Transmitter Selection for Secrecy in a Frequency Selective Fading Channel with Unreliable Backhaul

TL;DR

This paper investigates transmitter selection strategies to enhance physical layer security in frequency selective channels with unreliable backhaul links, analyzing the impact of backhaul knowledge on secrecy outage probability.

Contribution

It introduces both optimal and sub-optimal transmitter selection schemes considering backhaul reliability, providing closed-form secrecy outage probability expressions and insights into their performance trade-offs.

Findings

Optimal scheme significantly improves secrecy performance with backhaul knowledge.

Sub-optimal scheme offers reduced complexity and feedback overhead.

Closed-form expressions for secrecy outage probability are derived.

Abstract

In this paper, a communication network using single carrier with cyclic prefix modulation over frequency selective channels is considered, where an access point provides connectivity to a legitimate destination through multiple transmitters with unreliable backhaul links in the presence of an eavesdropper. A sub-optimal and an optimal transmitter selection scheme are proposed to improve the secrecy of the system, depending on whether the active backhaul channel knowledge is available a priori or not. The secrecy outage probability (SOP) and its asymptotic limit are presented in closed-form. This provides some insights regarding how knowledge of the active backhaul links affects the secrecy performance of the network. Our results show that the optimal transmitter selection scheme obtains a larger benefit than the sub-optimal scheme from the knowledge of the active backhaul links, resulting in a significantly improved system performance; however, the sub-optimal transmitter selection scheme can reduce the complexity and feedback overhead.