Transmitter Selection for Secrecy in Cognitive Small-Cell Networks with Backhaul Knowledge

TL;DR

This paper investigates transmitter selection strategies in cognitive small-cell networks with unreliable backhaul links to enhance secrecy, deriving outage probabilities and demonstrating performance improvements with backhaul knowledge.

Contribution

It introduces both optimal and sub-optimal transmitter selection schemes that leverage backhaul link knowledge to improve secrecy performance in cognitive small-cell networks.

Findings

Secrecy outage probability is reduced with backhaul knowledge.

Asymptotic expressions for outage probabilities are derived.

Performance gains are significant compared to no backhaul knowledge.

Abstract

A small-cell network with multiple transmitters and unreliable wireless backhaul is considered for secrecy enhancement. The small-cell network is operating under a spectrum sharing agreement with a primary network in a cognitive radio system. A constraint on the desired outage probability at the primary receiver is assumed as a part of the spectrum sharing agreement. The reliability of the wireless backhaul links are modeled by a set of independent and identically distributed Bernoulli random variables. A sub-optimal and an optimal small-cell transmitter selection (TS) scheme is proposed to improve the performance of the system, depending on the availability of channel state information. Selection schemes are designed for the scenario where knowledge is available regarding which backhaul links are active. The corresponding secrecy outage probabilities along with their asymptotic expressions are derived. It is shown that the secrecy performance is significantly improved compared to the case where knowledge of the active backhaul links is unavailable.