Design and development of Visible light transceiver

Radio frequency (RF) communication suffers from interference and high latency issues. Along with this, RF communication requires a separate configuration for the transmission and reception of RF waves. Visible Light Communication (VLC), which goes beyond the above limitations, is preferred Commu

Project Title

Design and development of Visible light transceiver

Project Area of Specialization

Information & Communication Technology

Project Summary

Radio frequency (RF) communication suffers from interference and high latency issues. Along with this, RF communication requires a separate configuration for the transmission and reception of RF waves.
Visible Light Communication (VLC), which goes beyond the above limitations, is preferred Communication technique due to its high bandwidth and immunity to interference electro-magnetic sources. Revolution in solid state lighting, Fluorescent lamps from light emitting diodes (LEDs) that further motivate the use of VLC.

Visible light communication (VLC) is a wireless data communication medium using solid state light sources in our case, while receiving transmitting data it was conveyed that solid-state light sources can be used for lighting purpose. VLC systems are currently being developed for ultra-high speed, high security, biologically friendly communication networks allowing seamless creation and expansion of computing applications using large bandwidth, high frequency pulsed light instead of radio waves and microwaves.
This branch of communication has several advantages, such as the fact that the infrastructure already exists and can offers the extra security that traditional wireless communications lack. All that needs to be done is to replace the current bulbs with smart and efficient light bulbs capable of transmitting data. This project explores the communication of visible light through a prototype implementation. The implementation consists of transmitter and Receiver, using a light emitting diode for transmission and a photodiode for reception.

Project Objectives

The Objective of this project is to perform digital, point-to-point, communication over visible light and to illuminate the area where the transmission is intended. The transmission must be stable enough to allow for reliable communication and must be capable of compensating for transmission errors. The distance and rate at which data can be sent is also parameters that will be taken into account since these limits its applications. Furthermore, the project must be easily extensible to allow for further development.

The main task of this project is to develop and build a pair of devices capable of sending and receiving respectively data over visible light. This can be done using any light source emitting visible light that is capable of switching quickly. This project will focus on the use of LEDs for transmission. In order for the system to be useful, it must be capable of performing a continuous transfer of a 10 MB file.

The system must be able to:

• Send arbitrary data over visible light.
• Receive arbitrary data over visible light.
• Transfer data while producing 450 lumens (equivalent to a 40 W light bulb).
• Send data over at least 1 meter in a brightly lit room.
• Send data in one direction.
• Perform an uninterrupted transfer of 10 MB.

Project Implementation Method

The project Implementation method presents how the VLC system will be developed and implemented. It includes both a software implementation, referred to as the VLC driver, and a hardware transmitter-receiver implementation.

Development platform

During the project a Beaglebone Black (BBB) will be used as development platform. It is a small, inexpensive and relatively powerful single board computer.  The BBB is a single-board computer, which means it can run a variety of Linux distributions, such as Debian, Ubuntu and Ångström. That means the project can use the functionality already present in the operating system, such as the network stack and TCP/IP protocol suite. Furthermore, the operating system makes it easy to run several execution threads in parallel. These reasons should make development easy, and is the reason why an SBC is chosen over a micro controller.

Hardware

The physical layer is the hardware used between the two BBBs, i.e., all the electrical components. The hardware was implemented using LEDs transmitting data via light to a photodiode which converts it back to an electrical signal so that the BBB can interpret it as data. To process the electrical signal correctly the transmitter and receiver have to be designed and optimized for this purpose.  All active components need a power supply to work properly. In this project 5 V will be used due to it being the maximum voltage the BBB can deliver.

Implementation Framework

The VLC driver is implemented as a Linux network module and it has to be taken into account during all parts of the software implementation. The reason for choosing to implement it in this way is that it allows any application, that can be run on a Linux computer, to transmit data over visible light. This is because the VLC driver will integrate seamlessly with the Linux kernel, and will be displayed as a network card in the operating system which makes the implementation much more useful. Furthermore, the existing TCP/IP protocol suite will handle address resolution and transport protocols. The downside is some loss in flexibility. The driver has to conform to the specifications of Linux modules, which means some functionality cannot be used.

Benefits of the Project

Benefits of Visible Light communication are,

• No radiation exposure
• No interference with radio systems
• Data transmission with commercially available high-power led lamps
• Combination of lighting and data communication
• Cost-effective retrofitting possible
• Parallel operation of several VLC systems possible
• Optically opaque surfaces make data protection easy

Technical Details of Final Deliverable

Technical Details of visible light communication transmitter and receiver (Hardware) and software

Transmitter

The job of the transmitters is to convert digital data into visible light. An LED, suitable component due to the relatively linear relationship between current and light density. The general idea is to modulate the light intensity of the LED, that is, the intensity of the light corresponds to the symbol transmitted. Microcomputer ports cannot provide the correct amount of current to create the light intensity, strong enough and fast. To overcome this problem, a transistor working as a switch made it possible to switch a larger current faster. The overall design is shown to give an overview of the transmitter. LED Microcomputer Switching transistor

                                         Figure 1   General transmitter block diagram

The transmitter will be designed according to the specification of the microcomputer, ie using limited power output. To be done using the transmitter three Transistors, as can be seen in Figure 2. These three independent transistors, each is controlled using GPIO ports on the microcomputer and therefore it is possible to arrange three transistors independently. This means the current flowing through the LED, and thus the density can be changed in eight steps. Have more than one step It is possible to use different encoding styles such as Pulse Amplitude Modulation (PAM) or OOK. A transistor is constantly on and turn the other two on and off. This also made it possible to use regular resistors with a maximum tolerant power rating of 0.25 W. Two ripple capacitors, one large of 100 ?F, and one small of 100 nF will be used to remove ripple from the power source.

Figure 2 Proteus based VLC Transmitter final design

Receiver

The receiver converts the incident light into current using a photodiode. A photodiode is a semiconductor that converts light into electric current. This electric current must be converted into a voltage that the microcomputer can handle. not to exceed the constraints of the microcomputer. For a digital signal, the microcomputer cannot get a voltage above 3.3 V. The electronics of the receiver must convert current to voltage to amplify and filter it. To be able to change the distance between transmitter and receiver without the risk of receiving a very small signal or a very high signal, an automatic gain controller (AGC) will be designed. This component amplifies or reduces input voltage to a selected output voltage. To make sure the signal is digital and stable Before the microcomputer, a transistor will be used as an analog-to-digital converter (ADC). The general design is shown in Figure 3 and the final design in Figure 4.

                              Figure 3 General receiver block diagram

                                                   Figure 4 VLC Receiver final design

The software implementation of the project will consist of the following separate parts:

• Data packaging

• Hardware control

• Transmission synchronization

• Transmission encoding and decoding

• Error handling

 

 

Final Deliverable of the Project

Hardware System

Core Industry

Telecommunication

Other Industries

IT

Core Technology

Internet of Things (IoT)

Other Technologies

Clean Tech

Sustainable Development Goals

Industry, Innovation and Infrastructure

Required Resources

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