The visible light communication (VLC) by LED is one of the important communication methods because LED can work as high speed and VLC sends the information by high flushing LED. We use the pulse wave modulation for the VLC with LED because LED can be controlled easily by the microcontroller, which has the digital output pins. At the pulse wave modulation, deciding the high and low voltage by the middle voltage when the receiving signal level is amplified is equal to deciding it by the threshold voltage without amplification. In this paper, we proposed two methods that adjust the threshold value using counting the slot number and measuring the signal level. The number of signal slots is constant per one symbol when we use Pulse Position Modulation (PPM). If the number of received signal slots per one symbol time is less than the theoretical value, that means the threshold value is higher than the optimal value. If it is more than the theoretical value, that means the threshold value is lower. So, we can adjust the threshold value using the number of received signal slots. At the second proposed method, the average received signal level is not equal to the signal level because there is a ratio between the number of high slots and low slots. So, we can calculate the threshold value from the average received signal level and the slot ratio. Unfortunately, the first proposed method adjusts the threshold value after receiving the data, once the distance between the sender and the receiver is changed, then the performance becomes worse. And after adjusting the threshold, the performance becomes better. Therefore, this method should be used in stable environments. The second proposed method can change the threshold value during the signal is received. That means this method can work very quickly. So, this method can show good performance for the wide range. We show these performances as real experiments.
Visible light communication is a high-speed developing technique with LEDs for both lighting and data communication. In this paper, examined the visible light communication performance over Mach Zehnder Modulation via Optisystem simulation tool. Quality factor and BER values of different link distance are predicted by optisystem simulation tool. The planned system can support 5 Gbps data rate up to 50 meter of link distance with a Quality factor of 15.71 for without any external noise interruption. In the case of external noise influence, the planned VLC system performance is also investigated through simulation tool. Consider the external noise interruption, the designed system can support 2Gbps data rate up to 20-meter link distance of Quality factor of 11.935. Quality factor for the system without any external noise influence is better compared to the system with external noise influence.
Development of an Audio Transmission System Through an Indoor Visible Light ...Mohammad Liton Hossain
This study presents an approach to develop an indoor visible light communication system capable of transmitting audio signal over light beam within a short distance. Visible Light Communication (VLC) is a pretty new technology which used light sources to transmit data for communication. In any communication system, both analog and digital signal transmission are possible, though, due to having the capability of providing a faithful quality of signal regeneration after the transmission process, digital communication system is much more popular than the analog one. In the current project, digital communication process was adopted also. To convert the analog audio signal into the digital transmission signal and vice versa, Pulse Width Modulation (PWM) was used as the signal encoding strategy. As the light emitter, white Light Emitting Diodes (LEDs) were used and as photo sensor, a solar cell was used instead of a photodiode to obtain greater signal power and sensitivity. In the system, the carrier signal for transmission was chosen to have a frequency of 50 KHz. At the receiving end, a 4th order Butterworth lowpass filter having a cutoff frequency of 8 KHz was used to demodulate the audio signal. Using only 2 white LEDs, the indoor transmission range of this visible light communication system was found to be 5 meters while reproducing a satisfactory quality audio.
Visible light communication is a high-speed developing technique with LEDs for both lighting and data communication. In this paper, examined the visible light communication performance over Mach Zehnder Modulation via Optisystem simulation tool. Quality factor and BER values of different link distance are predicted by optisystem simulation tool. The planned system can support 5 Gbps data rate up to 50 meter of link distance with a Quality factor of 15.71 for without any external noise interruption. In the case of external noise influence, the planned VLC system performance is also investigated through simulation tool. Consider the external noise interruption, the designed system can support 2Gbps data rate up to 20-meter link distance of Quality factor of 11.935. Quality factor for the system without any external noise influence is better compared to the system with external noise influence.
Development of an Audio Transmission System Through an Indoor Visible Light ...Mohammad Liton Hossain
This study presents an approach to develop an indoor visible light communication system capable of transmitting audio signal over light beam within a short distance. Visible Light Communication (VLC) is a pretty new technology which used light sources to transmit data for communication. In any communication system, both analog and digital signal transmission are possible, though, due to having the capability of providing a faithful quality of signal regeneration after the transmission process, digital communication system is much more popular than the analog one. In the current project, digital communication process was adopted also. To convert the analog audio signal into the digital transmission signal and vice versa, Pulse Width Modulation (PWM) was used as the signal encoding strategy. As the light emitter, white Light Emitting Diodes (LEDs) were used and as photo sensor, a solar cell was used instead of a photodiode to obtain greater signal power and sensitivity. In the system, the carrier signal for transmission was chosen to have a frequency of 50 KHz. At the receiving end, a 4th order Butterworth lowpass filter having a cutoff frequency of 8 KHz was used to demodulate the audio signal. Using only 2 white LEDs, the indoor transmission range of this visible light communication system was found to be 5 meters while reproducing a satisfactory quality audio.
Voice Transmission System Based on Laser Torchijtsrd
This paper is designed for voice transmission system based on laser torch. In this system, it has two parts transmitting section and receiving section. The transmitting section mainly comprises with condenser microphone, IC 741, BC 548, BD 139 and laser torch. The receiving section composes with L14f1 photo transistor, LM 386 and Loud speaker. If there is any obstruction in the path of the laser beam, no sound will be heard from the receiver. The gain of the op amp can be controlled with the help of 1 mega ohm pot meter variable resistor. The AF output from the amplifier is coupled to the base of transistor BD 139, which in turn, modulates the laser beam. The receiver circuit uses NPN photo transistor as the light sensor that is followed by two stage transistor preamplifier and LM 386 based audio power amplifier. The receiver does not need any complicated alignment. The photo transistor is kept towards the remote transmitter's laser point and the volume control is adjusted for a clear sound. Thet Thet Htun | Hla Yamin | May Zin Oo "Voice Transmission System Based on Laser Torch" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd26790.pdfPaper URL: https://www.ijtsrd.com/engineering/electronics-and-communication-engineering/26790/voice-transmission-system-based-on-laser-torch/thet-thet-htun
Transmission system used for optical fibers Jay Baria
In this presentation I have explained various types of transmission system used for optical transmission and also described about the budget method that has to be followed while selecting an source for optical fibers and also about the factors that should be consider while selecting an source.
Performance Analysis of GSM Network for Different Types of Antennas IJEEE
Today, in metro cities BTSs are increasing day by day and interference is also increasing. This paper shows the received power of the cell depends on a number of factors. Antenna gain and antenna type are one of the important parameters for this. This paper reveals the effect of signal received power by changing the antenna gain and antenna type.The antenna used is omnidirectional and switched beam and gain varies from 5 to 15 dB.The GSM network is simulated for 6 users in Qualnet software.
