Artificial-Noise-Aided Transmission in Multi-Antenna Relay Wiretap Channels with Spatially Random Eavesdroppers

TL;DR

This paper proposes a secure multi-antenna relay transmission scheme with artificial noise to protect against spatially random eavesdroppers, providing analytical expressions for outage probabilities and optimizing secrecy throughput.

Contribution

It introduces a comprehensive analytical framework for secure relay communication with artificial noise, considering arbitrary antenna configurations and spatially random eavesdroppers.

Findings

Closed-form expressions for outage probabilities.

Asymptotic analysis for large antenna numbers.

Optimal system parameters for maximizing secrecy throughput.

Abstract

We design a new secure transmission scheme in the relay wiretap channel where a source communicates with a destination through a decode-and-forward relay in the presence of spatially random-distributed eavesdroppers. For the sake of practicality, we consider a general antenna configuration in which the source, relay, destination, and eavesdroppers are equipped with multiple antennas. In order to confuse the eavesdroppers, we assume that both the source and the relay transmit artificial noise signals in addition to information signals. We first derive a closed-form expression for the transmission outage probability and an easy-to-compute expression for the secrecy outage probability. Notably, these expressions are valid for an arbitrary number of antennas at the source, relay, and destination. We then derive simple yet valuable expressions for the asymptotic transmission outage probability and the asymptotic secrecy outage probability, which reveal the secrecy performance when the number of antennas at the source grows sufficiently large. Using our expressions, we quantify a practical performance metric, namely the secrecy throughput, under a secrecy outage probability constraint. We further determine the system and channel parameters that maximize the secrecy throughput, leading to analytical security solutions suitable for real-world deployment.