M2WPT - a large-scale Multi-antenna Multi-sine Wireless Power Transfer architecture

Wireless power transfer (WPT) via radio-frequency (RF) radiation has long been regarded as a possibility for energising low-power devices in the internet of things. It is, however, not until recently that WPT has become recognised as feasible, due to reductions in power requirements of electronics. Far-field WPT using RF could be used for long range power delivery to increase user convenience. In the same way as wireless disrupted communication, WPT using RF is expected to disrupt the delivery of energy.
The real challenge with far field WPT is to find ways to increase the DC power level at the energy harvester output without increasing the transmit power, and to ensure that sufficient range between transmitter and receiver can be achieved.
The project relies on the observation that far-field WPT RF-to-DC conversion efficiency is a function of the rectenna design but also of its input waveform. A proper design of far-field WPT therefore requires a complete transmitter-receiver optimization rather than just the receiver (rectenna) design. Unfortunately state of the art waveforms have been shown partially disappointing for far-field WPT. The fundamental question behind the project is "can we design a disruptive but practical WPT transceiver architecture to make wireless power transfer a reality at distances of tens (if not more) of meters within regulated transmit power levels?"
This visionary project, conducted at Imperial College London, will uniquely leverage signal processing tools to tackle a problem commonly investigated by the RF community. Motivated by recent results by the PI and Co-I and leveraging a unique set of complementary skills on multi-antenna signal processing (Clerckx) and WPT/rectenna design (Mitcheson), the project will design and show the feasibility of a disruptive M2WPT architecture based on optimized, adaptive and reliable large-scale multi-antenna multi-sine waveforms for single-user and multi-user scenarios, and identify its potential for far-field WPT. Thinking big, we advocate in this project that M2WPT will be to WPT what massive MIMO is to communication. M2WPT will enable highly efficient far-field WPT delivering sufficient power at long range for a wide range of applications.
To put together this novel M2WPT solution in a credible fashion, this project focuses on 1) designing and modelling the energy harvester, 2) designing large-scale multi-sine multi-antenna waveforms for single and multi-user scenarios, 3) demonstrate the feasibility through experiment and measurement.
The project will be performed in partnership with two leaders in equipment manufacturing and WPT standardization (Toshiba and Keysight), two well-established academic/research centres active in WPT (KULeuven and Eindhoven/IMEC) and the UK Office of the Chief Science Adviser. The project demands a strong and inter-disciplinary track record in microwave theory and techniques, circuit design, optimization theory, multi-antenna signal processing, wireless communication and it is to be conducted in a unique research group with a right mix of theoretical and practical skills. With the above and given the novelty and originality of the topic, the research outcomes will be of considerable value to transform the future of wireless networks supplied by remote wireless charging and give the industry a fresh and timely insight into the development of highly efficient remote wireless charging, advancing UK's research profile of wireless power in the world. Its success would radically change the design of radiative WPT, have a tremendous impact on standardization, and applications in a large number of sectors including building automation, healthcare, telecommunications, ICT, structural monitoring, consumer electronics.

Besides the academic beneficiaries, the project will benefit a much wider audience and have potential economic and societal impacts:
1) Wireless networks are expected to have applications in developed and emerging markets and a large number of sectors, e.g. building automation, healthcare (health monitoring), telecommunications, smart grid, structural monitoring, consumer electronics, military, etc. All those new applications will in the long term enhance the economic competitiveness of the UK and the quality of life of its residents. Reliable power supply remains a significant barrier to the adoption of the internet of things.
2) Given the enormous interest for wireless power and high speed communications (as evidenced by WPC, PMA, A4WP, 3GPP and IEEE standards), the project has a bright future to benefit the industry sector active in the area of wireless power transfer, energy harvesting, communication equipment manufacturing and standards. By benefiting from our industry partners Toshiba and Keysight, Toshiba's involvements in standards and by Dr. Clerckx's general experience in standardization, the project is expected to lead to several contributions in early standards creation on radiative WPT.
3) Supported by the UK Home Office (Office of the Chief Science Adviser), the project will also benefit the regulators and actors involved with policy implementations in the wireless sector and give them the opportunity to understand the benefits and feasibility of far-field WPT.
4) It is an absolute requirement to understand how to reduce ambient RF pollution and make our network greener and more energy efficient. Any additional transmission for the purposes of power transfer must not swamp existing communication systems, or cause them to boost their transmit power, in turn causing them to need additional power supply. Power transmission in an existing communication band would cause interference, but communication receivers could reject the noise from the power transmission due to the deterministic nature of the multi-sine, or alternatively the power transmission could be done in a separate band. Ultimately, M2WPT based on large scale multi-antenna and multi-sine waveforms will make a better use of the transmit power, and achieve significantly higher RF to DC conversion efficiency allowing lower transmit power than conventional approaches and could enable larger scale energy savings through deployment of the internet of things. The project will therefore also benefit researchers, policy makers, and government agencies active in understanding how technologies could be designed to make our environment greener.