NLOS visible light positioning and communication based on LoRa modulation.

With the rapid development of the Internet of Things, location-based services are becoming increasingly important, especially in indoor environments. Visible light positioning (VLP) has garnered widespread attention due to its high accuracy, low cost, and immunity to the radio frequency electromagnetic interference. However, traditional VLP relies on line-of-sight paths, making it impractical in complex and dynamic indoor environments.

Symmetry of constellation diagram-based intelligent SNR estimation for visible light communications.

Visible light communication (VLC) technology with rich spectrum resources is thought of as an essential component in the future ubiquitous communication networks. Accurately monitoring its transmission impairments is important for improving the stability of high-speed communication networks. Existing research on intelligently monitoring the signal-to-noise ratio (SNR) performance of VLC focuses primarily on the application of neural networks but neglects the physical nature of communication systems.

A nanonewton force sensor using a U-shape tapered microfiber interferometer.

Nanomechanical measurements, especially the detection of weak contact forces, play a vital role in many fields, such as material science, micromanipulation, and mechanobiology. However, it remains a challenging task to realize the measurement of ultraweak force levels as low as nanonewtons with a simple sensing configuration. In this work, an ultrasensitive all-fiber nanonewton force sensor structure based on a single-mode-tapered U-shape multimode-single-mode fiber probe is proposed and experimentally demonstrated with a limit of detection of ~5.

Adaptive-memory-length look-up table (LUT)-based digital pre-distortion for IM/DD underwater wireless optical communications.

A digital pre-distortion (DPD) scheme based on an adaptive-memory-length look-up table (AML-LUT) is proposed and experimentally demonstrated in a four-level pulse amplitude modulation (4-PAM) underwater optical wireless communication (UOWC) system. By implementing adaptive memory length for each pattern in the AML-LUT-based DPD, the size of the AML-LUT can be significantly reduced without sacrificing performance compared to both the full-size LUT and the multi-symbol simplified look-up table (MSS-LUT)-based DPDs. The performance of the proposed AML-LUT-based DPD is experimentally evaluated for a 625 Mbit/s 4-PAM UOWC over 1 m transmission length.

Inkjet-printed high-performance and mechanically flexible organic photodiodes for optical wireless communication.

Emerging areas such as the Internet of Things (IoT), wearable and wireless sensor networks require the implementation of optoelectronic devices that are cost-efficient, high-performing and capable of conforming to different surfaces. Organic semiconductors and their deposition via digital printing techniques have opened up new possibilities for optical devices that are particularly suitable for these innovative fields of application. In this work, we present the fabrication and characterization of high-performance organic photodiodes (OPDs) and their use as an optical receiver in an indoor visible light communication (VLC) system.

Curved OLED-based NLOS optical camera communications links.

In this paper, for the first time, to the best of our knowledge, we experimentally demonstrate the use of a curved organic light emitting diode (OLED) as a transmitter (Tx) in the non-line-of-sight (NLOS) optical camera communication (OCC) link for an indoor environment using a camera as a receiver. The proposed NLOS-OCC scheme is evaluated for the signal-to-noise ratio (SNR) and the reception success rates under key photographic and communication parameters, including exposure times and gain values , as well as the transmission frequency and the distance . The SNR analysis is performed using a binary classification procedure based on a Gaussian mixture model for the first time, to the best of our knowledge, for OLED-based NLOS-OCC links.

Non-line-of-sight optical camera communications based on CPWM and a convolutional neural network.

Non-line-of-sight (NLOS) optical camera communications (OCC) exhibit greater link availability and mobility than line-of-sight links, which are more susceptible to blocking and shadowing. In this work, we propose an NLOS OCC system, where the data signal is mapped into color pulse width modulation (CPWM) symbols prior to transmission using a red-, green-, and blue light-emitting diode. A convolutional-neural-network-based receiver is used to demodulate the CPWM signal.

Integrated label-free erbium-doped fiber laser biosensing system for detection of single cell Staphylococcus aureus.

A critical challenge to realize ultra-high sensitivity with optical fiber interferometers for label free biosensing is to achieve high quality factors (Q-factor) in liquid. In this work a high Q-factor of 10, which significantly improves the detection resolution is described based on a structure of single mode -core-only -single mode fiber (SCS) with its multimode (or Mach-Zehnder) interference effect as a filter that is integrated into an erbium-doped fiber laser (EDFL) system for excitation. In the case study, the section of core-only fiber is functionalized with porcine immunoglobulin G (IgG) antibodies, which could selectively bind to bacterial pathogen of Staphylococcus aureus (S.

General framework for calculating irradiance distributions of symmetric surface sources.

Symmetries in system modeling can be exploited to obtain analytical results on the system behavior and to speed up computations using the symmetric model. This work explores the use of symmetries in radiant surfaces for calculating the induced irradiance distributions by developing a general mathematical expression. The obtained model is applied to flat, cylindrical, and spherical sources to obtain explicit expressions.

Indoor 3D NLOS VLP using a binocular camera and a single LED.

In this paper, we propose a non-line of sight (NLOS) visible light positioning (VLP) system using a binocular camera and a single light emitting diode (LED) for the realization of 3D positioning of an arbitrary posture. The proposed system overcomes the challenges of the shadowing/blocking of the line of sight (LOS) transmission paths between transmitters and receivers (Rxs) and the need for a sufficient number of LEDs that can be captured within the limited field of view of the camera-based Rx. We have developed an experimental testbed to evaluate the performance of the proposed system with results showing that the lowest average error and the root mean square error (RMSE) are 26.

Optimization and design of a diffuse optical wireless sensor network.

Wireless sensor networks (WSNs) are currently being deployed in everyday objects to collect and transmit information related to humidity, temperature, heartbeat, motion, etc. Such networks are part of the massive machine-type communication (mMTC) scenario within the fifth/sixth generation of wireless networks. In this paper, we consider the optimization and design of an optical WSN composed of multiple battery-powered sensor nodes based on light-emitting diode transmitters.

The Usage of ANN for Regression Analysis in Visible Light Positioning Systems.

In this paper, we study the design aspects of an indoor visible light positioning (VLP) system that uses an artificial neural network (ANN) for positioning estimation by considering a multipath channel. Previous results usually rely on the simplistic line of sight model with limited validity. The study considers the influence of noise as a performance indicator for the comparison between different design approaches.

Visible light communication with OLEDs for D2D communications considering user movement and receiver orientations.

With the increasing use of organic light emitting diodes in lights, smart phones, wearable smartwatches, and computers, visible light-based device-to-device (D2D) communications has become more and more relevant. We propose D2D communications using smart phones' display pixels and their built-in cameras. We investigate the impact of receiver orientation and user mobility on the link performance.

Modeling turbulence in underwater wireless optical communications based on Monte Carlo simulation: erratum.

Corrections are given for errors in the presentation of equations in J. Opt. Soc.

Editorial to the Special Issue on "Visible Light Communications, Networking, and Sensing".

The next generation wireless technology networks and beyond (i [...

Optical camera communications link using an LED-coupled illuminating optical fiber.

In this Letter, we propose and demonstrate a novel wireless communications link using an illuminating optical fiber as a transmitter (Tx) in optical camera communications. We demonstrate an indoor proof-of-concept system using an illuminating plastic optical fiber coupled with a light-emitting diode and a commercial camera as the Tx and the receiver, respectively. For the first time, to the best of our knowledge, we experimentally demonstrate flicker-free wireless transmission within the off-axis camera rotation angle range of 0-45° and the modulation frequencies of 300 and 500 Hz.

Impact of Transmitter Positioning and Orientation Uncertainty on RSS-Based Visible Light Positioning Accuracy.

This paper present simulation-based results on the impact of transmitter (Tx) position and orientation uncertainty on the accuracy of the visible light positioning (VLP) system based on the received signal strength (RSS). There are several constraining factors for RSS-based algorithms, particularly due to multipath channel characteristics and set-up uncertainties. The impact of Tx uncertainties on positioning error performance is studied, assuming a statistical modelling of the uncertainties.

