We have had the same problem with neighbor cats on our balcony.
(1) Try talking to your neighbors, emphasizing how annoying barking dogs can be, if this does not work (as it did not for us);
(2) Catch the cat and start dumping large volumes of water at it (which worked for us only for a time); but then we purchased this which keeps them away and is not harmful
(3)
http://www.nextag.com/ultrasonic-cat...nt/search-html
and it has worked, and we are all at peace.