Comment 5 for bug 770232

Seems similar to bug 762987.

Try extracting a newer firmware rt2870.bin from here:
https://launchpad.net/ubuntu/oneiric/+source/linux-firmware/1.53/+files/linux-firmware_1.53.tar.gz
and copy it in /lib/firmware (rename the old one to e.g. rt2870.bin.disable)