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Jaime Duque Domingo, Carlos Cerrada, Enrique Valero, Jose A Cerrada
This work presents an Indoor Positioning System to estimate the location of people navigating in complex indoor environments. The developed technique combines WiFi Positioning Systems and depth maps, delivering promising results in complex inhabited environments, consisting of various connected rooms, where people are freely moving. This is a non-intrusive system in which personal information about subjects is not needed and, although RGB-D cameras are installed in the sensing area, users are only required to carry their smart-phones...
October 20, 2017: Sensors
Eun-Seok Cho, Yongbin Yim, Sang-Ha Kim
Face routing has been adopted in wireless sensor networks (WSNs) where topological changes occur frequently or maintaining full network information is difficult. For message forwarding in networks, a planar graph is used to prevent looping, and because long edges are removed by planarization and the resulting planar graph is composed of short edges, and messages are forwarded along multiple nodes connected by them even though they can be forwarded directly. To solve this, face routing using information on all nodes within 2-hop range was adopted to forward messages directly to the farthest node within radio range...
October 20, 2017: Sensors
Tobias Boxberger, Kevin Fleming, Massimiliano Pittore, Stefano Parolai, Marco Pilz, Stefan Mikulla
The Multi-Parameter Wireless Sensing (MPwise) system is an innovative instrumental design that allows different sensor types to be combined with relatively high-performance computing and communications components. These units, which incorporate off-the-shelf components, can undertake complex information integration and processing tasks at the individual unit or node level (when used in a network), allowing the establishment of networks that are linked by advanced, robust and rapid communications routing and network topologies...
October 20, 2017: Sensors
Roshan Fernandes, Rio D'Souza G L
Mobility prediction is a technique in which the future location of a user is identified in a given network. Mobility prediction provides solutions to many day-to-day life problems. It helps in seamless handovers in wireless networks to provide better location based services and to recalculate paths in Mobile Ad hoc Networks (MANET). In the present study, a framework is presented which predicts user mobility in presence and absence of mobility history. Naïve Bayesian classification algorithm and Markov Model are used to predict user future location when user mobility history is available...
October 19, 2017: Journal of Medical Systems
Junming Dong, Yanyu Zhang, Yijun Zhu
Visible light communications (VLC) using multi-color light-emitting diodes (LEDs) can support simultaneous high-speed data rate and high-quality lighting. However, since the radiation spectrum of LEDs has a limited width, spectral overlapping will result in multi-color cross talk even when optical filters are applied at the receivers. Moreover, since LEDs are used for illumination and wireless data transmission in the meantime, both lighting quality and communication performance must be considered in VLC systems...
August 10, 2017: Applied Optics
Yasuhiko Takeda, Hideo Iizuka, Noboru Yamada, Tadashi Ito
We have proposed a light-trapping concept for photovoltaic (PV) cells under monochromatic illumination with restricted incident angles. We employed a configuration consisting of a shortpass filter (SPF) on the front surface and a diffuse reflector on the rear surface of the cell. The SPF was designed so that it functioned as a polarization-insensitive angle-selective filter. We fabricated 30-80-μm-thick crystalline silicon samples for incident angles changing within 30°, and analyzed the measured results using a ray-trace simulation with the Monte Carlo method...
July 10, 2017: Applied Optics
Derek S Chew, Vikas Kuriachan
PURPOSE OF REVIEW: Pacing technology for many decades has been composed of a generator attached to leads that are usually transvenous. Recently, leadless pacemakers have been studied in clinical settings and now available for use in many countries. This includes the single-component Nanostim Leadless Cardiac Pacemaker and Micra Transcatheter Pacing System, as well as the multicomponent Wireless Stimulation Endocardial system. RECENT FINDINGS: Clinical studies in single-component leadless pacing technology has shown that they can be successfully implanted with minimal complications...
