In a 2011 TEDGlobal Talk titled Wireless Data from Every Light Bulb, Professor Harald Haas from the University of Edinburgh introduced the world to the transmission of data using visible light. It was at this talk that he coined the term Light Fidelity (LiFi)– a term he would use to describe the use of visible light for network connectivity.
Since the technology was introduced in the talk, many comparisons have been made between the prevailing WiFi (Wireless Fidelity) and its new “rival”. Here, we will do just that and talk about these two technologies – their similarities, features, and their advantages as well as their disadvantages.
A Look at WiFi Technology
WiFi is a term that is used to describe a wireless networking technology that uses radio waves as a medium for the transmission of data. Its radio signals are distributed within a given area from a specific access point, which are then received by numerous WiFi-enabled devices within that area. Its functionality is dependent on numerous standards that govern how wireless devices work in order to make connections faster and more secure.
How Does WiFi Work?
WiFi networks broadcast radio signals from a hotspot at different frequencies, typically within 2.4 GHz to 5 GHz (other frequencies can also be used depending on the setting). Each frequency has multiple channels on which devices can operate to help decongest potential usage traffic.
For a typical hotspot, the signal range can reach up to 100 meters in open air. Inside closed settings such as homes or offices, building materials such as the walls or ceiling can reflect the signal, greatly reducing the range to about 10 to 35 meters. The range will also depend on the frequency used to broadcast the signal since higher frequencies mean shorter wavelengths and vice versa. For instance, a signal broadcasted at 60 GHz will have a shorter range than at 5 GHz.
Any WiFi-enabled device can detect broadcasted signals and attempt to connect to the network, which raises concerns over data security. For this reason, standards such as the WPA, WEP, WPA2, and WPA3 were used to mitigate security issues.
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Advantages of WiFi
Compatibility. Any WiFi-enabled device can detect signals and attempt to connect to a wireless network. Computers, mobile phones, video game consoles, even radios can connect to a WiFi network simultaneously.
Mobility. WiFi signals are broadcasted using a transmitter called a hotspot and does so regardless of setting, whether public or private, indoor or outdoor.
Accessibility. Depending on the frequency used to broadcast wireless signals, the range of the network can reach up to 100 m and can be accessed anywhere within that range. Although some waves can be reflected by different surfaces, these cannot be blocked by walls, ceilings, or other possible barrier.
Low Cost. WiFi networks are generally cost-effective. All you need is a WiFi hotspot that is capable of broadcasting WiFi signals to which other devices can connect to create a wireless network.
Disadvantages of WiFi
Quality and Continuity of the Signal. WiFi signals can reach up to 100 m in open air, which is greatly diminished in enclosed areas and crowded spaces. The effective range of the signal will also depend on the frequency used. Higher frequencies correspond to shorter wavelengths, which greatly diminishes the range. Lastly, signal strength is also an issue since devices will need to be closer to the signal source to gain faster speeds.
Security. Many concerns have been raised over the security of WiFi networks due to the relative ease in which they are accessed. Virtually anyone within range can gain access to the network, which puts data at risk.
Safety. Radio waves can be disruptive, which causes problems in sensitive areas such as hospitals, airlines, and high-risk industries like petroleum.
The Technology Behind LiFi
LiFi is an optical networking technology that uses visible light as a medium for the transfer of data. But unlike other optical networks like fiber optics, it doesn’t involve any physical conduit to transmit light. Instead, it functions similarly to visible light communication (VLC) systems where only a transmitter (LED bulb) and receiver is needed to form a network.
How Does LiFi Work?
LiFi functions similarly to WiFi in that it allows the bidirectional transfer of data within the network. This means data can be downloaded and uploaded within the network. It is a type of VLC system that needs only two main components to function: a light transmitter and a transceiver.
Within a LiFi system, LED bulbs are used as transmitters. The light emitted by the LED bulbs are modulated at speeds undetectable to the human eye, so they do not appear to flicker at all. Through the modulated light, data is transferred from the transmitter to the photodiode, which acts as a transceiver. It receives signals conveyed through visible light, which is then transcribed into usable data, and transmits user requests back to the transmitter.
Advantages of LiFi
Data Speeds. Numerous tests done on LiFi found that it can transfer data at speeds as high as 224 Gbps.
Energy Efficiency. Instead of using separate systems for network connectivity and illumination, LiFi uses a single light bulb to act as both illuminating device and data transmitter. This creates a high-speed data network capable of transmitting high volumes of data while using minimal energy while still enjoying the benefits of illumination all in a single package.
Easy Installation. LiFi works on any LED bulb that can be found anywhere. Whether it’s in the home or office, all you need is a LiFi chip on the LED bulb.
Bigger Spectrum. The visible light spectrum is more than 1,000 times wider than the RF spectrum. This ensures many frequencies can be used to broadcast the network signal.
More Secure. One of the biggest advantages of LiFi is that it uses overhead lighting to create a network, which is localized to a certain area. Light cannot pass through opaque surfaces such as walls and floors, which limits its reach considerably. This keeps all private data secure over the network.
Safety. Unlike radio waves, visible light cannot pass through walls and doesn’t emit any radiation. This makes it more ideal for applications that are considered sensitive such as hospitals, military bases, airlines, or high-risk industries.
Localized and Immobile. Overhead illumination devices cannot be easily transferred from one place to another, which makes access more difficult.
Line of Sight. One of the biggest flaws of LiFi is that it requires line-of-sight to get a decent signal. Once the path between the transceiver and the transmitter is blocked, no data can pass through. However, many steps are being taken to take care of this problem.