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Open Spectrum: Toward Ubiquitous Connectivity
obiwan2u writes "ACM's Queue magazine has a moderately dense article describing how new intelligent radios may free up under-utilized spectrum bandwidth, possibly providing solutions to the
last mile bottleneck."
If you live in the wilderness, is getting broadband really a priority?
As it is, most residential areas have telephone coverage. As the internet gets more mature, the need for broadband lessens because of improvements in packet technology and of course data compression. What was possible 5 years ago on a 56K modem doesn't even compare to what you can do with the Internet today with even a lowly 28.8. The improvements are just so vast.
So what's the big deal with broadband? So you get to view Slashdot 2 seconds faster. So you get to look at the daily news on MSNBC 2 seconds faster. So what? We are talking about lengths of time that don't even register on our awareness.
Look, people who live far away from civilization chose that lifestyle. One big reason was to get away from all this technology crap. Let those hermits live in peace. Not everyone needs or wants the latest and greatest, sometimes they just need the simple and natural.
I have been pwned because my
I believe that today under 20% of homes get TV via over the air broadcasts. And the number is dropping. The rest get satellite or cable.
It's clear that if we opened up all that broadcast spectrum to unlicenced use, it could easily generate enough revenue to provide free satellite or cable for those few homes still with an antenna.
And just think of the huge value from getting all that spectrum for new technology, largely unlicenced uses.
Of course, the National Association of Broadcasters is one of the most powerful forces in the country. They think of that spectrum as "their property" even though they are blocking much more productive use. Same with the military.
So it won't happen, but we can dream.
The FCC won't go for it. knowing Morse code is still a requirement to use HF ham bands, even though you can now use a computer to code/decode it. See www.nocode.org
I can't think of one positive the FCC has done for RF bandwidth in a long time. Why would they start with this?
One that filters out all talkback and boyband/britney clone pop.
Elminate that and you've cleared up a large chunk of the spectrum!
What is the inverse of the Matrix?
Seriously, I live only 3 miles from the DSL limit and it angers me greatly. I have a crappy 24.4 connection. This would be great if I could be able to download stuff at highspeed. A few weeks ago I had to drive into town and go to a business of a friend to download a patch for Mac OSX that was 85mb. Satellite sucks, if this could eliminate the last mile problem that would be great.
Wanting to live in a cave doesn't always mean one wants to turn his back on knowledge and information.
So what's the big deal with broadband? So you get to view Slashdot 2 seconds faster.
Apparently you live in a different kind of "wilderness." Sorry for you, but being a hermit doesn't have to mean being a luddite. Nor does choosing to live in a "green ecosystem." Modern technology presents all sorts of new opportunities - even to those who choose to separate themselves from the greater of "society." In fact, that's the best part of it.
Just like modern tuning and broadcasting equipment freed up spectrum resources for low power FM....
Tech's half the story. How the authorities see fit and/or are lobbied to allocate spectrum is the other half.
Tweet, tweet.
Xix.
"Everything is adjustable, provided you have the right tools"
Is there any GPL software, fairly widely used, that supports an open standard for voice communications? Sure, I know there are plenty of standards for VOIP, but what's being used, now? If I went to my neighbors and told them we could "unwire" the neighborhood using cheap PCs and have not only local phone service but also faster internet connectivity than we get now, half the people in this very rural "town" of 200 would pony up tomorrow.
But, so far as I know, that technology doesn't yet exist. And until it does - until "broadband" means reliable, versatile connection to your neighbors rather than just really fast porn access, you can hang pervasive broadband on a hatrack.
Well, I wouldn't say we live in the "wilderness" per se -- we're a short 15 minutes from the county seat, and lord knows Wal-Mart is just 10 miles down the road! But it sure would be nice to be able to hook into the DSL that's 3 [road] miles away.
;-)
....Bethanie....
A modem speed of 56K isn't the end of the world, but when that's all the bandwidth you have and you're both surfing at once, it can be torturous. I use the Net a LOT less since moving to the country (and away from our cable modem). Believe me -- I notice the difference!!
Another issue for us is that the max upload speed we're getting is 33K -- try e-mailing pix of the baby to parents on the left coast with THAT!! It takes *hours*.
So, just a few things to think of before "stating the obvious" about those of us who live "in the wilderness." We wanted to get away from suburban sprawl and be able to own some land and a nice house -- not abandon civilization (which is defined, of course, by the availability of high-speed Internet access!)
