D-Light (data-light) Project
A new project at the University of Edinburgh will enable light bulbs to be turned into high-speed
short range communications devices. The ground breaking D-light project has received the go-ahead
via Proof of Concept funding from Scottish Enterprise. The project will prove the commercial
viability of the technology developed at the University and aims to create a spin out company to
develop the technology for exploitation in international markets.
Background
Conventional lighting using incandescent and fluorescent lamps are certain to be replaced by high
efficiency LED lighting due to the benefits of low power, long-life, inherent safety and small
integrated packaging. The benefits are so compelling that only the costs, which are reducing, remain
as a barrier to mass market penetration.
It has long been known that light can be used for communications. Traditionally special lamps have
been switched on and off rapidly in order to convey information and optical fibres can now carry
data optically at rates of Gbits/s over long distances using coherent light from laser diode sources.
However, it is also possible to modulate non-coherent light generated by white LED based lamps in
order to carry large amounts of information over short distances without interfering with the
intended function of illumination.
Prof Harald Haas from the University of Edinburgh and his team has developed and patented methods
that will allow more than 100Mbit/s of data to be transmitted using the standard LEDs which
promise to become ubiquitous in industrial, domestic and automotive illumination of the future. In
essence every LED light bulb can become a high speed WiFi as well as a high efficiency light source.
The Problem Being Solved
Given that many of us now have WiFi in the home, what benefit will this be? Well, if you consider
that we now already use our WiFi for our PC, laptops and PDAs, printers, data storage devices, for
synchronising our mobile phones, for VoiP, for games consoles, maybe also for home security, video
streaming, wireless photo-frames and for MP3 players. Soon it will connect home automation, our
heating controllers, maybe the fridge, washing machine, health monitors, our car, etc. As more
devices connect to the system it becomes overloaded and uses up valuable and limited RF spectrum.
This creates electromagnetic interference (EMI) or 'electrosmog' which extends well beyond your
home.
Consider another example. A modern passenger aircraft must now be fitted with in-flight
entertainment systems -- audio and video for each passenger. This cannot be provided via WiFi due
to the interference it would create so each seat must have cables running to them. This creates
massive installation costs, adds weight and creates maintenance issues. By using LED illumination at
each seat and by transmitting the multimedia data via the illumination, these problems are solved.
Furthermore, since light-waves do not penetrate through walls, this technology inherently provides
security compared to WiFi installations at home or at office locations which emit radio frequency
signals which can be receive well beyond the respective premises. Since this technology uses light-waves
to convey data, it has the potential to find acceptance for wireless data transmission in
medical technology used in hospitals.
Overall there are huge environmental benefits from this technology in addition to the commercial
and technical advantages.
Environmental
- Less power than conventional light sources
- Less environmental waste due to long life
- Less heat generated (lower air conditioning bills)
- Does not cause electromagnetic interference (EMI)
- Does not use valuable regulated RF spectrum
Commercial & Technical
- White LEDs are an emerging market and will become ubiquitous.
- Unlike Infra-Red light communications, there is no health regulations on power.
- Low cost devices
- Low installation costs (lighting is already being installed)
- Long life (low maintenance)
- Unregulated spectrum
- More secure than wireless
- Can also be used as a localisation technology
Unique Technology
The technology invented in Edinburgh is special in that new transmission schemes have been
developed that are optimised for communication in the visible light spectrum using LED devices. The
light is modulated (varied in intensity) in a particular way that enables high speed communications
to be achieved which does not interfere with the normal illumination purpose of the lamp.
Conventional light communications, including infra-red remote controls for TVs etc, send data by
switching the lamp on and off in a coded pattern. With this new technology the lamp is never
switched fully off and the transmission technique mean that communications is not interrupted even
if there is other visible light present from sources such as daylight or from conventional light bulbs.
One obvious question is what happens to the communications when the lights are switched off?
Under this scenario modulation is applied to a low intensity light output which provides the required
communications but at a light intensity that does not create significant illumination.
Applications
Applications for the technology can cover a wide range of vertical markets:
- Domestic: e.g. Home automation, Internet access.
- Transport: Communications via street lighting, traffic lights, aircraft passenger lighting, aircraft navigation lights with identification transmission, car head/tail lamp communications.
- Hospitals: Equipment and staff communications with no RFI problems.
- Industrial: Industrial and office lighting with inbuilt communications and localisation, intrinsically safe communications -- e.g. in areas with flammable materials.
- Public sector: providing local information -- e.g. localised information transmission in museums, communications for civil contingencies.
- Homeland security and defence: additional secure communication means, ad-hoc communication.
Contact Information
Please direct all enquiries to Prof Harald Haas or head over to the blog at visiblelightcomm.com
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