No dark side to using LED lights to supplement WiFi, research reveals

Supplementary content information

Dr Wasiu Popoola

Dr Wasiu Popoola

Energy-saving Light Emitting Diodes (LEDs) could help meet demand for wireless communications without affecting the quality of light or environmental benefits they deliver, new research funded by the Engineering and Physical Sciences Research Council (EPSRC) has shown.

A University of Edinburgh team has found that transmitting digital data via LEDs at the same time as using them to generate light does not make the light dimmer or change its colour. Nor does it make the LED more energy-hungry. Dr Wasiu Popoola of the University of Edinburgh, who led the research, says these concerns have held back the more widespread adoption of Light Fidelity, or LiFi, which uses household LEDs to enable data transfer.

But these findings help eliminate key hurdles to using LEDs to help satisfy the increasing global thirst for wireless communications. Preserving the quality of lighting is, in particular, a vital consideration as it can have a major effect on the physical and mental wellbeing of people in both their homes and their workplaces. LEDs have secured a huge increase in their share of the worldwide lighting market in recent years, as well as being used extensively in TV and other displays.    

Although it has long been known that LEDs can be ‘piggy-backed’ to transmit data to and from mobiles, tablets, sensors and other devices, questions have surrounded the ability to do this without affecting LEDs’ core capabilities or the money-saving and ‘green’ benefits that make them so popular. 

Focusing on LEDs producing ‘warm white’ and ‘cool white’ light, the Edinburgh team looked at two different data transmission techniques: on-off keying, where the LED works like Morse code, switching on and off extremely rapidly and imperceptibly to human eyes; and continuous signalling, where imperceptible changes in light intensity are used to achieve the same goal.

Neither technique was found to significantly reduce the light bulb's brightness or their life expectancy, or to cause any significant change in the colour of the light. Both techniques also produced only a negligible change in the heat generated by the LEDs – a key consideration as any temperature increase would indicate the LED using more electricity to produce light, making it less energy-efficient and less carbon-friendly.

Dr Popoola adds: “Our ever more connected world will need more bandwidth than the overcrowded Radio Frequency part of the spectrum can provide. Plugging a key knowledge gap, our results are very encouraging for the future of light-based communications that could help realise the full economic and social potential of a wireless future. It’s vital that LED manufacturers know what impact the incorporation of data transmission capabilities would have on their products. Our research shows that there’s no dark side to using LED lights to supplement WiFi.”

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For media enquiries contact:

Dr Wasiu O. Popoola, Li-Fi R&D Centre and Institute for Digital Communications, School of Engineering, University of Edinburgh, tel: 0131 650 8232, e-mail: Dr Popoola; or the EPSRC Press Office, tel: 01793 444404.

Notes for Editors:

The 12 month project A Study of the Impact of Visible Light Communications on the Quality of Lighting and Display ran from March 2016 until February 2017. It received just over £99,000 in EPSRC funding.

To find out more about LiFi research at the University of Edinburgh, see the latest Li-fi Research News.

As well as personal devices, all kinds of household gadgets and other objects will increasingly be connected to the internet as part of the Internet of Things (IoT), adding to the torrent of data needing transmission and the demand for wireless communications. For more information on the use of light as a data transmission option and on the IoT, see the Li-Fi R&D Centre website and this Guardian article.

LEDs use about 90 per cent less electricity and last around 20 times longer than traditional lightbulbs. For more on the benefits of LED lighting, see

For more on the health effects of light, see this EU report.

Engineering and Physical Sciences Research Council (EPSRC):

As the main funding agency for engineering and physical sciences research, our vision is for the UK to be the best place in the world to Research, Discover and Innovate. By investing £800 million a year in research and postgraduate training, we are building the knowledge and skills base needed to address the scientific and technological challenges facing the nation. Our portfolio covers a vast range of fields from healthcare technologies to structural engineering, manufacturing to mathematics, advanced materials to chemistry. The research we fund has impact across all sectors. It provides a platform for future economic development in the UK and improvements for everyone's health, lifestyle and culture. We work collectively with our partners and other Research Councils on issues of common concern via UK Research and Innovation.

University of Edinburgh

The University of Edinburgh is one of the world's top universities. Host to more than 35,000 students, it is consistently ranked in the world top 50. Its entrepreneurial and cross-disciplinary culture attracts not only students but also staff from over 130 countries, providing a stimulating working, learning and teaching environment with access to excellent facilities and it attracts the world's best, from Nobel Prize winning laureates to future explorers, pioneers and inventors.

University of Edinburgh website

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