October 17, 2017: Current Opinion in Cardiology
Raghav Sharma, Naveen Sisodia, Ezio Iacocca, Ahmad A Awad, Johan Åkerman, P K Muduli
An important property of spin-torque nano-oscillators (STNOs) is their ability to produce a frequency modulated (FM) signal, which is very critical for communication applications. We here demonstrate a novel single sideband (SSB) modulation phenomenon using a magnetic tunnel junction (MTJ)-based STNO, which saves transmission bandwidth and in principle should minimize attenuation for wireless communication. Experimentally, lower single sidebands (LSSBs) have been successfully demonstrated over a wide range of modulation frequency, f m  = 150 MHz-1 GHz...
October 18, 2017: Scientific Reports
Anukul Pandey, Barjinder Singh Saini, Butta Singh, Neetu Sood
This paper presents a patient's confidential data hiding scheme in electrocardiogram (ECG) signal and its subsequent wireless transmission. Patient's confidential data is embedded in ECG (called stego-ECG) using chaotic map and the sample value difference approach. The sample value difference approach effectually hides the patient's confidential data in ECG sample pairs at the predefined locations. The chaotic map generates these predefined locations through the use of selective control parameters. Subsequently, the wireless transmission of the stego-ECG is analyzed using the Orthogonal Frequency Division Multiplexing (OFDM) system in a Rayleigh fading scenario for telemedicine applications...
October 18, 2017: Journal of Medical Systems
Meiwei Kong, Weichao Lv, Tariq Ali, Rohail Sarwar, Chuying Yu, Yang Qiu, Fengzhong Qu, Zhiwei Xu, Jun Han, Jing Xu
The availability of the underwater wireless optical communication (UWOC) based on red (R), green (G) and blue (B) lights makes the realization of the RGB wavelength division multiplexing (WDM) UWOC system possible. By properly mixing RGB lights to form white light, the WDM UWOC system has prominent potentiality for simultaneous underwater illumination and high-speed communication. In this work, for the first time, we experimentally demonstrate a 9.51-Gb/s WDM UWOC system using a red-emitting laser diode (LD), a single-mode pigtailed green-emitting LD and a multi-mode pigtailed blue-emitting LD...
August 21, 2017: Optics Express
Kai-Chun Zhang, Xiao-Xing Chen, Chang-Jian Sheng, Kelvin J A Ooi, Lay Kee Ang, Xue-Song Yuan
The terahertz band is an increasingly important spectrum in a wide range of applications from bioimaging and medical diagnostics to security and wireless communications. We propose a tunable terahertz coherent radiation source based on graphene plasmon-induced transition radiation. The transition radiation in terahertz regime arises from the graphene plasmons, which are excited by a normally incident bunched electron beam. We analyze the field-intensities and spectral-angular distributions of the transition radiation with respect to Fermi energy, substrate dielectric permittivity, and electron bunch energy for both the coherent and incoherent radiation...
August 21, 2017: Optics Express
Corey Pollock, Jessica Morrison, Matthias Imboden, Thomas D C Little, D J Bishop
MEMS mirrors are currently used in many applications to steer beams of light. An area of continued research is developing mirrors with varifocal capability that allows the beam to be shaped and focused. In this work, we study the varifocal capability of a 380 μm diameter, thermally actuated MEMS mirror with a ± 40° tip-tilt angle and a radius of curvature between -0.48 mm to 20.5 mm. Light is coupled to the mirror via a single mode optical fiber, similar to an indoor optical wireless communication architecture...
August 21, 2017: Optics Express
Ke Wang, Ampalavanapillai Nirmalathas, Christina Lim, Kamal Alameh, Hongtao Li, Efstratios Skafidas
The indoor user localization function is in high demand for high-speed wireless communications, navigations and smart-home applications. The optical wireless technology has been used to localize end users in indoor environments. However, its accuracy is typically very limited, due to the ambient light, which is relatively strong. In this paper, a novel high-localization-accuracy optical wireless based indoor localization system, based on the use of the mechanism that estimates background light intensity, is proposed...
September 18, 2017: Optics Express
Ling-Han Si-Ma, Jian Zhang, Bin-Qiang Wang, Yan-Yu Zhang
Recently, the single photon avalanche diode optical wireless communication (SPAD OWC) has attracted much attention due to its potential underwater applications. For such system, the channel noise is additive Poisson noise (APN) rather than the commonly encountered additive white Gaussian noise (AWGN) and the corresponding maximum likelihood (ML) detection is hard to provide a useful insight into energy-efficient signal design. By using the previously proposed Hellinger distance design criterion, we design an energy-efficient multi-dimensional constellation within the nonnegative integer set by minimizing the average optical power for a fixed minimum Hellinger distance...
