The AirPort Extreme Base Station with 802.11n is now shipping. The software enabler required to update existing Macs that have 802.11n technology built in is included with the base station, and can now also be purchased from the Apple Store for $2 (see "Two Bucks for 100 Mbps 802.11n Enabler," 2007-01-22). 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.
The enabler isn't locked to a particular Mac, a concern that arose when the enabler was first announced. In a briefing last week, David Moody, Apple vice president of worldwide Mac product marketing, said, "You can install it on all the Macs in your house." The license on the purchase page is even broader: "The software license for the 802.11n Enabler software allows you to install and use it on all computers under your ownership or control."
The new AirPort Extreme Base Station can work in either the 2.4 gigahertz (GHz) band, in which 802.11b (AirPort) and 802.11g (original AirPort Extreme) operate, or in the 5 GHz band, which hardly any wireless hardware uses today and which has greater available frequencies. While the new AirPort Extreme Base Station includes Wireless Distribution System (WDS) support for linking base stations wirelessly, and will work with older AirPort Extreme and Express base stations in 2.4 GHz, Moody said that the greater range of 802.11n should obviate the need for WDS connections in the home.
At 2.4 GHz, Apple won't allow 40 MHz "wide" channels that, in the absence of other Wi-Fi network signals, could double throughput (see "AirPort Extreme 802.11n Throughput Limits," 2007-01-29). Moody explained that Apple has a huge interest in preserving the functionality of Bluetooth, which has shipped alongside Wi-Fi in most Macs in recent years. "We need to make sure Bluetooth and 802.11n co-exist perfectly," he said.
Allowing 40 MHz wide channels in 2.4 GHz would have severely constrained Bluetooth since only about 80 MHz is available in the United States (and varying amounts elsewhere) in the 2.4 GHz band. While Bluetooth 1.2 and later can avoid frequencies in use - and 1.2 or 2.0 is found in all recent Macs - the 40 MHz wide channel squeezes Bluetooth's capability to deliver consistent throughput. This could cause audio transmitted to a Bluetooth headset to stutter, for instance.
Jai Chulani, a 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 with newer 802.11n hardware in 5 GHz.
The AirPort Extreme with 802.11n is configured to choose the best channel in 5 GHz automatically, but Chulani said that an advanced settings option would enable 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 with reduced range. Chulani also confirmed that the Apple TV could operate in either 2.4 GHz or 5 GHz bands, but that like the AirPort Extreme, the best mode of operation would be selected automatically, and could be overridden manually.
Apple's AirPort Admin Utility has been updated for the new standard with an overhauled interface that, Chulani said, "has two faces." One features more automatic, sensible choices for users who don't need or want to customize configuration. The other includes even more technical detail than earlier releases. For instance, the separate, free AirPort Client Monitor, which graphically displayed connected devices and their signal strength, is now part of the AirPort Admin Utility. An update to the AirPort Management Utility for configuring multiple base stations at once will be released in the indefinite future. Mac OS X 10.4.8 or Windows XP is required to run the new admin utility.
Macs in Apple's product pipeline do not yet have 802.11n enabled; that changeover will happen over an undisclosed period of time. Purchasers of new Macs that aren't enabled for 802.11n will need to purchase the $2 enabler; however, it's likely that only those who buy a new AirPort Extreme Base Station (which includes the enabler) would have any interest in using the new 802.11n standard.
The new AirPort Extreme Base Station started shipping last week, and orders placed at the time of announcement should be in purchasers' hands shortly, Moody said. I placed my order at Macworld Expo a few days after the keynote, and I received email from the Apple Store on 03-Feb-07 telling me that my new Extreme Base Station would arrive by 06-Feb-07.