the best precoding matrix for the derived secrecy rates, where we analyze their convergence and computational complexity. In contrast, what has been considered in the literature so far is zero-forcing (ZF) precoding, which is suboptimal. We present several numerical examples through which we demonstrate the substantial improvements in the secrecy performance achieved by the proposed techniques compared with those achieved by the conventional ZF. However, this comes at a slight increase in the complexity of the proposed techniques compared with ZF.