Physical Layer Security with Uncoordinated Helpers Implementing Cooperative Jamming

TL;DR

This paper explores how helpers with two antennas can improve wireless security by transmitting noise to confuse eavesdroppers, deriving optimal and nulling strategies, and showing that simple nulling performs nearly as well as complex optimal solutions.

Contribution

It introduces a method for helpers with two antennas to implement cooperative jamming, deriving the optimal noise structure and analyzing a simpler nulling approach.

Findings

Nulling noise is nearly as effective as optimal noise in secrecy rate.

Helpers with two antennas can significantly enhance security through cooperative jamming.

Nulling scheme requires only local link information, simplifying implementation.

Abstract

A wireless communication network is considered, consisting of a source (Alice), a destination (Bob) and an eavesdropper (Eve), each equipped with a single antenna. The communication is assisted by multiple helpers, each equipped with two antennas, which implement cooperative jamming, i.e., transmitting noise to confound Eve. The optimal structure of the jamming noise that maximizes the secrecy rate is derived. A nulling noise scenario is also considered, in which each helper transmits noise that nulls out at Bob. Each helper only requires knowledge of its own link to Bob to determine the noise locally. For the optimally structured noise, global information of all the links is required. Although analysis shows that under the two-antenna per helper scenario the nulling solution is sub-optimal in terms of the achievable secrecy rate, simulations show that the performance difference is rather small, with the inexpensive and easy to implement nulling scheme performing near optimal.