The H₂ Control Problem for Quadratically Invariant SystemsWith Delays

This technical note gives a new solution to the output feedback H₂ problem for quadratically invariant communication delay patterns. A characterization of all stabilizing controllers satisfying the delay constraints is given and the decentralized H₂ problem is cast as a convex model matching problem. The main result shows that the model matching problem can be reduced to a finite-dimensional quadratic program. A recursive state-space method for computing the optimal controller based on vectorization is given.