TP-Link selss two different versions of his USB wireless stick with the name TP-Link TL-WN821N. The two versions use different chipsets but fortunately are both fully supported by Linux.
The older version bases on the Atheros AR-9170 chipset (USB ID 0CF3:1002), while the newer one (product name TL-WN821N-v3.1, USB ID 0cf3:7015) uses the Atheros HTC chipset. Both USB sticks are fully supported by Linux since Ubuntu 11.04 (kernel version 2.6.39).
The newer version uses the kernel module ath9k_htc. The stick is recognized in the following wayby lsusb:
USB: 0CF3:7015 Atheros Communications, Inc. TP-Link TL-WN821N v3 802.11n [Atheros AR7010+AR9287]
This version of the stick needs additional firmware which can be installed under Debian by the follwing command:
aptitude update && aptitude install firmware-atheros
The firmware for the AR9170 chipset can be found at: