Performance of passive UHF RFID in cascaded correlated generalized Rician fading

Ultra high frequency radio frequency identification (UHF RFID) systems can use passive tags to reflect the signal from the reader’s transmitting antenna back to the reader’s receiving antenna for information delivery. This gives a cascaded channel that is a product of two fading components. In this work, the probability of detection, defined as the probability that the received power is above the receiver sensitivity, is derived when the two fading components suffer from correlated generalized Rician fading. This includes the Rayleigh, Rician and Nakagamim channels in the literature as special cases. Numerical results are presented to show the effects of link distances, receiver sensitivities and channel parameters on the detection probability

Analysis of energy transfer efficiency in UAV-enabled wireless networks

Wireless power transfer (WPT) is a promising charging technology for battery-limited sensors. In this paper, we study the energy transfer in a wireless network using an unmanned aerial vehicle (UAV). Instead of charging the remote wireless sensors directly from the access point (AP), we study the schemes of using a UAV to charge the remote wireless sensors after it is charged by the AP. To this end, two schemes are proposed. The performances of these two schemes are examined and compared with the conventional scheme without using a UAV. A distance threshold beyond which the new schemes have superiority over the conventional scheme is derived by solving energy equations. Numerical results show that the proposed schemes can achieve significantly higher energy efficiency than the conventional scheme when the transmission distance is within the derived critical range

UAV-enabled wireless power transfer with base station charging and UAV power consumption

Wireless power transfer (WPT) is a promising charging technology for battery-limited sensors. In this paper, we study the use of an unmanned aerial vehicle (UAV) as a charger for WPT. Unlike the previous works, our study takes into account the power consumption of the UAV (power consumption during hovering and flight), the charging process from a base station (BS) to the UAV and the conversion loss of the energy harvester. Both one-dimensional (1D) and two-dimensional (2D) WPT systems are considered. The sum-energy received by all sensors is maximized to find the optimal strategy for UAV deployment. Two different charging schemes are proposed. Numerical results show that the sum-energy received by all sensors is determined by sensors' topology, the flight speed of the UAV and the transmit power. They also show that, when the BS charging process and the UAV power consumption are considered in the optimization, the optimal location of the UAV in the 1D and 2D WPT systems is closer to the BS than in the previous works that ignore these two practical factors

Wireless powered communication networks using peer harvesting

For an energy-constrained wireless network, energy harvesting (EH) is a promising technology to prolong the network life. Whether traditional near-field wireless power transfer (WPT) using inductive and resonant coupling or far-field WPT via radiated electromagnetic waves, both of them draw considerable research interests these years [1], [2]. In particular, the far-field WPT is meaningful for wireless powered communication (WPC) networks. A fundamental tradeoff was first studied for simultaneous wireless information and power transfer (SWIPT) in [3], [4]. These results aroused the interest of researchers. Subsequently, wireless communication with EH technology was presented in [5], [6]

High Resolution Technology in Digital Imaging and its Remote Sensing Applications

Remote Sensing is a markable achievement in- last century. High resolution is a vital technol- ogy to digital image characteristics. Especially, in recent 20 years, digital technology promotes the development of spatial information field. As the increasing requirement of people, achieving high resolution images is urgent. For this target, we work from four parts: spatial resolution, ra- diant resolution, spectral resolution, temporal resolution and proposed schemes for each of them with different imaging manners, designed several prototype systems and carried out many experiments to verify their feasibilities