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802.11g Slows Down
Moosifer writes "Computerworld reports that in order to step on fewer 802.11b toes, the IEEE has reduced the actual throughput of 802.11g in its latest (and allegedly final) draft. I think I might keep old firmware on my linksys AP and card so that I can at least pretend I have faster gear." It's been moved from 54Mbps all the way down to 10-20Mbps, more than just a slight change.
US Robotics doubles up on 802.11g data rates
I don't think this has much to do with politics. Reading the article, it looks like a backwards-compatibility issue such that 802.11g devices don't interfere with 802.11b devices in a co-existing environment.
the blood has stopped pumping, and he's left to decay
the me that you know is now made up of wires
Don't upgrade your firmware. You will be fine as long as you're in a 802.11g only environment. The problem comes when 802.11g devices coexist with 802.11b devices. As it is now, your hardware should be fine.
the blood has stopped pumping, and he's left to decay
the me that you know is now made up of wires
802.11g is not and never has been 54Mps.
The effective throughput of 802.11 is about 22Mps.
54Mps is the effective raw bandwidth.
I have no idea what the new changes will do the speeds of 802.11g, but no one is or has ever gotten 54Mps.
Guys,
The 54Mbps is the signal rate of the 802.11g modulation scheme. With the per-packet overhead, the effective data rate is around 20 Mbps, and they're trying to clarify that to consumers.
FastEthernet is 100 Mbps, right? Well, actually, the signal rate on 100Base-TX is 125 Mbps. It takes 5 bits on the cable to carry 4 bits of actual payload data.
The rate on the box != the actual throughput you get.
Due to protocol overhead, backwards compatability overhead, physical environment, yada yada yada, you'll see varying throughput.
With current implementations of the draft solution mixed mode performance is *terrible*. 10 Mb/s mixed mode is an improvement. Right now your draft
The standards body hasn't throttled down
Still, by the end of the summer you'll see throughput at 30 Mb/s in pure
In a pure
The compatability
Everybody's going on and on about how it's hardly faster than .11b. Read the freakin article:
.11b is about 5Mbps true throughput. .11g will be twice that in "safe mode" and four times that in pure .11g mode.
"Li estimated that that in mixed 802.11b and 802.11g networks running standard TCP/IP Internet protocols, this will reduce actual throughput to 10Mbit/sec. -- while pure 802.11g networks will have actual data rates of around 20Mbit/sec. Li pointed out that even at these data rates the 802.11g devices still outperform 802.11b devices, which have a raw data rate of 11Mbit/sec. but an actual throughput of about half that speed. "
See that? He's saying
The article would have been much clearer if he had said ".11g is being reduced from 54Mbps raw data rate to X Mbps raw data rate, and from Y Mbps true throughput to 10 or 20Mbps true throughput." Instead he says it's getting reduced from 54Mbps raw data rate to 10 or 20Mbps true throughput. Way to mismatch your units to get the biggest reduction possible.
The problem here is just that the reporter seems to be twisting the numbers to try to make it sound worse than it is. His very first sentence compares "true throughput for Internet-type connections of between 10M and 20Mbit/sec" with "54Mbit/sec. raw data rate", which is misleading. Raw data rate and actual throughput are (unfortunately) only vaguely related. If you want accurate numbers for g and b, compare apples to apples. According to the article, if you pay close enough attention, the real numbers are:
Now, maybe in earlier drafts the actual throughput numbers for 802.11g were supposed to be higher, but you wouldn't know it from reading the article. Looking at his past articles it seems like the reporter might just not know the difference, he uses 'throughput', 'data', 'data rate', 'raw data rate', 'data speeds', 'raw data speeds', and 'bandwidth' all interchangeably. The differences between some of those are subtle (or non-existent), but if he's confused enough then comparing 'raw data rate' to 'actual throughput' could conceivably have been an honest mistake...
So if they made some change to the final 802.11g standard such that the througput is only 20 Mbps, that's not much of a change from the draft.
And it has always been the case that in a mixed enviornment (802.11b coexisting with 802.11g), you can't get maximum 802.11g throughput. The exact amount of slowdown will vary.
So in summary, I'm not convinced that anything this Computerworld article is reporting about the 802.11g standard is actually a significant change from the draft. They've just compared some numbers in a meaningless way to sensationalize the story.
Disclaimer: At work I'm involved in the development of 802.11g products.
Is this even really news?
At work we've been using 802.11a and 802.11g devices (not to mention 802.11b) since the absolute first days they were each available. All the testing I've ever done was far from impressive and probably close to what they are saying in this article:
802.11b
Advertised Speed: 11 megabit or 1.38 megabytes/sec
Advertised Range: 150 feet
Real-world Speed: 4.5 megabit or 0.55 megabytes/sec
Real-world Range: 100-250 feet depending on interference
802.11a
Advertised Speed: 54 megabit or 6.75 megabytes/sec
Advertised Range: 150 feet
Real-world Speed: 21.5 megabit or 2.7 megabytes/sec
Real-world Range: 50-100 feet (outside of that and the link is so weak the real throughput is worse than 802.11b)
802.11g
Advertised Speed: 54 megabit or 6.75 megabytes/sec
Advertised Range: 150 feet
Real-world Speed: 19.5 megabit or 2.45 megabytes/sec
Real-world Range: 100-200 feet (at 200 feet you can still get better than 802.11b throughput, while 802.11a usually is completely gone at 100 feet unless you are in an open field)
The reality is that they had better start advertising the true speeds and problems of 802.11a/g because a lot of people get disappointed when they compare them to standard 100Base-T wired connections -- to me it's flat-out false advertising. The real-world range of 802.11g is similar to 802.11b and its real-world throughput is consistently 3-5 times faster than 802.11b.
But to say that 802.11a/g are "54 megabit" so people compare them to a 100 megabit ethernet connection is REALLY wrong. It reminds me of the "56k" modems we have in our computers that never connect faster than 40k-45k for most people.
(for the record, our wired 100Base-T network that all these devices are plugged into is very fast -- we have no problem getting 8 to 11.5 megabytes-per-second of throughput)