September 21, 2016

LEDs for smart cities

					ICE Gateway

Changing to LEDs not only saves power. It can be the key for efficient networking of cities and factories as well as vehicles, drivers and passengers.

Adlershof Science and Technology Park in Berlin, Germany, pools concentrated intelligence on a daily basis. About 23,000 people in more than 1,000 companies, university institutes and research centers work in areas such as optics, photonics, microsystems technology, renewable energies, and environmental engineering. Just recently, the intelligence even made the leap to street lamps.

In a pilot project, the Adlershof start-up ICE Gateway retrofitted 160 street lamps with LED lighting. The fact that their power consumption will reduce by 80 percent is almost a side note. Primarily, the lamps will become network nodes. The key components are gateways via which the light-emitting diodes are controlled. For example, this allows the lighting to be dimmed if it is not required. Sensors monitor when pedestrians or vehicles are approaching. The system then makes the lamps brighter in real time. But the sensors are also used to record traffic data. This is also possible with Bluetooth devices in your vehicle or your coat pocket. But there's more. Thanks to the network connection the data can also be sent to control centers. Vice versa, data can also be sent to the devices of pedestrians or drivers of vehicles who are able to access broadband WiFi and other networks if they are in the vicinity of the lamps. Whether they are used for real-time marketing, logistics support or for integration into safety concepts: smart LED lamps will have a key function in smart cities.

Flexible and smart

The project in Berlin is designed as a nucleus. More roads can be networked when the lamps are being changed over to efficient LEDs. The gateways are open for many different LEDs. As the technology advances, integration is guaranteed. The same applies to sensor technology and data networks. The solution is flexible and smart. And it delivers statistics and data which, with the help of big data analyses, can offer a new basis for city and traffic planners. Consequently, as more and more smart street lamps are rolled out, the city structures will become smarter and more efficient.

A few miles away, a team at the Berlin-based Fraunhofer Heinrich Hertz Institute for Photonic Networks and Systems led by Dr. Anagnostis Paraskevopoulos is working on a technology in which the LEDs grow directly together with information technology: Visible Light Communication. Or also high-speed Internet from a lamp. LEDs act as transmitters, while photo diodes receive data that is transferred optically. To do this, a modulator switches the LEDs light and dark at very fast speed. The human eye does not detect any flickering. And, according to findings to date, the LEDs also do not suffer, as the modulator changes their output by just a few percent. However, Paraskevopoulos says that long-term trials are still needed.

Broadband Internet via LED and photo diode

Research results to date are very impressive: data rates of 1 Gbit/s are feasible—for each light color. In other words, 3 Gbit/s are possible with conventional LEDs, which combine red, green and blue. The first pilot projects have recently been launched in conference centers and schools. The charm of data transfer via LED is that data can be received only in the light cone. In other words, access is spatially restricted and cannot be manipulated. Visible Light Communication also does not cause any radio interference, which is important in airplanes and hospitals. The Berlin-based scientists see many other use cases: Digital networking of machinery in Industry 4.0, local Internet access in trade center halls, or car-to-X communication are just a few of the applications Paraskevopoulos mentions. But there is one small problem. Smartphones and laptops have to be equipped with photo diodes to get Internet access from the ceiling lamp. But this does not put the scientist off. “The first cell phones and laptops didn't have cameras—back then you needed an external device. When people realize the potential of Visible Light Communication, photo diodes can be integrated in the future,” he believes.