Optimal solution and approximate solutions of SISO mixed H/sub 2//l/sub 1/ problem

The SISO mixed H/sub 2//l/sub 1/ problem for discrete time systems is studied. It is shown that there exists a unique optimal solution for this problem. The optimal solution can be approximated within any prescribed missing error bound in l/sub 2/ norm with solvable suboptimal solutions and solvable super-optimal solutions.