The TP-Link TL-WN821NC bases on the Atheros chipsets AR7010 and AR9287 and support transmission up to 300Mbps according to the IEEE 802.11n standard.
The stick is recognized by the kernel in the following way:
Bus 001 Device 015: ID 0cf3:7015 Atheros Communications, Inc. TP-Link TL-WN821N v3 802.11n [Atheros AR7010+AR9287]
and is fully supported by Linux vie the kernel module ath9k_htc. This driver is included in the Linux standard kernel since version 2.6.30.
A firmware file is necessary to initiate the TL-WN821NC. This file is part of the Atheros Firmware-Package and can be installed in Debian-based distributions in the following way:
apt-get update apt-get install firmware-atheros
The automatic initialization of the TL-WN821NC can be seen in the kernel log:
usb 1-4: ath9k_htc: Transferred FW: htc_7010.fw, size: 72992 ath9k_htc 1-4:1.0: ath9k_htc: HTC initialized with 45 credits ath9k_htc 1-4:1.0: ath9k_htc: FW Version: 1.3 ath: EEPROM regdomain: 0x809c ath: EEPROM indicates we should expect a country code ath: doing EEPROM country->regdmn map search ath: country maps to regdmn code: 0x52 ath: Country alpha2 being used: CN ath: Regpair used: 0x52 Registered led device: ath9k_htc-phy0 usb 1-4: ath9k_htc: USB layer initialized usbcore: registered new interface driver ath9k_htc