Performance of Vehicular Visible Light Communications under the Effects of Atmospheric Turbulence with Aperture Averaging.

In this paper, we investigate the performance of a vehicular visible light communications (VVLC) link with a non-collimated and incoherent light source (a light-emitting diode) as the transmitter (Tx), and two different optical receiver (Rx) types (a camera and photodiode (PD)) under atmospheric turbulence (AT) conditions with aperture averaging (AA). First, we present simulation results indicating performance improvements in the signal-to-noise ratio (SNR) under AT with AA with increasing size of the optical concentrator. Experimental investigations demonstrate the potency of AA in mitigating the induced signal fading due to the weak to moderate AT regimes in a VVLC system.

The Utilization of Artificial Neural Network Equalizer in Optical Camera Communications.

In this paper, we propose and validate an artificial neural network-based equalizer for the constant power 4-level pulse amplitude modulation in an optical camera communications system. We introduce new terminology to measure the quality of the communications link in terms of the number of row pixels per symbol Npps, which allows a fair comparison considering the progress made in the development of the current image sensors in terms of the frame rates and the resolutions of each frame. Using the proposed equalizer, we experimentally demonstrate a non-flickering system using a single light-emitting diode (LED) with Npps of 20 and 30 pixels/symbol for the unequalized and equalized systems, respectively.

A 40 Mb/s VLC System Reusing an Existing Large LED Panel in an Indoor Office Environment.

With advances in solid-state lighting, visible light communication (VLC) has emerged as a promising technology to enhance existing light-emitting diode (LED)-based lighting infrastructure by adding data communication capabilities to the illumination functionality. The last decade has witnessed the evolution of the VLC concept through global standardisation and product launches. Deploying VLC systems typically requires replacing existing light sources with new luminaires that are equipped with data communication functionality.

An Indoor Visible Light Positioning System Using Tilted LEDs with High Accuracy.

The accuracy of the received signal strength-based visible light positioning (VLP) system in indoor applications is constrained by the tilt angles of transmitters (Txs) and receivers as well as multipath reflections. In this paper, for the first time, we show that tilting the Tx can be beneficial in VLP systems considering both line of sight (LoS) and non-line of sight transmission paths. With the Txs oriented towards the center of the receiving plane (i.

Spatial frequency-based angular behavior of a short-range flicker-free MIMO-OCC link.

In this paper, we provide a solution based on spatial frequency to study the angular behavior of a flicker-free, short-range indoor multiple-input multiple-output (MIMO) optical camera communications (OCC) link. We focus on the experimental investigation of OCC's performance for the transmitters (Txs) [i.e.

Utilization of an OLED-Based VLC System in Office, Corridor, and Semi-Open Corridor Environments.

Organic light emitting diodes (OLEDs) have recently received growing interest for their merits as soft light and large panels at a low cost for the use in public places such as airports, shopping centers, offices, and train or bus stations. Moreover, the flexible substrate-based OLEDs provide an attractive feature of having curved or rolled lighting sources for the use in wearable devices and display panels. This technology can be implemented in visible light communications (VLC) for several applications such as visual display, data communications, and indoor localization.

Optical Axons for Electro-Optical Neural Networks.

Recently, neuromorphic sensors, which convert analogue signals to spiking frequencies, have ‎been reported for neurorobotics. In bio-inspired systems these sensors are connected to the main neural unit to perform ‎post-processing of the sensor data. The performance of spiking neural networks has been ‎improved using optical synapses, which offer parallel communications between the distanced ‎neural areas but are sensitive to the intensity variations of the optical signal.

Optical Camera Communications for IoT-Rolling-Shutter Based MIMO Scheme with Grouped LED Array Transmitter.

In optical camera communications (OCC), the provision of both flicker-free illumination and high data rates are challenging issues, which can be addressed by utilizing the rolling-shutter (RS) property of the image sensors as the receiver (Rx). In this paper, we propose an RS-based multiple-input multiple-output OCC scheme for the Internet of things (IoT) application. A simplified design of multi-channel transmitter (Tx) using a 7.