First Public White-Space Network Is Alive

An anonymous reader writes "The first public white space network officially launched on Wednesday in Claudville, Virginia. It uses sensing technology from Spectrum Bridge with software and Web cams supplied by Microsoft and PCs from by Dell. The project was funded the TDF Foundation. White space networks use unlicensed television spectrum and have been called 'WiFi on steroids.' They offer more bandwidth, over larger areas, than does WiFi. IT companies duked it out with broadcasters for years to get white spaces approved by the FCC. They finally got the FCC's nod in November, 2008."

Comments

As a broadcast engineer...

[jjoelc]

while I am personally glad this finally went through... I can vouch for the potential issues this can cause with existing broadcasts. ATSC is so sensitive to multi-path as it is... (and other forms of interference to boot, but I digress) Throwing out a bunch of unlicensed transmitters, borrowing the space between TV stations is a very scary proposition.

Re:Is this statement misleading?

[spottedkangaroo]

It really doesn't matter what frequency when you're talking bandwidth. When you're talking size of the antenna or signal loss the wavelength might matter, but not for bandwidth. The reason you get more bandwidth here is because the spectrum is wider. The ISM spectrum is very very narrow and low power channels all bunched up around 2.4Ghz. With the new white spaces, they can use tons more and much louder. But, yes, they need longer antennas.

As far as the range? You can make a microwave signal go light years and a HAM signal go a few feet (although, there will be some distortion for transmitting a signal over a distance shorter than the wavelength). The range is more of a function of signal power.

It's Obvious Where This is Heading

[segedunum]

Interested parties (whose businesses rely and will expand with cheap or free bandwidth) are angling to use it as a means to get around current mobile operators, and it can't come a moment too soon in many ways as far as I'm concerned. However, I can only see this being a recipe for disaster given the state of many wireless devices and all their broken firmware updates today if it's accurate:

Devices must both consult an FCC-mandated database to determine which channels are available for use at a given location, and must also monitor the spectrum locally once every minute to confirm that no legacy wireless microphones, video assist devices or other emitters are present.

Re:Is this statement misleading?

[slifox]

I think the OP was referring to data transfer bandwidth (the throughput, or data rate), rather than the traditional electronics use of "bandwidth" (referring to the width of the transmitted signal in the frequency spectrum; though "channel width" is a more exact term).

Of course higher carrier frequencies don't have a higher bandwidth, because bandwidth is a property of the whole system, including the data signal and modulation method. You can make the bandwidth as big or small as your system's constraints allow (e.g. one constraint might be to keep most of your transmitted power inside the allocated bandwidth).

If your data signal is modulated in the exact same manner regardless of the carrier, varying the frequency of the carrier will not affect the transmitted signal's bandwidth. The carrier frequency imposes the upper limit on the data signal's frequency, and thus a higher carrier frequency will theoretically allow for a high data rate.

Practically, however, the data signal is almost always much smaller than the carrier signal, and the transmitted frequency is subject to many other important factors such as noise, signal propagation through the environment, etc... In the case of 2.4GHz vs. 800MHz carrier frequencies, there is no practical gain in potential data rate.

This is all based on my limited understanding of communication theory. Please correct me and/or provide further details if possible!

I don't think that word means what you think it...

[owlnation]

"First Public White-Space Network Is Alive"

I think you mean "live". If it's "alive" we have some real problems ahead of us.

Re:Good thing

[FooAtWFU]

The last Nobel Prize in economics was basically saying, "Hey, a lot of important 'commons' have a small set of people who use them in repeated interactions, and so you can use game theory principles to describe how these people self-regulate the use of the commons. Oh, and therefore the government getting in on the action is less important than it might otherwise be."

It would be interesting to see whether the use of this spectrum white space "commons" will be effective.