Light fidelity (Li-Fi) is a wireless communication technology that transmits data by modulating the intensity of a visible light source, such as an LED bulb.

“Li-Fi can support data transfer rates of up to 10 Gbps, which is significantly faster than traditional Wi-Fi, which has a maximum data transfer rate of around 7 Gbps,” said Jeroen van Gils, founder and CEO of Estonia-based
LiFi.co, a website to promote Li-Fi technology. “Li-Fi also uses the whole spectrum of visible light. This means it has a much wider bandwidth available compared to radio waves.”

Additional advantages include reduced interference with other wireless technologies; increased reliability because Li-Fi is not affected by weather or other environmental conditions; and improved security, as Li-Fi operates on a separate spectrum from radio waves, making it less susceptible to interference and hacking.

“These advantages make Li-Fi an attractive option for industries such as healthcare, transportation and retail, as well as for industrial and commercial applications where high-speed, secure and reliable wireless communication is needed,” van Gils said.

How it works

Li-Fi works like this: the LED bulb is connected to a Li-Fi transmitter, which encodes the data into light signals, according to van Gils. The light signals are sent to a Li-Fi receiver, which decodes the signals and converts them back into the original data.

The Li-Fi receiver, which can be a small dongle or a built-in device, receives the light signals and converts them into an electrical current, which is sent to a computer or other device for processing, he said. It uses a photodiode—a semiconductor that converts light into electrical current—to detect the light signals.

The global Li-Fi market is expected to reach $4.5 billion by 2035, growing at a compound annual growth rate of roughly 65%, according to a Research Nester report.

Driving the market is the growing number of connected devices used in the workplace, which has led to a demand for distributed indoor networks, according to the report. In addition to the aforementioned industries, Li-Fi can also be advantageous in marine and undersea applications.

“For instance, the U.S. Navy currently uses an antiquated and slow underwater communication system that is incompatible with the poor acoustics of the submerged environment,” the report’s authors write. “To overcome the challenge of communicating underwater, the U.S. Navy is developing advanced communication technology based on Li-Fi technology.”

The global Li-Fi market is projected to grow due to increasing ICT sector initiatives to manage energy, the rise in the number of smart buildings using LED lamps as lighting and the growing popularity of smart city programs in developing countries, according to the report.

Pros and cons of limited range

One drawback to Li-Fi is its limited range due to the need for line of sight, van Gils said.

“The fact that light can’t penetrate through walls might be a good thing when it comes to security, but this also means that Li-Fi has a very limited range,” he said. “That means you can only use it effectively in closed spaces.”

Lights must be tactically placed in rooms and halls to expand the scope of the Li-Fi network, van Gils said. In open spaces, Wi-Fi’s coverage can go up to 32 m, but Li-Fi can only go up to 10 m.

But there are ways to counter this—Li-Fi does not require a direct line of sight because reflected light from surfaces and in illuminated areas is enough to maintain a connection, said John Parello, principal engineer at Cisco Innovation Labs, a group of Cisco Systems Inc., San Jose, Calif.

“Like that of radio, there’s signal degradation without direct line of sight—but there is no loss. That said, a completely covered optics would not transmit,” Parello said. “But that is a key feature of Li-Fi, because it’s used as an intentional connection that fits between wired and radio wireless.”

Because of the intrinsic difference between light and other wireless mediums, Li-Fi has some interesting benefits, he said. Light has a sharp drop-off in coverage compared to radio, resulting in smaller and more precise coverage areas. Therefore, a coverage area can be targeted and adapted for intentional connections, such as a desk or specific seat at a table under a lighting source.

“These intentional connections allow light to be used with a location­-based security scheme, and the precise location of a connection can be used as a component of access control,” Parello said. “In areas where radio waves can cause interference with equipment, such as in industrial, medical and aviation, light is a safer carrier medium. It does not interfere with equipment or have any health impacts in sensitive areas.”

One of the key benefits of Li-Fi is that the containment and direction of light is easy to predict, he said. Radio waves can pass through barriers in nonobvious ways. Light does not transmit through walls and objects, however. So, to secure a transfer, very simple means can be used to contain a signal.

The latest developments in Li-Fi have been in speed, size and deployment, Parello said. Li-Fi can achieve up to a 1 gigabyte per second connection, with 100 kilobytes per second acting as the norm. Major Li-Fi vendors have been making improvements in the size of the optics and silicon needed to embed Li-Fi into devices. Additionally, customers with extreme security needs are now deploying Li-Fi. These combined factors lend an opportunity to scale the technology.

Netherlands-based Signify sees “significant potential” for the application of Li-Fi in the government and defense sector, said Floris Maassen, marketing and communications manager for Trulifi, a range of Li-Fi systems manufactured by Signify that offer reliable connections at up to 940 Mbps—guaranteeing transmission of heavy data loads.

"Li-Fi saves the effort of pulling miles of cables around an airstrip, as nothing can run over or under the runway.”
—Floris Maassen, Trulifi

“There are areas such as ammunition storage sites and field command posts where radio-based technologies are prohibited due to interference, or [because it is] just not possible,” Maassen said. “For example, Li-Fi saves the effort of pulling miles of cables around an airstrip, as nothing can run over or under the runway.”

Li-Fi is also a great solution in aerospace, particularly for onboard entertainment systems that require high-speed data connectivity, he added.

Trulifi solutions can be retrofitted in existing luminaires or installed as a single system, Maassen said. While sitting under an invisible cone of light, end-users simply plug a USB access key into a laptop or tablet to receive or transmit data to and from the receiver.

The future “looks bright” for Li-Fi, Parello said.

Lighting fixtures using power over ethernet and fault-managed power as the energy source can be used simultaneously for illumination and data, he said. Cabling a light with ethernet could enable a convergence in wiring.

“With LED lighting based on DC wiring becoming most prevalent in buildings, there’s a future state in which Li-Fi will be as ubiquitous as a lighting fixture,” Parello said.

Header image: Li-Fi offers wireless connectivity where radio-based technologies such as Wi-Fi and 4G/5G might interfere with sensitive equipment or munitions or can’t be used for security reasons. Signify and KIXS used Trulifi to create a Fast Field Data Link across runways and taxiways at Airbase Volkel in the Netherlands.