http://www.winlab.rutgers.edu/~zhibinwu/html/network_simulator_2.html

Introduction

Ns-2 is a widely used tool to simulate the behavior of wired and wireless networks. Useful general information can be found at

Official ns-2 website (http://www.isi.edu/nsnam/ns/ ) 
An ns-2 Documentation generated by Doxygen is in http://www-rp.lip6.fr/ns-doc/ns226-doc/html/index.htm
Two good tutorials about ns-2.
     Wireless tutorial by Marc Greis
     ns by example
My presentation: ns2 tutorial for wireless simulation  WINLAB, June 2003
My Lecture : Introduction to ns2 ECE 330:543 Class Lecture, Oct. 2007
Another good tutorial of ns-2

Installation & Debug

Install ns-2.27 in Red Hat Linux
Install ns 2.28 in Debian with gcc 4.0 or above
Debug ns-2 with gdb

Simulation Configuration

1. Basic simulation scripts of wireless scenarios.
2. Traffic, Topology and Mobility generation in ns-2
3. Analyze CMU traces (for wireless simulation) and awk code.
4. Header and Address Handling in ns-2
5. Understanding OTcl syntax in ns-2

Physical Layer

1. Demystify TwoRayGround Propagation Model
2. Introduce Ricean Fading to produce probabilistic Link Error
3. Why list-based improvements in channel.cc of ns-2.27 cause problems?

MAC layer

1. Interfacing MAC
2. Understand IEEE 802.11 MAC Standard
3. Analysis of the 802.11 MAC code
4. Simulation example: Measuring the effects of RTS/CTS on 802.11 link
   
5. Practice: Implement Multi-Rate MAC
   
6. Discussion of bugs and issues of IEEE802.11 MAC implementation

Routing

1. Analysis of the DSR sourcecode in ns-2.
2. Analysis of the DSDV in network simulator-2.
3. How to produce a new Routing Agent with Fixed Routing Table.
4. Calculate Routing Performance Metric from trace file

Summary of ns-2 bugs for wireless simulation

channel.cc List-based improvement causes "Segmentation Fault".
mac-802_11.cc: Bug in Defer timer causes "Event UID not valid!".
dsdv.cc: double IP header bug.