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TV White Space & The Future of Wireless Broadband
DeviceGuru writes "The unoccupied radio spectrum between broadcast TV channels may soon become a source of low-cost, ubiquitous broadband connectivity. Earlier this month, the U.S. Federal Communications Commission began Phase II testing of 'white space device' prototypes, to determine whether WSDs can operate without interfering with the other wireless devices commonly used in homes, offices, and public locations. A key advantage of white space wireless technology, compared to the combination of WiFI and WiMAX, is its TV-like ability to cover broad areas and penetrate walls and trees, using relatively low power levels."
Will I be able to play Duke Nukem forever over the TV spectrum?
I smoked pot once. But I DID NOT inhale. Will you hire me?
I can hear it now:
Broadcast TV: Senator, this new scheme causes huge interference with our broadcast signal
Senator: This wouldn't have anything to do with Time Warner giving you the broadcast rights to a bunch of their movies and TV shows for a song, would it?
Broadcast TV: Don't be silly. We can answer any other questions you may have at the campaign fundraiser we're holding for you tonight.
Senator: I think I'm beginning to appreciate your point of view.
-Eric
SJW: Someone who has run out of real oppression, and has to fake it.
While we in rural communities who are not served by broadband, can be skipped by another technology. Yeah, TV transmitters will give internet. Too bad there's no TV transmitters around here.
I have no broadband choices (I connect at 26.4kbps) but at least I get 0 over-the-air-channels. All right! Problem solved.
... these tests are open to the public. Why not go and watch?
The problem with this idea is that it assumes that TV broadcasting will always be done the way it is today with unused space between the channels. If "white space" equipment gets deployed it is going to create a massive problem for any attempts to change use of the existing TV spectrum. Any future users of this spectrum are going to have to work around the applications now running in what used to be the "white space".
Surely it's black if there's nothing there? Doesn't "white" mean filled with all kinds of frequencies, as in white noise? I suppose if you think of the spectrum as a sheet of paper...
ccalam - acoustic versions of new songs.
I think this is a bad idea. If we start transmitting data in whitespace, words will become very difficult to distinguish from each other in any given sentence. For example "The quick red fox jumped over the brown lazy dog." by itself, is very readable. But once you transmit extra data in the whitespace it becomes: "The1quick0red1fox0jumped1over0the0brown1lazy0dog." - An invariable piece of shit. It's only a matter of time before the greedy providers decide they need more bandwidth and bleed over in to the primary data stream.
Now if we were to transmit in the margins or between the lines, that may just work!
Are they planning to have repeaters all over the place like the public wifi? If not they are going to need a lot of power. Some UHF TV stations run with a megawatt of RF. Its especially true in cities where the buildings create multipath distortion and/or block the signals entirely.
So with these wavelengths that can travel through walls much more easily, my internet will go down due to interference from my neighbor's automated channel search on his off-brand Korean knock-off TV?
I wonder though if this sort of technology could allow your wireless internet card to double as a wireless tv card. The same modem would take the cable data and broadcast the entire band and your computer would just sort out the data on it's end.
Maybe we could find a way to create a p2p wireless internet this way. Get rid of ISPs and make the internet free again like it should be.
There is a whole lot of unused network bandwidth on our personal computers and I know that there are enough neighbors around me that it would be like a bit torrent model of a decentralized internet.
TV, unlike the internet, is a one-way medium. My TV may be able to pick up signals from a giant transmitter thirty miles away, and that's great. How would this work for internet connections? Something tells me that putting an antenna powerful enough to reach back to that tower inside my laptop isn't going to be too friendly with my battery life, let alone my non-shielded nuts.
How are sites slashdotted when nobody reads TFAs?
Isn't there just as much bandwidth between 3Ghz and 4Ghz as there is between 0Ghz and 1Ghz? Why do we carve out larger chunks at higher frequencies? It seems to me that the real answer is finer-grained transmitters and receivers.
Iraq billions
The problem with opening this for personal devices is that we will create another 2.4 GHz mess. 2.4 GHz has become nearly useless in many areas for delivering Internet to people's homes because of the background noise created by home wireless routers, wireless phones, etc. We've been a wireless ISP for 7 years now and seen 2.4 GHz drop in the toilet sinking further every year to the point where it is time to flush. Lets not do this again.
I'm hoping, like 900 MHz the equipment will be too expensive to use for consumer devices.
It's been asked at least 3 times in comments on this article yet still no one seems to know the answer to how uploading will work?
anyone?!
