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Why Li-Fi Might be Better than Wi-Fi

Originally posted on spectrum.

An expert on IEEE’s new standard weighs in

The recent adoption of IEEE 802.11bb has launched light fidelity, or Li-Fi, which opened the door into an era of wireless communication for advanced Wi-Fi technologies. Li-Fi enables Wi-Fi to use light waves instead of radio waves to transmit and receive data.

IEEE 802.11bb defines the rules for how Li-Fi devices will communicate with each other and how fast they can transfer data. According to the standard, such devices should be able to send and receive data at speeds between 10 megabits per second and 9.6 gigabits per second.

The standard introduces a new realm of fast, reliable wireless communication that promises to revolutionize the way we connect and communicate.

Li-Fi uses special light fixtures that have small control units and solid-state light emitters and photosensitive receivers. The fixtures can send and receive information using light waves. To connect to Li-Fi, smartphones, tablets, and other devices need emitters and sensors that can send and see the light signals. Advanced mobile phones already use the emitters and sensors for other applications such as face recognition and lidar.

In a typical installation, we connect to the Internet via a local-area network. LANs now will be able to offer a new wireless access opportunity via Li-Fi-enabled access points (APs) installed in areas such in ceilings or inside desk lamps connected via power over Ethernet or power-line communications.

The Li-Fi APs enable bidirectional communication with battery-powered devices and provide a seamless, robust wireless experience.

The new experience comes from operating in the light spectrum that has fewer contenders. In comparison, Wi-Fi operates in unlicensed radio spectrum in competition with other technologies including Bluetooth, Zigbee, and ultra-wideband.

“As Li-Fi technology matures, advancements in range, bandwidth, and interoperability will expand its applications and market potential.”—VOLKER JUNGNICKEL

One of the key factors driving the adoption of Li-Fi is that it enables peak rates by using the same advanced modulation techniques to encode data onto light waves that are used for Wi-Fi. The optical wireless transmission channel is less disturbed by multipath, Doppler, phase noise, and other interference. Therefore, it can realize the highest speeds through a variant of multicarrier modulation, called orthogonal frequency division multiplexing. OFDM implements subcarriers transmitting multiple parallel data streams. By leveraging the properties of light, Li-Fi results in unprecedented data transfer speeds over short distances typically inside one room.

The Institute spoke with IEEE 802.11 Working Group member Volker Jungnickel, who played a crucial role in promoting optical wireless communication standards. He chairs the IEEE 802.15.13 project and is technical editor of IEEE 802.11bb. He heads the Metro, Access- and In-house group in the photonic networks department at the Fraunhofer Heinrich Hertz Institute (HHI), in Berlin. The interview has been condensed and edited for clarity.

The Institute: What are some advantages and limitations of Li-Fi over Wi-Fi?

Volker Jungnickel: Li-Fi enables high-speed wireless connectivity with data rates of up to 100 Mb/s per square meter, making it ideal for densely populated areas, i.e., conference rooms and classrooms. The technology operates in additional unregulated spectrum, where it has no interference with RF-based wireless technologies.

Enhanced security is another advantage, as Li-Fi communication is confined to the physical boundaries of the light signal, such as the inside of a room, making it difficult to intercept.

However, Li-Fi has limitations. Its range is relatively short—typically limited to a few meters in a single room—which means that it requires a dense network of access points for broader coverage.

Additionally, the available bandwidth can be constrained by the capabilities of light sources and detectors. Implementing Li-Fi infrastructure can also be more expensive compared with Wi-Fi.

What impact do you think the approval of the IEEE standard will have on the adoption of the technology?

Jungnickel: The standards provide a framework for developing Li-Fi products that cater to specific market segments, such as industrial applications and residential use. They also instill confidence in customers and promote interoperability among different vendors. This approval will likely boost the global adoption of Li-Fi and drive further advancements in the field.

What are some insights into the advancements, applications, and prospects of Li-Fi?

Jungnickel: It offers numerous advantages over traditional Wi-Fi, such as uncontended high-speed bidirectional communication, enhanced security, the ability to operate in additional unregulated spectrum, and precise indoor navigation achieved by, for example, time-of-flight measurements. Its applications range from smart buildings and hospitals to vehicle-to-vehicle communication and fixed wireless access.

What are some important milestones in the development of the technology?

Jungnickel: One was the introduction of adaptive OFDM for Li-Fi by Fraunhofer HHI around 2005—which allowed adaptation to mobile channels and efficient use of LEDs. In 2011 the term Li-Fi was coined by researchers at the University of Edinburgh, which helped define and popularize the technology.

In 2015 pureLiFi, the company that chaired the IEEE task group behind the new standard, conducted the first handover demonstration. It showcased seamless data transfer when moving between different Li-Fi access points. The demonstration used a proprietary protocol, and it addressed challenges related to packet loss and latency.

Another important milestone was the introduction of first prototypes based on a ITU-T G.vlc chipset in 2016. They specified the system architecture, the physical layer, and the data link layer for high-speed indoor optical wireless communication transceiver using visible light. These ITU chipsets were commercially available and marked a significant step toward commercialization and early product development by further vendors such as Signify and Oledcomm.

Moreover, in 2017, the Fraunhofer HHI introduced the concept of distributed multiple-input multiple-output technology for Li-Fi, enabling seamless mobility without packet loss and improved performance in case of the line-of-sight blockage. This technology is specified in the separate IEEE Std 802.15.13 for industrial Li-Fi.

In 2021 Fraunhofer HHI demonstrated that centimeter precision is possible by using Li-Fi for indoor navigation and the same protocols available for Li-Fi transmission. This is substantially better than using conventional Wi-Fi techniques.

Are there any notable projects that contributed to the advancement of Li-Fi technology?

Jungnickel: Yes, OMEGA and ELIoT. OMEGA aimed to develop an ultrahigh-speed home access network capable of speeds up to 1 gigabit per second. The ELIoT project intended to develop mass-market solutions using Internet of Things devices with Li-Fi. These projects focused on research, development, and innovation within the European Union, addressing various aspects of the technology, including mobility, standardization, and interoperability.

What collaborations, challenges, and future integration do you foresee?

Jungnickel: Collaboration among governments, major market players, and research institutions is crucial for driving the advancement of the new technology. Government funding for research projects and pilot initiatives can stimulate technology development in the precompetitive phases and market establishment.

In terms of challenges, competition among companies in the Li-Fi domain can be a hurdle, particularly for smaller players. In the precompetitive phase, collaboration and identification of profitable market segments can help overcome these challenges. In particular, standardization helps to overcome proprietary technologies and enable interoperability. The customer can buy similar products from different vendors that integrate into the same network. This reduces the risk for both customers and vendors to invest in new technologies.

In the future, we can expect to see the technology integrated into everyday devices, like TVs and cellphones. Standardized Li-Fi chipsets and increased investment in product development will play a crucial role in expediting this integration process. As the technology matures, advancements in range, bandwidth, and interoperability will expand its applications and market potential.

Source: spectrum

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