  This paper proposes a novel method for distributed controller synthesis of
homogeneous interconnected systems consisting of identical subsystems. The
objective of the designed controller is to minimize the L2-gain of the
performance channel. The proposed method is an extended formulation of the Full
Block S-Procedure (FBSP) where we introduce an additional set of variables.
This allows relaxing the block-diagonal structural assumptions on the Lyapunov
and multiplier matrices required for distributed control design, which reduces
conservatism w.r.t most existing approaches. We show how to decompose the
proposed extended FBSP into small synthesis conditions, of the size of one
individual subsystem.
