Slashdot Mirror
FCC Considers Expanding Unlicensed Spectrum
Syntari writes "Reuters is reporting that the US Federal Communications Commission has begun to seek comment (the first step in promulgating regulations) "on whether unlicensed devices, like wireless home networks for Internet service, could operate on television broadcast airwaves in areas where they are not being used or at times when the spectrum lay fallow". The news release by the FCC itself, in MS-Word format, is online.
This is pretty big, as these things go - especially since television spectrum, being of a wavelength that easily penetrates walls and is not overly affected by rain or snow, is ideal for wireless services. Should any slashdotter actually want to submit a comment (gasp! could it be?), read this first (FCC's rules on electronic comment submission), and then go here."
more on this topic here: http://www.fcc.gov/Speeches/Abernathy/2002/spkqa21 8.pdf
FCC BEGINS INQUIRY REGARDING ADDITIONAL
SPECTRUM FOR UNLICENSED DEVICES
As part of the ongoing effort to promote efficient use of spectrum, the FCC today asked for public comment on the possibility of permitting unlicensed transmitters to operate in additional frequency bands. Such changes could allow the development of new and innovative types of unlicensed devices. This inquiry examines new and creative ways to utilize the spectrum resource more efficiently by considering new spectral frontiers for unlicensed use.
In a Notice of Inquiry approved today, the Commission stated that the current rules for unlicensed transmitters have been a tremendous success. A wide variety of devices have been developed and introduced under those rules for consumer and business use, including cordless telephones, home security systems, electronic toys, anti-pilfering and inventory control systems, and computer wireless local area networks. The success of those rules shows that there could be significant benefits to the economy, businesses and consumers in making additional spectrum available for unlicensed transmitters. Unlicensed transmitters may be operated under the provisions of Part 15 of the Commission's Rules. Part 15 transmitters generally operate on frequencies shared with authorized services at relatively low power, levels and must operate on a non-interference basis.
The Notice seeks comments on whether unlicensed operations should be permitted in additional frequency bands. Specifically, it seeks comments on the feasibility of allowing unlicensed devices to operate in the TV broadcast spectrum and locations and times when spectrum is not being used. It also seeks comment on the feasibility of permitting unlicensed devices to operate in other bands, such as the 3650-3700 MHz band, at power levels higher than other unlicensed transmitters with only the minimal technical requirements necessary to prevent interference to licensed services.
The Commission noted that there have been significant advances in technology that may make it feasible to design new types of unlicensed devices that are able to share spectrum in the TV bands without causing interference to licensed services operating in those bands. Advances in computer technology make it possible to design equipment that could monitor the spectrum to detect frequencies already in use and ensure that transmissions only occur on open frequencies. The low cost of GPS equipment could allow a device to determine its location and use information from a database to determine whether there are any licensed operations in its vicinity. Equipment can be designed that is frequency agile, with the capability of changing frequency as needed to avoid interference to licensed users.
Action by the Commission December 11, 2002 by Notice of Inquiry (FCC 02-328). Chairman Powell, Commissioners Abernathy and Copps, with Commissioner Martin approving in part and dissenting in part, Commissioner Adelstein not participating and Chairman Powell, Commissioners Abernathy, Copps and Martin issuing separate statements.
OET Docket No. 02-380
- FCC -
Office of Engineering & Technology Contact: Hugh L. Van Tuyl (202) 418-7506
Good point but I think this enables wireless to take a necessary step forward. Using the T.V. part of spectrum will allow transmissions through media that would previously have blocked the signal and they will no longer suffer from being a highly directional signal.
?-|||-----x<*))))><
If they open up these frequencies now, doesn't this mean that these areas are never going to get tv signals over the air ?
No, the advent of DTV [2] assures that this will happen. The FCC, NAB, and networks seem to be pushing DTV on us - a lot of people I know don't want it (it means being forced to buy new TV sets, digital-rights management, etc). But the FCC's clear on the matter; we're going to have DTV (eventually[2]) - DTV uses a different set of frequencies so within a relatively short amount of time, all the standard television frequencies we use now will become quiet and unused.
