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Tue 22 Mar 2011
More Wireless Speed
Category : Technology/MoreWirelessSpeed.txt
While I'm waiting for the Macs to all get up to 10.6.7, a couple of tech updates that might help some people.
Here's one about getting the best speed out of your Airport Extreme wireless network.
All my Macs are now capable of operating at 802.11n speeds and so I should be able to switch my Airport Extreme Base Station to work exlusively on the less crowded and much faster 802.11n 5 GHz space, right? And get 300 Mbit/s Link Speed for all my Macs instead of the anaemic 120 Mbit/s at 802.11b/g/n mode. Right?
In practice, it's not so simple. It should be and one day it'll be but now it's not.
That's because, if you switch the Airport Extreme Base Station to the 802.11n 5 GHz range, you will find that some of the Macs will mysteriously lose contact with the base station's network when they come out of sleep or when they restart. All my Macs do that except, fortunately, the new Thunderbolt early 2011 MacBook Pro.
I spent a few days tracing this and found that it coincides with the Airport cards in the Macs thinking that they have a different country code from what they should be, e.g., DE or TW instead of SG in my case. When this happens, they can't find the Airport Base Station.
So this makes some sense, because my Airport Extreme Base Station's country is set to Singapore and this probably determines the range of frequencies or channels the base station would use. If the Airport card on the client Mac thinks it's operating in a different country, that will set that airport card's operating frequencies and these two - the range carried by the station and the one listened to by the client - may not coincide and that would explain why the client Mac can't find an obviously operating Airport base station.
So the question really boils down to, why does the Airport card randomly think it's operating in a different country (from what it should most obviously be) when the Mac comes out of sleep or when it's been rebooted?
The answer is, if you'll search the web, it's not random but it's definitely a bug. It's not random because the wireless cards of the world, and not just the Airport cards, determine the country code from the first operating beacon that they encounter and not just the base station that they're supposed to tune in to. So among the 2Wires and Linksys in my neighbourhood, there are many that still think that they're operating in Germany (DE) or Taiwan (TW), because their owners neglected to set the operatng country parameter correctly.
The new MacBook Pro seems to have that bug fixed because it always (or maybe, mostly) gets the country code right when it comes out of sleep. But the other Macs need some help. I've determined empirically that the country most of the Airport cards think they are operating from, when they come out of sleep, is DE, probably because of the preponderance of PC-type wireless routers that have their operating country left as Germany in my neighbourhood.
In the Aiport Extreme Base Station, you can select a specifc channel to use in 802.11n 5 GHz mode, overriding the default choice ("Automatic"), if you hold down the option key while clicking on the pop-up menu. I've set the channel to 36, which is one that is used both by DE and SG.
And this has solved the problem. So I get all my Macs now operating at 300 Mbit/s over our Airport network. And things like file transfers feel that much zippier.
End of a happy story? Mostly. But occasionally, a rogue router that thinks it's in Taiwan will pipe in with TW please, before the DE's could respond and the Mac that is so stupid to listen to it will lose contact with the Airport base station (because TW doesn't operate with the channel 36, that DE and SG do). Usually for me, that Mac is an old MacBook that my kid uses and I've taught him to turn off and on Airport to get that out of the way because DE usually prevails here.
It's definitely a bug. It seems to have gone away with the new MacBook Pros. Apple should provide a firmware update to fix this for the older cards. Otherwise people will be operating far below the Nirvana they have the right to attain, just by being smart enough to use a Mac, or an iPhone or an iPad.