A Tutorial of 802.11 Implementation in NS-2
  By analyzing the source codes of ns-2, we discuss the simulated implementations of wireless channels, network interfaces and mostly the 802.11 MAC protocol in ns-2. We also notice the "bugs" of the 802.11 simulation compared with the reality, and present an extension to fading channels as well. 
Yue Wang, On-Ching Yue
cs.NI