Congestion

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Congestion

Postby Paxton » Tue Aug 12, 2008 2:22 am

I am interested in hearing about any places people think that there may be congestion problems. This is part of some research I am doing. I will be publishing the results but will not be naming any person or organisation.

I want to work out whether or not there more spectrum needs to be allocated in the 2.4GHz band, or any other licence-exempt band.

All my enquiries so far suggest that, despite people predicting congestion, there is very little real evidence.

Any hard facts, anecdotes, opinions and rants are welcome!

Thanks

Paxton
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Postby Thorn » Tue Aug 12, 2008 4:13 am

Paxton wrote:I am interested in hearing about any places people think that there may be congestion problems. This is part of some research I am doing. I will be publishing the results but will not be naming any person or organisation.

I want to work out whether or not there more spectrum needs to be allocated in the 2.4GHz band, or any other licence-exempt band.

All my enquiries so far suggest that, despite people predicting congestion, there is very little real evidence.

Any hard facts, anecdotes, opinions and rants are welcome!

Thanks

Paxton
I see a lot of congestion & RFI. Some areas are ridiculous with the amount of RF used in the ISM band to the point where it's damned near useless for any distance, especially on Ch 6. The problem is that the users do not understand, why or what is happening, and certainly don't take the time to RTFM or look into what or why it is happening. They then don't take the time or effort to do things like actually coordinate channel use.

Get a spectrum analyzer and look in any downtown area.
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Postby streaker69 » Tue Aug 12, 2008 4:22 am

I want to work out whether or not there more spectrum needs to be allocated in the 2.4GHz band, or any other licence-exempt band.


Sure they could allocate more channels to the band, problem is you'd still have the same problem. Manufacturer's would still put their gear on channel 6, clueless lusers would still open their box, plug it in and say "hey it works!" and then go about surfing for pr0n.

Until people do what Thorn said, read the book and set things up properly, there's always going to be congestion.

What I do think should happen is that if you're going to be running wireless inside a business or any non-residential area, you should have certain channels assigned that you may use that residential equipment cannot use. The band could be expanded in such a way so that hospitals and such would have clear channels to use and not have to fight with consumer grade gear for space.
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Postby Paxton » Tue Aug 12, 2008 5:23 am

I have certainly seen the emphasis on channel 6 and that is confirmed by the WiGLE statistics. It would probably be relieved if home routers could automatically determine the best channel to use without people having to choose themselves.

Doesn't your suggestion that the channels should be assigned to different types of users go against the principle of licence-exempt spectrum? Assigning the channels goes back to putting the spectrum in the hands of the the regulators.

I have used a spectrum analyser in urban areas and it does, on the face of it, look very busy. The max hold view gets saturated very quickly. When you carefully look at the bursts, though, you see that there are plenty of time gaps.

The highest frame rate I have recorded so far in urban areas is just 650 frames per second, which is not very much at all.

There seems to be a gap between what people think is there and what you get when you try measuring it.

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Postby streaker69 » Tue Aug 12, 2008 5:29 am

Paxton wrote:
Doesn't your suggestion that the channels should be assigned to different types of users go against the principle of licence-exempt spectrum? Assigning the channels goes back to putting the spectrum in the hands of the the regulators.



Paxton


My point was that part of the spectrum could be regulated for commercial uses and deregulated for non-commercial uses. That way the people who really NEED to use the spectrum would have it without the interference from the people that are using it because it's neat and shiny.
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Postby Thorn » Tue Aug 12, 2008 6:26 am

Paxton wrote:I have certainly seen the emphasis on channel 6 and that is confirmed by the WiGLE statistics. It would probably be relieved if home routers could automatically determine the best channel to use without people having to choose themselves.
Ugh. There would have to be a lot of intelligence built in, or the things would go into a state where one change would trigger a ripple effect where channels were constantly changing.

Paxton wrote:Doesn't your suggestion that the channels should be assigned to different types of users go against the principle of licence-exempt spectrum? Assigning the channels goes back to putting the spectrum in the hands of the the regulators.
Protecting a licensed band for some industries (e.g. healthcare, or SCADA controls) might be a good thing.

Paxton wrote:I have used a spectrum analyser in urban areas and it does, on the face of it, look very busy. The max hold view gets saturated very quickly. When you carefully look at the bursts, though, you see that there are plenty of time gaps.

The highest frame rate I have recorded so far in urban areas is just 650 frames per second, which is not very much at all.

There seems to be a gap between what people think is there and what you get when you try measuring it.

Paxton
Again, it depends where you are, and what you are looking at. Sure, in some areas, you may have 25 people in one build using ch. 6 and no one is really moving a lot of traffic, so that it isn't congested based on the time bursts. However, add a couple of people downloading ISOs or <gag> using a P2P file sharing (mal)ware, and you can have a real mess.
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Postby streaker69 » Tue Aug 12, 2008 6:37 am

Thorn wrote:

Protecting a licensed band for some industries (e.g. healthcare, or SCADA controls) might be a good thing.



I completely agree with this. I think a dedicated Wifi system for SCADA would be great.

I think one of the issues is that many people can't see outside of their own little world and don't realize that there's other people out there that NEED to use it instead of wanting to use it.