A low-cost fiber based displacement sensor for industrial applicationsTELKOMNIKA JOURNAL
In this paper, a low-cost fiber optic displacement sensor (FODS) using a bundle of plastic optical fiber (POF) as a probe is developed and presented. The sensor consists of a high power light emitting diode (LED) as light source, a probe with multiple receiving plastic optical fiber and a photodiode detector. The sensor is characterized at millimeter distance and the sensor output is analyzed from 0 mm to 13 mm displacement. The sensitivity of the sensor is found to be 5.38 mV/mm over 2.6 mm sensing range. The sensor is very useful for close distance target since it is highly sensitive at the front slope. The low development cost, high degree of sensitivity and simplicity of the design make it suitable for wide range of industrial applications.
ENERGY HARVESTING METHOD IN WIRELESS SENSOR NETWORKijejournal
With the advent of modern micro mechanical system technology and wireless communication wireless
sensor networks are finding a lot of application in modern day life. The design of the sensor network
depends on the specific application. This paper gives a description of the components of the wireless
sensor nodes used. It also describes how the lifetime of a wireless sensor network can be increased by the
use of energy harvesting sensor nodes.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
2.1 Theoretical Basis For Data Communication
What every sophomore EE knows !!! How much data can be put on a wire? What are the limits imposed by a medium?
2.2 Transmission Media
Wires and fibers.
2.3 Wireless Transmission
Radio, microwave, infrared, unguided by a medium.
2.4 The Telephone System
The system invented 100 years ago to carry voice.
2.5 Narrowband ISDN
Mechanisms that can carry voice and data.
Background/Objectives: The main aim of this research paper is to evaluate thedifferent linearly polarized
modes for two channel MDM passive optical network. Methods/Statistical Analysis: In this work mode division
multiplexing from 48 users. Three different combinations of linear polarized modes is tested for odd modes,
even modes and consecutive modes.System evaluated for 55 Km also on higher launched powers.Findings:
Results revealed that mode number 1,3 and 5 perform better and suffered from less mode crosstalk. However
even modes perform less effective than odd modes but better than mode number 1,2 and 3.Further 16 user for
each mode is splitted and 10 dB optimal power is found, beyond this power system performance degrated.LP 01
provide maximum quality factor and worst in case of LP 21 mode.
Voice Transmission System Based on Laser Torchijtsrd
This paper is designed for voice transmission system based on laser torch. In this system, it has two parts transmitting section and receiving section. The transmitting section mainly comprises with condenser microphone, IC 741, BC 548, BD 139 and laser torch. The receiving section composes with L14f1 photo transistor, LM 386 and Loud speaker. If there is any obstruction in the path of the laser beam, no sound will be heard from the receiver. The gain of the op amp can be controlled with the help of 1 mega ohm pot meter variable resistor. The AF output from the amplifier is coupled to the base of transistor BD 139, which in turn, modulates the laser beam. The receiver circuit uses NPN photo transistor as the light sensor that is followed by two stage transistor preamplifier and LM 386 based audio power amplifier. The receiver does not need any complicated alignment. The photo transistor is kept towards the remote transmitter's laser point and the volume control is adjusted for a clear sound. Thet Thet Htun | Hla Yamin | May Zin Oo "Voice Transmission System Based on Laser Torch" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd26790.pdfPaper URL: https://www.ijtsrd.com/engineering/electronics-and-communication-engineering/26790/voice-transmission-system-based-on-laser-torch/thet-thet-htun
Transmission system used for optical fibers Jay Baria
In this presentation I have explained various types of transmission system used for optical transmission and also described about the budget method that has to be followed while selecting an source for optical fibers and also about the factors that should be consider while selecting an source.
Performance Analysis of GSM Network for Different Types of Antennas IJEEE
Today, in metro cities BTSs are increasing day by day and interference is also increasing. This paper shows the received power of the cell depends on a number of factors. Antenna gain and antenna type are one of the important parameters for this. This paper reveals the effect of signal received power by changing the antenna gain and antenna type.The antenna used is omnidirectional and switched beam and gain varies from 5 to 15 dB.The GSM network is simulated for 6 users in Qualnet software.
A low-cost fiber based displacement sensor for industrial applicationsTELKOMNIKA JOURNAL
In this paper, a low-cost fiber optic displacement sensor (FODS) using a bundle of plastic optical fiber (POF) as a probe is developed and presented. The sensor consists of a high power light emitting diode (LED) as light source, a probe with multiple receiving plastic optical fiber and a photodiode detector. The sensor is characterized at millimeter distance and the sensor output is analyzed from 0 mm to 13 mm displacement. The sensitivity of the sensor is found to be 5.38 mV/mm over 2.6 mm sensing range. The sensor is very useful for close distance target since it is highly sensitive at the front slope. The low development cost, high degree of sensitivity and simplicity of the design make it suitable for wide range of industrial applications.
ENERGY HARVESTING METHOD IN WIRELESS SENSOR NETWORKijejournal
With the advent of modern micro mechanical system technology and wireless communication wireless
sensor networks are finding a lot of application in modern day life. The design of the sensor network
depends on the specific application. This paper gives a description of the components of the wireless
sensor nodes used. It also describes how the lifetime of a wireless sensor network can be increased by the
use of energy harvesting sensor nodes.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
2.1 Theoretical Basis For Data Communication
What every sophomore EE knows !!! How much data can be put on a wire? What are the limits imposed by a medium?
2.2 Transmission Media
Wires and fibers.
2.3 Wireless Transmission
Radio, microwave, infrared, unguided by a medium.
2.4 The Telephone System
The system invented 100 years ago to carry voice.
2.5 Narrowband ISDN
Mechanisms that can carry voice and data.
Background/Objectives: The main aim of this research paper is to evaluate thedifferent linearly polarized
modes for two channel MDM passive optical network. Methods/Statistical Analysis: In this work mode division
multiplexing from 48 users. Three different combinations of linear polarized modes is tested for odd modes,
even modes and consecutive modes.System evaluated for 55 Km also on higher launched powers.Findings:
Results revealed that mode number 1,3 and 5 perform better and suffered from less mode crosstalk. However
even modes perform less effective than odd modes but better than mode number 1,2 and 3.Further 16 user for
each mode is splitted and 10 dB optimal power is found, beyond this power system performance degrated.LP 01
provide maximum quality factor and worst in case of LP 21 mode.
