ISSN (Online) 2321 – 2004 IJIREEICE ISSN (Print) 2321 – 5526 International Journal of Innovative Research in Electrical, Electronics, Instrumentation and Control Engineering ISO 3297:2007 Certified Vol. 4, Issue 11, November 2016 Review Paper: Advantages and Limitations of Li- Fi over Wi-Fi and iBeacon Technologies By Deepika D Pai Asst. Professor, (Sel Grade), Department of Electronics and Communication Engineering. Vemana Institute of Technology Abstract: Li-Fi can be thought of as a light-based Wi-Fi. That is, it uses light instead of radio waves to transmit information. And instead of Wi-Fi modems, Li-Fi would use transceiver-fitted LED lamps that can light a room as well as transmit and receive information. Light is inherently safe and can be used in places where radio frequency communication is often deemed problematic, such as in aircraft cabins or hospitals. So visible light communication not only has the potential to solve the problem of lack of spectrum space, but can also enable novel application. The visible light spectrum is unused; it's not regulated, and can be used for communication at very high speeds. This paper compares the Li-Fi technology with Wi-Fi and iBeacon technologies. Keywords: Li-fi, Wi-Fi, iBeacon, visible light communication, BLE communication I. INTRODUCTION In recent trends, wireless communication Wi-Fi is gaining government licence. This new Ethernet standard was tremendous importance. CISCO reported that the compatible with devices and technology working on radio compound annual growth rate (CAGR) of mobile data waves and came to be known as ―Wi-Fi‖ only in 1999. usage per month is around 80% which has led to the saturation of the network spectrum consequently bringing iBeacon: The technology was first introduced by Apple at down its efficiency. It is unlikely that a significant new the Apple Worldwide Developers Conference in 2013. It spectrum may be made available for mobile uses beacons which are low-cost, low-powered communications; the only option is to increase the transmitters equipped with Bluetooth Low Energy or BLE spectrum efficiency of wireless systems. To resolve this that can be used to deliver proximity-based, context-aware the following problems need to be addressed which are (a) messages. the elimination of interference, (b) a massively improved reuse of the available frequency resources, and (c) Technology details of Li-Fi utilisation of the free, vast and unlicensed infrared and A. Core Technology- visible light spectrum leading to hybrid radio frequency Li-Fi: Li-Fi is a form of Visible Light Communication (RF) and optical wireless systems. These drawbacks may (VLC) technology. VLC technology is an optical wireless be overcome with the use of Li fi technology. Section II data communications medium which uses visible light gives the overview of Li-Fi technology, Section III gives between 400 and 800 THz (780–375 nm) to transmit the overview of Wi-Fi technology, Section IV gives the binary data in the form of light pulses.This Optical overview of iBeacon technology, and Section V gives the Wireless Communication technology uses light from light- brief comparison of the three technologies applications emitting diodes (LEDs) as a medium to deliver networked, and future scope of Li-Fi technology. mobile, high-speed communication in a similar manner to Wi-Fi. Origin of the three terminologies- Visible Light Communications (VLC) works by switching Li-Fi: Light Fidelity (Li-Fi) is a bidirectional, high-speed the current to the LEDs off and on at a very high rate, and fully networked wireless communication technology which is too quick to be noticed by the human eye. similar to Wi-Fi. The term was coined by Harald Has and Although Li-Fi LEDs would have to be kept on to transmit is a form of visible light communication and a subset of data, they could be dimmed to below human visibility optical wireless communications (OWC) and could be a while still emitting enough light to carry data. The light complement to RF communication (Wi-Fi or cellular waves cannot penetrate walls which makes a much shorter networks), or even a replacement in contexts of data range, though more secure from hacking, relative to Wi-Fi. broadcasting. This technology has been proposed as a Direct line of sight is not necessary for Li-Fi to transmit a solution to the RF-bandwidth limitations. signal; light reflected off the walls can achieve 70 Mbit/s. Wi-Fi: Introduced by the visionary ruling by Federal It uses common household LED (light emitting diodes) Communications Commission (FCC) in 1985 allowing the light bulbs to enable data transfer, boasting speeds of up to use of bands of wireless spectrum without the need for a 224 gigabits per second. Copyright to IJIREEICE DOI 10.17148/IJIREEICE.2016.41122 116 