I can't tell you the number of people that I've talked that have no need for wireless in their homes, but still have it. People with a desktop machine sitting 5 feet from an AP with a USB dongle sticking out of the front. Damnit, just plug the CAT5 cable in.
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Postby Beard » Tue Aug 12, 2008 6:46 am

Thorn wrote:Ugh. There would have to be a lot of intelligence built in, or the things would go into a state where one change would trigger a ripple effect where channels were constantly changing.

Protecting a licensed band for some industries (e.g. healthcare, or SCADA controls) might be a good thing.

Again, it depends where you are, and what you are looking at. Sure, in some areas, you may have 25 people in one build using ch. 6 and no one is really moving a lot of traffic, so that it isn't congested based on the time bursts. However, add a couple of people downloading ISOs or <gag> using a P2P file sharing (mal)ware, and you can have a real mess.


Then there's the gray areas; hotels, motels, RV parks and all the other public hot spot providers; high usage times; and areas of mixed or adjoining residential/industrial areas.
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Postby streaker69 » Tue Aug 12, 2008 6:50 am

Beard wrote:Then there's the gray areas; hotels, motels, RV parks and all the other public hot spot providers; high usage times; and areas of mixed or adjoining residential/industrial areas.


Anything that is not accessible to the standard consumer should be in it's own band.
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Postby Beard » Tue Aug 12, 2008 6:57 am

streaker69 wrote:Anything that is not accessible to the standard consumer should be in it's own band.


Isn't there some rf bands already dedicated to industrial/business use?
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Postby Thorn » Tue Aug 12, 2008 7:09 am

Beard wrote:Isn't there some rf bands already dedicated to industrial/business use?
Yeah, there are several. For example, the local sewer system here has a SCADA over RF data link ring connecting all the substations and remote pumps, that uses a low-power license in the 460 MHz area. It functions fine for limited instructions ("Turn off pump 1") which are a few bytes, but the bandwidth is so limited that it makes more complex data unreasonably slow. They can't do real-time monitoring of pump station tanks levels for instance.

As far as I know however, there is no licensed band designed for mid-to-high power, high-speed data, akin to 802.11 (i.e. a licensed "wireless Ethernet".) Admittedly, I haven't looked at it in a while, so maybe the FCC has allocated some band someplace. They had been looking at re-allocating some 1.9MHz stuff a while back, but I'm not sure what happened with that, or if any was set aside for business/industrial.

Wrzwaldo and Beakmyn might have some insight into that. They deal with SCADA & industrial apps all the time.
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Postby Beard » Tue Aug 12, 2008 7:50 am

Thorn wrote:Yeah, there are several. For example, the local sewer system here has a SCADA over RF data link ring connecting all the substations and remote pumps, that uses a low-power license in the 460 MHz area. It functions fine for limited instructions ("Turn off pump 1") which are a few bytes, but the bandwidth is so limited that it makes more complex data unreasonably slow. They can't do real-time monitoring of pump station tanks levels for instance.

As far as I know however, there is no licensed band designed for mid-to-high power, high-speed data, akin to 802.11 (i.e. a licensed "wireless Ethernet".) Admittedly, I haven't looked at it in a while, so maybe the FCC has allocated some band someplace. They had been looking at re-allocating some 1.9MHz stuff a while back, but I'm not sure what happened with that, or if any was set aside for business/industrial.

Wrzwaldo and Beakmyn might have some insight into that. They deal with SCADA & industrial apps all the time.


Doesn't 802.11a work or is the range too limiting?
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Postby Thorn » Tue Aug 12, 2008 8:11 am

Beard wrote:Doesn't 802.11a work or is the range too limiting?
You guessed it. Range is the problem. Realistically, 802.11a works to about 60-100 feet. After that it's pretty useless.

The particular SCADA systems I was speaking of are 1 or more miles apart.
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Postby streaker69 » Tue Aug 12, 2008 8:14 am

Thorn wrote:You guessed it. Range is the problem. Realistically, 802.11a works to about 60-100 feet. After that it's pretty useless.

The particular SCADA systems I was speaking of are 1 or more miles apart.


Or, like in our case, we're talking covering about 60 square miles across 40 different stations. While Wifi is not a good solution for that, we haven't found a decent one in any other band either. Problem with our situation is, all of our assets are in the low ground, so getting wireless anything to be reliable is tough.
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Postby Beard » Tue Aug 12, 2008 8:41 am

streaker69 wrote:Or, like in our case, we're talking covering about 60 square miles across 40 different stations. While Wifi is not a good solution for that, we haven't found a decent one in any other band either. Problem with our situation is, all of our assets are in the low ground, so getting wireless anything to be reliable is tough.


Too bad there isn't a mixed or dual band solution.

Kind of got off the subject somewhat I think.
This kind of reminds me of the CB/ Business band issue a bunch of years ago.
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"We hold these truths to be self evident"....
Religous: "Thou shalt not steal."
Amish: "You shall burn in hell for theft of wifi." {courtesy streaker69}
Secular: What's on the books. {courtesy beakmyn}
Redneck; "Thievin' bastard, [blam, blam]"

Solutions for the most common problems or questions of new members are here, here, and here .
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