Wednesday, January 31, 2007

Airport Extreme 802.11n: integrating with 802.11b

Tidbits has an excellent summary of the Airport Extreme. The best part is the discussion of integration with an older WLAN and the Bluetooth issues (emphases mine):
TidBITS - Apple Ships 802.11n Base Station, Software Upgrade

... All Macs with Intel Core 2 Duo processors (except the 17-inch 1.83 GHz iMac) or Xeon processors can be updated to 802.11n, including Mac Pro desktops that had the AirPort Extreme option added. Apple isn't offering 802.11n options for any older Macs; third-party adapters will be required...

...AirPort Extreme with N can work in either the 2.4 gigahertz (GHz) band, in which 802.11b (AirPort) and 802.11g (AirPort Extreme) operate, as well as in the 5 GHz band, which is less occupied and has greater available frequencies... Moody said that the greater range of 802.11n should obviate the need for WDS connections in the home.

In 2.4 GHz, Apple won't allow 40 MHz "wide" channels that, in the absence of other Wi-Fi network signals, could double throughput.... Allowing 40 MHz wide channels in 2.4 GHz would have severely constrained Bluetooth. Starting with version 1.2 of Bluetooth, that short-range networking standard actively avoids frequencies that are in use by Wi-Fi.

Jai Chulani, senior product manager at Apple, suggested that many users would be better served by preserving a legacy 2.4 GHz network for 802.11b/g devices with an existing base station, and plugging that older base station into an Ethernet port on the new AirPort Extreme, which would then operate to its best advantage in 5 GHz.

... an advanced settings option would allow 5 GHz channel selection. This could be important, because four of the nine channels in 5 GHz that Apple is offering are restricted to a low-power mode...
I have an existing Airport Extreme and I have an Airport Express. Since my primary laptop will run 802.11n, and my creaky still-living G3 iBook is 802.11b, I might well end up buying the AExtN, putting the old AExt in legacy mode, and putting the AExp in my luggage as a travel router/WLAN...

Two concerns. Our phones are 5.8 GHz, and I wonder what the relative power and cpu price is for running 802.11n ...

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