IEEE Access Special Section Editorial: Emerging Trends of Energy and Spectrum Harvesting Technologies

Billions of low-end wireless devices, such as sensors, are permeating into almost every aspect of personal life, such as vehicles, washing machines, and air conditioners. These miniaturized and low-end devices are a promising solution to collect information and assist users in interacting with real-world objects. Frost and Sullivan reported that the global market of miniaturized devices is forecast to increase from 1.4 billion to 3.26 billion from 2014 to 2024. Unfortunately, the performance of miniaturized devices, which generally operate with limited battery power and transmit data over an unlicensed spectrum, is highly deteriorated due to resource scarcity issues in terms of energy and spectrum. The energy scarcity issue limits the longevity of devices and requires the operator to manually replace the depleted battery, which results in considerable maintenance costs. Even with sufficient energy supply, data transmission conflicts with other networks that coexist in the unlicensed spectrum band, leading to spectrum scarcity issues. To alleviate these energy and spectrum scarcity issues, numerous energy and spectrum harvesting technologies have emerged, such as mini solar panels, piezoelectric transducers, and cognitive radio. By embedding these modules, the devices can harvest energy from the ambient energy sources and explore the idle licensed spectrum for data transmission, leading to energy and spectrum harvesting-enabled devices.