scholarly journals Improved optical camera communication systems using a freeform lens

2021 ◽  
Vol 29 (21) ◽  
pp. 34066
Author(s):  
Ziwei Liu ◽  
Lin Yang ◽  
Yanbing Yang ◽  
Rengmao Wu ◽  
Lei Zhang ◽  
...  
Keyword(s):  
Communication Systems ◽  
Freeform Lens ◽  
Optical Camera Communication

scholarly journals Some practical constraints and solutions for optical camera communication

2020 ◽  
Vol 378 (2169) ◽  
pp. 20190191 ◽  
Author(s):  
Weijie LIU ◽  
Zhengyuan Xu
Keyword(s):  
Wireless Communication ◽  
Communication Systems ◽  
Consumer Electronics ◽  
Frame Rate ◽  
Future Research ◽  
Optical Wireless Communication ◽  
Optical Wireless ◽  
Atmospheric Scattering ◽  
Practical Constraints ◽  
Optical Camera Communication

Mobile wireless communication heavily relies on the radio frequency to convey message and data. However, its limited spectrum can hardly meet the demands for the future high data rate applications. Optical wireless communication, in particular visible light communication, opens up vast optical spectrum for communication, and meanwhile can retrofit the light sources as the communication transmitters in the existing working or living environments. In conjunction with the ubiquitous cameras in hand-held consumer electronics such as smartphones and pads, optical camera communication (OCC) further takes advantages of image sensors as the communication receivers and realizes low-cost communication systems. This article first provides an overview of OCC systems. It then addresses some practical constraints, ranging from sensor low frame rate and instability, rolling shutter readout, to visual qualities of displayed images and videos, and link blockage between the transmitter and receiver. Accordingly, it introduces existing and new solutions to deal with those constraints by data modulation, newly developed camera structures, post-processing of sensed signals and non-line of sight OCC as a new form. In particular, indirect paths by either the indoor surface reflection or the outdoor atmospheric scattering are explored for link connectivity under blockage. Finally, some future research directions are suggested. This article is part of the theme issue ‘Optical wireless communication’.

scholarly journals Design and Implementation of 2D MIMO-Based Optical Camera Communication Using a Light-Emitting Diode Array for Long-Range Monitoring System

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3023
Author(s):  
Huy Nguyen ◽  
Vanhoa Nguyen ◽  
Conghoan Nguyen ◽  
Van Bui ◽  
Yeongmin Jang
Keyword(s):  
Wireless Communication ◽  
Visible Light ◽  
Channel Coding ◽  
Communication Systems ◽  
Light Emitting Diode ◽  
Focal Length ◽  
Modulation Scheme ◽  
Light Emitting ◽  
Led Array ◽  
Optical Camera Communication

Wireless technologies that use radio frequency (RF) waveforms are common in wireless communication systems, such as the mobile communication, satellite system, and Internet of Things (IoT) systems. It is more advantageous than wired communication because of the ease of installation. However, it can negatively impact human health if high frequencies are used to transmit data. Therefore, researchers are exploring the potential of optical wireless communication as an alternative, which uses the visible light bandwidth instead of RF waveforms. Three possibilities are being investigated: visible light communication, light fidelity, and optical camera communication. In this paper, we propose a multiple-input multiple-output modulation scheme using a light-emitting diode (LED) array, which is applicable to the IoT system, based on on–off keying modulation in the time domain. This scheme is compatible with the two popular types of camera in the market, rolling shutter cameras and global shutter cameras, as well as the closed-circuit television camera, which is used in factories, buildings, etc. Despite the small size of the LED array, implementing this scheme with 10 links in different positions at a communication distance of 20 m is possible for efficient performance (low error rate) by controlling the exposure time, shutter speed, focal length, channel coding and applying the matched filter.

Plant peptide hormone signalling

2015 ◽  
Vol 58 ◽  
pp. 115-131 ◽  
Author(s):  
Ayane Motomitsu ◽  
Shinichiro Sawa ◽  
Takashi Ishida
Keyword(s):  
Communication Systems ◽  
Cell Communication ◽  
Peptide Hormone ◽  
Peptide Hormones ◽  
Target Cells ◽  
Signalling Molecules ◽  
Receptor Complexes ◽  
Environmental Responses ◽  
Plant Life Cycle ◽  
Multicellular Organisms

The ligand–receptor-based cell-to-cell communication system is one of the most important molecular bases for the establishment of complex multicellular organisms. Plants have evolved highly complex intercellular communication systems. Historical studies have identified several molecules, designated phytohormones, that function in these processes. Recent advances in molecular biological analyses have identified phytohormone receptors and signalling mediators, and have led to the discovery of numerous peptide-based signalling molecules. Subsequent analyses have revealed the involvement in and contribution of these peptides to multiple aspects of the plant life cycle, including development and environmental responses, similar to the functions of canonical phytohormones. On the basis of this knowledge, the view that these peptide hormones are pivotal regulators in plants is becoming increasingly accepted. Peptide hormones are transcribed from the genome and translated into peptides. However, these peptides generally undergo further post-translational modifications to enable them to exert their function. Peptide hormones are expressed in and secreted from specific cells or tissues. Apoplastic peptides are perceived by specialized receptors that are located at the surface of target cells. Peptide hormone–receptor complexes activate intracellular signalling through downstream molecules, including kinases and transcription factors, which then trigger cellular events. In this chapter we provide a comprehensive summary of the biological functions of peptide hormones, focusing on how they mature and the ways in which they modulate plant functions.

Instruction Using Augmentative and Alternative Communication Supports: Description of Current Practices by Speech-Language Pathologists Who Work With Children With Autism Spectrum Disorder

2020 ◽  
Vol 29 (2) ◽  
pp. 586-596 ◽  
Author(s):  
Kaitlyn A. Clarke ◽  
Diane L. Williams
Keyword(s):  
Autism Spectrum Disorder ◽  
Augmentative And Alternative Communication ◽  
Communication Systems ◽  
Diagnostic Category ◽  
Children With Autism ◽  
Autism Spectrum ◽  
Spectrum Disorder ◽  
Alternative Communication ◽  
Speech Language Pathologists ◽  
Processing Differences

Purpose The aim of this research study was to examine common practices of speech-language pathologists (SLPs) who work with children with autism spectrum disorder (ASD) with respect to whether or not SLPs consider processing differences in ASD or the effects of input during their instruction. Method Following a qualitative research method, how SLPs instruct and present augmentative and alternative communication systems to individuals with ASD, their rationale for method selection, and their perception of the efficacy of selected interventions were probed. Semistructured interviews were conducted as part of an in-depth case report with content analysis. Results Based on completed interviews, 4 primary themes were identified: (a) instructional method , (b) input provided , (c) decision-making process , and (d) perceived efficacy of treatment . Additionally, one secondary theme, training and education received , was identified . Conclusions Clinicians reported making decisions based on the needs of the child; however, they also reported making decisions based on the diagnostic category that characterized the child (i.e., ASD). The use of modeling when teaching augmentative and alternative communication to individuals with ASD emerged as a theme, but variations in the method of modeling were noted. SLPs did not report regularly considering processing differences in ASD, nor did they consider the effects of input during instruction.

Sign in / Sign up

Export Citation Format

Share Document