Physical Layer Security with Uncoordinated Helpers Implementing Cooperative Jamming
This addresses physical layer security for wireless networks, offering a practical, low-cost solution for scenarios like military or private communications, though it is incremental as it builds on existing cooperative jamming methods.
The paper tackles the problem of securing wireless communication against eavesdropping by using helpers with two antennas to implement cooperative jamming, deriving optimal jamming noise structures and showing that a simpler nulling scheme performs near-optimally with minimal performance loss.
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.