[ns] I am confused with the difference between the Backoff and Defer timers in 802.11MAC

[Carterchan]

Hi all:

            I want to do something with the wireless timers recently, but
I'm confused with the difference between Backoff and Defer timers in 802.11
MAC.

           Why do we need two timers to do about Backoff? It will cause the
double backoff problem, isn't it?

           Could anyone help me to understand the detail work of them?

           Thanks for your reply, I'll appreciate very much.

                                                      Carterchan