Internet of Things (IoT) is a perfect candidate to realize efficient observation and management for Smart City concept. This requires deployment of large number of wireless devices. However, replenishing batteries of thousands, maybe millions of devices may be hard or even impossible. In order to solve this problem, Internet of Energy Harvesting Things (IoEHT) is proposed. Although the first studies on IoEHT focused on energy harvesting (EH) as an auxiliary power provisioning method, now completely battery-free and self-sufficient systems are envisioned. Taking advantage of diverse sources that the concept of Smart City offers helps us to fully appreciate the capacity of EH. In this way, we address the primary shortcomings of IoEHT; availability, unreliability and insufficiency by the Internet of Hybrid Energy Harvesting Things (IoHEHT). In this work, we survey the various EH opportunities, propose an hybrid EH system, and discuss energy and data management issues for battery-free operation. We mathematically prove advantages of hybrid EH compared to single source harvesting as well. We also point out to hardware requirements and present the open research directions for different network layers specific to IoHEHT things for Smart City concept.

Electric-field energy harvesting (EFEH) can be denoted as an emerging and promising alternative for selfsustainable next-generation wireless sensor networks (WSNs). Unlike conventional harvesting methods that rely on ambient variables, EFEH provides more reliable and durable operation as it is operable with any voltage-applied conductive material. It is therefore better suited for advanced throughput and quality-ofservice (QoS) required applications. In this article, we introduce this newly-emerging WSN paradigm, and focus on enabling EFEH technology for Smart Grid (SG) architectures, such as home; building; and near area networks (HANs, BANs, and NANs), where the field intensity is relatively low. To this end, a practical methodology and a general use implementation framework has been developed for low-voltage applications by regarding compelling design issues and challenging source scarcity. The proposed double-layer harvester model is experimentally evaluated. Its performance in terms of implementation flexibility; sensor lifetime, and communication throughput is investigated. In addition, current challenges, open issues and future research directions are discussed for the design of more enhanced EFEH wireless networks.

Extensive use of amateur drones (ADrs) poses threat to the public safety for their possible misuse. Hence, surveillance drones (SDrs) are utilized to detect and eliminate potential threats. However, limited battery, and lack of efficient communication and networking solutions degrade the quality of surveillance. To this end, we conceptualize Energy Neutral Internet of Drones (enIoD) to enable enhanced connectivity between drones by overcoming energy limitations for autonomous and continuous operation. Power provisioning with recharging stations is introduced by wireless power transfer (WPT) to energize the drones. Renewable energy harvesting (EH) is utilized to realize energy neutrality, which is minimization of deficit in harvested and consumed energy in enIoD. Communication and networking architectures and protocols for realization of multidimensional objectives are presented. Finally, possible application areas are explained with a case study to show how enIoD operates.

No abstract

Widespread and pervasive IoT adoption is threatened by finite-capacity batteries of wireless devices. To mitigate this issue, energy harvesting (EH) and wireless power transfer (WPT), in addition to energy-efficient communication techniques, have been widely explored. Although these efforts achieved longevity to some extent, ever-evolving IoT services seek fully autonomous things without energy constraints. To meet this demand and relieve the ongoing networking challenges, we propose a new concept called the Internet of MIMO Things (IoMIMO). The IoMIMO envisions a self-sufficient architecture that adopts only single-and double-hop energy and data transitions to enable efficient energy sharing and reduced data traffic in networks. In particular, single-hops are performed by hybrid access points (HAPs), while relaying via double-hops are actuated by unmanned aerial vehicles (UAVs). The HAPs will handle multiple-input and multiple-output (MIMO) of energy and data, and coordinate their transitions between the network components in a concurrent and automated manner. Benefiting from the recent advances in multi-source EH, WPT, and UAVs, the IoMIMO can fulfill Smart City services without being limited by energy and networking challenges. Device types specialized for the IoMIMO, and their operation modes are evaluated in a simple network scenario to clearly explain the principles and the potential benefits of the envisioned concept. Future research directions are also identified to ease the realization of such a next-generation networking architecture.