A HYBRID MODULATION METHOD FOR DIMMING IN VISIBLE LIGHT COMMUNICATION IJCNCJournal
In visible light communication in which information is superimposed on light, its communication range is visible. On the other hand, when the modulation that brightness is changed according to information is used, it is not good for the human eye because human feels flicker for the changed brightness. Therefore, the pulse width modulation which is used in the infrared remote controller, is not suitable for the visible light communication. And the pulse position modulation that sends information at the position of a pulse is often used. In pulse position modulation, for example, when one symbol uses four slots, quad information can be sent by turning on only one slot among the four slots and turning off the other three slots. In this
method, the brightness becomes ¼ and feels not flicker but darker than when it is always on. On the other hand, when inverted pulse position modulation in which these slots of ON and OFF are reversed is used, since one slot is OFF, and three slots are ON, the brightness becomes 3/4, which does not become too dark. In this paper, we propose a hybrid modulation that can vary the brightness other than 1/4(25%) or
3/4(75%) by combining these pulse position modulation and inverted pulse position modulation. We have two experiments; one is measuring its communication performance and the other is the evaluation for visual flicker by the human eye and. From the view of the communication performance, each brightness is
the same performance. So, the changing brightness does not affect to the performance. For the dimming, we interviewed 10 people how to feel the flicker in visible light communication. As the result, they do not feel the flickers. So, our proposed hybrid modulation method can be adapted for the dimming lighting
equipment.
A Measurements Project on Light Detection sensorsvrohith 9
The main aim of this project is to saving system with LDR this is to save the power. We want to save power automatically instead of doing manual. So it’s easy to cost effectiveness. This saved power can be used in some other cases. So in villages, towns etc. we can design intelligent systems for the usage of light or we can also use this to reduce the electricity bill of our home. This project can also be used for security of the houses, banks, etc.
Wireless Networks using Visible Light Communication: A Reviewijwmn
Provisioning of quality of service (QoS) is a critical issue in visible light communication (VLC) systems and other wireless communication systems. LED lights are becoming widely used for homes and offices for their luminous efficacy improvement. VLC is a new way of wireless communication. Typical transmitters used for visible-light communication are visible-light LEDs, and receivers are photodiodes and image sensors. We present new applications that will be made possible by visible light communication technology. Especially location-based services are considered suitable for visible light communication applications.
A W ARNING S YSTEM F OR O VERSPEED A T T HE C ORNER U SING V ISIBLE L...ijasuc
When a car enters a
corner
with
over speed,
it rise
s
the accident risk higher
.
To warn the risk and urging
the caution to drivers, many of the accident
-
prone corners have warning rights. The driver can decelerate
the car smoothly and pass through the
corner safety by those
devices.
However
, appropriate speed for each
corner is differ
ent by curvature of the corner and characteristics of the vehicle.
The driver
has
to suppose
the safe speed for every corner only by experience,
usually. Of
co
urse too much slow causes traffic jam.
Especially at the first road in the first place for the dr
iver, it is difficult to suppose the curvatures of the
corners. Then
, we propose a visible light communication system so that the warning lights in the corner
send appropriate warning information. V
isible light communication transmits
a signal by blinking the light.
One of the characteristics of
visible light communication is that it can use
existing
lighting equipment as a
transmitter.
In our system, we
can distribute the
warning
information to the driver using the visible light
commun
ication.
Though
the curvature(R:radious) of the corner does not change, the speed of each vehicle
to approach the corner always to different.
Focusing the distance from the corner to the car, we consider a
communication system to send different kind of inf
ormation according to that
distance.
If
the distance is
enough long, the driver has a plenty of time to decelerate the
vehicle. The
more the distance becomes short,
the more the driver is required rapid
deceleration. Therefore
, to distribute the appropriat
e warning
information to the driver, dividing the distance from the corner into some areas, we make the system to send
different information in each
area. Generally
in communication system, modulation primarily changes the
amplitude, phase or
frequency. In
visible light communication, change of the amplitude changes the
brightness, which causes flickering that burdens the
drivers. Therefore
we cannot use amplitude based
modulation.
Next
we consider the varying the
phase.
Unfortunately
, it is difficult for t
he receiver using
photodiode or phototransistor to read the difference of the phase of the signals, because the frequency of
the light is very high
in visible light communication.
Then we employ 'symbol length' with the Pulse
Position
Modulation (
PPM).In our method, brightness does not change when the symbol length is
changed.
We
investigate the system performance by changing the communication
speed. Short
symbol length in high
frequency is sensitive and vulnerable to noise, instead of low frequenc
y with strong against
noise.
Using
this characteristic of symbol length modulation, dif
A WARNING SYSTEM FOR OVERSPEED AT THE CORNER USING VISIBLE LIGHT BASED ROAD-T...ijasuc
When a car enters a corner with over speed, it rises the accident risk higher. To warn the risk and urging
the caution to drivers, many of the accident-prone corners have warning rights. The driver can decelerate
the car smoothly and pass through the corner safety by those devices. However, appropriate speed for each
corner is different by curvature of the corner and characteristics of the vehicle. The driver has to suppose
the safe speed for every corner only by experience, usually. Of course too much slow causes traffic jam.
Especially at the first road in the first place for the driver, it is difficult to suppose the curvatures of the
corners. Then, we propose a visible light communication system so that the warning lights in the corner
send appropriate warning information. Visible light communication transmits a signal by blinking the light.
One of the characteristics of visible light communication is that it can use existing lighting equipment as a
transmitter. In our system, we can distribute the warning information to the driver using the visible light
communication.
Bidirectional Underwater Visible Light Communication IJECEIAES
In this paper, a novel bidirectional underwater visible light communication (BiUVLC) is proposed. The VLC transmitter transmits an information signal using the one of RGB LED through the water tank that represents an underwater environment and then is received by VLC receiver via a color filter. The color LEDs and color filters are utilized in bidirectional systems. The single link is created by a LED on the transmitter and the color filter on the receiver with the same color which represents a single wavelength. The performance of the proposed BiUVLC system was evaluated via implementations. The experimental result shows that the transmitted signal undergoes attenuation over the underwater optical channel and the pair of the blue wavelength in link 1 and the green wavelength in link 2 have the best performance than the other wavelength pair. In the crosstalk measurement, the red wavelength color is the worst in the underwater environment.
