What does the term "fixed" mean on the radio spectrum?

Question

On the United States Radio frequency allocation chart, the term "fixed" radio comes up a lot. What does that mean? Who is allowed to used "fixed"?

Answer 1

Generally we distinguish two types of stations:

• Mobile, when the device is portable
• Fixed, when the device stays on one location

See Amateur Radio Stations for more information:

_{(left: fixed; right: mobile)}

Answer 2

Fixed wireless is normally used as a term for radio communications between fixed locations such as buildings that don't move as opposed to mobile communications. One reason the allocations are treated differently is that for a fixed location it's often possible to allocate the same frequency to different regions.

For example for a given installation it may be determined for a specific frequency / power range that interference is only likely within a 10km radius, giving the possibility that the same frequency may be used hundreds of times by different users within a country as long as they are geographically far enough apart. That assumption of course can't be made for mobile communications systems that move around.

License costs are normally a combination of power and bandwidth and how far the signals are likely to emanate and also population density. I can only only speak from an Australian perspective but I believe here anyone is allowed to use fixed frequencies if you pay the license fee and it is approved. That may range from hundreds of dollars per year for a narrowband low-power license (for example courier voice communications over a limited area) and into millions for the sort of allocation you'd need for TV broadcasting over a large area.

Answer 3

http://www.ntia.doc.gov/files/ntia/publications/2003-allochrt.pdf ? (That is one ugly chart.)

Opposite of "mobile": the transmitter is at a fixed location. Why are there different rules for fixed and mobile? Because an interference problem caused by a mobile transmitter is a lot harder to track down.