scholarly journals Spectrally efficient multicarrier modulation system for visible light communication

2019 ◽  
Vol 9 (2) ◽  
pp. 1184
Author(s):  
T. Deepa ◽  
Harshita Mathur ◽  
K. A. Sunitha
Keyword(s):  
Visible Light ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Reliability ◽  
Visible Light Communication ◽  
Coded Modulation ◽  
High Data ◽  
Delta Sigma ◽  
Trellis Coded ◽  
High Spectral Efficiency ◽  
Trellis Diagram

<span lang="EN-US">Visible Light Communication (VLC) has become an accolade to its radio frequency counterpart. In VLC system, orthogonal frequency division multiplexing (OFDM) has drawn much attention, because of simple equalization, high spectral efficiency, high data rate and robustness to intersymbol interference (ISI). Besides, there are emerging applications that ought to be gotten with low latency and high reliability. To diminish power requirements with no transmission capacity extension, Trellis coded modulation (TCM) is utilized as a part of the framework in which the free distance of trellis diagram is equivalent to the minimum distance between the points of constellation focuses in partitioned subsets, which augments the coding gain up i.e. the performance parameter viably. TCM together with VLC-OFDM enhances the transmission execution in reasonable frameworks. In this paper, we propose OFDM which is based on TCM and is planned and exeuted for digitized OFDM frameworks by presenting delta sigma modulation (DSM) considering VLC channel. Simulation results show that the proposed TCM based VLC-OFDM offers incredible robustness against noises and nonlinear degradation.</span>

scholarly journals A Novel Transceiver Model for Polar Transform Optical (PTO-) OFDM for Visible Light Communication (VLC) Based on Peak to Average Power Ratio Reduction using Precoding

2020 ◽  
Vol 9 (10) ◽  
pp. 307-315
Keyword(s):  
Visible Light ◽  
Power Efficiency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Light Emitting Diode ◽  
Average Power ◽  
Visible Light Communication ◽  
Intensity Modulation ◽  
Power Ratio ◽  
Positive Real ◽  
High Data

Indoor visible light communication (VLC) has the potential of providing high data rates for short-range wireless communication with a relative spatial elevated security in contrast to a radiofrequency wireless one. To support that high data stream, Orthogonal Frequency Division Multiplexing (OFDM) is used; however, due to the limited operational bandwidth of the commercial white light-emitting diode (LED), signal processing techniques are used to increase the efficiency of the OFDM and to adapt OFDM to VLC systems. As a major concern, the intensity modulation direct detection necessary for VLC requires positive real signal, this is dealt with by imposing Hermitian pre-possessing or Cartesian to polar conversion post-processing to the OFDM. The use of the Cartesian to polar converter allows the transmission of complex OFDM symbols through the intensity modulation channel. A polar transform optical (PTO-) OFDM presented here as an improvement and simplification of previous polar optical OFDM schemes gives an efficient transceiver architecture. Nevertheless, both OFDM transmission techniques for Visible optical links, similar to radiofrequency (RF), suffer greatly from irregular excessive Peak-to-Average power ratio (PAPR). Higher PAPR reduces the power efficiency of the On-Off Keying (OOK) based on pulse amplitude modulation (PAM). Furthermore, it also is recommendable to reduce the PAPR for conformity with eye safety. A precoding technique is proposed to reduce the PAPR of intensity-modulated for direct detectability of the OFDM signal destined for the wireless optical link using Cartesian-to-Polar conversion. Based on the enhanced processing at the front ends and using MATLAB simulation, it is proven that the presented model can improve the link parameters including the bit error rate (BER) and signal to noise ratio (SNR) and bandwidth efficient compared to Hermitian modified ones.

scholarly journals Estudio y simulación de técnicas para reducir la PAPR en HACO-OFDM

2021 ◽  
Vol 9 (17) ◽  
pp. 40-55
Author(s):  
Evelyn Nathaly Bermeo Granda ◽  
Diego Javier Reinoso Chisaguano
Keyword(s):  
Visible Light ◽  
Orthogonal Frequency Division Multiplexing ◽  
Convex Sets ◽  
Average Power ◽  
Electromagnetic Spectrum ◽  
Visible Light Communications ◽  
Ofdm Systems ◽  
High Data ◽  
Data Rates ◽  
High Spectral Efficiency

VLC (Visible Light Communications) have been recently proposed as a new form of wireless communications. The VLC advantages are its usage of the spectrum of visible light which is not licensed; additionally, it gives high data rates, protects the user against espionage and does not suffer from interference of the electromagnetic spectrum. One of the main techniques used in VLC is HACO-OFDM (Hybrid Asymmetrically Clipped Optical - Orthogonal Frequency Division Multiplexing), which offers a high spectral efficiency. However, one of its main problems is its high PAPR (Peak-to-Average-Power Ratio). This article presents a study and simulation of Clipping, CE-POCS (Constellation Extension – Project Onto Convex Sets), OPS (Orthogonal Pilot Sequences) and SAP (Simple Amplitude Predistortion) techniques for the reduction of the PAPR in HACO-OFDM systems. The simulation results show that the SAP technique gives the best results in PAPR reduction without significant degradation in the BER (Bit Error Rate).

