We consider the problem of optimal distributed controller design of semi-decentralized controllers for a special class of spatially distributed systems. This class includes spatially invariant and distributed systems with an inherent temporal delay in the interaction of distant sites. We consider the problem of optimal design of distributed controllers where controller information passing is as fast or faster than the plant. We show how the YJBK parametrization of such stabilizing controllers yields a convex parametrization for this class.