The old proverbial saying “what goes around comes around” has special meaning to me. Not wishing to date myself, my Thesis about “Free Space Laser Communications” was close to 27 years ago. With the emergence of visible light as a vehicle for communications (VLC) I now, somehow, feel vindicated.
Why visible light communications?
The exponential growth of data has placed significant demand for a flexible, reliable, secure, high-bandwidth, low-cost network medium. While wireless provides flexibility, radio does not have unlimited bandwidth. Also, the cost, security and reliability requirements of radio remain a challenge.
Visible light communications may provide us with an answer to this conundrum with 4 unique characteristics.
1. Visible light has much higher available bandwidth than radio frequency (RF) systems (Wi-Fi, cellular,…). The spectrum graphic below from an article by Harald Haas, shows the visible light spectrum to be 10,000 times larger than the entire radio frequency spectrum.
2. Visible light exhibits higher security than radio frequency (RF) systems. Unlike RF systems which broadcast their communication to anyone listening (even through walls), visible light communications can be easily confined. Also visible light communication is currently considered point to point and interference with the light beam can alert for the detection of eavesdropping.
3. Like all wireless, visible light is flexible. Unlike the current use of light as a form of communications propagating within fiber optic networks (and now through the promise of silicon photonics), Visible light based communications are wireless.
4. Has lower deployment costs. By leveraging the use of existing lighting infrastructure (in your house, on the streets, in your car,…) visible light communications reduces the need for new infrastructure deployment. Lights exist in massive numbers and are considered pervasive, making the visible light network pervasive.
There are 2 other significant benefits of visible light communications that should be mentioned:
1. Safety. Devices using radio gear can be dangerous in places like :
Oil platforms (where it can cause sparks) and underwater (where the salt conducts electricity),
On planes (where it may interfere with other equipment on the plane),
In hospitals which use apparatuses that are sensitive to radio interference.
Visible light communications have a significant advantage over cellular and Wi-Fi in that visible light transmission does not cause electromagnetic interference.
2. VLC as an indoor GPS. Philips developed a “connected lighting system” that it demonstrated in 2013 at EuroShop and LIGHTFAIR. Phillips placed LED luminaires in a dense network that provided illumination while also functioning as a positioning grid. Each luminaire was identifiable and able to communicate its position to an application on a shopper’s smart device. The light fixtures themselves communicate this information by virtue of their presence everywhere in the store as discussed in this article.
What is Visible light communications?
The VLC acronym commonly refers to an illumination source (like a light bulb), which in addition to providing illumination can also become a vehicle for transmitting data using the same light source.
VLC = Illumination + Communication
Imagine a flashlight sending a Morse code signal. While such flickering of light would not be a good “illumination”, one could send signals by flashing the light so quickly, that the eye cannot see the flashes (representing data that is obscured from humans because of the human eye “flicker fusion threshold”). The result is that VLC technology can be applied in “any” environment that is currently lit.
The communication aspects of VLC essentially makes VLC another wireless access method that uses light emitted by LEDs to deliver networked, mobile, high-speed data similar to Wi-Fi (leading to a newly coined term: Li-Fi).
Most people do not realize that Visible Light Communications (VLC) pre-dates the transmission of speech through radio. The first of what you could reasonably call a VLC apparatus dates back to 1880 when Alexander Graham Bell invented the “photophone” on June 3rd, 1880; which transmitted speech on modulated sunlight over several hundred meters and received a US patent. Unfortunately, the unpredictability of weather phenomena and the necessity for bright daylight greatly diminished the practicality of this technique. From that point on, VLC has been extremely slow to develop until recently.
Why Now? (Is an obvious question, asked by most people).
The exponential growth of LED light bulbs driven by energy savings and a longer life expectancy is enabling a transformation in the general lighting industry. While such monitory benefits are obvious to most people, the technological opportunities presented by LEDs are not quite as apparent.
One factor for the rise of visible light communications is a result of another important property of LED bulbs. Unlike incandescent bulbs, LED’s use semiconductors to create light. It's this electroluminescence source of light that can easily be modulated for seamless integration into digitally communicating networks.
This Trojan horse approach of extending the utility of a simple light bulb is a timely intervention as we propel headlong into the Internet of Things. Now signals can be piggybacked on lights that are already in use — street lamps, car headlights, room lighting, signs, televisions, etc. to transmit data to gadgets such as mobile phones, tablets, and wearable devices. Such capability is already showing up in products as was recently demonstrated by multiple vendors at the Light and Building fair in Frankfurt, March 2016.
This is just the beginning! VLC along with LED technology is rapidly evolving, allowing faster speeds, increasing functional capabilities, more cost effective architectures and ever expanding reach.
Now, with the advent of smart cities, smart homes/buildings and even smart cars (communicating with other cars through headlights, running lights, turn signals…), VLC is extending the reach of the internet of things.
Visible light communications will become a significant driver for the final stage of the Internet of Things; one that completely ushers in an age of constant connectivity for people, places ...and now things!
It has the potential to completely disrupt the communications industry through lighting deployments, as well as utilizing any illuminated surface, to provide ubiquitous high-speed access to Internet and telecommunications services. As the enormous VLC opportunity unfolds, multiple organizations are rushing to create standards (IEEE, ANSI, JEITA, Li-Fi consortium,….). In fact, evolution is already underway in one market segment as mobile networks are now considering VLC in their 5G standards
It is also no surprise that VLC and IoT are maturing within the same time frame. They are highly synergistic and enable each other. More importantly, as “things” become ever more mobile we can expect VLC to not only extend the reach of IoT but greatly enhance the overall capacity of future networks.
One expectation is that deployed networking solutions will evolve their current networking environments to embrace expanding usage of VLC (in fact mobile networks are now considering VLC in their 5G solutions).
This unprecedented convergence of power, lighting and networking will also force a convergence of IT and facilities departments.
This convergence is something that has already begun with Lighting/Building Automation control systems and ends up impacting business property owners (CBRE, Cushman & Wakefield, Kimco realty,...), municipalities, and ultimately even the homeowner.
While the technology is disruptive, a second possible consequence of this disruption is the potential impact to the well-established verticals and the key players in those verticals.
On one hand, embedded network technology manufacturers are expected to grow their existing networking footprint to include the massive footprint of deployed lights.
Do the CISCO's, Juniper's, Ericsson's, Huawei's... become lighting companies as well?
On the other hand, VLC is also an important extension to the lighting industry to leverage their ubiquitous physical presence and drive the conversion of a 100+-year-old lighting technology into future market opportunities.
Do the Phillips, OSRAM'S, Zumtobel's, GE's, Acuity's, CREE's,... become networking companies as well?
This opportunity to approach IoT through networking or lighting is unprecedented in that two massive and entirely diverse industries are now innovating and furiously competing to capture the IoT opportunity. This competition is expected to produce life to change technology breakthroughs as this marketplace battle will continue for many years to come!
For more great industry insights follow Sohrab at https://www.linkedin.com/in/sohrabmodi.