Hybrid diffuse IR transmitter supporting VLC systems with imaging receivers

Indoor visible light communication (VLC), using white-LED lighting, generally assumes lights are ON during communications. In this paper, we propose a new Hybrid diffuse Infrared transmitter (HDIrT) coupled with an imaging receiver to support VLC system when the light is dimmed or is totally turned off. Infrared (IR) optical communications boasts similar advantages as VLC systems. It can also provide high transmission rates. The ultimate goal of our proposed system is to increase the signal to noise ratio (SNR), mitigate the channel delay spread and the effect of inter-symbol-interference (ISI) when the system operates at a high data transmission rate. The delay spread is reduced from 1.55 ns to about 0.1 ns when a narrow field-of-view (FOV) imaging receiver replaces a wide FOV non-imaging receiver. At a higher data rate of 2.5 Gb/s, the simulation results show that the imaging HDIrT system achieves about 17 dB SNR in the presence of multipath dispersion, receiver noise and mobility

25 Gbps Mobile Visible light Communication System Employing Fast Adaptation Techniques

Visible light communication (VLC) systems have typically operated at data rates below 20 Gbps and operation at this data rate was shown to be feasible by using laser diodes (LDs), beam steering, imaging receivers and delay adaptation techniques. However, an increase in the computational cost is incurred. In this paper, we introduce fast computer generated holograms (FCGHs) to speed up the adaptation process. The new, fast and efficient fully adaptive VLC system can improve the receiver signal to noise ratio (SNR) and reduce the required time to estimate the position of the VLC receiver. In addition, an imaging receiver and a delay adaptation technique are used to reduce the effect of inter symbol interference (ISI) and multipath dispersion. Significant enhancements in the SNR, with VLC channel bandwidths of more than 36 GHz are obtained resulting in a compact impulse response and a VLC system that is able to achieve higher data rates (25 Gbps) with full mobility in the considered indoor environment

Adaptive receiver for visible light communication system

The future of visible light communication (VLC) systems relies on achieving moderate to high data rates and the ability to design a low complexity system, as these will play a major role in the next generation communication networks. In this paper, we propose, design, and evaluate the use of an adaptive receiver to mitigate the inter-symbol interference (ISI) and improve the overall VLC system performance while using a single element wide field of view (FOV) photodetector. In addition, we optimise the adaptive receiver by employing a different number of buffers to find the optimum configurations in terms of reducing the complexity and achieving the best performance. The proposed adaptive receiver is able to provide data rates of 1 Gbps with a BER of 10¯⁵ for OOK modulation in the worst case scenario

20 Gbps Mobile Indoor Visible Light Communication System Employing Beam Steering and Computer Generated Holograms

Visible light communication (VLC) systems have typically operated at data rates below 10 Gbps and operation at this data rate was shown to be feasible by using laser diodes (LDs), imaging receivers and delay adaptation techniques (DAT imaging LDs-VLC). However, higher data rates, beyond 10 Gbps, are challenging due to the low signal to noise ratio (SNR) and inter symbol interference (ISI). In this paper, for the first time, to the best of our knowledge, we propose, design and evaluate a VLC system that employs beam steering (of part of the VLC beam) using adaptive finite vocabulary of holograms in conjunction with an imaging receiver and a delay adaptation technique to enhance SNR and to mitigate the impact of ISI at high data rates (20 Gbps). An algorithm was used to estimate the receiver location, so that part of the white light can be directed towards a desired target (receiver) using beam steering to improve SNR. Simulation results of our location estimation algorithm (LEA) indicated that the required time to estimate the position of the VLC receiver is typically within 224 ms in our system and environment. A finite vocabulary of stored holograms is introduced to reduce the computation time required by LEA to identify the best location to steer the beam to the receiver location. The beamsteering approach improved the SNR of the fully adaptive VLC system by 15 dB at high data rates (20 Gbps) over the DAT imaging LDs-VLC system in the worst case scenario. In addition, we examined our new proposed system in a very harsh environment with mobility. The results showed that our proposed VLC system has strong robustness against shadowing, signal blockage and mobility

Dynamic Online Communities: DynaMail

DynaMail is a Mailing List Manager which automatically creates mailing lists based on user attributes and a history of their message interactions. A DynaMail Mailing List Manager creates dynamic mailing lists by providing a single email address to which messages are sent. From there, messages are distributed to subscribers belonging to different mailing lists. In a DynaMail system there are no actual mailing lists stored on the system, the user attributes define the mailing lists which are computed and generated dynamically. These attributes are entered into the system using a Web-based system which allows users and administrators to configure the system to their needs

