Fix perl setting locale failed

perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
LANGUAGE = (unset),
LC_ALL = (unset),
LC_CTYPE = "iso_8859_1",
LANG = "en_US.UTF-8"
are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").

使用以下指定設定環境變數，並且安裝 locale files
$ export LANGUAGE=en_US.UTF-8
$ export LC_ALL=en_US.UTF-8
$ export LANG=en_US.UTF-8
$ sudo locale-gen en_US.UTF-8
$ sudo dpkg-reconfigure locales

QualNet Set 802.11 Data Rate

當採用 auto-rate fallback 而設定
PHY802.11-AUTO-DATA-RATE-FALLBACK YES
PHY802.11-DATA-RATE 6000000
PHY802.11-DATA-RATE-FOR-BROADCAST 12000000

unicast data rate 會根據 source node 和 destination node 之間的 distance 而動態決定，若距離越短，則 data rate 越大。broadcast data rate 則是根據 PHY802.11-DATA-RATE-FOR-BROADCAST 參數的設定值(12 Mbps)。

當取消 auto-rate fallback 而設定
PHY802.11-AUTORATE-FALL-BACK NO
PHY802.11-DATA-RATE 6000000

broadcast 和 unicast data rate 都會採用 PHY802.11-DATA-RATE 的設定值(6 Mbps)。不可以再設定 PHY802.11-DATA-RATE-FOR-BROADCAST 之值，否則會發生錯誤訊息：

Error in file ../libraries/wireless/src/phy_802_11.cpp:944
Specified PHY802.11-DATA-RATE-FOR-BROADCAST is not in the data rate set
Abort trap


參考資料

• 802.11b rate selection policy, http://support.scalable-networks.com/entries/20921757-802-11b-rate-selection-policy