After lots of googling I got this useful blog with lots of must-to-have links for NS2, ZigBee and most of the tools to do the simulation.

We are going to have a course project for network simulation on WPAN and ZigBee and these rare resources are very handy to start with.

NS2 for IEEE 802.15.4/ZigBee LR-WPANs :

1. Simulation of IEEE 802.15./ZigBee With NS-2
2. IEEE 802.15.4 Mac Implementation in NS-2
3. Low Rate Wireless Personal Area Networks (LR-WPANs) NS-2 Platform
4. Simulative Investigation of ZigBee/802.15.4Zigbee/IEEE 802.15.4
   
5. Module for NS2 simulator : http://www.cs.uwm.edu/~mukul/wpan.html

NS « Udin Harun