The Li-Fi Technology | A Step Towards Future
LiFi is a wireless optical networking technology that uses light-emitting diodes (LEDs) for data transmission.
LiFi is designed to use LED light bulbs similar to those currently in use in many energy-conscious homes and offices. However, LiFi bulbs are outfitted with a chip that modulates the light imperceptibly for optical data transmission. LiFi data is transmitted by the LED bulbs and received by photoreceptors.
Step aside, Wi-Fi. Scientists have just taken to the streets with a new wireless technology called Li-Fi, and it’s 100 times faster than current speeds. Li-Fi transmits data using visible light communication, and it’s now being tested in offices and industrial environments in Tallinn, Estonia. This new wireless system hit speeds of 224 gigabits per second in the lab, and has the potential to revolutionize internet usage.
how li-fi works
LiFi’s early developmental models were capable of 150 megabits-per-second (Mbps). Some commercial kits enabling that speed have been released. In the lab, with stronger LEDs and different technology, researchers have enabled 10 gigabits-per-second (Gbps), which is faster than 802.11ad.
Benefits of LiFi:
Higher speeds than Wi-Fi. 10000 times the frequency spectrum of radio. More secure because data cannot be intercepted without a clear line of sight. Prevents piggybacking. Eliminates neighboring network interference. Unimpeded by radio interference.
Does not create interference in sensitive electronics, making it better for use in environments like hospitals and aircraft. By using LiFi in all the lights in and around a building, the technology could enable greater area of coverage than a single WiFi router. Drawbacks to the technology include the need for a clear line of sight, difficulties with mobility and the requirement that lights stay on for operation.
Standards
Like Wi-Fi, LiFi is wireless and uses similar 802.11 protocols; but it uses visible light communication (instead of radio frequency waves), which has much wider bandwidth.
One part of VLC is modeled after communication protocols established by the IEEE 802 workgroup. However, the IEEE 802.15.7 standard is out-of-date, it fails to consider the latest technological developments in the field of optical wireless communications, specifically with the introduction of optical orthogonal frequency-division multiplexing (O-OFDM) modulation methods which have been optimized for data rates, multiple-access and energy efficiency.The introduction of O-OFDM means that a new drive for standardization of optical wireless communications is required.
Nonetheless, the IEEE 802.15.7 standard defines the physical layer (PHY) and media access control (MAC) layer. The standard is able to deliver enough data rates to transmit audio, video and multimedia services. It takes into account optical transmission mobility, its compatibility with artificial lighting present in infrastructures, and the interference which may be generated by ambient lighting. The MAC layer permits using the link with the other layers as with the TCP/IP protocol.
The standard defines three PHY layers with different rates:
- The PHY I was established for outdoor application and works from 11.67 kbit/s to 267.6 kbit/s.
- The PHY II layer permits reaching data rates from 1.25 Mbit/s to 96 Mbit/s.
- The PHY III is used for many emissions sources with a particular modulation method called color shift keying (CSK). PHY III can deliver rates from 12 Mbit/s to 96 Mbit/s.
The modulation formats recognized for PHY I and PHY II are on-off keying (OOK) and variable pulse position modulation (VPPM). The Manchester coding used for the PHY I and PHY II layers includes the clock inside the transmitted data by representing a logic 0 with an OOK symbol “01” and a logic 1 with an OOK symbol “10”, all with a DC component. The DC component avoids light extinction in case of an extended run of logic 0’s.
The future internet
Li-Fi technology will in future enable faster, more reliable internet connections, even when the demand for data usage has outgrown the available supply from existing technologies such as 4G, LTE and Wi-Fi. It will not replace these technologies, but will work seamlessly alongside them.
Using light to deliver wireless internet will also allow connectivity in environments that do not currently readily support Wi-Fi, such as aircraft cabins, hospitals and hazardous environments.
Light is already used for data transmission in fibre-optic cables and for point to point links, but Li-Fi is a special and novel combination of technologies that allow it to be universally adopted for mobile ultra high speed internet communications.
A dual use for LED lighting
The wide use of solid state lighting offers an opportunity for efficient dual use lighting and communication systems.
Innovation in LED and photon receiver technology has ensured the availability of suitable light transmitters and detectors, while advances in the modulation of communication signals for these types of components has been advanced through signal processing techniques, such as multiple-input-multiple-output (MIMO), to become as sophisticated as those used in mobile telecommunications.
An integrated communication solution
Li-Fi technology is being developed into a ubiquitous systems technology, consisting of application specific combinations of light transmitters, light receivers including solar cells, efficient computational algorithms and networking capabilities that can be deployed in a wide range of communication scenarios and in a variety of device platforms.
Originally published at www.vivek-chan.in.