Vehicle Ad Hoc Networks (VANETs) have become a viable technology to improve traffic flow and safety on the roads. Due to its effectiveness and scalability, the Wingsuit Search-based Optimised Link State Routing Protocol (WS-OLSR) is frequently used for data distribution in VANETs. However, the selection of MultiPoint Relays (MPRs) plays a pivotal role in WS-OLSR's performance. This paper presents an improved MPR selection algorithm tailored to WS-OLSR, designed to enhance the overall routing efficiency and reduce overhead. The analysis found that the current OLSR protocol has problems such as redundancy of HELLO and TC message packets or failure to update routing information in time, so a WS-OLSR routing protocol based on improved-MPR selection algorithm was proposed. Firstly, factors such as node mobility and link changes are comprehensively considered to reflect network topology changes, and the broadcast cycle of node HELLO messages is controlled through topology changes. Secondly, a new MPR selection algorithm is proposed, considering link stability issues and nodes. Finally, evaluate its effectiveness in terms of packet delivery ratio, end-to-end delay, and control message overhead. Simulation results demonstrate the superior performance of our improved MR selection algorithm when compared to traditional approaches.
A Novel Medium Access Control Strategy for Heterogeneous Traffic in Wireless ...IJCNCJournal
So far, Wireless Body Area Networks (WBANs) have played a pivotal role in driving the development of intelligent healthcare systems with broad applicability across various domains. Each WBAN consists of one or more types of sensors that can be embedded in clothing, attached directly to the body, or even implanted beneath an individual's skin. These sensors typically serve asingle application. However, the traffic generated by each sensor may have distinct requirements. This diversity necessitates a dual approach: tailored treatment based on the specific needs of each traffic typeand the fulfillment of application requirements, such asreliability and timeliness. Never the less, the presence of energy constraints and the unreliable nature of wireless communications make QoS provisioning under such networks a non-trivial task. In this context, the current paper introduces a novel Medium AccessControl (MAC) strategy for the regular traffic applications of WBANs, designed to significantly enhance efficiency when compared to the established MAC protocols IEEE 802.15.4 and IEEE 802.15.6, with a particular focus on improving reliability, timeliness, and energy efficiency.
May_2024 Top 10 Read Articles in Computer Networks & Communications.pdfIJCNCJournal
The International Journal of Computer Networks & Communications (IJCNC) is a bi monthly open access peer-reviewed journal that publishes articles which contribute new results in all areas of Computer Networks & Communications. The journal focuses on all technical and practical aspects of Computer Networks & data Communications. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on advanced networking concepts and establishing new collaborations in these areas.
A Topology Control Algorithm Taking into Account Energy and Quality of Transm...IJCNCJournal
The efficient use of energy in wireless sensor networks is critical for extending node lifetime. The network topology is one of the factors that have a significant impact on the energy usage at the nodes and the quality of transmission (QoT) in the network. We propose a topology control algorithm for software-defined wireless sensor networks (SDWSNs) in this paper. Our method is to formulate topology control algorithm as a nonlinear programming (NP) problem with the objective to optimizing two metrics, maximum communication range, and desired degree. This NP problem is solved at the SDWSN controller by employing the genetic algorithm (GA) to determine the best topology. The simulation results show that the proposed algorithm outperforms the MaxPower algorithm in terms of average node degree and energy expansion ratio.
Multi-Server user Authentication Scheme for Privacy Preservation with Fuzzy C...IJCNCJournal
The integration of artificial intelligence technology with a scalable Internet of Things (IoT) platform facilitates diverse smart communication services, allowing remote users to access services from anywhere at any time. The multi-server environment within IoT introduces a flexible security service model, enabling users to interact with any server through a single registration. To ensure secure and privacy preservation services for resources, an authentication scheme is essential. Zhao et al. recently introduced a user authentication scheme for the multi-server environment, utilizing passwords and smart cards, claiming resilience against well-known attacks. This paper conducts cryptanalysis on Zhao et al.'s scheme, focusing on denial of service and privacy attacks, revealing a lack of user-friendliness. Subsequently, we propose a new multi-server user authentication scheme for privacy preservation with fuzzy commitment over the IoT environment, addressing the shortcomings of Zhao et al.'s scheme. Formal security verification of the proposed scheme is conducted using the ProVerif simulation tool. Through both formal and informal security analyses, we demonstrate that the proposed scheme is resilient against various known attacks and those identified in Zhao et al.'s scheme.
Advanced Privacy Scheme to Improve Road Safety in Smart Transportation SystemsIJCNCJournal
In -Vehicle Ad-Hoc Network (VANET), vehicles continuously transmit and receive spatiotemporal data with neighboring vehicles, thereby establishing a comprehensive 360-degree traffic awareness system. Vehicular Network safety applications facilitate the transmission of messages between vehicles that are near each other, at regular intervals, enhancing drivers' contextual understanding of the driving environment and significantly improving traffic safety. Privacy schemes in VANETs are vital to safeguard vehicles’ identities and their associated owners or drivers. Privacy schemes prevent unauthorized parties from linking the vehicle's communications to a specific real-world identity by employing techniques such as pseudonyms, randomization, or cryptographic protocols. Nevertheless, these communications frequently contain important vehicle information that malevolent groups could use to Monitor the vehicle over a long period. The acquisition of this shared data has the potential to facilitate the reconstruction of vehicle trajectories, thereby posing a potential risk to the privacy of the driver. Addressing the critical challenge of developing effective and scalable privacy-preserving protocols for communication in vehicle networks is of the highest priority. These protocols aim to reduce the transmission of confidential data while ensuring the required level of communication. This paper aims to propose an Advanced Privacy Vehicle Scheme (APV) that periodically changes pseudonyms to protect vehicle identities and improve privacy. The APV scheme utilizes a concept called the silent period, which involves changing the pseudonym of a vehicle periodically based on the tracking of neighboring vehicles. The pseudonym is a temporary identifier that vehicles use to communicate with each other in a VANET. By changing the pseudonym regularly, the APV scheme makes it difficult for unauthorized entities to link a vehicle's communications to its real-world identity. The proposed APV is compared to the SLOW, RSP, CAPS, and CPN techniques. The data indicates that the efficiency of APV is a better improvement in privacy metrics. It is evident that the AVP offers enhanced safety for vehicles during transportation in the smart city.
April 2024 - Top 10 Read Articles in Computer Networks & CommunicationsIJCNCJournal
The International Journal of Computer Networks & Communications (IJCNC) is a bi monthly open access peer-reviewed journal that publishes articles which contribute new results in all areas of Computer Networks & Communications. The journal focuses on all technical and practical aspects of Computer Networks & data Communications. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on advanced networking concepts and establishing new collaborations in these areas.
