2D Image Transmission using Light Fidelity Technology Undergraduate Student, Computer Engineering Department Dwarkadas J. Sanghvi College of Engineering, Mumbai, India. Abstract : Recently wireless technology has bloomed to a great extent we require wireless technology to transmit a lot of data every day. Nowadays, wireless communications has become important in communication process. The main way we transmit wireless data is by using electromagnetic waves i.e. radio waves. However, radio waves can support less bandwidth because of compact spectrum availability and intrusion. Solution to this is data transmission using Visible Light Communication (VLC). Wi-Fi deals with wireless coverage within premises, whereas Li- Fi is perfect for high compactness wireless data coverage in defined area and for mitigating radio interference issues. In Li-Fi basically we focus to transmitting multimedia data between two terminals using LED s. Keywords : Wi-Fi (Wireless Fidelity), Li-Fi (Light Fidelity), VLC (visible light communication), LED (light emitting diode). I. INTRODUCTION In 21 st century communication between two terminals is very important and takes place on every day. Li-Fi plays an important role is communication as discussed earlier which uses light for data transmission instead of radio waves used in wireless communication. The speed of data transmission was about 10 mbps, though Dr. Haas is aiming to have it reach 100 mbps[1]. Wireless communication which uses[5] radio waves for data transmission and communication between terminals proves fatal in areas like oil petroleum which can harm the 121 environment causing vast destruction so to avoid such situation using of light in some area proves beneficial. Li-Fi is more secure as it does not allow data leakage[2]. Figure 1: Beam of LED s II. Proposed System Li-Fi technology consist of transmission of data using light. So the proposed system has LED s which is useful for data transmission and implement the basic concept of Li-Fi. It is divided into two modules Transmitter and Receiver. i. Transmitter Figure 2: Transmitter working
On the transmitter side the terminal which is the PC used should contain MATLAB software which will help us in converting the image into its binary format and later transmitting the binary conversion to the receiver via LED. Next is the USB to TTL which is used so deal the communication of a microcontroller. And microcontroller helps to generate square wave form the binary converted image by MATLAB and inputs the square wave to the LED. Which later helps the LED to glow and allow transmission[1]. ii. Receiver III. Implementation The basic hardware implementation used in Li- Fi is AT89C2051 integrated circuit of microcontroller with L14G2 integrated circuit of phototransistor. And essential capacitor and regulator to control the process of microcontroller. i. Flow of implementation Figure 3: Receiver working On the receiver side exact opposite operation takes place the light received from the LED is captured by the phototransistor which acts as a sensor and passes the output to the comparator which compares the binary input and similary the original image is recovered using Matlab software[1]. iii. Visible Light Communication Visible light Communication (VLC) is a modern communication technology which employs visible light sources (LEDs). Li- Fi is implemented using LED s. If the LED is ON we transmit a digital 1 and if the LED is OFF we transmit a digital 0. The continuous flickering of LED helps in data travelling from one terminal to another[7]. Figure 4: Visible light communication 122 Figure 5: Flowchart ii. Algorithm Step 1: Image/text or video is given as an input to the sender PC consisting of a matlab program reserved for image processing of the input image. Step 2: Image processing is done in the sender PC,the output of which is processed by the microcontroller connected to PC via a serial port using MAX232. Step 3: Depending upon the output of microcontroller
the led's connected to one of its port get toggled Step 4: At the receiver side photodetection takes place using phototransistor placed at the receiver end. Step 5: Then the microcontroller at the receiver side conducts the binary conversion of the input data taken from phototransistor output. Step 6: This data is received by the receiver PC connected to microcontroller via serial port processed the data in order to reconstruct the send image at the receiver side by using the matlab program. iii. Block diagram of Li-Fi : PC. Phototransistor: It produces some voltage at its output terminal connected to microcontroller when lights from led s fall on it. Phototransistor is a device that converts light energy into electric energy. Phototransistors are same as photo resistors produce both current and voltage, while photo resistors only produce current. USB to TTL: The cable is easiest way ever to connect to your microcontroller router serial solace port. Comparator (LM358N) : In electronics, a comparator is a device that equate two voltages or currents and outputs a digital signal indicating larger voltage. IV. Experimental Setup Experimental setup basically comprises of transmitter setup and receiver setup. i. Transmitter setup Figure 6: Block Diagram of Li-Fi MICROCONTROLLER: Microcontroller is low power, high performance 8bit CMOS microcomputer with 4kb of EPROM (electrically programmable read only memory). PC (Transmitter & Receiver): It is used to provide the operation of image processing to be done at the transmitter side for sending the input image and at the receiver side for reconstructing the send image.this processing is done using Matlab software in Figure 7: Transmitter setup 123