Open spectrum advocates can gain a lot of credibility by demonstrating techniques like SDR, cognitive radio, and mesh networking in the existing unlicensed bands. (The article mentions LocustWorld, which is a commendable example.) Once there's quantitative information on the benefit of the technology it will be appropriate to ask the FCC to reconsider the current spectrum policy.
The open spectrum concept raises its ugly head again. I suppose I shouldn't be surprised; it combines the sexiest of terms (Moore's Law! Metcalfe's Law! SDR! UWB! Spread Spectrum! Mesh Networks! Open Source!) in one neat package, tied with a bow. If only they could work in the magnetic bracelet that cures arthritis, it would be a marketer's dream.
There are other reasons for spectrum allocation besides the "technology limitations" cited in the ACM article. Two of the most significant are:
1. The spectrum is used for many different services, with differing Quality of Service (QoS) requirements. Some of these, like the Instrument Landing Systems at airports, emergency services, GPS, etc. I'd like to have dedicated spectrum available solely to them 24x7; the idea that a trapped fireman's call on his handheld 2-way radio is not heard because of interference from a nearby mesh network providing video packets of a football game (or, if you like, the trapped fireman's call on his limited-range Open Spectrum radio is not heard because the burning building's network is already down) is not very appealing.
Other services, like industrial heating (and even microwave ovens) do not even use the RF spectrum for communication at all; if not limited in spectrum these large transmitted power services can render people incommunicado over large physical areas. Open Spectrum advocates will claim that this last problem will be overcome by the processing gain of the Open Spectrum radio itself; I merely note that increasing processing gain is increasingly expensive, and getting 60 dB of processing gain is a severe pain at wideband bit rates, while it is a trivial exercise for a tuned circuit if the spectrum is allocated properly.
2. The spectrum has different physical properties that make certain frequencies (and frequency bands) more suitable for certain services. Services that require ionospheric refraction need to operate below 30 MHz; systems using satellite-earth links must operate above 30 MHz. Systems requiring a lot of antenna gain, such as space probes and terrestrial point-to-point links, need to be a high frequency (multiple GHz), where high gain can be achieved in a small physical size by the use of parabolic antennas. Systems requiring worldwide underwater coverage must be below 100 Hz. There are atmospheric attenuation peaks at 24 and 60 GHz (and others higher) caused by oxygen absorption that make these frequencies useless for any trans-atmospheric links, but ideal for short-range unlicensed systems (that's why there are ISM unlicensed bands there). Rain (a.k.a. hydrometeors) becomes a significant attenuator above 5-20 GHz, depending on the rate at which it falls; this affects systems in tropical regions more than those in more temperate areas (see a graph of atmospheric attenuation). The hydrogen line (1420.40575 MHz), used by astronomers, is a fixed frequency. Etc.--this is just a partial list. All frequencies are not created equal.
However, if you'd like to stick to technical problems, consider the multiple access problem for these systems.
The success of 802.11b is often cited as an example for the Open Spectrum initiative--an unlicensed band being used productively. However, 11b has now become the 800-lb. gorilla in the 2.4 GHz ISM band; other services attempting to use that band must coexist with it, but it doesn't have to coexist with them. Any interference it causes to these new services must be borne by them; as a result, we have created a de facto allocated band.
...that I have found is tabbed browsing. I'm one of those on a slow staticy rural dialup, just too far away from the nearest telco switch, and even then, the cost would be prohibitive for what they offer for *dsl. Well, to me anyway. 56k modems just slap don't work, I have three of them, they lose connectivity so quickly that they are useless. Next down I use a 33k modem, and only when the weather is perfect. That's my main modem, fairly robust and reliable, but again, the minute the lines get more static and noise, poof, they dropconnection. Right now, the only way I can even stay online is by using a 14.4 modem, as it is storming out. This might last all summer, just depends on the weather. The workaround is social,there is no actual hardware solution that I think I can do (satellite is out, that's one thousand bucks or something) I just load various tabs with content, then go do something else. It takes minutes sometimes to load pages, even with images turned off,etc. I will say that xmms playing radio mp3 streams is very nice no matter what,it gives me one more cool *thing* to do with the net, I only listen to lower bitrate talk stations, beats the pants off any other streaming tech out there, real, quicktime, windows media, winamp, etc. The old mac classic soundjam does the next best job on slow connections with mp3s. Of course I have a lot of other "real" radios as well,I just like the ability to get exactly what I want off the net, I mean this thing is sitting here turned on anyway, one less hardware device to power up.
