Is wireless communication using light the future of the internet?

In the not-too-distant future, installed lights at your home will serve as wireless antennas, allowing you to connect multiple devices to the internet. You will be able to stream on YouTube while standing by light bulbs. 

Light-based wireless connectivity has earned great potential in the realm of numerous wireless communication technologies. 

On record, the first demonstration of visible light communication (VLC) was done by Alexander Graham Bell, when the photophone was invented to transmit modulated speech signals using sunlight over a few metres of distance. 

However, with the invention of infrared (IR) light-emitting diodes (LEDs) in 1962, the use of invisible light for remote control has become widespread. 

Undoubtedly, this is one of the most successful applications of optical wireless communication (OWC) technology to date. In the past few decades, several researchers have also considered using white LEDs. As such, Harald Haas from the University of Edinburgh coined the term "light-fidelity" (LiFi) to define light-based indoor communication as an alternative to "wireless fidelity" (WiFi).

How OWC Works 

Similar to any conventional wireless communication system, the OWC system has three parts: transmitter (Tx), propagation channel and receiver (Rx). 

At the Tx, the information bits to be transmitted are first converted to an electrical signal and then fed into an optical source using a drive circuit after modulation. 

At the Rx, propagated optical signals are collected by a photodetector, and the resulting photocurrent is converted to a voltage signal by an amplifier before being sampled. 

Finally, original transmitted bits are recovered after signal demodulation. Typically, bi-directional light-based access in indoor scenarios uses the visible and IR spectrums for uplink and downlink communications, respectively.

Internet of the Future

Due to the availability of unregulated spectrum and high-speed light connectivity, LiFi is considered among the most effective candidates for the future 6G networks. 

In particular, lights typically do not pass through opaque walls, resulting in enhanced privacy and security as well as allowing for frequency reuse. Moreover, as compared to traditional WiFi, LiFi may offer 100 times faster internet access. 

As such, PureLiFi, a LiFi startup, designed a Gigabit LiFi system transmitting data at a speed of up to 1 Gbps, while laboratory studies demonstrated theoretical speeds of up to 224 Gbps. On the other hand, Oledcomm, a French tech company, has developed a bi-directional Gigabit chip based on IR that may be integrated into mobile and laptop devices. 

In addition to LiFi, optical wireless communication (OWC) technology is particularly preferred in environments where radio-frequency is prohibited, e.g, military confinements. 

A common misconception is that this technology is only suitable for indoor communication. However, laser diodes could be used for point-to-point communication in long-distance transmission systems, e.g, in free space and underwater.

Due to higher bandwidth efficiency, lower power consumption and smaller antenna size, OWC has recently gained increased popularity in inter- and intra-satellite communications, vehicle-to-vehicle communications, and outdoor wireless access. 

Recently, Oledcomm has been working on a project to replace network cables inside satellites with optical wireless networks, which would save crucial weight and space for satellites. More interesting applications include drone-to-drone communication, farm surveillance, smart homes, trains and underground stations.

Research Opportunities 

Although the LiFi industry is expanding, there are also several limiting factors. For instance, they include user mobility, obstacles in indoor scenarios, fog, cloud and dust for outdoor applications etc. 

Moreover, multiple users may need to transfer their data at the same time, which would require appropriate modulation and multiple access techniques. Increasing the reliability of the communication system is another interesting area of research.

In Bangladesh, AIUB (American International University Bangladesh) has already started funding research on the next generation of LiFi. AIUB researchers, in particular, are working on innovative modulation and multiple access approaches for LiFi use cases. The long-term goal is to design and develop experimental testbeds for LiFi in Bangladesh for the first time.