Visible light communications: demand factors, benefits and opportunities [Guest Editorial]

isible light communications (VLC) is an emerging field of optical communications that focuses on the part of the electromagnetic spectrum that humans can see. Much existing work in optical communications exists, mainly optimized for capacity and transmission performance in fiber and free-space with biases toward spectrum that minimizes attenuation in the medium. However, the use of the visible spectrum has gained interest due to its availability and the ease at which it can be modulated using light emitting diodes (LEDs). Recent demand factors due to the burgeoning mobile industry and the rapid evolution of LED-based lighting are also driving this interest. Here, and in this special issue, we outline the context of VLC, its unique benefits, and describe the state of the art research contributions of the assembled papers. The potential for VLC is being driven by the increasing adoption of mobile electronic devices. The demand for wireless capacity as predicted most recently by Cisco (Cisco VNI, Feb 2015) indicates a 10x growth in mobile traffic over the next five years. But over the same time period, mobile carrier speed is predicted to grow by only 9 percent. Because more than 70 percent of all mobile traffic occurs indoors, and much occurs at fixed locations, there is a huge opportunity to offload traffic to localized access points as WiFi or small cells. Key to this technology is the placement of access points where mobile users are active but also to reconcile contention caused by these populous indoor spaces. The problems with contention are where VLC can provide significant benefits over RF technologies. VLC can provide very high data rates when used directly as a directional medium. When combined with a lighting mission — providing light — VLC is ideally suited for where humans exist in these indoor spaces because they consume light at the same time that they consume data. In its basic form, VLC uses light that is intensity modulated to transmit data. LEDs are inexpensive, fast, and are widely adopted in lighting, and hence VLC is and ideal match in lighting systems using LEDs. Because of their efficiency as compared to other lighting sources, LEDs appear in many applications in lighting and display including traffic lights, flat panel displays, and instrumentation. In this sense, any LED-based applications fall into the category of " green " technologies. In terms of communications, LEDs are " fast " in that they …