AirPort dual-band support

Apple's recently released 802.11n AirPort Extreme Base Station is capable of serving both 2.4GHz and 5GHz radio bands, but offers better performance in one mode and improved range in the other, according to a new study. Apple's AirPort Extreme is one of two wireless routers that implement the new 802.11n standard, maintaining backward compatibility with 802.11b/g and 802.11a standard to support legacy wireless clients. According to eWeek's recent review, Apple's router does not implement channel bonding in the 2.4GHz band, thus restricting clients to using only 20MHz channels while 5GHz clients can use a full 40GHz client. "In 5GHz mode, each client would receive and transmit at the 300M bps link rate, while 2.4GHz clients could attach at only a maximum rate of 144M bps."

The study also noted variances in results between clients at longer distances, with a Lenovo notebook seeing a 32 percent drop off in performance in the 5GHz band compared to a 19 percent drop in the 2.4GHz band. Apple's MacBook saw a 7 percent performance decrease in the 5GHz band at the same distance, with a 28 percent drop in the 2.4GHz band.

Interestingly, both machines use Atheros' XSPAN draft-802.11n wireless chipsets, which is the same technology used in Apple's AirPort Extreme router.

"This indicates that, with the standards still in flux, consistent interoperability still remains a moving target—even within the same chip-set family."

However, recent tests revealed "clean and consistent" results in different trials of the same pairing of devices.

by MacNN Staff