Communications and Signals Design for Wireless Power Transmission (1611.06822v1)

Abstract: Radiative wireless power transfer (WPT) is a promising technology to provide cost-effective and real-time power supplies to wireless devices. Although radiative WPT shares many similar characteristics with the extensively studied wireless information transfer or communication, they also differ significantly in terms of design objectives, transmitter/receiver architectures and hardware constraints, etc. In this article, we first give an overview on the various WPT technologies, the historical development of the radiative WPT technology and the main challenges in designing contemporary radiative WPT systems. Then, we focus on discussing the new communication and signal processing techniques that can be applied to tackle these challenges. Topics discussed include energy harvester modeling, energy beamforming for WPT, channel acquisition, power region characterization in multi-user WPT, waveform design with linear and non-linear energy receiver model, safety and health issues of WPT, massive MIMO (multiple-input multiple-output) and millimeter wave (mmWave) enabled WPT, wireless charging control, and wireless power and communication systems co-design. We also point out directions that are promising for future research.

• The paper introduces novel communication strategies that optimize radiative wireless power transfer using energy beamforming.
• It demonstrates the application of massive MIMO for precise channel estimation and improved power conversion efficiency.
• The study outlines future research directions for integrating wireless power with next-generation networks while ensuring safety compliance.

Analyzing Advances in Wireless Power Transmission Design

The paper "Communications and Signals Design for Wireless Power Transmission" by Yong Zeng, Bruno Clerckx, and Rui Zhang provides a comprehensive exploration of wireless power transfer (WPT), detailing the technological advancements and research directions in this area. The authors focus on the contrast between WPT and more traditional wireless communication, discussing both the challenges involved and the potential for innovation in WPT systems.

WPT technologies, as outlined, range from near-field methods such as inductive and magnetic resonant coupling to far-field solutions like electromagnetic radiation and laser power beaming. The comparison among these techniques illustrates a trade-off between efficiency, range, and practical applications, with implications for various industries, from biomedical implants to electric vehicles and consumer electronics. The authors convey a historical context that traces the development of these technologies from early experiments by pioneers such as Heinrich Hertz and Nicola Tesla to modern applications.

Radiative WPT stands out as particularly noteworthy due to its capability to power devices over long distances without the need for close alignment or contact. This flexibility makes it a candidate for powering consumer electronics wirelessly and achieving significant societal and environmental benefits. However, the design challenges in radiative WPT are formidable given considerations like channel acquisition, electromagnetic compatibility, and the power conversion efficiency at both the transmission and reception points.

The paper explores signal design and energy beamforming, crucial for maximizing the efficiency of radiative WPT systems. Massive MIMO (multiple-input multiple-output) technology emerges as a promising enabler by enhancing directed transmission capabilities, albeit with a need for effective channel estimation and control methodologies to manage complex multi-path environments typical of practical deployments.

Numerical results suggest that proper alignment between transmit waveform and rectifier non-linearity can significantly enhance power transfer efficiency. Furthermore, the research underscores the importance of adopting advanced communication strategies and exploiting the inherent non-linear characteristics of energy harvesters to realize efficient WPT systems. These considerations are pivotal as wireless charging expands beyond low-power devices to include broader applications.

For a full utilization of WPT across varied use cases, the authors emphasize the need for a pragmatic approach to safety and health, given the exposure to electromagnetic fields. This necessitates ensuring compliance with exposure limits, as delineated in guidelines such as SAR (Specific Absorption Rate) and MPE (Maximum Permissible Exposure). Research in distributed antenna systems and the use of real-time feedback loops may provide pathways to safely enhance WPT technologies.

This paper serves as a visionary perspective on WPT. It identifies future research challenges and potential breakthroughs, looking toward integration with 5G technologies and millimeter wave communications. Significantly, this focus points to the possibility of redefining the landscape of wireless networks by incorporating WPT principles alongside traditional communication pathways, enabling systems that are both power-efficient and versatile.

The progression of WPT research detailed here is impressive, and as more questions are answered, the potential societal benefits of wireless power transfer—ranging from extended device autonomy to sustainable energy practices—make this an exciting area for continued investigation. The blend of communication theory and practical energy transference considerations will likely form the core of ongoing research in this evolving field.