Thanks a lot for the information.
I need to try using 802.11e after installing NS-2.28, so the link you suggested is very helpful.
I will try to install gcc34 and then try installing NS-2.28 on Fedora17.
Currently I had installed it on Fedora7 and trying to use 802.11e.
I will get back if I get stuck again.
Thanks for all the timely replies, really means a lot