On the Secrecy Rate Maximization With Uncoordinated Cooperative Jamming by Single-Antenna Helpers

A practical uncoordinated cooperative jamming (UCJ) scheme is proposed in this paper to enhance the physical layer security of the single-input-single-output (SISO) wiretap channel. Differing from the existing works, all the helpers in this UCJ scheme are uncoordinated single-antenna uplink users, and each helper transmits a jamming signal independently to confound the eavesdropper. The intended receiver plays the role of base station in the cellular systems as well as a control center to properly allocate the jamming power of each helper to maximize the secrecy rate. Two cases are addressed in solving the secrecy rate maximization problem, namely, the global channel state information (CSI) case and the partial CSI case. The optimal solution is obtained in the global CSI case, and a near-optimal solution is obtained under the secrecy outage probability constraint in the partial CSI case. Numerical results show that the performance of the proposed scheme is comparable with the existing works.