Theoretical analysis of visible-light code-shift keying using extended pseudo-orthogonal M-sequence in line-of-sight link

2016 ◽  
Author(s):  
Shota Takayanagi ◽  
Hiromasa Habuchi ◽  
Yusuke Kozawa
Keyword(s):  
Theoretical Analysis ◽  
Visible Light ◽  
Line Of Sight ◽  
M Sequence ◽  
Shift Keying

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

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 920
Author(s):  
Neha Chaudhary ◽  
Othman Isam Younus ◽  
Luis Nero Alves ◽  
Zabih Ghassemlooy ◽  
Stanislav Zvanovec ◽  
...  
Keyword(s):  
Visible Light ◽  
Polynomial Regression ◽  
Power Level ◽  
Least Square ◽  
Line Of Sight ◽  
Received Power ◽  
Strength Based ◽  
Complex Linear ◽  
Linear Least Square ◽  
First Time

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.e., the pointing center F), the received power level is maximized due to the LoS components on F. We also show that the proposed scheme offers a significant accuracy improvement of up to ~66% compared with a typical non-tilted Tx VLP at a dedicated location within a room using a low complex linear least square algorithm with polynomial regression. The effect of tilting the Tx on the lighting uniformity is also investigated and results proved that the uniformity achieved complies with the European Standard EN 12464-1. Furthermore, we show that the accuracy of VLP can be further enhanced with a minimum positioning error of 8 mm by changing the height of F.

scholarly journals Interference Mitigation for Visible Light Communications in Underground Mines Using Angle Diversity Receivers

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 367 ◽  
Author(s):  
Pablo Palacios Játiva ◽  
Milton Román Cañizares ◽  
Cesar A. Azurdia-Meza ◽  
David Zabala-Blanco ◽  
Ali Dehghan Firoozabadi ◽  
...  
Keyword(s):  
Visible Light ◽  
Mine Working ◽  
Channel Model ◽  
Underground Mining ◽  
Cumulative Distribution ◽  
Line Of Sight ◽  
Delay Spread ◽  
Noise Power ◽  
Working Face ◽  
Angle Diversity

This paper proposes two solutions based on angle diversity receivers (ADRs) to mitigate inter-cell interference (ICI) in underground mining visible light communication (VLC) systems, one of them is a novel approach. A realistic VLC system based on two underground mining scenarios, termed as mining roadway and mine working face, is developed and modeled. A channel model based on the direct component in line-of-sight (LoS) and reflections of non-line-of-sight (NLoS) links is considered, as well as thermal and shot noises. The design and mathematical models of a pyramid distribution and a new hemi-dodecahedral distribution are addressed in detail. The performances of these approaches, accompanied by signal combining schemes, are evaluated with the baseline of a single photo-diode in reception. Results show that the minimum lighting standards established in both scenarios are met. As expected, the root-mean-square delay spread decreases as the distance between the transmitters and receivers increases. Furthermore, the hemi-dodecahedron ADR in conjunction with the maximum ratio combining (MRC) scheme, presents the best performance in the evaluated VLC system, with a maximum user data rate of 250 Mbps in mining roadway and 120 Mbps in mine working face, received energy per bit/noise power of 32 dB and 23 dB, respectively, when the bit error rate corresponds to 10 − 4 , and finally, values of 120 dB in mining roadway and 118 dB in mine working face for signal-to-interference-plus-noise ratio are observed in a cumulative distribution function.

scholarly journals Passive Visible Light Detection of Humans

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 1902 ◽  
Author(s):  
Kenneth Deprez ◽  
Sander Bastiaens ◽  
Luc Martens ◽  
Wout Joseph ◽  
David Plets
Keyword(s):  
Visible Light ◽  
Detection Rate ◽  
Detection System ◽  
Light Emitting Diode ◽  
Line Of Sight ◽  
Controlled Environment ◽  
Ambient Light ◽  
Light Emitting ◽  
Light Sensing ◽  
Reflected Light

This paper experimentally investigates passive human visible light sensing (VLS). A passive VLS system is tested consisting of one light emitting diode (LED) and one photodiode-based receiver, both ceiling-mounted. There is no line of sight between the LED and the receiver, so only reflected light can be considered. The influence of a human is investigated based on the received signal strength (RSS) values of the reflections of ambient light at the photodiode. Depending on the situation, this influence can reach up to ± 50 % . The experimental results show the influence of three various clothing colors, four different walking directions and four different layouts. Based on the obtained results, a human pass-by detection system is proposed and tested. The system achieves a detection rate of 100% in a controlled environment for 21 experiments. For a realistic corridor experiment, the system keeps its detection rate of 100% for 19 experiments.

scholarly journals Doubly Orthogonal Wavelet Packets for Multi-Users Indoor Visible Light Communication Systems

Photonics ◽  
2019 ◽  
Vol 6 (3) ◽  
pp. 85 ◽  
Author(s):  
Arslan Khalid ◽  
Hafiz Muhammad Asif ◽  
Konstantin I. Kostromitin ◽  
Sattam Al-Otaibi ◽  
Kazi Mohammed Saidul Huq ◽  
...  
Keyword(s):  
Visible Light ◽  
Communication Systems ◽  
Multiple Access ◽  
Visible Light Communication ◽  
Wavelet Packets ◽  
Easy Access ◽  
Line Of Sight ◽  
Detection Scheme ◽  
Time Frequency ◽  
Code Division Multiple

Visible Light Communication (VLC) is a data communication technology that modulates the intensity of the light to transmit the information mostly by means of Light Emitting Diodes (LEDs). The data rate is mainly throttled by the limited bandwidth of the LEDs. To combat, Multi-carrier Code Division Multiple Access (MC-CDMA) is a favorable technique for achieving higher data rates along with reduced Inter-Symbol Interference (ISI) and easy access to multi-users at the cost of slightly reduced compromised spectral efficiency and Multiple Access Interference (MAI). In this article, a multi-user VLC system is designed using a Discrete Wavelet Transform (DWT) that eradicates the use of cyclic prefix due to the good orthogonality and time-frequency localization properties of wavelets. Moreover, the design also comprises suitable signature codes, which are generated by employing double orthogonality depending upon Walsh codes and Wavelet Packets. The proposed multi-user system is simulated in MATLAB software and its overall performance is assessed using line-of-sight (LoS) and non-line-of-sight (NLoS) configurations. Furthermore, two sub-optimum multi-users detection schemes such as zero forcing (ZF) and minimum-mean-square-error (MMSE) are also used at the receiver. The simulated results illustrate that the doubly orthogonal signature waveform-based DWT-MC-CDMA with MMSE detection scheme outperforms the Walsh code-based multi-user system.

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