DEF: Deep Ensemble Neural Network Classifier for Android Malware DetectionIJCNCJournal
Malware is one of the threats to security of computer networks and information systems. Since malware instances are available sufficiently, there is increased interest among researchers on usage of Artificial Intelligence (AI). Of late AI-enabled methods such as machine learning (ML) and deep learning paved way for solving many real-world problems. As it is a learning-based approach, accumulated training samples help in improving thequality of training and thus leveraging malware detection accuracy. Existing deep learning methods are focusing on learning-based malware detection systems. However, there is need for improving the state of the art through ensemble approach. Towards this end, in this paper we proposed a framework known as Deep Ensemble Framework (DEF) for automatic malware detection. The framework obtains features from training samples. From given malware instance a grayscale image is generated. There is another process to extract the opcode sequences. Convolutional Neural Network (CNN) and Long Short Term Memory (LSTM) techniques are used to obtain grayscale image and opcode sequence respectively. Afterwards, a stacking ensemble is employed in order to achieve efficient malware detection and classification. Malware samples collected fromthe Internet sources and Microsoft are used for theempirical study. An algorithm known as Ensemble Learning for Automatic Malware Detection (EL-AML) is proposed to realize our framework. Another algorithm named Pre-Process is proposed to assist the EL-AML algorithm for obtaining intermediate features required by CNN and LSTM.Empirical study reveals that our framework outperforms many existing methods in terms of speed-up and accuracy.
High Performance NMF Based Intrusion Detection System for Big Data IOT TrafficIJCNCJournal
With the emergence of smart devices and the Internet of Things (IoT), millions of users connected to the network produce massive network traffic datasets. These vast datasets of network traffic, Big Data are challenging to store, deal with and analyse using a single computer. In this paper we developed parallel implementation using a High Performance Computer (HPC) for the Non-Negative Matrix Factorization technique as an engine for an Intrusion Detection System (HPC-NMF-IDS). The large IoT traffic datasets of order of millions samples are distributed evenly on all the computing cores for both storage and speedup purpose. The distribution of computing tasks involved in the Matrix Factorization takes into account the reduction of the communication cost between the computing cores. The experiments we conducted on the proposed HPC-IDS-NMF give better results than the traditional ML-based intrusion detection systems. We could train the HPC model with datasets of one million samples in only 31 seconds instead of the 40 minutes using one processor), that is a speed up of 87 times. Moreover, we have got an excellent detection accuracy rate of 98% for KDD dataset.
A Novel Medium Access Control Strategy for Heterogeneous Traffic in Wireless ...IJCNCJournal
So far, Wireless Body Area Networks (WBANs) have played a pivotal role in driving the development of intelligent healthcare systems with broad applicability across various domains. Each WBAN consists of one or more types of sensors that can be embedded in clothing, attached directly to the body, or even implanted beneath an individual's skin. These sensors typically serve asingle application. However, the traffic generated by each sensor may have distinct requirements. This diversity necessitates a dual approach: tailored treatment based on the specific needs of each traffic typeand the fulfillment of application requirements, such asreliability and timeliness. Never the less, the presence of energy constraints and the unreliable nature of wireless communications make QoS provisioning under such networks a non-trivial task. In this context, the current paper introduces a novel Medium AccessControl (MAC) strategy for the regular traffic applications of WBANs, designed to significantly enhance efficiency when compared to the established MAC protocols IEEE 802.15.4 and IEEE 802.15.6, with a particular focus on improving reliability, timeliness, and energy efficiency.
A Topology Control Algorithm Taking into Account Energy and Quality of Transm...IJCNCJournal
The efficient use of energy in wireless sensor networks is critical for extending node lifetime. The network topology is one of the factors that have a significant impact on the energy usage at the nodes and the quality of transmission (QoT) in the network. We propose a topology control algorithm for software-defined wireless sensor networks (SDWSNs) in this paper. Our method is to formulate topology control algorithm as a nonlinear programming (NP) problem with the objective to optimizing two metrics, maximum communication range, and desired degree. This NP problem is solved at the SDWSN controller by employing the genetic algorithm (GA) to determine the best topology. The simulation results show that the proposed algorithm outperforms the MaxPower algorithm in terms of average node degree and energy expansion ratio.
Multi-Server user Authentication Scheme for Privacy Preservation with Fuzzy C...IJCNCJournal
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Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
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About Digital Communication Methods for Visible Light Communication
1. International Journal of Computer Networks & Communications (IJCNC) Vol.13, No.3, May 2021
DOI: 10.5121/ijcnc.2021.13301 1
ABOUT DIGITAL COMMUNICATION METHODS
FOR VISIBLE LIGHT COMMUNICATION
Wataru Uemura, Yasuhiro Fukumori and Takato Hayama
Department of Electronics and Informatics, Ryukoku University, Shiga, Japan
ABSTRACT
The visible light communication (VLC) by LED is one of the important communication methods because
LED can work as high speed and VLC sends the information by high flushing LED. We use the pulse wave
modulation for the VLC with LED because LED can be controlled easily by the microcontroller, which has
the digital output pins. At the pulse wave modulation, deciding the high and low voltage by the middle
voltage when the receiving signal level is amplified is equal to deciding it by the threshold voltage without
amplification. In this paper, we proposed two methods that adjust the threshold value using counting the
slot number and measuring the signal level. The number of signal slots is constant per one symbol when we
use Pulse Position Modulation (PPM). If the number of received signal slots per one symbol time is less
than the theoretical value, that means the threshold value is higher than the optimal value. If it is more
than the theoretical value, that means the threshold value is lower. So, we can adjust the threshold value
using the number of received signal slots. At the second proposed method, the average received signal level
is not equal to the signal level because there is a ratio between the number of high slots and low slots. So,
we can calculate the threshold value from the average received signal level and the slot ratio.
Unfortunately, the first proposed method adjusts the threshold value after receiving the data, once the
distance between the sender and the receiver is changed, then the performance becomes worse. And after
adjusting the threshold, the performance becomes better. Therefore, this method should be used in stable
environments. The second proposed method can change the threshold value during the signal is received.
That means this method can work very quickly. So, this method can show good performance for the wide
range. We show these performances as real experiments.
KEYWORDS
Visible Light Communication, Digital Communication, Pulse Position Modulation.
1. INTRODUCTION
Light Emitting Diode (LED) becomes widespread as a lighting source which can save power
consumption. And because the response speed of LED is high, LED is focused on as the sender
element of the visible light communication (VLC) which transmits the information by blinking
the light [1 - 4]. For visible light communication, pulse modulation is used often because it is
easy for the output pin of a microcomputer to control the power of the LED. If we assign 0 and 1
information to the voltages of LED which turn off and on (which are high and low voltage,
respectively), flicker has occurred because the lighting time (that means turning on time) is
changed by the information. One of modulation methods to avoid the flicker is Pulse Position
Modulation (PPM). On PPM, the lighting time per information is constant [5, 6]. When the
distance between the sender and the receiver becomes larger, there are more communication
errors like the other wireless communications because of the decreasing receiving signal level [7].
