Energy-Efficient Power Allocation for Secure Communications in Large-Scale MIMO Relaying Systems

TL;DR

This paper proposes an energy-efficient power allocation scheme for secure large-scale MIMO relaying systems, improving secrecy energy efficiency without requiring eavesdropper channel information.

Contribution

It introduces a novel power allocation method that maximizes secrecy energy efficiency in LS-MIMO relays under practical CSI assumptions.

Findings

Secrecy outage capacity is a concave function of relay transmit power.

The proposed scheme outperforms capacity maximization methods.

Energy efficiency is significantly improved with the new allocation scheme.

Abstract

In this paper, we address the problem of energy-efficient power allocation for secure communications in an amplify-and-forward (AF) large-scale multiple-input multiple-output (LS-MIMO) relaying system in presence of a passive eavesdropper. The benefits of an AF LS-MIMO relay are exploited to significantly improve the secrecy performance, especially the secrecy energy efficiency (bit per Joule). We first analyze the impact of transmit power at the relay on the secrecy outage capacity, and prove that the secrecy outage capacity is a concave function of transmit power under very practical assumptions, i.e. no eavesdropper channel state information (CSI) and imperfect legitimate CSI. Then, we propose an energy-efficient power allocation scheme to maximize the secrecy energy efficiency. Finally, simulation results validate the advantage of the proposed energy-efficient scheme compared to the capacity maximization scheme.