RaLink RT3090 Wireless 802.11n 1T/1R PCIe [1814:3090]

Install drivers:

https://launchpad.net/~smirnov-arkady/+archive/rt3090

1. Download kernel source RaLink RT3090 ( amd64 | i386 )

2. Download modaliases package ( amd64 | i386 )

3. Install by console

sudo dpkg -i rt3090-kernel-source_2.4.0.4-0ubuntu0~ppa1_amd64.deb rt3090-modaliases_2.4.0.4-0ubuntu0~ppa1_amd64.deb

or doubleclick and use Ubuntu Software Center

To solve the problem with wireless reconnects try to adjust smp affinity
for your card:

1. Get IRQ number in the first column in /proc/interrupts for wlan or ra device

$ cat /proc/interrupts | egrep “wlan|ra”

2. Dedicate our first CPU (CPU0) to handling the card interrupts

$ echo 1 > /proc/irq/ < IRQ > /smp_affinity

PS.  Working with rt2860sta driver too.
PS.  Must have uninstalled the irqbalance package