Technology Comparison
Millimeter wave technology provides the highest availability and longest distance of existing gigabit wireless technologies.
Free Space Optics (FSO) has a number of issues that affect performance most notably fog, but also rain. Accordingly, FSO cannot guarantee better than 99.9% availability at distances greater than a few hundred meters. FSO is also affected by birds flying or leaves falling through beams and atmospheric effects called scintillations. For these reasons, many FSO companies have formed or are seeking alliances with millimeter wave wireless companies to develop higher-availability alternatives to FSO alone.
Communication links based upon 60GHz millimeter wave technologies are limited to ranges of less than 1 km (0.6 miles) due to oxygen absorption associated with this spectrum. This spectrum is license-free, requiring no approval from the FCC for deployment. This could ultimately pose a problem for customers, especially in densely populated metropolitan areas, because of the potential for interference.
Microwave communication links are limited in speed and there is no equipment available today that will provide Gigabit speeds. There are options to combine multiple microwave links to achieve Gigabit speeds but this is generally very expensive.
The table below shows a comparison between different technologies.
|
Loea |
Free Space |
Microwave |
60 GHz |
Fiber Cable Buried |
99.999% at 1 km (0.6 mi) |
Yes |
No |
Yes |
No |
Yes |
99.9% at 3 km (1.8mi) |
Yes |
No |
Yes |
No |
Yes |
Installation time |
4-8 hours |
4-8 hours |
Days |
4-8 hours |
Several Months |
$ per duplex Gbps per km |
Low |
Low |
Moderate |
Low |
High |
Regulatory Protection |
Yes |
No |
Sometimes |
No |
Yes |
Link Availability |
|||||
Fog |
Yes |
No |
Yes |
Yes |
Yes |
Snow/Hail |
Yes |
No |
Yes |
Yes |
Yes |
Rain* |
Yes |
Yes |
Yes |
Yes |
Yes |
Oxygen |
Yes |
Yes |
Yes |
No |
Yes |
Back Hoe/Disaster |
Yes |
Yes |
Yes |
Yes |
No |
Dust/Smoke |
Yes |
No |
Yes |
Yes |
Yes |
Small Occlusions |
Yes |
No |
Yes |
Yes |
Yes |
