Ambient RF Energy-Harvesting Technologies for Self-Sustainable Standalone Wireless Sensor Platforms

Wireless Power Transfer for Distributed Estimation in Sensor Networks

“…Exploiting multiple antenna technologies in WPT has been widely studied: multiple-input-multiple-output broadcast channels [8], beamforming designs for multiuser multiple-input-single-output (MISO) [23], physical-layer security problems for multiuser MISO [24], and multiple-antenna interference channels [25]. On the other hand, there are a relatively limited number of studies on WPT for WSNs; different WPT technologies for addressing energy/lifetime problems in WSNs were reviewed in [26], [27]; in [28], the authors studied a distributed estimation system in which some of the multiple-antenna sensors, named super sensors, are capable of WPT to its neighboring sensors via beamforming; and in [29], several multiple-antenna RF-based chargers were used to replenish the wireless sensors and then to switch to the information transmission phase, where each sensor sent a quantized version of its measurement to the FC for estimation.…”

Radio Frequency Energy Harvesting Sources

“…Among these ambient energy sources, there has been a dramatic growth of RF energy harvesting mainly because of the abundant availability of electromagnetic signals such as television/ digital television (TV/DTV) [11][12][13], FM/AM radio [14,15], mobile base stations and mobile phones [16][17][18][19], and Wi-Fi signals [20][21][22][23][24]. The recent interest in RF harvesting has also been driven by the great progress in both wireless communication systems and broadcasting technologies that have availed a lot of freely propagating ambient RF energy [25][26][27][28][29]. While ambient RF sources have a comparably low power density of 0.2 nW/cm 2 to 1 W/cm 2 [26,[30][31] relative to other ambient energy sources such as solar, RF signals have the advantage of being fairly ubiquitous and the associated energy is radiated continuously.…”

“…As we get into the future, and the society gets even more wirelessly interconnected, the number of RF energy sources will continue to increase, especially as the number of mobile subscribers to wireless networks increases. The increase in the number of operating mobile phones, together with Wi-Fi routers, laptops and smartphones will greatly avail electromagnetic signals from which useful electrical energy can be extracted [25][26][27][28][29][30][31][32][33][34]. The ubiquitous ambient RF energy can be extracted and used to charge batteries [27] or energize a multiple range of low-power electronic devices, including wearable smart devices [21], RFID tracking tags [35], and wireless sensor devices [13][14][15]36].…”

Ambient Light Backscatter Communication for IoT Applications

“…Therefore, ambient RF backscatter devices must depend on a relatively large array antenna to fully use weak ambient RF power. By contrast, solar power has a high power density of 100 mW/cm 2 during daytime [4]. Various lighting infrastructures, including white LEDs, have been widely deployed for illumination purposes.…”