The gain control for the receiving signal is important for this problem. If we use the pulse
modulation, the decision method which compares the amplified voltage as the half voltage of
high is equal to the decision method which compares the received voltage as the threshold
2. International Journal of Computer Networks & Communications (IJCNC) Vol.13, No.3, May 2021
2
voltage. In this paper, we propose two methods for the receiving signal level; one method adjusts
the threshold voltage, and the other method controls the gain for the received voltage
automatically. The number of signal slots is constant per one symbol when we use PPM. If the
number of received signal slot per one symbol time is less than the theoretical value, that means
the threshold value is higher than the optimal value. If it is more than the theoretical value, that
means the threshold value is lower. So, we can adjust the threshold value using the number of
received signal slot. At the second proposed method, the average received signal level is not
equal to the high signal level because there is the ratio between the number of high slots and the
number of low slots. So, we can calculate the threshold value from the average received signal
level and the slot ratio.
Section 2 shows the communication method which uses visible light instead of the radio wave.
And Section 3 describes the comparator voltage which uses to decode the signal. We proposed
two methods in Section 4. And we show the experimental results in Section 5. Finally, we
conclude this paper in Section 6.
2. THE VISIBLE LIGHT COMMUNICATION
VLC is wireless communication that uses light instead of the radio wave [8 - 10]. In this section,
we describe the modulation method for visible light communication and its applications.
2.1. The Frequency and Modulation of the Visible Light Communication
VLC is one of the wireless communications. It uses light for communication, which is visible to
the human eyes and is one of the electromagnetic waves like the infrared. We can see the visible
light which frequency range is about from 360-400 [nm] to 760-830 [nm]. We cannot sense the
electromagnetic waves which frequency is over about 830 [nm]. The shorter wavelengths than
the visible light is called ultraviolet rays and shorter than it is called as X rays and gamma rays.
And the longer one is called infrared rays and longer than it is called the radio wave.
At VLC, we send the information by the changing blinking patterns of the light. The LED is an
element for the lighting source of visible light communication. LED has some better features than
traditional lighting elements, for example, the low power consumption, the long lifetime, the
highspeed response, and the small size. From the view of the highspeed response, LED can turn
on and off very quickly. And by this feature, VLC can communicate at a very high speed. And
from this quick response, we can have a variety of modulations for VLC. In this paper, we use
LED as the lighting source.
2.2. The Features of VLC
In this subsection, we show some characteristics of visible light communication when we use it
as wireless communication. At first, we can see the communication area because the medium of
the communication is visible light. This characteristic is only for visible light communication
comparing with other wireless communications. And it is easy to cut and change the
communication range by using a wall, a mirror, a lens, and so on. In such a case, we can modify
the communication range by checking it with our eyes. By the reason of using the ordinal lighting
elements, it is not affected to the human, that means it is safe for the body, and in addition to it, it
is not affected to the other devices using the radio wave. Furthermore, it has high directivity, so
we can control the directional of communication and we can get a high resolution. But there is a
defect, for which there are a lot of noise sources which are natural and artificial lighting. In the
3. International Journal of Computer Networks & Communications (IJCNC) Vol.13, No.3, May 2021
3
remainder of this section, we describe the features of visible light communication comparing with
other electromagnetic wave communication, like radio and infrared.
2.3. Comparison with the Radio Wave Communication
The radio wave communication is the wireless communication with the electromagnetic wave
which frequency is less than 3 [THz] under the Japanese radio law. The radio wave has some
features; the refraction, the diffraction, and reflection regarding its frequency. And the
wavelength becomes shorter, directivity becomes stronger.
It is difficult for us to find the source of the radio wave because it has more refraction than visible
light. So, it is difficult for the sender to control the area where the information can be transmitted.
That means some security issues will happen more frequently than VLC. And there is a
possibility that the radio wave affects human health. Besides, because it affects electric devices, it
is prohibited to use radio wave communication in a hospital, a train, an airplane, and so on. And
the radio law limits the power and the frequency used by radio wave communication.
On the other hand, VLC has the following features against radio wave communication. Because
the visible light goes straight without few refractions, the obstructs can cut off the communication.
It is easy for the receiver to find the sender location because the transmitter is bright. And it is
easy for the sender not to send the information to the undesirable receivers because the sender
can control the receivable range. If the power of the visible light is too big, it is dangerous for us
same as the radio wave. But if we face such a situation, we can avoid it because we recognize its
dangerously by eyes. And we can use VLC in a hospital, a train, an airplane, and so on because of
no effect on the electrical device. Also, VLC is not under the radio law, so we can set any power
and any frequency for VLC as you want.
2.4. Comparison with the Infrared Communication
The infrared communication is the wireless communication with the infrared wave which
frequency is longer than red light and shorter than the radio waves, and its wavelength is about
from 0.7 [m] to 1 [mm]. Its characteristics from the view of the electronic wave and visible are
similar to that of visible light because the frequency of the infrared is close to that of the visible
light.
However, the infrared wave cannot be seen by a human, so the transmitter of the infrared cannot
be lighting that we cannot use as visible elements. And then the human cannot recognize the
communication range. It is dangerous for us to use more than certain strengths because we cannot
see the effect for the human eyes. Furthermore, we cannot find where the transmitter device is set
on and cannot see the communication range. Then there is the possibility that the receiver whom
the sender does not want to send the information to can receiver gets the packet, and if that will
happen, the sender cannot know it. This is not good for security, so we need to use infrared
communication to avoid this incident.
From the view of VLC, it has similar characteristics against infrared communication because the
frequency of it is very close to the frequency of infrared. But some characteristics of VLC are
different for infrared. One of the most different characteristics is visibility.
4. International Journal of Computer Networks & Communications (IJCNC) Vol.13, No.3, May 2021
4
2.5. About Modulations
We need to modulate the signal to send the information using wireless communications. The
modulation is to change the frequency, amplitude, or phase of the carrier to send the information
by the signal. Usually, in digital communication, the electronic signal is changed by the
information ‘0’ and ‘1’.
There are a lot of kinds of modulation. For example, we can change the strength of LED or the
pattern of LED for visible light communication. We call the amplitude modulation (AM) where
we change the voltage of LED regarding the sending information. And we call the frequency
modulation (FM) where we change the frequency as the LED bringing speed regarding the
sending information. And if we switch the power of LED to on or off regarding the information,
we call it as on-off keying (OOK) [11]. If we change the duty rate of the pulse regarding the
sending information, it is called the pulse width modulation (PWM) [12]. If we change pulse
position in the time slots regarding the sending information, it is called pulse position modulation
(PPM). When we use the modulation, which changes the something of pulse, usually the pulse
forms not the sine curve but the rectangular. For the considering of the usage for the lighting
equivalent, we need to not occur the flicker and need to brightness light [13, 14]. In this paper,
we use the PPM as the lighting modulation method because it keeps the same lighting power for
any information.
