Transmitter Selection for Secrecy in Frequency-Selective Fading with Multiple Eavesdroppers and Wireless Backhaul Links

TL;DR

This paper analyzes the secrecy performance of transmitter selection schemes in frequency-selective fading channels with multiple eavesdroppers, considering unreliable backhaul links and different knowledge scenarios, providing closed-form and asymptotic expressions.

Contribution

It introduces new closed-form and asymptotic expressions for secrecy outage probability and ergodic secrecy rate considering backhaul unreliability and knowledge scenarios.

Findings

Secrecy performance depends on the number of transmitters and backhaul reliability.

Backhaul knowledge affects the influence of backhaul reliability on secrecy metrics.

Secrecy diversity order is the same for both selection schemes when all backhaul links are active.

Abstract

This paper investigates the secrecy performance of sub-optimal transmitter selection (SS) and optimal selection (OS) schemes in a system comprising multiple transmitters, multiple eavesdroppers, and a single destination in frequency-selective fading channels with single carrier cyclic prefix modulation. Considering unreliable backhaul links between the access point and the transmitters, we analyze secrecy performance in two scenarios: when backhaul activity knowledge is available (KA) and when backhaul activity knowledge is unavailable (KU). Closed-form expressions for the secrecy outage probability (SOP) and ergodic secrecy rate (ESR) are derived. We also provide the corresponding asymptotic expressions when the backhaul links are unreliable as well as when the backhaul links are active in both KA and KU scenarios. We show that in the backhaul KA scenario, the asymptotic SOP and the slope of the ESR are governed by the number of transmitters and the backhaul reliability factor. In contrast, only the backhaul reliability factor influences these two parameters in the backhaul KU scenario. These parameters are independent of the number of eavesdroppers in both backhaul KA and KU scenarios. We also observe that the secrecy diversity order of both selection schemes is identical when all backhaul links are active.