scholarly journals Hadamard Coded Modulation for Visible Light Communication

2017 ◽  
Vol 4 (1) ◽  
pp. 96 ◽  
Author(s):  
Surendra Shrestha
Keyword(s):  
Visible Light ◽  
Frequency Spectrum ◽  
Secure Communication ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Microwave Frequency ◽  
Visible Light Communication ◽  
Coded Modulation ◽  
Local Networks ◽  
Very High

<p class="Default">In the recent days, Visible Light Communication (VLC), a novel technology that enables standard Light-Emitting-Diodes (LEDs) to transmit data, is gaining significant attention. However, to date, there is very little research on its deployment. The enormous and growing user demand for wireless data is placing huge pressure on existing Wi-Fi technology, which uses the radio and microwave frequency spectrum. Also the radio and microwave frequency spectrum is heavily used and overcrowded. On the other hand, visible light spectrum has huge, unused and unregulated capacity for communications (about 10,000 times greater bandwidth compared to radio spectrum). Li-Fi, the wireless technology based on VLC, is successfully tested with very high speed in lab and also implemented commercially. In the near future, this technology could enable devices containing LEDs, such as car lights, city lights, screens and home appliances, to form their own networks for high speed, secure communication. In this paper the performance analysis of Hadamard Coded Modulation (HCM) for Visible Light Communication (VLC) is carried out. Its performance is compared with that of Orthogonal Frequency Division Multiplexing (OFDM). Also wide overview of need of VLC, applications of VLC and design challenges for VLC are observed. The potential application areas of VLC that are identified include smart lighting of buildings, vehicular communication, defense &amp; security, indoor positioning, road safety, hospitals &amp; healthcare, aviation etc. Aside from the high bandwidth availability of VLC, it has the advantages of very high speed, enhanced security of local networks, less susceptible to interference, less expensive due to co-existence with illumination devices and obviously no fear of health hazards due to radiation.</p><p><strong>Journal of Nepal Physical Society</strong><em><br /></em>Volume 4, Issue 1, February 2017, Page: 93-96</p>

Dynamic Hyperchaotic Key Generation Using Optical Orthogonal Frequency Division Multiplexing-based Visible Light Communication Networks

2021 ◽  
Author(s):  
Mohammed Alresheedi ◽  
YAHYA AL-MOLIKI ◽  
Yahya Al-Harthi ◽  
Ali Alqahtani
Keyword(s):  
Visible Light ◽  
Communication Networks ◽  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Visible Light Communication ◽  
Frequency Division Multiplexing ◽  
Key Generation ◽  
Frequency Division ◽  
Degree Of Protection ◽  
Communication Time

Abstract This paper introduces an optical orthogonal frequency division multiplexing (OFDM)-based hyperchaotic key generation encryption approach that can improve confidentiality in visible light communication (VLC) networks. Using a hyperchaotic four-dimensional method, the bipolar real-valued OFDM signal can be used for constructing dynamic cypher keys modified at every frame over the communication time, resulting in a superior degree of protection against statistical and correlation attacks. In accordance with our findings, this approach decreases the ratio of peak-to-average power of the transmitted signal, and enhances the bit error rate efficiency and secrecy capacity of the OFDM-based VLC network, which improves confidentiality.

Light fidelity optical network a comparative performance evaluation

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Devendra Kr. Tripathi ◽  
Pallavi Singh
Keyword(s):  
Communication Systems ◽  
Optical Network ◽  
Visible Light Communication ◽  
Data Rate ◽  
Comparative Performance ◽  
Modulation Formats ◽  
High Data ◽  
Modulation Format ◽  
Output Performance ◽  
High Spectral Efficiency

Abstract Light-Fidelity (Li-Fi) is the bidirectional communication technique, tenders almost unlimited bandwidth, exploit unlicensed spectrum of light waves. Accordingly, this manuscript illustrates usage of visible light communication (VLC) applied as Li-Fi, an efficient scheme to broadcast data wirelessly as well safer technique in contrary to the customary Wireless-Fidelity (Wi-Fi) networks. In support numerical simulations have been executed over the proposed Li-Fi model for the parametric variation with the data rate, laser power, modulation format and wavelength, communication length. Investigations have showed good output performance, with hike in data rate BER variation as 10−94–10−23 and testing length. Simulations of network with DPSK and NRZ modulation formats at high data transmission of 10 Gbps have showed good output performance with 10−40 with DPSK format. Li-Fi systems are quality solution for the impending communication systems save cost, provide high spectral efficiency.

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