You can do that by creating a mesh link between the two APs the one with the wired connection back to the switch will be the Mesh portal and the other AP with no wired connection will be Mesh point, but be aware that the mesh link will be created over the 5 Ghz band and users will be served over the 2.4 Ghz band.
To power up the other AP you can either get a brick or a PoE injector.
Here's the guide:
http://www.arubanetworks.com/techdocs/ArubaOS_60/UserGuide/Mesh.php