Proceedings of 2015 RAECS UIET Panjab University Chandigarh 21-22nd December 2015
Visible Light Communication-An Emerging Wireless Communication Technology SUKHVIR SINGH Dept. of Information Technology UIET, Panjab University Chandigarh, India
[email protected]
GHOLAMREZA KAKAMANSHADI Dept. of Computer Science & Eng. UIET, Panjab University Chandigarh, India
[email protected]
Abstract-The Visible Light Communication (VLC) is an emerging technology, which provides distinct facilities such as fast data communication, secure data communication, high data rate wireless communication, etc. Instead of radio frequency, VLC uses light, to transfer data. The visible light spectrum is unlicensed and 10,000 times larger than the range of radio frequencies. It can be used as an alternate to the existing radio based wireless communication technologies or in hybrid. Moreover, Integrated VLC resolves issue of load balancing in existing wireless networks. Light Fidelity is a recent technology under VLC, which can be used for wireless communication as it has many advantages such as no electromagnetic interference, low cost and high data rate. This paper emphasizes on the Visible Light Communication technologies and their applications. Moreover, their advantages and limitations are also covered.
SAVITA GUPTA Dept. of Computer Science & Eng. UIET, Panjab University Chandigarh, India
[email protected]
A simple VLC system has two main components: the first part is a LED lamp equipped with a signal-processing unit and the second one is a receiver with a photo-detector to receive light signals. A structure of an indoor visible light communication technology is shown in Figure 1. It clearly demonstrates that Ceiling LED lights are connected to the internet and can transfer data to the end devices.
Keywords: Visible Light Communication (VLC), Light Fidelity (Li-Fi), Wireless Data Communication, Ceiling LEDs
I.
INTRODUCTION
The Visible Light Communication (VLC) is a recent technology that uses light instead of radio frequency signals to transmit the data. It is also known as short-range optical wireless communication. Prof. Harald Haas introduced Light Fidelity (Li-Fi) which resolves the issue of overuse of radio frequency in Wi-Fi [1] [7]. The objective of VLC is to increase data rates in wireless communication and to have better performance of networks especially for indoor networks using light emitting diode (LED) lamps [2]. LED, has many benefits such as low power consumption, small size, long life, low cost, low heat radiation. So they are used in numerous applications, like traffic lights, advertisement displays, indoor lighting equipment and so on. LED based Li-Fi can provide internet connectivity to users instead of using existing wireless technologies as it has many advantages such as no electromagnetic interference, easy installation, high data rate, secure data communication and low cost [3]. Ceiling LED lights are used to transmit data to the users inside the building. The VLC technology based on LED will play a significant role in the next broadband wireless communication technology. The IEEE standard that has been defined for VLC is 802.15.7; it refers to standard for free-space optical communication using visible light.
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End Devices
Figure 1: A structure of an indoor VLC system
A ceiling LED lamp with signal processing technology encodes and modulate data from internet and spreads data embedded in its beam at rapid speeds. The photo-detector attached with an end device converts received light signals
Proceedings of 2015 RAECS UIET Panjab University Chandigarh 21-22nd December 2015 having different light intensities into an electrical signal, which in turn converted into data stream at the end device.
modification of the existing infrastructure to achieve the purpose of illumination and communication simultaneously [8].
The rest of this paper is organized as follows: Section II is about applications of visible light communication. Section III investigates comparison of Li-Fi, Wi-Fi and Wi–MAX technologies. Section IV presents advantages of VLC. Section V presents limitation of VLC. Finally, the conclusion is drawn in section VI.
Traffic management system: VLC may be used for traffic management system; in this case, traffic lights can communicate with each other and with the car. Furthermore, cars can communicate with each other and can exchange information to prevent accidents.
II.