PPM change the time slot of the symbol which is one of the sending information. One symbol
allows only one pulse which width is one slot. So, this modulation has only a single lighting slot
per one symbol for any information. Then the flicker has not occurred because the average power
of a certain time is the same as any information. If the number of positions per symbol becomes
larger, we can send more information per one symbol. For example, we use 2-PPM for 2 slots per
symbol, 4-PPM for 4 slots per symbol (shown in Figures 1 and 2, respectively). Furthermore, we
can send the information even if the state of the slot is changed to upside down, for example, the
high becomes low and low becomes high. We call it Inversed-PPM (shown in Figure 3). If we
use 2-PPM, 2-IPPM is the same as 2-PPM. When we use more than two -PPM, like 4-PPM, the
brightness is different between PPM and IPPM. For example, using 4-IPPM, the lighting time
ratio of on and off is 3:1, the brightness can be suppressed to 3/4. So, the lighting time becomes
longer, and the average power becomes bigger. Then from the human eyes, the lighting LED of
the transmitter becomes bright. This characteristic is good for lighting equipment.
5. International Journal of Computer Networks & Communications (IJCNC) Vol.13, No.3, May 2021
5
Figure 3. 4-Inversed PPM for 4 slots per symbol
Figure 2. 4-PPM for 4 slots per symbol
Figure 1. 2-PPM for 2 slots per symbol
6. International Journal of Computer Networks & Communications (IJCNC) Vol.13, No.3, May 2021
6
Generally, a filter circuit is used for reducing the influence of noise. However, when a filter
circuit is used in visible light communication with a rectangular wave, its waveform is deformed,
and the edge of the rectangular wave is lost. And it becomes difficult to decide 0 or 1 with its
deformed waveform. Now we focus on the comparator circuit which compares two input voltages
and outputs high or low voltages according to its result. By setting the threshold value as fixing
the input voltage, if the input voltage exceeds a threshold voltage, the output becomes high
voltage, otherwise, the output becomes low voltage. As a result, the output waves become the
rectangular wave that does not include an unnecessary waveform other than the transmission
waveform, and the influence of noise can be reduced. Here, in the visible light communication
using the rectangular wave, there is no problem even if the received signal is deformed into a
rectangular wave shape by the comparator circuit. Therefore, by using the threshold voltage set
by the comparator as a reference, the waveform can be adjusted by the comparator, and
communication with fewer errors can be performed. For example, waveforms deformed by the
filter circuit, waveforms distorted by a noise that cannot be completely cut, and waveforms
distorted by noise generated in the circuit, can be adjusted.
3. ADJUSTING THE COMPARATOR VOLTAGE
The receiver sets threshold voltage for determining high and low from the signal voltage received
by the lighting element. Here, as in other communication methods, the influence of noise is a
problem to decode the signal. In this paper, we propose a comparative voltage adjustment method.
3.1. About Noise in Digital Communication of Visible Light
A filter is used for reducing the influence of noise. There are several filters; a low-pass filter that
cuts high-frequency signal, a high-pass filter that cuts low-frequency signal, a bandpass filter that
cuts frequencies other than certain frequencies, and so on. In this way, filters cut noise from
specific frequencies. However, the noise like white noise generally does not depend on the
frequency and affects all frequency bands, so that noise remains even after being filtered. On the
other hand, when rectangular waves are used as modulation, the shape of the wave is known, and
the waveform can be adjusted by the comparator. By preparing a threshold value to distinguish
between high and low from the signal, we can create square waves by outputting using only high
and low voltages.
3.2. Problems in Setting the Reference Voltage
Usually, the threshold value for the comparator is manually adjusted using a variable resistor. In
this case, if the communication distance between the sender and the receiver becomes longer, the
signal strength decreases, and it becomes impossible to distinguish between high and low by the
fixed threshold value. Therefore, the threshold value adjusted first is not always appropriate. We
need to adjust the threshold value of the comparator.
3.3. About Adjusting the Threshold Value for the Comparator
In this subsection, we discuss the setting method for the comparator threshold value.
The best value for the threshold at the comparator should be half value of the signal voltages. But
it is depended on the distance between the sender and the receiver because the receiving signal
levels are decreasing as long as its distance. Considering this effect, it is the good value which is
a little bigger value than the low voltage, for example, +0.1 [v]. If we set such a value as the
threshold value, it has the effectiveness to decode the signal for the long distance.
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Unfortunately, in the real world, there is noise that changes the signal level from low to over the
threshold. One of the methods which avoid this noise, we can use the comparator element like in
the previous Section. The comparator outputs the high voltage if the input level is more than the
threshold voltage. Otherwise, it outputs the low voltage. By using the comparator, we can output
the just rectangle wave which includes only the signal when the threshold value can be set more
than the noise voltage. However, the receiving signal level will be changed whenever the distance
between the sender and the receiver is changed. After that, some parts of the output waveform
will be changed to high or low form according to its receiving signal level, and it causes the bit
errors. Figure 4 shows the result by three kinds of threshold values. Usually, we adjust the
threshold value manually according to the communication distance.
3.4. Threshold Detection Methods
If there is no noise signal, we should set the threshold value to a little bigger value than 0 [v].
And if we get the noise information, we can calculate the threshold value using the noise voltage.
M. Usman et al. discussed the characteristics of photo receivers and light sources. And they
estimated the noise distribution [15]. The goodness of the fit is determined by Bayesian
Information Criterion and the non-centrality parameter of the corresponding Rician distribution is
used to calculate the decision threshold.
On the other hand, Y. H. Kim et al. used the optical and color filters to decide the threshold [16].
They estimate the noise level using the differential value between the received signal and the
threshold value is be changed regarding the differential.
4. AUTOMATIC ADJUSTMENT OF THRESHOLD VALUE OF THE
COMPARATOR
We propose the method for adjusting a comparison voltage of a comparator according to a
change in voltage of a received signal. In this Section we propose the following two adjusting
methods. Both methods use the PPM. In the first method, we focus on the number of signal slots.
The number of PPM signal slots is constant per one symbol. If the number of received signal slot
Figure 4. This figure shows how to adjust the threshold value. If there is no noise, the optimal value for
the threshold value is a little more than 0V. But due to noise, if we use such value for the threshold, there
are a lot of high signal. And if we set the threshold value more than the optimal value, we do not receive
the signal. We adjust the threshold value using the variable register.
