Comment 35 for bug 459933

This is due to periodic scanning. If you don't want periodic scanning (which allows intra-SSID roaming and faster reassociation on connection loss) then you can disable it by "locking" your connection to a specific BSSID in the connection editor.

Right-click on the network applet and choose Edit Connections... or run 'nm-connection-editor', click the Wireless tab, double-click on your wifi connection, and in the Wireless tab in that edit window, enter your AP's MAC address. Then click Apply, and re-select your wifi network from the applet's menu.

NM will then tell the supplicant and driver to lock the connection to that specific AP, and will no longer request periodic scans.