And, if these frequencies aren't being used now, doesn't this imply that the utility of e.g. wireless is somewhat diminished in these areas, if only because it seems likely that there aren't that many people there ??
That depends on what type of wireless system this is talking about - and I just don't know. Short range, say; between houses or you and your neighbors house, no problem. Long range - sure, your comment has merit to some extent, but remember that most TV frequencies are taken up. This is due to interference, signal propagation, and other things that prevent two tv stations on adjacent channels from being anywhere near each other. The same problem would plague high-powered/long-range wireless services.
footnotes:
[1] - DTV includes such services as HDTV
[2] - the date's been pushed back from (i think) 2004 to 2007, and probably will be pushed back again.
"The low cost of GPS equipment could allow a device to determine its location and use information from a database to determine whether there are any licensed operations in its vicinity. Equipment can be designed that is frequency agile, with the capability of changing frequency as needed to avoid interference to licensed users."
This means the devices will include the additional expense of a GPS chip and some way to contact the database to check if the location is safe for the frequency it wants, but this is certainly affordable. Heck, you can get a $130 phone from Sprint PCS that does all that (GPS and data network over 1xRTT). So, worst case, these devices will cost as much as a wireless NIC and a cell phone at the start. It is also possible that the database could be stored locally on the device (since TV stations don't move too often) with an expiration date, and need to be reloaded via a cable at some point or the device quits.
But cost aside, the problems you mention are addressed already in the proposal.
digital-rights management
Uh... sure... just as much as a DAT had DRM. The DTV signal has a single content control flag in it, which basically states whether or not it's recordable. To my knowledge, no content has been broadcast to date with this flag set (except by accident).
Additionally, the first D-VHS recorder that was available utterly ignored the flag. The two newer versions now available do respect the flag though. But I don't know of any PC-based DTV tuners that respect it - it would be rather difficult, since they'd have to essentially turn off the data feed entirely. That or process everything onboard and output it only to component/svideo - which they can't do.
Yes, studios, broadcasters, and the cable cos tried to get more draconian DRM into DTV. They failed. Utterly. The manufacturers told them to fuck off and now it's too late to change the standard, especially with mandated integrated tuners coming in 2004.
The concern about buying a new set is certainly valid, but it's falling on deaf ears.
the date's been pushed back from (i think) 2004 to 2007, and probably will be pushed back again.
The original date was 2006. It's been pushed back to "when 80% of the public is capable of receiving DTV" (note that this is dependant not on the public having DTV tuners, but upon broadcasters putting out signals). My best guess is 2010-2012 at this point.
If you change the last three characters of the URL to pdf, you will see the pdf version, likewise with txt. I'm not sure why the story submitter chose to link to the word version.
Every official release from the FCC is in all three formats.
-Alison
How about trying PDF or text if you don't want the word version. In this case, the story submitter messed up, not the FCC.
-Alison
Ever wonder why the US has the most powerful military (arguably) in the world? I guess it is a trade-off. I'd rather have a more functional military and less functional cell phone than the other way around (as in Europe).
It's that military that keeps me free to use my cell phone in relative security. Oh yeah, one more thing... read this statement by Col Skinner if you want to understand more aobut military spectrum requirements.
Full-Featured GPL Web Hosting Control Panel
You would think that in an age of encryption and such, those bands could all be opened up
Uh... encryption just makes sure nobody can understand you, it does no good at all if you're broadcasting from the field on a 5W handheld unit but can't be heard because Joe Schmoe is broadcasting on the same frequency using a wireless toy that outputs 500W.
Yes, the military is moving toward digital spread-spectrum, encrypted technology (mostly because it's a helluva lot harder to jam or intercept), but they'd still like clear channels thank-you-very-much.
