Slashdot Mirror
Apple Clarifies 802.11g Controversy
Wireless Spider writes "A couple of days ago there was a controversy over the 802.11g data rates and supposed changes in IEEE specification. Apple has clarified this controversy, stating that nothing has changed in the spec. It seems the article from Computerworld was somewhat misleading. Quote from an Apple Vice President: "802.11g is still a 54Mbit/sec standard," Bell told MacCentral. "802.11b is 11Mbit/sec, but your actual throughput is somewhere between 4 and 5-1/2Mbit/sec. The number that's quoted is the data rate that's used between the radios (raw data rate, which includes the protocols etc.)" After reading this article featured on Macworld, 802.11g transfer rate controversy meaningless, says Apple, it seems clear that the people at Computerworld didn't do their homework for the article featured on May 22. Also, there seems to be a lot of politics between 802.11g and a supporters, and that every article posted on the Internet about this subject might not be true, or could be politically motivated."
This is the result of reporters not doing their jobs properly. Those reporters SHOULD have talked with our (IEEE 802.11g) Working Group chairperson. Some did, and some didn't. Some of those who did talk with Sheung Li didn't bother to ask intelligent questions.
I guess it is a sign of the quality of journalism-school education these days....
It is perfectly reasonable to expect only 20 mbps throughput with a 802.11a or 11g network, for the same reason that 4-5 mbps is average using a 10baset hub or 802.11b. These are all shared mediums. Clients must use Collision Detection and avoidance. There is competition for the available bandwidth. All wireless must contend with clients that are connected at different rates. If a host is far enough from a 11a access point that it associates at 12 mbps, It's communications with the AP will take a longer timeslice from the available airspace. Clients associated at a higher rate will have their effective communication rate drastically effected.
Does it matter? Is it bad to market 11a and 11g at their 5x mbps? or 11b at 11mbps? Not really. (IMHO) Just like Hard drives are advertised at they size before putting a file system on them, it is up to the user to understand what the numbers really mean.
If you are the only client associated with an AP, your throughput will probably be much closer to the theoretical maximum, just as if there are only two things connected to a hub, their communications with each other will be better than if there were five.
The problem is that as soon as you introduce one 11b device into the same cell as an 11g network you will reduce the effective throughput of the even the faster devices down to around 11-15Mbps vs the 25+Mbps that a pure 11g or 11a network achieves. Basically you pay a 40-50% real world performance penalty for mixed mode operation a 2.4Ghz. Since 11a is in the fairly unused 5Ghz range it doesn't have these problems. The reality is it won't matter in 6-9 months because every chipset provider will have tri-mode dual band chipsets so you can use 11b for legacy networks, 11g for those that bought equipment while it was a draft spec, and 11a for those who bought that equipment or who will buy trimode equipment in the future.
There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
I have a question.
Since 802.11g and b are backward compatible.
It would seem the controversy stems from the fact that, if you already invested in 802.11b equipment, mixing 802.11g in with your environment is going to cause the 802.11g access point to step down or send RTS/CTS signals after each packet as a courtesy to 802.11b equipment trying to communicate in the same area.
So, here is something I propose then:
Say you decide to deploy 802.11g equipment in your wharehouse. You have not invested in anything WiFi and you have a nice radio free environment.
So you deply your 802.11g network in your wharehouse and everything is ducky.
Now, along comes Joe Shmoe. Joe Shmoe decides he is going to open a Steppen Brew right next door to your wharehouse.
He has this brilliant plan about offering Customers free internet access while they sip there latte's.
So he deploys a 802.11b access point on his roof next to your wharehouse operating with 802.11g equipment.
All of a sudden, you start getting complaints about crappy through put on your Wharehouse wireless LAN.
You can't seem to figure it out, but your 802.11g network is now half the network it was when your deployed it.
So you look for anyone using 2.4Gigahertz bluetooth devices, remote phones, cordless radio headsets...etc.
Nothing?
In short, the question is: will 802.11g equipment step down in the presence of any 802.11b device, or does it only step down if that device is actually transmitting on your network?
Couldn't find anything in the specs that would rule out this completely NASTY scenario.
Anyone care to comment?
-Hack
Got Geometrodynamics? Awe, too hard to figure out? Too bad.
You have to remember, Apple doesn't really offer a huge product line like some vendors. They have a core set of laptops, desktops, one type of server product, and several accessories and gadgets (mainly the iPod).
The Apple "Airport Extreme" was the first commercial 802.11g device to market - and Apple did their best to put a "spin" on it that it was somehow their own invention. ("That's right folks... good old Steve J. is bringing you the next insanely great thing. Faster wireless than anyone else offers!") Can't really blame them.... They were the only one willing to stick their neck out and start selling the product at the time. Everyone else waited until Apple had it on the shelves before rushing to release their own.
If people start publically attacking the 802.11g spec now and making it look bad, Apple stands to lose the most from it. They've already built all of their systems with it either integrated inside, or upgradable by expansion board.