Communicating LED lamps

LEDs are used for a long time for all kinds of data communications applications ranging from wireless IR remote controls and IrDA to wired fiber optics communication. There has been many years ago also ideas on optical wireless LANs based on infrared, but they faded quickly. But now when LED lights are becoming very popular this idea could see a second coming.

Ceiling lights in Minn. send coded Internet data article tells about LED lights that will transmit data to specially equipped computers on desks below by flickering faster than the eye can see. The first few light fixtures built by LVX System will be installed in six municipal buildings in the central Minnesota. The LVX system puts clusters of its light-emitting diodes in a standard-sized light fixture. The LEDs transmit coded messages A light on the modem talks back to the fixture overhead, where there is sensor to receive the return signal and transmit the data over the Internet. It works in almost exactly the same way that fiber optic systems do, except the sender and receiver aren’t connected by a cable. Communicating lights are set up using just ordinary power connections. The first generation of the LVX system will transmit data at speeds of about 3 megabits per second. If you are interested check video from Get ElectricTV.

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There is another application that also combines wireless communications and LED lights. Finnish article Wlan ohjaa yksittäisiä led-loisteputkia (read English translation) tells about LED light tubes can be controlled by a WLAN connection, even individually. Finnish company Valtavalo has licensed Netled control technology from Yashima Dengyo Co., Ltd. and sells their products. Netled technology is designed to provide means to monitor in electricity consumption in real time and control the various LED light tube groups.

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  1. Tomi Engdahl says:

    Lab-Based “Li-Fi” Link Exceeds 7 Gb/s Using Blue Micro LED
    https://www.electronicdesign.com/industrial-automation/article/21142473/labbased-lifi-link-exceeds-7-gbs-using-blue-micro-led

    Taking advantage of a blue GaN micro LED, researchers succeeded in operating a free-space optical link at over 7 Gb/s, possibly functioning as a precursor of a super-speed LiFi type link.

    As an optically based complement to RF-based Wi-Fi, Li-Fi (light fidelity) offers distinct attributes including potentially extremely high throughout over limited distances and immunity from (and non-sourcing of) EMI/RFI. One other characteristic of an optical link can be considered either a benefit or a drawback: Its line-of-sight path provides outstanding immunity to eavesdropping and hacking, but also limits user mobility.

    Adoption of Li-Fi in the marketplace has been very limited thus far. However, there’s an industry association that provides standards and support, and there’s the potential for using a single LED bulb/photoreceptor unit as both light source and Li-Fi node (see Resources below).

    Researchers, of course, see pushing the envelope of optical-based data links as an area of great interest. A team at Leti (a research institute of CEA Tech, Grenoble, France) has achieved a visible light communication (VLC) test-bed transmission at 7.7 Gb/s (significantly exceeding the previous 5.1-Gb/s record) using a single, 10-µm diameter, gallium-nitride (GaN) blue micro LED (Fig. 1). (In general, a smaller emissive area of the LED yields a higher bandwidth—here, 1.8 GHz in the institute’s single-blue micro LED project.)

    In addition to the micro LED, the team also developed an advanced multi-carrier modulation scheme combined with digital signal processing to achieve their results. This high spectrum-efficiency waveform was transmitted by the single LED, received on a high-speed photodetector, and demodulated using a direct sampling oscilloscope

    While the Light Communications Alliance (created in 2019) is intended to encourage the industry to implement standardization and promote interoperability between LiFi systems from different manufacturers, CEA-Leti is planning to continue its research in two areas:

    Developing a better understanding of the electrical behavior of single LEDs in high-frequency regimes and the link between bandwidth and electromigration patterns.
    Investigating techniques to improve the range and/or increase the data rate using a matrix of multi-LED emissive devices. This requires adapting the waveform generation as well as a CMOS interposer to drive the matrix on a pixel basis.

    Lab-Based “Li-Fi” Link Exceeds 7 Gb/s Using Blue Micro LED
    Taking advantage of a blue GaN micro LED, researchers succeeded in operating a free-space optical link at over 7 Gb/s, possibly functioning as a precursor of a super-speed Li-Fi type link.
    https://www.mwrf.com/technologies/systems/article/21142476/labbased-lifi-link-exceeds-7-gbs-using-blue-micro-led

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