I have no broadband choices (I connect at 26.4kbps) but at least I get 0 over-the-air-channels. All right! Problem solved.
:) But just because you don't get TV (which is very wide bandwidth, analog video and voice) doesn't mean you won't get a digital internet connection.
Just because you don't get TV channels DOES NOT mean this won't work for you. It depends on bandwidth and encoding.
For example, in amateur radio, when voice communications are insufficient, Morse code (much narrower badwidth) tends to work over great distances, and when Morse doesn't work a digital mode like PSK31 (narrower) works even better, and often at lower powers.
It will really come down to the bandwidth and power output, it always does
Here's my question. If the spectrum can be used for Internet connectivity, why bother with having the TV over-the-air channels at all?
I used to work for NetQoS. I no longer do, but want to keep the excellent karma attached to this account.
I am an amateur radio operator and can attest to how easy working with VHF/UHF is on a small scale level. A 100watt VHF "repeater" on a tall hill can usually be reached 20-30 miles away with a 5 watt handheld radio and line-of-sight, and much less power for towers closer. Multipath is a problem, like anything else. Nonetheless, if the towers are properly placed so that line-of-sight is maximized (i.e. they do their homework), I have no doubt you would be able to work it with a PCMCIA laptop card and a small antenna off of it. Of course the wider the bandwidth signal the more power needed, however VHF is magnitudes better for long distance than 2.4GHz.
We have come full circle.
I remember, back when I was a youth, and TV was just over the air, the Sunday afternoon ritual of standing outside with my father during football season, making adjustments to an ever complicated contraption of antenna.
All manners of materials and shapes were experimented on, and my mother would yell, "better", "worse", or, "oh my god", depending on just how our adjustments altered the picture.
Now, my son and I will be standing outside, in the not too distant future, adjusting the antenna as my wife stands by some sort of a bandwidth meter, yelling, "better", "worse", or "oh my god".
This is my sig.
Broadcasters are avoiding channels 2 through 6 when given a choice which channels to select after the digital switchover. There will be almost no TV stations in that band in the USA after Feb 17, 2009 (and in Canada after Aug 31, 2011). That's 30 mhz of usuable frequency space (not counting the 4-mhz gap between channels 4 and 5).
While these frequencies may not be so great for a 6mhz wide TV channel, they're perfectly usable for digital internet. And you're guaranteed no interference with TV, because there won't be any TV stations in that spectrum.
You asked your grandparents why there isn't a channel 1... your grandchildren will be asking you why there aren't any channels 1-through-6.
I'm not repeating myself
I'm an X window user; I'm an ex-Windows user
My big concern is that some of the TV space is used for wireless microphones and monitors in theater, live sound and conferences. There's a huge amount of that hardware deployed already, much of it unable to change frequency past a relatively narrow band. Since it's low-power one can conceive the signal not always being detected by other white space hardware. With the signal being analog instead of digital, interference can really matter.
I was a little confused about the entire WSD vs 700MHz debate, so I looked this up. There's actually a chart available, I'm not sure exactly where I got it, but it is from a document called: "Unlicensed Broadband Device Technologies: "White Space Device" Operations on the TV Band and the Myth of Harmful Interference"
Anyway, here is the frequency breakdown:
Channels 2-6: 54-88Mhz
Channels 7-13: 174-216MHz
Channels 14-51: 470-698MHz
Channels 52-69: 698-806MHz
The last block, channels 52-69, are the 700MHz block that is being auctioned off for tons of moolah. The Channels 2-51, and other unoccupied spectrum, are the zones of contention for the so called White-Space Devices (WSD).
So, to answer your question, we will shortly have devices that function in these channels. 700MHz and WSD are meant to address different issues. The 700Mhz spectrum auction is being held to find out who wants to build a national network in this space. Analog TV is going off the air (I still don't know what frequency range they'll use for OTA digital). 700MHz winners will fill the gap, apparently. Keep in mind that there are a whole host of regional players competing for little chunks of the spectrum in rural and under-served areas. The regional players may address the needs of folks without broadband now. Then again, they may just go ahead and ignore the rural market and concentrate on building their networks in the most profitable places possible. There may be something like Universal service for Broadband, in the future, but don't count on it from the current Congress and FCC.
Where does that leave WSD? WSD is like Wifi. Smaller companies (Cisco, Belkin, Netgear, etc.) are building WSD that should work either on the one-router-per-home model or the wifi mesh "cloud" model. Quite possibly, the WSD could be used in a configuration which is a hybrid of those two. Some people will have customer premise equipment (CPE) some folks will pull their data from the "cloud". Here's another thing that gets me: no one complains that their cell phones or wifi cards are too weak to interface with their "uplink" whatever that uplink is. Yet, we still have this controversy over using WSD. It's a strawman. Think of WSD as a more powerful wifi, or cell phones (phones and towers) and you'll get an idea of how it will be used.
