The definitions of Clear Channel Assessment (CCA) in IEEE 802.11

Please refer to the following link:
http://www.quora.com/Wireless/What-is-clear-channel-assessment-CCA

在c語言中以微秒(us)顯示時間差

這邊有一篇很實用的範例，可以參考看看
http://blog.csdn.net/tigerjibo/article/details/7039434

errno in C

可以參考這篇文獻的用法，了解目前在c語言下錯誤發生的原因
http://blog.csdn.net/21aspnet/article/details/6740110