Abstract
In this paper, we investigate a robust transmit design in underlay energy harvesting (EH) cognitive radio networks (CRNs), where the malicious energy receivers (ERs) can be treated as potential eavesdroppers (Eves) due to their ability of wiretapping the desired information. Considering a general case of statistical Eves' channel state information (CSI), to transmit signals in a secret and energy-efficient manner, an outage-constrained secrecy energy efficiency (OC-SEE) optimization problem is formulated to design transmit beamforming vectors. The original problem is non-convex and challenging to solve. To make it more tractable, we first rewrite this problem by semi-definite relaxation (SDR), and Bernstein-type inequality (BTI) approach is resorted to conservatively approximate the probabilistic constraints. Then, based on the fractional programming theory, an equivalent parametric reformulation is proposed to convert the original problem into a subtractive form. Furthermore, by introducing auxiliary variables, with the aid of Sphere Bounding method, the tractable solution of this OC-SEE maximization problem can be obtained through solving a two-stage optimization problem. Finally, numerical results are provided to validate the efficacy of the proposed design.
Highlights
Nowadays, the exponential growth of data traffic and mobile computing have brought the increasing demands for wireless communication, such as scarce spectrum resources and energy supply [1]
We provide numerical results to demonstrate the performance of our proposed design
This can be explained by the fact that the secure beamforming is required to be designed to guarantee the secrecy rate of the secondary receiver (SR), which is susceptible to the number of the Eves
Summary
The exponential growth of data traffic and mobile computing have brought the increasing demands for wireless communication, such as scarce spectrum resources and energy supply [1]. As an auspicious approach to simultaneously improving both spectrum efficiency (SE) and energy efficiency (EE) in fifth generation (5G) and beyond wireless networks, the energy harvesting (EH) cognitive radio network (CRN) has recently attracted great research attention [2]. In underlay CRNs, the secondary users (SUs) can use the same spectrum allocated to the. In contrast to other natural-resource EH techniques (such as solar, wind, thermal, etc.), the flexible radio frequency (RF)-based EH technology is more suitable for stable energy provision, especially in energy-constrained wireless communication systems [3]. RF signals have the capability to transfer information and energy through the same electromagnetic waves, which facilitates the implementation of simultaneous wireless information and power transfer (SWIPT) [4]–[6].
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