APPLICATIONS OF VLC
The Visible Light Communication is an advanced technology that has variety of applications in different domains especially for indoors. The main applications, which extracted from literature, are listed below: Underwater communication: Radio waves are not good for underwater communication as they get absorbed in water, but light penetrate through water and can be used for underwater communication. The divers for both lightning and data transfer purpose simultaneously can be used the Li-Fi technology [6]. Therefore, it can allow communication from diver to diver, diver to mini-sub, diver to drilling rig, etc. Urban Light Infrastructure: With dense light infrastructure, high data rate interference free wireless communication can be achieved. Cellular Communication: Street lamps could be used for cellular communication instead of radio base stations. It will also reduce the cost of cellular system. Education Sector: A person using LED lamp for studies can use the same light to establish a connection between internet and laptop or mobile device. Moreover, students in a classroom can use Li-Fi for video conferencing. Indoor navigation system for visually impaired: By providing an identifying code to each light, we can establish indoor navigation system. These codes would be linked to a particular position. For example, light signals received from the nearby light device can be used to provide directions to a visually impaired person walking in a corridor [5] [10].
III. Li-Fi, Wi-Fi and Wi - MAX COMPARISON Now a days wireless data communication technologies have a significant impact on routine of human beings. Basically Wi-Fi technology is meant for wireless local area network, while the main idea behind establishing Wi-MAX technology is to support wireless metropolitan area network communications. On the other hand, Li-Fi is designed to overcome the issue of overuse of radio frequencies by existing technologies and provide higher data rates with low cost. Comparison of Li-Fi, Wi-Fi and Wi-MAX is presented in Table 1. TABLE 1: COMPARISON OF WIRELESS COMMUNICATION TECHNOLOGIES Specification IEEE Standard
Wireless Data Communication Technologies Li-Fi
Wi-Fi
Wi-MAX
802.11a/b/g/n/ac/ ad Radio 11 Mbps 6.75Gbps
802.16 a/c/d/e/…/m Microwave 4 Mbps 1Gbps
10 meters
20-250 meters
50 km
Point-to-Point
Point-to-Multi Point
400-800 THz
2.4/3/5/60 GHz
Point-toMulti Point 2.3/2.5/3.5 GHz
802.15.7 Light
Medium Speed
1-10Gbps
Communication Range Network topology Frequency
Cheaper than Wi-Fi & WiMAX High High
Cost Data density Security
Cheaper than WiMAX
Costly
Low Medium
Low Medium
Augmented Reality Mobile Application: An augmented reality smart phone application is basically used for positioning. It may use GPS for positioning but suffer errors inside the building or may simply not work in this environment. The VLC can easily provide location information for indoor AR applications.
There are many advantages of VLC technology over the other existing technologies as mentioned below:
Integrated VLC: An integrated Visible Light Communication (iVLC) system provides feature of scalable VLC networking and accurate VLC sensing of mobile users. Modulated LED lights are used for communications between networked devices, while at the same time these lights can be used to accurately identify and track users. They can sense and infer their gestures as a means of collecting user analytics and enabling interactions with objects in smart spaces [4]. Other example of iVLC is use of Power line communication (PLC) with VLC. PLC may be used as a communication medium between the LEDs and other network. It only requires little
2. High-density coverage: Li-Fi is perfect where high density coverage is required but Wi-Fi is meant for general wireless coverage.
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IV.
ADVANTAGES OF VLC
1. Speed: The VLC system can provide higher speed as compare to existing deployed wireless communication technologies, which is still in tens of Mbps. Li-Fi can achieve data rates of over 10 Gbit/s, which is 250 times faster than super-fast broadband.
3. Secure: Li-Fi is more secure than Wi-Fi as the light signal can be easily obscured by opaque materials and it cannot penetrate through walls. Moreover, VLC systems are comparatively secure because there will be no intrusion without a clear line of sight.
Proceedings of 2015 RAECS UIET Panjab University Chandigarh 21-22nd December 2015 4. Cost: Li-Fi technology is license free. Hence, it is considered cheaper than other licensed technologies. Li-Fi is expected to be ten times cheaper than Wi-Fi. 5. No Electromagnetic Interference: Li-Fi can be used in electromagnetic sensitive areas such as in aircrafts, hospitals, and nuclear power plants without electromagnetic interference. However, this is not true for Wi-Fi. Moreover, VLC systems can be deployed in places where it is difficult to lay optical fibers as in operation theatres.
radio based wireless technologies are not allowed such as aircraft and hospitals. REFERENCES [1]
Y. Wang, S. Videv and H. Haas, “Dynamic Load Balancing with Handover in Hybrid Li-Fi and Wi-Fi Networks,” 2014 IEEE 25th Annual International Symposium on Personal, Indoor, and Mobile Radio Communication (PIMRC), 2-5 Sept. 2014, pp. 575 – 579.
