Stuck beacon is a notorious problem on madwifi (the wireless driver DD-WRT used for Atheros routers). If you never experienced any wireless interruptions with DD-WRT then just ignore this article. However, if you're annoyed by this stuck beacon problem with constantly dropping wireless connection, then I hope this can be of help.
Below is a quick hack, not a completely fix but would make life a little easier. The idea is to watch the output of dmesg and when the "stuck beacon" error messages flood, reset the wireless interface to bring it back to life.