turning radio on and off without upsetting connections?

[Jim Snow]

I was wondering if there was some simple way to put a prism card into low
power mode from user space with hostap.  I'm attempting to write a
user-space quasi-token-ringish medium sharing algorithm to reduce
collisions and power consumption (at some cost to latency and bandwidth),
but to reduce power consumption I need a way to turn the card off for a
little while and then back on (without causing active tcp connections or
connection attempts to fail (just be delayed a little while) - thus
"ifconfig wlan0 down" is unacceptable, and the 802.11 power-save mode does
more than I'd like it to). 

-jim