I would really like broadband, I'll pay x-amount to me reasonable money for it WHEN it becomes avaialable, but yes, I won't trade my other real life interests and advantages I enjoy about living rural "just" for broadband. I lived heavy urban for years, nothanks, I'll pass now, did my time in crime city, constant loud, stinky (cities literally stink, you don't notice it until you've been away for awhile and go back into one), expensive this or that, etc. There are a lot of advantages, but a lot of disadvantages to urban life. And vice versa, neither is "perfect".
OK, back to connectivity. Whichever company that comes up with an easy to use, reliable and cheap universal wireless "solution" for that last mile WILL get my business, and there's millions of people out there who will buy it as well. Perhaps it's a niche market, but what ain't once you get down to it? Look at what happened with small dish cheap satellite TV when cable wouldn't go there to that last mile and when some mastermind noted that large dishes and hardware were too expensive for a lot of people, there was a niche market for something besides 1.5 fuzzy channels of over the air tv option, rural people jumped on it in droves. They weren't willing to move to the city for a lot of clear TV, that still didn't mean they didn't like to have some TV, a market that went begging for a long time.
It's like cheap downloadable music tracks, a market that went begging for years, literally went begging, people-potential customers- going "here, take our money we want this product". They got told to go &*&&^k themselves by the music monopoly. It was that insulting, hence the popularity of napster and etc and yada yada yada. Half of it was to just insult those bungers right back. Now how many songs has apple sold so far, because all they did was respond to a market going begging??
I will guarantee ANY of you companies or developers out there, you offer a wireless last mile that WORKS, that doesn't cost outrageous money, and that provides even a slightly more reliable and faster connection than most-alleged "56Kbps" rural dialup, you'll get rich, you'll get obscenely stinking rich, you have millions and millions of potential customers out there.
Sometimes the bean counters are wrong. A lot of times they are, really, they over estimate one potential profit maker while completely ignoring another one, and usually because the new potential is just that, new, or they aren't aware of it. I sincerely doub
To some degree I agree with you, however, the Open Spectrum crowd is lead primarily by computer scientists who as far I can tell have ignored some of the issues that crop up when designing radio real radio systems, especially when it comes to receivers. They wave their hands and say this new paradigm will leave all the old technology behind.
All of the literature I have read has focused on interference as occurring when two narrow band transmitters try using the same channel. This is the obvious case and the reason we have distinct allocations of the electromagnetic spectrum today. However, there are other modes of interference that occur even when two transmitters are transmitting on different channels. What about intermodulation interference (intermod)? Intermod occurs when two signals mix (multiply by one another) in the non-linear portions of a receiver to produce spurious signals that wipe out the real signal of interest. What about desense which occurs when one strong signal kilohertz or megahertz away from the signal of interest swamps the front end and makes the receiver deaf to all other signals? These types of problems have been dealt with by RF engineers for years in an environment where the spectrum was supposedly cafefully managed. (Some would say micromanaged.) If the spectrum turns into a free-for-all, I shudder to think the problems that will arise. Transmitting at a low power will mitigate these problems to a degree, but not all radio applications can be low power. (Think rural areas...)
You want to talk about actual claims? How about the claim that software defined radios (SDRs) are frequency agile and can operate anywhere they want. What you will find if you actually try to build an SDR receiver is that current CPU and A-to-D technology is not fast enough to work directly in the E-M spectrum. Depending on the design, you'll be limited to 0-30 MHz at best. To go higher, you'll need to use one of two methods, downconversion (mixing) or undersampling. Both of these processes require the use of filters and possibly other analog components that bring many of the same problems as they do in traditional radios. There are similar issues on the transmit side. There are still some excellent reasons to do SDR instead of traditional radios, however true frequency agility is still far out on the horizon.
I like many aspects of the Open Spectrum movement. There are some workable concepts there. However, I think it's being overtaken with hype and I worry that hype will hurt the credibility of the truly valid concepts. When I see engineers with real RF experience making the Open Spectrum movement's claims, I will be much less skeptical.
--zawada
In Soviet Russia, the Beowulf cluster imagines you!