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standardsarefun 12/5/2012 | 3:14:46 AM
re: WLAN: Future Imperfect? Actually the solution is very simple - in a shared spectrum the shorter link will always win in terms of its QoS. That's a simple result of geometry and the fact that radio propagation in multipath environments is worse than square law path losses (it ain't free space in an office).

This means that short range systems (WiFi in offices and homes, etc.) will always find radio resources at the expense of long range ones sharing the same band (WiFi in metro mesh, long hop interconnection, etc.).

This is the same problem that DECT faced years ago when people tried to use this cordless phone system as a fixed wireless access system and no magic new standard is ever going to fix this issue. 802.11n MIMO systems will only make it worse! Especially when this sort of high capacity technique is used for short range links...
El Rupester 12/5/2012 | 3:16:08 AM
re: WLAN: Future Imperfect? rjbUnstrung said: "The Tragedy of the Commons only impacts domains with limited resources".

But spectrum /is/ a domain with limited resource: the statement about how many MHz are available is an implicit recognition of this fact.

"There is no destructive interference in radio communications"

I'm not sure I understand this remark; surely all wireless is interference limited? What else does SINR refer to?

The reality is that Shannon's Law defines a limit. Better technologies (CDMA, MIMO, etc) help us get closer and increase capacity.

But that doesn't mean that there is no conflict, no limit - nor does it allow 'anything goes'. Why should that change the laws of economics?

As an analogy, the invention of the skyscraper allows us to increase capacity (more users per square foot of land) but it has not made property rights irrelevant, nor has it made land "free".

Why should spectrum be different? Increased capacity might reduce the cost, but why should it make anarcho-communism ("lets all just get along") a viable system?


More generally, this shows up a difference between managed networks (GSM, WiMAX, switched Ethernet) which can (surprise!) manage access, and a "democratic" system like WiFi. You mention mesh & .11t/k/s - but those only solve the problem if someone manages the network. If there are 50+ independent networks in a room, all "equal", how does that happen? Another consequence of a fundamental philosophical issue - technology can help but may not solve it.
rjbUnstrung 12/5/2012 | 3:16:10 AM
re: WLAN: Future Imperfect? The Tragedy of the Commons only impacts domains with limited resources. Communications Media are only limited by technological innovation. Interference is in the "Ear of the Receiver" There is no destructive interference in radio communications.

Thought there isn't a "magic bullet", tere are technological mechanisms to get past the current limitations of today's 802.11 / WiFi.

WiFi is still at a very early stage of evolution. It is in a similar stage as Ethernet when it went from the big fat single yellow cable with vampire taps to hubs and bridges. Its still in one contention domain. At that time all the dire predictions for the end of Ethernet due to congestion of a common medium were being sounded in the tech media.

We do have some nice stuff coming down the pike in the form of MIMO, this will have a big impact but its not a silver bullet. There needs to be a next stage in the 802.11 MAC that will get us past the single CSMA collision domain. The 802.11s (mesh) may be the Task Group that codifies some of this. There are new mechanisms in 802.11t and 802.11k that will allow upper layers to know more about the radio layer and thus act more intelligent. These new mechanisms will be used by startups and others to develop next gen devices that can mitigate many of these problems.

Also note that most cellular providers have only 30Mhz per city to work with. WiFi has almost 500Mhz and another 300Mhz+ has been allocated by the FCC (though its still tied up in politics).

So WiFi still has lots of room for improvement and there are lots of mechanisms and paths for this improvement to happen. There are no fundamental technical reasons why there will be a "Tragedy of the Commons" and there is more of a chance of radical innovation in the open standards realm of WiFi than in celluar.
joset01 12/5/2012 | 3:16:24 AM
re: WLAN: Future Imperfect? Hi

I hope you are right and this issue does get solved in due time. But my sense is that the time when this does become a problem outside the show floor might be sooner than we think. And despite some startups looking at this -- Autocell, Colubris, etc. -- there doesn't seem to be a huge amount of concern in the wider industry yet.

P.S Oh, and I wish my cellphone had worked flawlessly at the show.

DJ
freetoair 12/5/2012 | 3:16:27 AM
re: WLAN: Future Imperfect? Of course the problem can be solved, in many ways. But I think the article was very good in pointing out a very real, every increasing problem. So in that respect the article was far from nonsense but actually spot on.

And goes to the heart of many of the issues with FMCA, WiFi VoIP, etc. Using unlicensed spectrum with no coordination between devices or at least networks, it can quickly become an unusable scenerio. Having experienced the same scenerio described in the article I can related, you feel like, the heck with it, give me a connection that comes up fast, stays up and let me do my work. In that regard a nice mobile phone/pda combo for a quick email check would be a welcome relief, not to mention the burden of carrying a laptop.

So think about the glorious vision of the WiFi phone and trying to make or receive a call under such conditions and throw UMA into to further complicate matters. No thanks as it stands today and for the foreseeable future. Just give me the cell phone with the relatively cheap air time and a ever increasingly nice combo unit like the Sony-Ericsson 910 and I am happy.

On the other hand perhaps the unstrung guys have a good startup idea brewing themselves and will attack this problem.
lrmobile_millomar 12/5/2012 | 3:16:27 AM
re: WLAN: Future Imperfect? The difference between WiFi and GSM that will prevent "them" from finding a solution to congestion?

WiFi - unlicensed spectrum
GSM - licensed

There is a specific limit as to how much data can be pushed across a chunk of spectrum. It's physics and not commerce. With licensed spectrum you can manage this use. With unlicensed you cannot. On a five lane highway, once you have each lane fully occupied you have nowhere else to go. If you own the highway you can do something about it. If you don't you get stuck behind that slow moving RV.

What has happened historically is that as now unlicensed spectrum has been released it has been filled up to past the point of usefulness. 2.4 Ghz is no different as Unstrung is finding out.
freetoair 12/5/2012 | 3:16:27 AM
re: WLAN: Future Imperfect? Exactly.
Hey but maybe MIMO II is the godsend!
Pooh...its magic.
clinks 12/5/2012 | 3:16:28 AM
re: WLAN: Future Imperfect? About 5 years ago the same was true for cell phones on a trade show floor... no outside connection because of overflow... that problem seems to have been solved; so why would it not be solved also for Wi-Fi in due time?

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