Song signed for the Catalans from Arsenal last summer but has failed to make a real impact.
“Barcelona put much effort into signing him last summer and Alex turned down many great teams in order to sign with them,” Song told Calciomercato.
“Getting into the first team at Barcelona is not easy, but this season he has acted only as a substitute.
“He is not happy as at Arsenal he was a leader on and off the field. At Barcelona he does not feel as well and that makes him feel bad.”