[2]
S. V. Tiwari, A. Sewaiwar and Y. Chung, “Color coded multiple access scheme for bidirectional multiuser visible light communications in smart home technologies,” J. of Optics Communications, vol. 353, pp. 1-5, 2015.
[3]
7. Dynamic Load Balancing: Li-Fi and Wi-Fi can be used as a hybrid network. In case Wi-Fi is having very high load it can be shared by Li-Fi after handover so as to balance the load [1] [9].
W. Jia-yuan, Z. Nian-yu, W. Dong, I. Kentaro, I. Zensei and N. Yoshinori, “Experimental study on visible light communication based on LED,” J. of China Univ Posts Telecommun., vol.19, pp. 197-200, 2012.
[4]
X. Zhou and A. T. Campbell, “Visible Light Networking and Sensing,” in: Proc. of the 1st ACM workshop on Hot topics in wireless ACM HotWireless, 2014, pp. 55-60.
LIMITATIONS OF VLC
[5]
J. Aleksandar, J. Li, and T. Richardson. "Visible light communication: opportunities, challenges and the path to market," IEEE Communications Magazine, vol. 51, pp. 26-32, 2013.
[6]
A. Kumar Das, A. Ghosh, A. M. Vibin and S. Prince, “Underwater Communication System For Deep Sea Divers Using Visible Light,” in: proc. of Photonics Global Conference (PGC), pp. 1-3, 2012.
[7]
A. Sonnad, A. Gopan, R. Sailakshmi, S. Divya and R. Ambika, “Recent advancements in Li-Fi technology,” International Journal of Electrical, Electronics and Data Communication, vol. 10, pp. 61-63, 2013.
[8]
Y. Yan, W. Ding, H. Yang and J. Song, "The video transmission platform for The PLC and VLC integrated system," IEEE International Symposium on Broadband Multimedia Systems and Broadcasting (BMSB), pp. 1-5, 2015.
[9]
Y. Wang, D. A. Basnayaka and H. Haas, “Dynamic Load Balancing for Hybrid Li-Fi and RF Indoor Networks,” in: proc. IEEE International Conference on Communication Workshop (ICCW), 2015, pp. 14221427.
6. Bigger Spectrum: Wi-Fi uses radio spectrum and is close to full capacity whereas Li-Fi has almost no limitations on capacity. The visible light spectrum is 10,000 times larger than the radio frequency spectrum.
V.
The Visible Light Communication technologies as compare to other wireless communication technologies have following limitations: • As light cannot penetrate through obstacles, data communication may get obstructed. • The VLC systems work only if there is direct Line of sight between two communication devices. • During night, VLC indoor system may disturb human life. • Interference from other light sources is also one of the drawbacks of the VLC technologies. Bulbs, sun light and opaque materials may interrupt data communication link. • The VLC systems are restricted to short-range communication as very high frequencies (400-800 THz) are used for data communication. VI.
CONCLUSION
The VLC technology has grown significantly during last few years. It has a great importance especially for indoor applications. A person can utilize lights available at home for communication without disruption. Li-Fi as compare to Wi-Fi is having better features like security, higher speed, bigger spectrum, low cost and no electromagnetic interference. There are numerous possibilities for VLC as it is considered as good, green and safe technology. The VLC is an adaptive technology and can be integrated to existed infrastructure to provide variety of services. As more people are opting mobile wireless communication technology, the frequency spectrum being used is becoming congested, making it difficult to get a reliable and high-speed signal. Li-Fi solves this issue of the shortage of radio-frequency bandwidth and also allows internet access where traditional
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[10] H. Shinichiro, "Advances in visible light communication technologies," in: proc. 38thEuropean Conference and Exhibition on Optical Communication, pp.1-3, 2012.