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per one symbol time is less than the theoretical value, that means the threshold value is higher
than the optimal value. If it is more than the theoretical value, that means the threshold value is
lower. So, we can adjust the threshold value using the number of received signal slot. In the
second method, we focus on the average received signal level. The average received signal level
is not equal to the high signal level. Because there is the ratio between the number of high's slots
and the number of low's slots. So, we can calculate the threshold value from the average received
signal level and the slot ratio.
4.1. Setting the Threshold Value from the Receiving Slot Information
At first, we propose the adjusting method which uses the slot rate for high and low. When we use
the constant value for the threshold to decide the receiving signal is high or low, if the receiving
signal is stronger, the high slot number is more than the low slot number in the output slots. And
if the receiving signal is weaker, the low slot number is more than the high. The slot ratio of high
and low is 1:1 at the 2-PPM, so we change the threshold value larger or smaller until the ratio
becomes 1:1. When we use 4-PPM, the ratio is 1:3. Figure 5 which includes the noise signal,
shows the relationship between the threshold value and the received signal level. If the
number of received signal slot per one symbol time is more than the theoretical value, that means
the threshold value is lower than the optimal value. If it is less than the theoretical value, that
means the threshold value is higher. So, we can adjust the threshold value using the number of
received signal slot. Figure 6 shows a block diagram of its automatic adjustment circuit.
Figure 5. This figure shows how to adjust the threshold value. If the threshold value is less than the
optimal value, the number of high slots is more than 1. Then the threshold value should become higher. If
the threshold value is more than the optimal value, the number of high slots is less than 1 (= 0). Then the
threshold value should become lower.
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4.2. Set the Threshold Value from the Receiving Voltage
Second, we propose the adjusting method which uses the threshold value from the receiving
voltage. Figure 7 shows a block diagram of its automatic adjustment circuit. To determine the
threshold value, it is important to obtain the voltage value of the signal, but the analogue
converter in the microcomputer operates slowly. Therefore, an analogue-digital (AD) converter
IC is used. From the view of the receiver, the voltage of the high signal and the voltage of the low
signal (expressed as VA[V] and VB[V], respectively) fluctuates depending on the distance between
the transmitter and the receiver. So, they must be decided from the signal level of the receiving
waveform. Then, the average voltage of the received signal Vaverage is (VA
2
+ VB
2
) / (TA + TB),
where TA and TB are the signal time, respectively. When TA : TB = 1 : 1, then Vaverage = (VA + VB) /
2, and this is suitable for the threshold value.
Figure 7. The circuit and block diagram of proposed method which changes the reference value step by
step in order to adjust the receiving signal level
Figure 6. The circuit and block diagram of proposed method which change the reference value step by
step in order to adjust the ratio of receiving high and low slots.
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5. EXPERIMENTAL RESULTS
5.1. About the Threshold Value by Counting the Slot Number for High Voltage
For the first proposed method which changes the threshold value by counting the slot number for
high voltage, we measure the communication throughput for distances from 1 [cm] to 60 [cm].
We send the pseudo-random binary sequence (PRBS) and calculate the throughput [bps] from the
correct data and its receiving time.
Figure 8 shows the performance by the conventional method and our proposed method. The
conventional method sets the constant threshold value which adjusts at the 1 cm distance between
the sender and the receiver. So over about 23 [cm], the receiver cannot decode the information
because the threshold value is over than the received high slot voltage. On the other hand, our
proposed method can decode the information for a wide range, but its throughput is not good
because our proposed method adjusts the threshold value after receiving data. That means the
adjusting time is slow against the receiving data speed. The performance is dependent on the stay
time at the same point. So, this method will be good for the slow speed or the stable receiver.
5.2. About the Threshold Value by Calculating the Average of Receiving Signal
Level
Second, we measure the three methods to show the performance for our second proposed method
which adjusts the threshold by the receiving voltage. Three methods are as follows; 1) the
constant threshold adjusting for the close distance, 2) the auto-adjusting threshold which is our
proposed method, and 3) the constant threshold adjusting for the long distance. We got the bit
error rate for the points which distances between the sender and the receiver are from 10 [cm] to
90 [cm]. The communication speed is 4,000 bits per second, and we sent 100,000 bits of
information for each point. Figure 9 shows the experimental results by three methods. If we use
the constant threshold adjusted for the close distance, we can receive the data to 20 [cm].
Figure 8. The experimental result shows the communication throughput from 1cm to 60cm.
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But we cannot decode the data because the threshold value is over the received signal level from
20 [cm]. And if we use the constant threshold adjusted for the long-distance, we cannot decode
the data to 50 [cm] because the non-signal level with noise is more than the threshold value. Both
constant threshold methods are not good performance against the distance which is not assumed
by the method. We confirmed the good effect by adjusting the threshold automatically.
6. CONCLUSIONS
The visible light communication by LED is focused on because LED can work as high speed and
the VLC sends the information by high flushing LED. We use the pulse wave modulation for the
VLC with LED because LED can be controlled by the micro controller, which has the digital
output pin. At the pulse wave modulation, deciding the high and low voltage by the middle
voltage when the receiving signal level is amplified is equal to deciding it by the threshold
voltage without amplification. In this paper, we proposed two methods which adjust the threshold
value using counting the slot number and measuring the signal level.
In the first method, we can decide the threshold value by counting the receiving slot because the
number of high and low slots is constant in the pulse position modulation. Unfortunately, because
this method adjusts the threshold value after receiving the data, once the distance between the
sender and the receiver is changed, always the performance becomes worse. And after adjusting
the threshold, the performance becomes better. Therefore, this method should be used under the
stable environments.
Figure 9. The experimental result shows the communication performances by three methods; the
constant thresholds for close and long distance, and proposed method which adjusts the threshold
automatically.
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Next, we proposed the method which decides the threshold value from the receiving voltage. This
method can change the threshold value during the signal is received. That means this method can
work very quick. So, this method can show the good performance for the wide range.
For future work, we will focus on the sensitivity of receiving elements because adjusting them
will be equal to adjusting the threshold value.
CONFLICTS OF INTEREST
The authors declare no conflict of interest.
REFERENCES
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AUTHORS
Wataru Uemura was born in 1977, and received B.E, M.E. and D.E. degrees from
Osaka City University, in 2000, 2002, and 2005. He is an associate professor of the
Department of Electronics and Informatics, Faculty of Engineering Science, Ryukoku
University in Shiga, Japan. He is a member of IEEE, RoboCup and others.
Yasuhiro Fukumori was born in 1993 and received B.E, and M.E from Ryukoku
University, in 2016, 2018. He is interested in visible light.
Takato Hayama was born in 1992 and received B.E, and M.E from Ryukoku
University, in 2015, 2017. He is interested in card games.