[support] automatical handoff using signal strength

[liu jianwei]

Have anyone used the signal intensity to handoff automatically? I used
iwconfig any, but it could only handoff when the first linkage is
totally broken down. Therefore, the handover time increased. I tried
to set the sensitivity, but it could set up to 30; and the linkage is
down before it decreased to 40, I think. The driver in my notebook
(Ubuntu 7.10) is ipw2200.
I have other problems when using rt73 driver in the arm board. This
driver could not even support iwlist. And it doesn't support iwconfig
essid XXX too. But it supports iwconfig any. It's kind of weird.
Have anyone  implemented this automatical handoff in embedded system?
I will appreciate your help very much!

Jianwei