September 18, 2017: Optics Express
Tian Liang, Ke Wang, Christina Lim, Elaine Wong, Tingting Song, Ampalavanapillai Nirmalathas
In this paper, we report a novel mechanism to simultaneously provide secure connections for multiple users in indoor optical wireless communication systems by employing the time-slot coding scheme together with chaotic phase sequence. The chaotic phase sequence is generated according to the logistic map and applied to each symbol to secure the transmission. Proof-of-concept experiments are carried out for multiple system capacities based on both 4-QAM and 16-QAM modulation formats, i.e. 1.25 Gb/s, 2 Gb/s and 2...
September 4, 2017: Optics Express
Yurong Dong, Meng Shi, Xilu Yang, Pan Zeng, Junyi Gong, Sunming Zheng, Mengjie Zhang, Rongqing Liang, Qiongrong Ou, Nan Chi, Shuyu Zhang
Visible light communication (VLC) is a promising candidate for high-speed wireless communication with numerous unlicensed spectrum. To achieve high-speed data communication, it requires intense light signals concentrated on a tiny fast photodiode. The common way of using focusing optics reduces the field of view (FoV) of the photodiode due to the conservation of étendue. Luminescent solar concentrators (LSC) provide a solution to enhance the signals without affecting the FoV. In this paper we demonstrate nanopatterned LSCs fabricated on flexible plastics that achieve a doubling of optical gain compared to its traditional rectangular counterparts...
September 4, 2017: Optics Express
Meiwei Kong, Jiongliang Wang, Yifei Chen, Tariq Ali, Rohail Sarwar, Yang Qiu, Shilian Wang, Jun Han, Jing Xu
In this work, for the first time, we uncover that the level of security we have traditionally taken for granted on underwater wireless optical communication (UWOC) may not always be there. We first numerically investigate the security weaknesses of UWOC via Monte Carlo simulation. With the link distance increasing or the water becoming more turbid, the simulation results indicate that the possibility of information leakage increases, which may pose a great threat to the security of UWOC. By using a high-sensitivity multi-pixel photon counter (MPPC) placed aside the water tank, a 5-MHz square wave signal is successfully tapped at 1-m, 3-m, and 5-m underwater transmission distances, which preliminarily verifies the probability of information leakage...
September 4, 2017: Optics Express
Shengli Ding, Jiankun Zhang, Anhong Dang
This paper investigates an adaptive threshold decision (ATD) scheme without the knowledge of channel state information (CSI) for optical wireless communication (OWC). Based on the low-pass characteristic of atmospheric turbulence channels, a low-pass filter is designed for the received signals, and the filtered signal can be employed as decision threshold. Theoretical analyses show that performance of ATD is very close to that with perfect CSI. Monte Carlo simulations demonstrate that the proposed scheme shows only 0...
October 2, 2017: Optics Express
Maria Freire Hermelo, Po-Tsung Boris Shih, Matthias Steeg, Anthony Ng'oma, Andreas Stöhr
We report on a record spectral efficient terahertz communication system using a coherent radio-over-fiber (CRoF) approach. High spectral efficient back-to-back and wireless THz transmission around 325 GHz is experimentally demonstrated using a 64-QAM-OFDM modulation format and a 10 GHz wide wireless channel resulting in a data rate of 59 Gbit/s.
August 7, 2017: Optics Express
Ximing Li, Jingjing Yang, Yun Feng, Meixia Yang, Ming Huang
A metasurface (MS) is highly useful for improving the performance of patch antennae and reducing their size due to their inherent and unique electromagnetic properties. In this paper, a compact and broadband antenna based on a step-shaped metasurface (SMS) at an operating frequency of 4.3 GHz is presented, which is fed by a planar monopole and enabled by selecting an SMS with high selectivity. The SMS consists of an array of metallic step-shaped unit cells underneath the monopole, which provide footprint miniaturization and bandwidth expansion...
August 7, 2017: Optics Express
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