Navigant Research Blog

Li-Fi Turns Light into a Data Stream

Benjamin Freas — July 13, 2014

Since Harald Haas demonstrated the ability of light-emitting diode (LED) lights to transmit data during a TED Talk in 2011, the promise of Li-Fi (short for light fidelity) has received a lot of attention.  As researchers develop faster and faster communication speeds, the application of the technology to the building space appears both realistic and attractive.  Commercially, General Electric (GE) has demonstrated the viability of the technology through its launch of LED-based communication for retail environments.  Li-Fi could be cheaper and consume less energy than existing wireless communication technologies that rely on radio frequencies (RF).  Smart buildings, which require a dense and flexible control network, present an interesting application for a Li-Fi deployment, particularly with the increased adoption of LED lighting.

Non-Interfering

Li-Fi seems to be a compelling alternative to the RF technologies that are currently in use today.  First, the RF available to building automation is crowded.  Moreover, as the Internet of Things becomes more pervasive, more and more communication nodes will further saturate the environment.  RF travels through walls.  So, a node in an adjacent room will be competing for detection.  But Li-Fi is impervious to this problem.  Since the range of any individual Li-Fi node extends only to the nearest wall, the communication in one room will never interfere with other communication in a different room.  In other words, the inherent limitations on Li-Fi range are an ideal solution for saturated networks.  Moreover, more than just crowding, interference from microwaves and other devices can be a problem, particularly in medical environments.  Li-Fi is immune to RF interference.

Security is another area of concern for wireless communication.  It’s relatively easy to hack a Wi-Fi network.  Li-Fi, on the other hand, has a shorter range and requires line-of-sight.  As a result, it is inherently more secure.  You have to be within the range of the transmitter and receiver, shifting the threat of IT security to more manageable physical security.

The Bad News

The technology faces some serious technical challenges before widespread adoption, though.  In addition to enhancing security, the line-of-sight requirement also presents challenges.  Though Li-Fi is immune to RF interference, it is susceptible to interference from a more ubiquitous source: the sun.  Receivers placed close to windows could be rendered ineffective.  Additionally, lighting in buildings is typically designed to be unidirectional, from the light source to the space to be illuminated.  But communication networks must be bidirectional to both send and receive data.   In order to create a Li-Fi network, lights would need to be installed to point at each other, which is at odds with their intended functionality.

Despite these drawbacks, Li-Fi could overcome several of the barriers facing wireless.  Though most of the current buzz focuses on visible light communication, using infrared light could solve many of the hurdles.  Windows can be designed to block infrared light but allow visible light to pass, eliminating problems of solar interference.  Infrared also has greater potential throughput of up to 5 to 10 gigabits per second.  Overall, the challenges facing Li-Fi are no greater that the challenges facing RF.  The technology appears to be several years away from successful deployment in building automation.  But it’s coming.

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