Why are we having these auctions/spectrum give-aways? The analog crowd can no longer justify exclusive control of the spectrum. In the WSD space, hardly anyone broadcasts OTA anymore, and those that do will be forced to switch to "digital" whatever that means. So, there is room here for license-free devices. We just need the go ahead from the FCC to build them. Notice here that the companies in the 700MHz race (AT&T, Verizon, Sprint, Google) are not the ones in the WSD space (Phillips, Cisco, Microsoft). Basically, anyone can build WSD, as long as it conforms to the "listen-before-talk" principle, is fairly low-power, and is able to avoid interference.
What advantage do these things bring? Finally, we are able to do Wifi right. The problem with wireless communication at 2.4Ghz, is that ranges are horrible. Also, there is so much interference from competing technologies that signal is usually drowned out in noise. With WSD, the ranges can become a lot longer. This introduces the problem of multiple devices communicating all at once to a central hub or router, but given enough "eyeballs on the problem" I believe that this problem, when it comes up, will be surmountable.
I am very optimistic about the viability of this technology. Then again, I think that people are basically good, and look where that belief has gotten me. Well, here's hoping that the 700Mhz auction isn't hijacked by a bunch of scoundrels and that WSD isn't sabotaged by the broadcasters who are so greedy that they won't give up their largely unused spectrum.
It would be nice if amateur radio could get a tiny bit of the T.V. spectrum added on to the 6 meter band.
I read Slashdot for the headlines, because the headlines, unlike the articles, are usually original and never duplicated
PSK31 uses 31hz of bandwidth.
:)
... and in reality could be much higher, or possibly a bit lower.
The formula for CW bandwidth is the bits per second (BPS) times a shape factor, K. CW speed is generally in words per minute, the word "PARIS" is the general word benchmark, 5 letters with 50 bits of information. 50/60 = 0.83 bits/second.
With a shape factor K=4, at 10 WPM (relatively slow), the signal width is about 40hz, wider than PSK31. At 25wpm (what I personally find comfortable) it's about 100hz. More experienced practitioners can speak even faster
The shape factor is a function of the wave modulating the carrier
(this information can be found a number of places, including here)
Mobile phones manage to transmit back to their towers despite being small, low-power devices. The key: the base station's receivers are very sensitive and the coding schemes used for uplink transmission include more error detection/correction.
Granted, mobile phones don't work over the vast distances used by broadcast radio and television, but they serve as a good example of a low-power, two-way transmission system.
OTA digital is in the same spectrum as analogue TV. Difference is, no one is using VHF any more and licenses for the high UHF channels are not being issued (63-69, I believe), which frees them up for the 700MHz auction
http://www.hdtvprimer.com/
I'm wondering what will become of the VHF spectrum (2-13).
I did not realize that a future service would come along to obsolete my house! NOW I have to move out?!?
I'm guessing if a dirty bomb goes off in your city and your house is made unlivable, you wouldn't just kick back and say "Well, it serves me right for choosing to live here." But believe me, I'll be thinking it.
Running fibre in a subdivision where you have a house every 100 or 200 feet is one thing. Subsidizing fibre to every farmhouse, log cabin, and cottage would bankrupt the USA or Canada. Please don't compare the wide open spaces of North America with densely populated cites, or the even more densely populated cities of Europe and Asia.
I'm not repeating myself
I'm an X window user; I'm an ex-Windows user
You get to pick two.
I am very small, utmostly microscopic.
The truth is that there is no effective limit to the bandwidth available other than the limits we arbitrarily decide. There are an infinite number of frequencies between 1 Khz and 2 Khz. On a given frequency, the amount of information that can be transferred increases with the frequency, so while there's an infinite number of frequencies between any point and any other, the amount of data that can be transferred on a given frequency rises as the frequency increases.
.5 Ghz, average of 1...2 is 1.5 Ghz, given 3x the bandwidth, X infinity.
So, assuming that all the bandwidth between 0 and 1 Ghz is Inifinity, the bandwidth between 1 and 2 Ghz is about 3x of the Infinity represented between 0 and 1. (Average of 0...1 is
Practically, the limit is purely technical - how tight can frequency separation get with our current technologies?
I have no problem with your religion until you decide it's reason to deprive others of the truth.