Zero-forcing beamforming for physical layer security of energy harvesting wireless communications

Fengchao Zhu,Feifei Gao,Minli Yao

doi:10.1186/s13638-015-0278-5

Abstract

Abstract In this paper, we consider the physical layer security for simultaneous wireless information and power transfer (SWIPT) in a multiple-input single-output (MISO) system that is consisted of three nodes: one transmitter with multiple antennas, one information decoding (ID) receiver with single antenna, and one energy harvesting (EH) receiver with single antenna. We propose a new zero-forcing based strategy that contains both the information beamforming and the energy beamforming, pointing to different receivers. To prevent the energy receiver from possibly eavesdropping the information, our target is to maximize the secrecy-rate of the ID receiver while at the same time maintaining a minimum required energy for the EH receiver. For the case that artificial noise is not used, the original non-convex problem can be directly converted into convex subproblems, where the closed-form optimal solutions are derived. For the case that artificial noise is used, the initial non-convex problem can be decomposed into two quasi-convex subproblems where closed-form solutions are derived, and the global optimal solutions are obtained with the aid of one-dimensional search. Simulations results demonstrate the trade-off between the maximum secret information rate and the transferred energy, which is characterized by the boundary of secret rate-energy (R-E) region.

Highlights

Since radio-frequency (RF) signals that carry information can, at the same time, be used for transporting energy, simultaneous wireless information and power transfer (SWIPT) is made possible in energy-constrained wireless networks and has become an interesting research area recently [1,2,3,4,5].In [1], Varshney proposed a capacity-energy function for SWIPT, where a fundamental trade-off between the energy and the reliable information transmitted over a single noisy line is studied
We study information secrecy of SWIPT using zero-forcing beamforming which has lower computational complexity than the algorithm proposed in [26]
We designed zero-forcing-based joint information beamforming and energy beamforming to maximize the secret rate under the transmit power constraint and the energy harvesting constraint

Summary

Introduction

Since radio-frequency (RF) signals that carry information can, at the same time, be used for transporting energy, simultaneous wireless information and power transfer (SWIPT) is made possible in energy-constrained wireless networks and has become an interesting research area recently [1,2,3,4,5].In [1], Varshney proposed a capacity-energy function for SWIPT, where a fundamental trade-off between the energy and the reliable information transmitted over a single noisy line is studied. The physical layer security for SWIPT system was first studied in [26], where secret information beamforming vector and artificial noise transmit covariance were designed. The feasibility problem For the case that there is no ID receiver, Tx can use its whole power to satisfy the EH receiver’s energy constraint in Equation 5.

Results

Conclusion