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 can also now be purchased from the Apple Store for $1.99. The enabler is included with the $179 Extreme gateway. All Core 2 Duo and Xeon-based Macs with Wi-Fi can be updated, except a single iMac model, but 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. David Moody, an Apple vice president, said, "You can install it on the 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."
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. While the new Extreme includes Wireless Distribution System (WDS) support for linking base stations wirelessly, and will work interoperably with the older AirPort Extreme and AirPort Express models. However, 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. 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 [802.11]g co-exist perfectly," he said. 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. The AirPort Extreme with N is configured to automatically choose the best channel in 5 GHz, but Chulani said that 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.
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 automatically selected, and could be manually overridden.
The 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, used to view connected devices and their signal strength, is now part of the AirPort 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 configure the new base station.
The pipeline for Apple's 802.11n is just revving up, and Macs sold at retail could need enabling. Purchasers of Macs that don't have the newer software installed will have to pay the $1.99 fee unless they also purchase the AirPort Extreme Base Station. It seems likely that the base station will drive the upgrade to 802.11n. The base station started shipping today, and orders placed at the time of announcement should be in purchasers' hands shortly, Moody said.