Sr Abbreviation Component no. 1 D1 DIODE 2 SW1 SWITCH 3 C1,C3 CAPACITOR 4 C2 CAPACITOR 5 C4,C5 CAPACITOR 6 X1 CRYSTAL 7 RT1 REGULATOR 8 IC1 20 PINS SOCKET(89C2051) 9 L1 LED 10 R1 RESISTOR 11 SIL1 SIL SOCKET 12 B1 BUG STRIP Table 1 : components of transmitter Sr Abbreviation Component no. 1 D1 DIODE 2 SW1 SWITCH 3 C1,C3 CAPACITOR 4 C2 CAPACITOR 5 C4,C5 CAPACITOR 6 X1 CRYSTAL 7 RT1 REGULATOR 8 IC1 20 PINS SOCKET(89C2051) 9 L2 PHOTODETECTOR 10 R1 RESISTOR 11 SIL1 SIL SOCKET 12 B1 BUG STRIP Table 2: components of receiver ii. Receiver setup iii. Power supply 124 Figure 8: Receiver setup Figure 9: Power supply Connector: 2-pin screw terminal is basically a connector which is used to interface power supply section with other circuits through wires. Bridge Rectifier: W10 full wave bridge rectifier is used to convert incoming AC signal into varying DC signal. i.e it consist of ripple at the output. Filter Capacitor : Filter capacitor of 2200uf at output of bridge rectifier is used to provide less ripple at the output which is suitable for most electronic circuits.
Regulator: Regulator IC is used to provide constant DC or smooth output with no ripple. Sr no. Abbreviation Component 1 BR1 BRIDGE RECTIFIER 2 RT1 REGULATOR 3 C1 CAPACITOR 4 C2 CAPACITOR 5 C3 CAPACITOR 6 CN1 CONNECTOR 7 B1 BUG STRIP Table 3: component table of power supply V. Results and Discussion Using light as a data transmission medium helps to securely transmit data as it overcomes the disadvantage of data leakage and efficiently transmit multimedia data over a medium. It uses Visible light communication technology[3]. Visible light communication using white LEDs offers the potential for such alternative. The main reasons are as follows[7]: Bandwidth is not limited. Existing local power line infrastructure can potentially be utilized. Transmitters and receivers devices are cheap, and there is no need for expensive RF units. Table4: Comparison between communication technologies VI. CONCLUSION AND FUTURE SCOPE Conclusion from the above implemented concept is data Transmission using light is cheaper and secured We can use Li-Fi in future in which data for smart phones, tablets etc can be dealt using lights fitted in the room. Radio waves cannot be used by commuters in aircrafts. LED-based lights are already used in aircraft cabins and each of these lights could be potentials VLC transmitters to provide both illumination and media services for travelers. Moreover, this will reduce the aircraft construction costs and its weight[6]. Underwater ROVs (Remotely Operated Vehicles) operate from large cables that supply their power and allow them to receive signals from their pilots above. They could also use their front lights to communicate with each other, processing data independently and sending their information back to the surface[4]. VII. REFRENCES [1] H. Elgala, R. Mesleh, H. Haas and B. Pricope, OFDM Visible Light Wireless Communication Based on White LEDs in International University Bremen 28759 Bremen, Germany in 2007 IEEE. Figure 10: Visible light communication using LOS 125 [2]. H. Park and J. Barry, Modulation Analysis for Wireless Infrared Communications, in Proceedings of International Conference
on Communications ICC 95, vol. 2, June,18 22 1995, pp. 1182 1186. [3] Lopez-Hernandez-Fj, Poves-E, Perez- Jimenez-R, and Rabadan-J: Lowcost diffuse wireless optical communication system based on white LED. Proc. 2006 IEEE Tenth International Symposium on Consumer Electronics. St. Petersburg, Russia. 28 June 1 July 2006., pp. [4] P. Amirshahi and M. Kavehrad, (2006). Broadband Access over Medium&Low Voltage Power-lines and use of White LEDs for Indoor Communications. In IEEE CCNC 2006 proceedings [5] Amirshahi, P. and Kavehrad, M. 2006. Broadband access over medium and low voltage power- lines and use of white light emitting diodes for indoor communications. In IEEE Consumer Communications & Networking Conference, Las Vegas, Nevada. Citeseer. [6] J. Carruthers and J. Kahn, Multiple- Subcarrier Modulation for Nondirected Wireless Infrared Communication, IEEE Journal on Selected Areas in Communication, vol. 14, pp. 538 546, April 1996 [7] Dobroslav Tsonev, Sinan Sinanovic and Harald Haas, Novel Unipolar Orthogonal Frequency Division Multiplexing (U- OFDM) for Optical Wireless, IEEE, 2012 126