The military has given back quite a bit of spectrum recently though, since they just don't need as much. A good bit of that is not horribly useful to the public though since it has miserable propogation properties.
and carry LESS information than 2.4Ghz the amount of information you are able to carry in a frequency channel is DIRECTLY coupled with the frequency and width of the channel you use. in the 50MHZ range where channels 2 and 3 reside you CANNOT transmit very much without using alot of the spectrum with a wide channel. I.E. you are using tons of frequencies to transmit the same information that is able to be transmitted on a few in the higher frequencies. and to do this you need Gobs more power.
Huh? The bandwidth required is not dependent on frequency. A television channel takes 6MHz no matter where you put it in the spectrum... 50MHz, 400MHz, 1.2GHz, etc.
The power required for an equivalent coverage area varies, yes, but the bandwidth required does not. If you modulate a 10MHz carrier with a television signal, you'll suck up 6MHz of space.
I think this is a common misconception because of the way the spectrum is currently laid out. The reason that high-bandwidth items are higher in frequency is simply that they were developed later in history than other uses. Therefore, they got higher frequencies because those below it were allocated and didn't provide enough available space for that particular purpose.
If you could find a 25MHz chunk of bandwidth at any frequency you could run 802.11 stuff. Your power requirements would vary, of course, and your antenna would change size (and perhaps shape).
It's not magical. we use 2.4ghz because at low powers and small channel widths we can spew lots of information... as your frequency goes down the wider you need to be and the more powerful you need to be.
That is just wrong. We use 2.4GHz because that's where the available spectrum is, not because there's something magical about 2.4GHz itself.
The only thing special about higher frequencies versus lower ones is propogation concerns (higher frequencies tend to go less distance with an equivalent power output) and antenna design.
The bandwidth required does not change.
All opinions presented here aren't mine.
I would see these networks as being used for long distance building to building networking. The size of the antenna for the "TV" wavelength would be acceptable on the roof but not for my desk. I certainly would not want an antenna that big sticking out of my laptop.
For many years, the FCC has allowed part (470-512 MHz) of the UHF television band to be used for land mobile radio services in areas where those channels are not being used by television stations. My local police department uses frequencies in this band.
Mea navis aericumbens anguillis abundat
Yes, actually, high bandwidth things do better at higher frequencies for technical reasons. It includes antenna and circuitry issues. If you put a 25MHz wide signal at 50MHz, you will need to have circuits that deal with everything from 37 to 63 MHz (and an antenna to do the same). That's almost an octave.
It is MUCH easier to deal with relatively smaller chunks of spectrum than with large ones, and at 2.4GHz, 25MHz is a relatively small chunk of spectrum. It would be hard to make a high gain antenna at 2.4GHz that didn't cover at least 25MHz, while the same thing at 50MHz isn't so easy. The same is true for filters, which would be required to exclude interference from nearby (in space and frequency) signal emitters like radio broadcasters.
That being said, I think this is an extremely bad idea. The A and B contours of typical TV broadcasters are very much smaller than the actual reception range. The places where this low-power unlicensed networking is most likely to work well (the rural, non-RF polluted areas) are also the places most likely for people to have already invested money in towers and antennas to pick up the distant stations. These people are well outside the FCC-defined B contour, and unless the networking device has a high-gain antenna on a high tower, it isn't going to see that the frequency is already in use.
The cities are already RF-polluted to the extent that this won't work very well there, and those are also the places where the FCC has already started opening unused TV frequencies for public safety use.
Another poster commented that this sudden splurge of spectrum would push innovation. Not true. It is only the shortage of spectrum in the lower frequencies that has pushed development of the gigahertz bands now appearing in consumer equipment. Had there been unlimited space at 49MHz, you'd never have seen your 2.4GHz or even 900MHz cordless phones.
Since it's been mentioned in several reply posts,
the following URL points to a web page where you
can download a somewhat detailed PDF format spectrum chart (105 kb):
http://www.ntia.doc.gov/osmhome/allochrt.htm
I don't know how up to date it is, but it still
gives you an overall picture who has the lion's
share of usage.