ENG Partners in NSF Challenge to Create Next Generation Wireless Network

By Kathleen Fink

Professors Jeffrey Carruthers, Thomas Little and Hatice Altug (from left) using an LED-based transceiver to send messages between laptop computers wirelessly.
Professors Jeffrey Carruthers, Thomas Little and Hatice Altug (from left) using an LED-based transceiver to send messages between laptop computers wirelessly.

The National Science Foundation has chosen the College of Engineering to partner in a major initiative to develop the next generation of wireless communications technology based on visible light instead of radio waves. Researchers expect to piggyback data communications capabilities on low-power light emitting diodes, or LEDs, to create “Smart Lighting” that would be faster and more secure than current network technology.

The NSF today announced that the Smart Lighting project has been selected for funding as one of five new Engineering Research Centers nationwide. The $18.5 million, multi-year award went to a group that includes BU, Rensselaer Polytechnic Institute and the University of New Mexico to develop the optical communication technology that would make an LED the equivalent of a WiFi access point. Smart Lighting, which will be headquartered at RPI, is the fourteenth research center affiliated with the College of Engineering.

“This is a unique opportunity to create a transcendent technology that not only enables energy efficient lighting, but also creates the next generation of secure wireless communications,” said Professor Thomas Little (ECE) “As we switch from incandescent and compact florescent lighting to LEDs in the coming years, we can simultaneously build a faster and more secure communications infrastructure at a modest cost along with new and unexpected applications.”

Little, who is leading the BU team that also includes Associate Professor Jeffrey Carruthers and Assistant Professor Hatice Altug, said LEDs are poised to replace fluorescent and incandescent bulbs within the next 10 to 15 years because of their greater efficiency and durability. Because LEDs can be pulsed on and off rapidly – so fast the human eye cannot perceive the change – they can be used to light a room and transmit information to and from enabled devices simultaneously. Beaming information from lights may replace or augment the radio frequencies used today in computers, cell phones and other portable devices to connect to the Internet and send and receive data.

The researchers may also try polarizing the light; using multiple colors of LEDs; or slightly varying the intensity of the light – such as fluctuating between 99 percent and 100 percent intensity -- to carry out communications.

“Imagine if your computer, iPhone, TV, radio and thermostat could all communicate with you when you walked in a room just by flipping the wall light switch and without the usual cluster of wires,” Little said. “This could be done with an LED-based communications network that also provides light – all over existing power lines with low power consumption, high reliability and no electromagnetic interference. Ultimately, the system is expected to be applicable from existing illumination devices, like swapping light bulbs for LEDs.”

RPI and UNM will work on creating novel devices along with systems applications to better understand the proliferation of smart lighting technologies, plus materials needed for wireless devices to interface with the network. Boston University researches will focus on developing computer networking applications, notably the solid state optical technology that will form the network’s backbone. Together with BU, the three partners will have 30 faculty researchers plus students, postdoctoral researchers and visiting industry engineers as regular contributors to the research conducted by the Smart Lighting ERC.

Carruthers said the task groups have a friendly push-and-pull relationship. “We try to envision how the lighting will be used for future applications and imagine what we would like it to do,” he said. “At the same time we’re listening to what the devices and materials people are doing -- if they come up with a new property, we may be able to use that.”

Little and Carruthers will examine what capabilities the lights should have for the communication tasks people will require. By thinking ahead to how people will use these lights, the researchers can influence the design of the devices at this crucial time, just before LEDs begin to gain ubiquity as a lighting source.
Altug will work on design and fabrication of new materials and devices used to build the next-generation LEDs, in coordination with the UNM and RPI groups, which will primarily focus on the device aspect of the work.

“All these aspects we can engineer –the spectral composition, polarization, temporal modulation--will add the ‘smartness’ to the lights,” said Altug, “And we’d like to control these properties at will to transmit information.”

Little envisions indoor optical wireless communications systems that use white LED lighting within a room – akin to the television remote control device – to provide Internet connections to computers, personal digital assistants, television and radio reception, telephone connections and thermostat temperature control.
With widespread LED lighting, a vast network of light-based communication is possible, Little noted. A wireless device within sight of an enabled LED could send and receive data though the air – initially at speeds of 1 to 10 megabits per second – with each LED serving as an access point to the network. Such a network would have the potential to offer users greater bandwidth than current RF technology that has a limited bandwidth available for use, making a massive download by one person in an office or neighborhood sometimes slow others’ nearby data transfers.  With visible light the BU team envisions that each person on an airplane, for example, might be able to simultaneously download different high-definition movies directly to their laptops, without any interference or slowdowns.
Moreover, since this white light does not penetrate opaque surfaces such as walls, there is a higher level of security, as eavesdropping is not possible. LED lights also consume far less energy than RF technology, offering the opportunity to build a communication network without added energy costs and reducing carbon emissions over the long term. 

The technology is not limited to indoor lights; its first real test may very well come outdoors, in the automotive industry.

“This technology has many implications for automobile safety,” Little said. “Brake lights already use LEDs, so it’s not a stretch to outfit an automobile with a sensor that detects the brake lights of the car in front of it and either alerts an inattentive driver or actively slows the car.”

Beyond the indoor and outdoor applications the researchers have thought of, there are likely many others not yet imagined.

“This center does not exist because of one application,” said Altug, “but because it can have a huge variety of applications. It’s not only transportation or communication. Everywhere you have a light you can find a new application area.”

“As a research area it is rich with unanswered questions,” Little added. “And there will be a lot more interesting applications as we move toward ubiquity.”

For more information, please see http://smartlighting.bu.edu.

Michael Seele and Ronald Rosenberg contributed to this story.

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