The Truth About 2.4 GHz Radios

Reader describes, in detail, the role of Part 15 wireless devices as defined by the government, and says that cooperation between ISPs and amateur radio operators is necessary.

[Response to Hams Are Your Friends from November 9, 2001.]

[December 21, 2001]

Dear Editors:

I was most interested in your article in the Fixed Wireless Business section entitled "Hams Are Your Friends" and appreciate the premise of the article. However, the members of the ISP-Wireless list held some rather substantial misconceptions about the status of Amateur Radio allocations and the use of them by unlicensed RF devices such as wireless LANs and other Part 15 Devices. I have served as the General Counsel for ARRL, the National Association for Amateur Radio for more than 20 years, and practice communications law exclusively.

A concern in your article is that high-powered Amateur transmitters might preclude the operation of Part 15 wireless internet access devices, especially in the 2.4 GHz band. A recurring theme was that, while this could happen in some instances, Amateurs are precluded from causing "intentional interference" and that they could be precluded from operating if interference to these Part 15 devices occurs. Not so.

Part 15 unlicensed devices operate without any spectrum allocation at all. They can continue to operate in bands used by licensed radio services (1) only as long as they do not cause harmful interference to licensed services, and (2) provided that they accept any and all interference received from licensed radio services. FCC rules are very clear on this subject. It wouldn't matter whether or not a licensee in, for example, the Amateur Radio Service knows that a wireless LAN is receiving interference at 2.4 GHz; the Part 15 user operates devices in that band on an "at sufferance" basis.

Why the distinction? Only this: the Communications Act of 1934 requires that all radio communications be done pursuant to a license from the FCC. Part 15 devices are allowed to operate without licenses because their potential to cause interference is extremely low (in theory; in practice, the FCC has pushed the concept to, if not beyond, the breaking point) and because they are not protected from interference. The big benefit is for the manufacturer and the user, who can sell and use products that don't have to be licensed. Avoiding licensing is a big benefit to users, but it comes with the price tag of the complete absence of protection from interference and the absolute obligation not to cause any.

The thrust of your article, that cooperation between Amateur Radio operators and users of Part 15 devices is key to coexistence, is correct. Amateur Radio operators are generally willing to cooperate in addressing interference situations and happy to help if asked. But the Part 15 device user is not entitled to any interference protection, and must protect all licensed services against interference. It is good for all parties to know how the playing field looks before the game starts.

Regards,
Chris Imlay
General Counsel
ARRL, the National Association for Amateur Radio
5101 Wisconsin Avenue, N.W., Suite 307
Washington, D.C. 20016
202.686.9600 telephone
202.686.7797 facsimile