LiDAL: Light Detection and Localization

In this paper, we present the first indoor light-based detection and localization system that builds on concepts from radio detection and ranging (radar) making use of the expected growth in the use and adoption of visible light communication (VLC), which can provide the infrastructure for our Light Detection and Localization (LiDAL) system. Our system enables active detection, counting, and localization of people, in addition to being fully compatible with the existing VLC systems. In order to detect human (targets), LiDAL uses the visible light spectrum. It sends pulses using a VLC transmitter and analyses the reflected signal collected by a photodetector receiver. Although we examine the use of the visible spectrum here, LiDAL can be used in the infrared spectrum and other parts of the light spectrum. We introduce LiDAL with different transmitter-receiver configurations and optimum and sub-optimum detectors considering the fluctuation of the received reflected signal from the target in the presence of Gaussian noise. We design an efficient multiple input multiple output (MIMO) LiDAL system with a wide field of view (FOV) single photodetector receiver, and also design a multiple input single output (MISO) LiDAL system with an imaging receiver to eliminate the ambiguity in target detection and localization. We develop models for the human body and its reflections and consider the impact of the color and texture of the cloth used as well as the impact of target mobility. A number of detection and localization methods are developed for our LiDAL system, including cross correlation and a background subtraction method. These methods are considered to distinguish a mobile target from the ambient reflections due to background obstacles (furniture) in a realistic indoor environment

Artificial Neural Network for LiDAL Systems

In this paper, we introduce an intelligent light detection and localization (LiDAL) system that uses artificial neural networks (ANN). The LiDAL systems of interest are MIMO LiDAL and MISO IMG LiDAL systems. A trained ANN with the LiDAL system of interest is used to distinguish a human (target) from the background obstacles (furniture) in a realistic indoor environment. In the LiDAL systems, the received reflected signals in the time domain have different patterns corresponding to the number of targets and their locations in an indoor environment. The indoor environment with background obstacles (furniture) appears as a set of patterns in the time domain when the transmitted optical signals are reflected from objects in LiDAL systems. Hence, a trained neural network that has the ability to classify and recognize the received signal patterns can distinguish the targets from the background obstacles in a realistic environment, especially given the mobility of targets (humans) which distinguishes them from static obstacles (furniture). The LiDAL systems with ANN are evaluated in a realistic indoor environment through computer simulation

Parallel Data Transmission in Indoor Visible Light Communication Systems

This paper presents an indoor visible light communication (VLC) system in conjunction with an imaging receiver with parallel data transmission (spatial multiplexing) to reduce the effects of the inter-symbol interference (ISI). To distinguish between light units (transmitters) and to match the light units used to convey the data with the pixels of the imaging receiver, we propose the use of subcarrier multiplexing (SCM) tones. Each light unit transmission is multiplexed with a unique tone. At the receiver, a SCM tone decision system is utilized to measure the power level of each SCM tone and consequently associate each pixel with a light unit. In addition, the level of co-channel interference (CCI) between light units is estimated using the SCM tones. Our proposed system is examined in two indoor environments taking into account reflective components (first and second order reflections). The results show that this system has the potential to achieve an aggregate data rate of 8 Gb/s with a bit error rate of 10 –6 for each light unit, using simple on-off-keying (OOK)

The Moore-Penrose Pseudoinverse. A Tutorial Review of the Theory

In the last decades the Moore-Penrose pseudoinverse has found a wide range of applications in many areas of Science and became a useful tool for physicists dealing, for instance, with optimization problems, with data analysis, with the solution of linear integral equations, etc. The existence of such applications alone should attract the interest of students and researchers in the Moore-Penrose pseudoinverse and in related sub jects, like the singular values decomposition theorem for matrices. In this note we present a tutorial review of the theory of the Moore-Penrose pseudoinverse. We present the first definitions and some motivations and, after obtaining some basic results, we center our discussion on the Spectral Theorem and present an algorithmically simple expression for the computation of the Moore-Penrose pseudoinverse of a given matrix. We do not claim originality of the results. We rather intend to present a complete and self-contained tutorial review, useful for those more devoted to applications, for those more theoretically oriented and for those who already have some working knowledge of the sub ject.Comment: 23 page

Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set

We report a measurement of the bottom-strange meson mixing phase \beta_s using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity. We report confidence regions in the two-dimensional space of \beta_s and the B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2, -1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +- 0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +- 0.009 (syst) ps, which are consistent and competitive with determinations by other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012