Wireless Information and Power Transfer

2Fundamentals of Signal Design for WPT and SWIPT

Bruno Clerckx* and Morteza Varasteh

Department of Electrical and Electronic Engineering, Imperial College London, United Kingdom

2.1 Introduction

Standardized wireless communication systems based on radio frequency (RF) radiation are one of the important technologies in our modern societies. However, demand growth for using wireless‐based applications has made the spectral efficiency a bottleneck for this technology. Moreover, the emergence of low‐power autonomous wireless devices, such as ubiquitous sensing through wireless sensor networks (WSN) or an Internet‐of‐Things (IoT), has made the powering of such devices another challenge for the next generation 5G mobile networks. One solution for this powering problem is wireless power transfer (WPT). Indeed for very short ranges, WPT via inductive power is a reality with available products and standards, such as the Wireless Power Consortium, Power Matters Alliance, Alliance for Wireless Power, and Rezence. For long distances (1 m and beyond), though, far‐field or radiative WPT¹ is a promising technology that has attracted growing attention, motivated by the increase in the electrical efficiency of computer technology [1].

In general, one can either harvest ambient wireless energy (known as wireless energy harvesting, WEH) or transmit dedicated signals (simply denoted as WPT throughout this chapter). In the case of WEH, the aim is to harvest the ambient energy of the RF signals ...