An LED wireless (light emitting diode) system is similar to a microwave wireless system except that the information is carried on optical or infrared rather than a microwave carrier. LED wireless systems generally have higher capacities, smaller antennas and smaller beam widths. They are also referred to as Free Space Optical (FSO) or Infrared (IR) communications systems. LED wireless transmitters use light-emitting diodes (LEDs) or Lasers.

The systems are designed to work in the infrared region of the electromagnetic spectrum, a region invisible to the eye. The operating wavelength is typically in the region of 850 Nm corresponding to a frequency of 350 THz, 4 to 5 orders of magnitude greater than that used for microwave links.

There is no hard upper limit and terrestrial links have been demonstrated over 25 miles. However, the range is closely related to the visibility. LED wireless is best suited to locations with little or no fog. The WaveBridge systems are designed with margins up to 23 dB against poor visibility over a 1 km range. The margin should be reduced by 6 dB for each doubling of this range and by 0,5 dB per kilometre (or 0,8 dB per mile). Some WaveBridge products reach 9 miles (14 km) in clear conditions.

There is no hard upper limit and terrestrial links have been demonstrated up to 160 Gb/s. The WaveBridge product range includes major telecom and datacom rates from 1,544 Mb/s (T1) to 155Mb/s Open Channel. Some of the datacom products are supplemented with T1/E1 telecom side channels.

On bright days, a sunlit background will result in a reduction of margin. The range is normally set with more than sufficient margin to allow for this and there will be no impact on performance. Links deployed on an east-west axis may suffer a short outage when the sun passes directly into the field of view of a receiver during sunrise or sunset.

A large bird could momentarily disable the link if it flew through the middle of the beam. In datacom applications, this would result in a brief delay while the packet is resent. In a telecom application, there would be a very short break, but the impact would be much less than that of the other impairments commonly experienced on cellular phones. Large flocks of birds could present a more serious problem and deployment planning should bear this in mind.

LED wireless systems are more secure than microwave and RF wireless systems. This is because the optical beams are very well confined, usually to within half a degree of spread or less. As the beams are generally also high up in the air, any attempt at interception is necessarily very obvious and also risks partially blocking transmission raising the attention of the system manager.

Please read our security whitepaper for more information.

Yes, provided that there is a line of sight to the other end of the link. Note, however, that windows with solar heat-reflecting coatings may prevent efficient transmission of LED wireless signals.

Unlike radio and microwave signals, optical signals do not penetrate and dissipate in body tissue raising long-term health issues. However, they can enter the eyes. WaveBridge systems using LEDs are rated Class 1 (eye-safe under all conditions) under IEC 60825-1. Systems using lasers can be hazardous to the eye retina unless the wavelength is greater than 1 400 Nm.

Buildings twist and bend under gusty conditions and the orientation of rooftop LED wireless terminals may swing through changes of a degree or more. LED wireless systems with narrow (less than 1 degree) beam spreads will then momentarily lose the signal unless they are equipped with tracking. WaveBridge products are highly resistant to this problem as they include staring systems with wide beam widths.

LED wireless systems are designed to have margins to accommodate path losses due to rain, snow and fog. However, thick fog may incur sufficient losses to use up the margins. LED wireless is not recommended for use in regions subject to frequently recurring thick fog unless the link length is small. As a guide, LED wireless systems normally operate to a little beyond the visibility range.

No! With suitable design, LED-based systems can operate to long or short ranges and offer advantages of reliability, safety, and low susceptibility to scintillation and selective absorption impairments.

The tight confinement of LED wireless beams makes it possible for many systems to be co-located without interfering with each other. This is a major advantage over microwave systems.

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Plaintree offers two types of mounts. A wall mount meant for installing the units on walls or towers or any other vertical structure, and a roof mount meant for installing the units on roofs or any other horizontal structure.