[1] Univ Queensland, Sch Elect Engn & Comp Sci, Brisbane, Qld 4072, Australia
[2] Univ Milan, I-20122 Milan, Italy
[3] Iowa State Univ, Dept Elect & Comp Engn, Ames, IA 50011 USA
[4] Mississippi State Univ, Dept Elect & Comp Engn, Mississippi State, MS 39762 USA