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When 54 Mbps isn't 54 Mbps: 802.11g's Real Speed
eggboard writes "Matthew Gast, author of 802.11 Wireless Networks, filed this article for O'Reilly Networks explaining exactly how fast 802.11g really is: that is, what's the actual data payload and real throughput, not the rated maximum speed. His conclusion? In mixed 802.11b/g networks, which will be common for years to come, g is only 1.6 to 2.4 times faster than b, not 5 times faster as it is in its g-only mode. This article has real math based on the specs, rather than armchair speculation."
I agree; it seem like it would have been much less work to run benchmarks than to come up with a theoretical model. But at least someone is giving us real data: Small Net Builder 802.11g NeedToKnow - Part 2.
ok, so on a straight g system, you get 5 times the rate of b wireless... b gets ~11Mper second times 5 = 55... a nice approximate number to 54... where is the problem? Why is this a controversy worth discussing?
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54 Mbps has never been the advertised real bandwidth for g. 54 Mbps is the speed at which data goes between your card and your router. Guess what? There's a lot of correction code, synchronisation, etc.
Maybe the author should read the docs(RFCs aren't that ahrd to find, are they?) before jumping on a juicy story?
Oh, and... DUPE! "lie" was already covered a few months ago. Heck, there even was the same conclusion: g gives you around 20 Mbps, VS what, 11 Mbps max on b?
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Yes, there were. However, they simply ceased selling when smart sensing became available due to their catastrophic effect on bandwidth and the relative inexpense of adding smart sensing.
Great idea -- there's a company called Engim that has a very cool set of chips that allow you to run 3 or more channels of Wi-F at the same time: you can choose to run some using a, b, or g, depending on the configuration.
So you could have one AP with "a" on one of the 8 indoor "a" channel, "b" on a non-overlapping 2.4 GHz channel, and "g" on another one. You could offer "g" twice and "b" once. And so on.
Freelance tech journalist for the Economist, MIT Technology Review, Macworld, and others
Although you are heavily moderated up as insightful, it appears to me you have not read the article.
Even with infinitely fast hardware for the error correction and no interference at all, thoughput of 802.11g will drop to 13.4 or even 8.9 Mbps once an 802.11b station associates to an 802.11g network. The 802.11b station does not even need to transmit actual data for this!
So, yes, this is really a new issue stemming from the compatibility between 802.11g and 802.11b.
Note that 802.11a does not have the same issues, as it does not try to be interoperable with 802.11b.