ISSN (Online) 2321 – 2004 IJIREEICE ISSN (Print) 2321 – 5526 International Journal of Innovative Research in Electrical, Electronics, Instrumentation and Control Engineering ISO 3297:2007 Certified Vol. 4, Issue 11, November 2016 B. How it works- Steps involved in the working: Li-Fi: Li-Fi consists of four primary sub-assemblies as shown in figure 1: Fig 1: Sub-assemblies of Li-Fi Fig 4: Working Principle of Li-Fi Bulb RF power amplifier circuit (PA) As shown in figure 4 the working principle of Li-Fi Printed Circuit Board(PCB) technology can be explained in three steps: Enclosure Power supply. Step-1: A radio frequency signal is generated by the solid state Power Amplifier is guided into an electric field The functions of the individual sub-assemblies are enlisted about the bulb. below Step-2:The high concentration of energy in the electric field vaporizes the contents of the bulb to a plasma state at Function of the Bulb Assembly: the bulb‘s centre. The heart of the Li-Fi is the bulb sub-assembly where a Step-3: This controlled plasma generates an intense source sealed bulb is embedded into a dielectric material which of light. serves as a waveguide and electric field as shown in figure All of these sub- assemblies are enclosed in an aluminium 2. enclosure. Li-Fi and Wi-Fi are quite similar as both transmit data electromagnetically. However, Wi-Fi uses radio waves while Li-Fi is a Visible Light Communications (VLC) system a medium that uses visible light between 400 and 800 terahertz (THz).It accommodates a photo-detector to receive light signals and a signal processing element to convert the data into 'stream-able' content. Fig 2: Bulb sub assembly An LED light bulb is a semi-conductor light source meaning that the constant current of electricity supplied to Function of the RF driver: an LED light bulb can be dipped and dimmed, similar to As shown in figure 3, the power amplifier (PA) assembly switching a torch on and off according to a certain pattern uses an LDMOS device which converts electrical energy to relay a secret message. Flicking an LED on and off at to RF power. This assembly is designed for ruggedness extreme speeds can be used to write and transmit things in and efficiency. The RF driver also controls circuit for binary code. up and down at extremely high speeds, digital and analog lighting controls. without being visible to the human eye to write and transmit things in binary code. For example, as shown in figure 5, data is fed into an LED light bulb (with signal processing technology), it then sends data (embedded in its beam) at rapid speeds to the photo-detector (photodiode).The tiny changes in the rapid dimming of LED bulbs is then converted by the 'receiver' into electrical signal. The signal is then converted back into a binary data stream that we would recognise as web, video and audio applications that run on internet enables Fig3: RF driver sub assembly devices [2]. Copyright to IJIREEICE DOI 10.17148/IJIREEICE.2016.41122 117 ISSN (Online) 2321 – 2004 IJIREEICE ISSN (Print) 2321 – 5526 International Journal of Innovative Research in Electrical, Electronics, Instrumentation and Control Engineering ISO 3297:2007 Certified Vol. 4, Issue 11, November 2016 3. When the Wi-Fi enabled device encounters a hotspot the device can then connect to that network wirelessly. 4. A single access point can support up to 30 users and can function within a range of 100-150 feet indoors and 300 feet outdoors. 5. Many access points can be connected to each other via Ethernet cables to create a single large network. Once the network is built the connection works through a transmitting antenna which is connected to a DSL or cable internet connection.The antenna on the router will beam the radio signals through a specific range and another antenna which is on the laptop or computer will recive the signal as shown in figure 7 below. Fig 5: Overview of the Li-fi technology II. TECHNOLOGY DETAILS OF WI-FI Wi-Fi: Wi-Fi is based on Radio Frequency (RF) technology which uses a frequency within the electromagnetic spectrum associated with radio wave propagation. When a radio frequency current is supplied to an antenna, it creates an electromagnetic field capable of propagating through space. Devices equipped with wireless network adapters detect the wireless signal broadcasted by access points and tune into it. There are three elements that constitute the Wi-Fi network. Figure 7: Practical implementation of Wi-Fi They are: Applications include Home, Small Businesses, Large Access point (AP)-It is a wireless transceiver or ―base Corporations and Campuses, Health care etc. station‖ that can connect one or more wireless devices simultaneously to the Internet. III. TECHNOLOGY DETAILS OF IBEACON Wi-Fi cards: They can be external or internal.