[1] Tokyo Inst Technol, Dept Elect & Elect Engn, Tokyo, Japan
[2] Japan Adv Inst Sci & Technol, Sch Informat Sci, Kanazawa, Ishikawa, Japan
[3] CNRS, F-75700 Paris, France
[4] Delft Univ Technol, NL-2600 AA Delft, Netherlands
[5] Univ Tokushima, Tokushima, Japan
[6] Univ Electrocommun, Chofu, Tokyo 182, Japan
[7] Univ Tokyo, Sch Engn, Tokyo 1138654, Japan
[8] Univ Tokyo, Sch Informat Sci & Technol, Tokyo 1138654, Japan
[9] Stanford Univ, Informat Syst Lab, Stanford, CA 94305 USA