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Wireless WAN FAQs

Radio Frequency (RF)

What happens when I get heavy fog or rain?

Nothing, adverse weather conditions do not affect radio frequencies below 11GHz.

What happens when a bird flies through my line-of-sight link?

Nothing, radio communications rely on a path know as the fresnel zone. This can be described a virtual balloon and as long as 60% of this "balloon" is visible at either end, then the link will not be affected.

I have a link that seems to perform better in the autumn and winter months than in spring or summer?

This is something that should have been outlined at the time of survey by your supplier. It is more than likely that there are trees in the link path. During the colder times of year there will not be any leaves on the trees, but in spring/summer performance will deteriorate due to the leaves growing and absorbing some if not all of the radio frequency signal. This can be worse on a rainy day when the leaves are wet.

I work in a rented building and the landlord will not permit us to mount to the outside structure. Can I still have a Radio Frequency link?

Yes, windows will attenuate radio frequency signals very slightly but a good signal level / data rate can still be achieved. However, tinting in the glass or security wire that is sometimes in windows can mean higher levels of radio frequency attenuation.

I want a building to building link, leased lines are far too expensive but security is of the utmost importance and I do not trust radio frequency wireless?

The RF technology we use for wireless WAN links is part 802.11 standard and part proprietary. This means that the only way you could talk to one of the units is with another unit from the same manufacturer. They incorporate proprietary data scrambling techniques with its advanced air interface preventing decoding. They also use the most secure encryption technique available, which is Advanced Encryption Security (AES). AES has no known weak spots/keys and to this day has never been cracked, so reliable in fact, that it is used by the American military. On top of this, standard network solutions such as secure tunneling and VPNs are supported. We can provide full white papers to further ease security concerns.

Free Space Optics (FSO)

What happens when a bird flies through my link?

Ethernet will deal with this as if the medium is busy, ie. Hold off for random period of time then retransmit. Packet buffering by the switches at either end of the link will also help over come problems. The break in the beam will literally be a matter of micro seconds, however some switches may see the break as it would if the cable had been unplugged, resulting in the switch shutting the port down and causing a longer outage. This can be over come with simple commands reducing the port sensitivity levels.

What happens in heavy fog or rain?

A good rule of thumb is, if you can see 10% of your link, the link will work. For the occasion when there is very heavy fog, we would recommend a radio back up link that is not susceptible to bad weather.

I work in a listed building, and it is not possible to mount to the outside walls, can I still have a link?

Yes. The Free Space Optics heads can be mounted internally and pointed through the window. The grade of your glass will be obtained to ensure there is no tinting that may absorb or distort laser beam.

I want a building to building link, leased lines are far too expensive but security is of the utmost importance and am worried a Free Space Optics link can be easily tapped into.

Apart from laser power standards, there are no standards that FSO manufacturers have to follow. So, wavelengths and beam divergence differs from one manufacturer to another. This means that to receive and decode a laser signal, it is likely a head from the same manufacturer would be required.

Our narrow beam Free Space Optics systems have a beam diameter typically of only a few meters in diameter at the target location. This is another reason why it is extremely difficult to intercept the communication path of an FSO system. The intruder would need to know the exact origination or target location of the (invisible) infrared beam and be able to intercept the beam within the very narrow angle of beam propagation. Even more difficult, the intruder must have free and undisturbed access to the installation location of the Free Space Optics transceiver and be able to install electronic equipment without being observed.

The direct interception of a Free Space Optics beam between the two remote networking locations is practically impossible because the beam typically passes through the air at an elevation well above ground level. Due to the fact that the transmission beam is invisible and that any attempts to block the beam would occur near the FSO equipment terminus points, the transmission process imposes another obstacle. We can provide full white papers to further ease security concerns.