Visible Light Communication-History, Working & Applications

Over the few past years, a myriad of technological advancements has been evidenced in the lighting and communication sector. The most amusing one being visible light communication (VLC). Invented in the late in the 18th century, the means has not only undergone numerous advancements but also applied in different sectors. What is Visible Light Communication aka VLC? Visible Light Communication is a communication method where visible light within a particular frequency range is used as the medium of communication. The visible light frequency range for VLC is from 400 to 800 THz. VLC operates under the concept of transmission of data via light rays to send and receive messages in a given distance. Putting to use LED lighting, VLC can be used as a replacement for radio frequencies in areas it cannot be applied. In addition, VLC has the upper hand over radio frequencies as it offers ultra-fast data transmission and also high bandwidth transmission. This has been most evident in traffic lighting, besides other sectors. Being a complex field, it arouses questions on its significance, its operation, and areas in which it is well suited for. History of Visible Light Communication The concept of VLC (visible light communication) dates back as early as 1880 (4 years prior to the invention of radio transmission). This was first put into use by alexander graham bell, a Washington D.C resident when he invented the photophone. The method relayed speech over long distances via modulated sunlight. However, back then the idea was not applied much as it was centuries ahead of its time. Due to this, the technology paved way for slower communication media thus was never a big hit. However, this acted as a guiding line for fiber optic communication that was invented in the 80’s. later in 1995, students of Universidad de Buenos Aires worked on the concept and thus resulted in a laser diode that was used in photodiodes detection. in 2003, three undergraduates from Keio University, Japan, worked more on the concept using LED lighting. Given the presence of sophisticated technology, people were able to manipulate the technology and put it to use. In 2006, CICTR researchers combined LED lighting to power line communication and resulted in a number of indoor applications of VLC. Over the years, the technology underwent a number of researchers and changes and thus leading to various uses inclusive of High definition videos. This technology found its way into the security field, transport sector and even banking sectors between 2010 and 2017. Working – How Visible Light Communication Works? Given that light travels 186,000 miles in a second, communication via this source is virtually instantaneous. This makes VLC the fastest means of communication between all means available in the market. to function, VLC uses visible light between 780 to 375 nm which are visible to the human eye. Every form of data can be broken down into single units of ones and zeroes that can be deciphered as low or high signals. In VLC, this is achieved by fast turning of light on and off (also called on-off keying, OOK). However, this form of data transmission is dependent on how fast the light can go on and off. To achieve great results, LED lighting is well suited for the task as it has a short rise and fall time thus faster switching. Due to this, LED lighting is used in all wireless forms of VLC. To function, VLC requires a receiver (photodetector), a transmitter (LED’s) and a channel of communication. In addition, the circuit features a photodiode, transimpedance amplifiers, auto gain controllers, high pass filters...
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