In this paper we discuss structured H2 control methods for large-scale interconnected systems. Based on a relaxation of Riccati equations, we derive some linear matrix inequality (LMI) conditions for suboptimal controllers in which information structure can be imposed. In particular, we derive controllers by solving low-dimensional LMIs, which are decentralized except for the sharing information between neighbors, as determined by the plant interconnection; also we optimize a performance bound for each of the derived controllers.