New Radio Concept for Far Field Communication

Abstract

This thesis explores the state-of-the-art methods for the optimization of Wireless Power Transfer (WPT) for Radio Frequency (RF) energy harvesting with a view of increasing the efficiency of the Radio Frequency to Direct Current (RF-to-DC) conversion, which is a key parameter in the creation of Zero Energy Devices (ZEDs) in the context of Internet of Things (IoT). The research focuses on waveform shaping at the transmitter side as a technique of enhancing energy delivered to rectifiers. To achieve this, the project proposes to define arbitrary waveforms with high Peak-to-Average Power Ratio (PAPR) so as to direct more energy to the peaks of the waveform in order to enhance the rectification efficiency.

The study proposes multisine signals as a reference signal and these signals have higher PAPR compared to other signals. These signals are then processed by windowing techniques like Gabor pulses and raised cosine windows thereby increasing PAPR and in turn enhancing the efficiency of the RF-to-DC conversion. The work uses theoretical modeling, simulation, and experimental testing to show that the proposed waveform shaping strategies enhance rectifier performance. It has been proved that these waveform shaping pulses that can be applied to Far Field Communication (FFC) concerns enhance the rectified DC power in order to feed any type of passive device.

For the purpose of practical relevance, the thesis also provides the design and setup of a realistic test environment to evaluate the proposed ideas in a realistic setting. The experimental results also prove the efficiency of these techniques in improving the RF-to-DC conversion efficiency and the potential of energy harvesting technologies.

Popular Abstract

As the future wears on and low-power devices and Internet of Things (IoT) start to assume a greater role in our lives, things are going to change spectacularly. Consider how nicest would a smart thermostat, health monitor, or environmental sensor be, if only it would work without ever needing to change the batteries or plug into a wall. This is becoming a reality with the deployment of devices in environments where traditional power is either impracticable or unavailable. The urgent need linked with this shift is for innovative, sustainable manners of powering them.

Energy harvesting, in particular from radio frequency signals impregnating our environment, constitutes one of the most promising solutions. The system makes a lot more sense for IoT devices, as most of them operate autonomously for fairly long times. All these Radio Frequency (RF) signals are in our vicinity; they emanate from our mobile phones, from Wi-Fi routers, or even broadcast towers. By tapping these omnipresent signals, low-energy devices with no batteries or other external power supplies can be powered, called Zero Energy Devices (ZEDs).

Energy harvesting itself is nothing new; decades of research have been devoted to it, but its application to RF signals in IoT definitely stands at the bleeding edge. Generally speaking, energy harvesting is the process of capturing ambient energy-light, heat, or radio waves and converting it into electrical power that afterwards can serve for the function of powering an electronic device.

This concept is of great interest to the IoT nodes, which are expected to work autonomously for a pretty long time. This omnipresent RF signals we are talking about can be used to grant operation to low-energy devices with no classic batteries or external power supply. Considering the next step beyond, one may provide for Zero Energy Devices, or full self-sustainability. To put this into perspective, consider how far we have come: the development of wireless communication systems represents arguably one of the most revolutionary developments in the last hundred years or so-from early radio days to deployment of mobile networks across the globe. An invisible web of RF signals blankets much of this planet today. This RF energy, originally considered just a byproduct of communication, has been receiving attention as a useful resource that can be captured and converted to supply power in the next generation of IoT devices.

Wireless Power Transfer (WPT) may be defined as an energy harvesting system at the core of which lies the process of transmitting energy wirelessly over a short distance and then converting the energy into usable electrical power. The key challenge in WPT systems is improving the conversion efficiency of an RF signal to direct current, which is to be utilized for electronic device powering. It normally takes place with the help of a device called a rectifier, which converts the RF signal Alternating Current (AC) into Direct Current (DC) utilized by the electronics. However, it is important to have maximum efficiency in this RF-to-DC conversion, since any loss in the process will directly reduce the amount of power made available to the device.

• author: Undiano Ustarroz, Mikel
• supervisor: Pietro Andreani
• organization: Department of Electrical and Information Technology
• alternative title: Nytt Radiokoncept för Fjärrfältskommunikation
• course: EITM02 20241
• year: 2024
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: RF Energy Harvesting, Wireless Power Transfer, RF-to-DC, Waveform Shaping, PAPR, Rectenna
• report number: LU/LTH-EIT 2024-1019
• language: English
• id: 9176343
• date added to LUP: 2024-10-16 10:51:40
• date last changed: 2024-10-16 10:51:40