Full-Duplex Wireless-Powered Relay with Self-Energy Recycling (1411.3061v1)

Abstract: This letter studies a wireless-powered amplify-and-forward relaying system, where an energy-constrained relay node assists the information transmission from the source to the destination using the energy harvested from the source. We propose a novel two-phase protocol for efficient energy transfer and information relaying, in which the relay operates in full-duplex mode with simultaneous energy harvesting and information transmission. Compared with the existing protocols, the proposed design possesses two main advantages: i) it ensures uninterrupted information transmission since no time switching or power splitting is needed at the relay for energy harvesting; ii) it enables the so-called self-energy recycling, i.e., part of the energy (loop energy) that is used for information transmission by the relay can be harvested and reused in addition to the dedicated energy sent by the source. Under the multiple-input single-output (MISO) channel setup, the optimal power allocation and beamforming design at the relay are derived. Numerical results show a significant throughput gain achieved by our proposed design over the existing time switching-based relay protocol.

• The paper introduces a full-duplex AF relay system leveraging self-energy recycling to enable uninterrupted information transmission and outperform traditional TSR protocols.
• It employs rigorous analytical derivations for optimal power allocation and beamforming under MISO channels to maximize end-to-end throughput.
• The approach offers practical benefits for energy-constrained IoT and wireless networks by enhancing power efficiency and communication reliability.

Overview of Full-Duplex Wireless-Powered Relay with Self-Energy Recycling

This paper by Yong Zeng and Rui Zhang introduces an innovative wireless-powered amplify-and-forward (AF) relaying system employing full-duplex technology to enhance simultaneous wireless information and power transfer (SWIPT). The paper explores a two-phase protocol where an energy-constrained relay node operates in full-duplex mode, simultaneously handling information transmission and energy harvesting without the need for time switching or power splitting techniques typically used in half-duplex systems.

Key Innovations and Contributions

The research presents two notable enhancements over established time-switching-based relaying (TSR) and power-splitting-based relaying (PSR) protocols:

1. Uninterrupted Information Transmission: By functioning in full-duplex mode, the relay achieves continuous data transmission, eliminating the need for alternation between energy harvesting and information forwarding stages.
2. Self-Energy Recycling: Integrating a unique concept where the self-interfering energy loop created at the relay is harnessed and reused, effectively elevating the relay's power utilization without requiring additional external power.

The authors provide detailed analytical derivations for the optimal power allocation and beamforming strategy under the multiple-input single-output (MISO) channel configuration, aiming at maximizing the end-to-end throughput of the relay system. They rigorously compare these results against existing TSR protocols.

Numerical Results and Implications

The numerical results underscore significant throughput enhancements attributable to the proposed full-duplex relay protocol, marking a substantial improvement over traditional TSR mechanisms with optimal time allocation. This performance boost is primarily facilitated by the dual benefits of self-energy recycling and uninterrupted information transmission, demonstrating its potential to significantly mitigate the limitations posed by energy-constrained relay nodes.

Theoretical and Practical Implications

The findings offer both theoretical insights and practical implications:

• Theoretical Advancement: The paper extends the understanding of SWIPT by exploring the advantageous use of self-interference for energy recycling, providing a novel dimension to the existing literature on wireless energy transfer.
• Practical Application: In practical scenarios, such as IoT networks or other low-energy wireless communication systems, implementing this model could drastically enhance their operational efficiency and sustainability.

Future Directions

While this paper sets a foundation for leveraging full-duplex wireless relaying with self-energy recycling, several future directions can be considered:

• Extension to Alternative Channel Models: Investigating varying channel conditions beyond MISO could provide broader applicability and deeper insights into different network scenarios.
• Integration with Advanced Interference Cancellation: Combining self-energy recycling protocols with advanced interference cancellation techniques could further optimize performance, possibly addressing any remaining self-interference challenges more comprehensively.

Overall, this research adds a meaningful piece to the ongoing development of energy-efficient wireless communication networks, proposing new methodologies with promising merit for both academic inquiry and real-world application.