1. Research Institute of Electrical Communication Tohoku University Sendai 980-8577 Japan
2. Institute of Ultra High Frequency Semiconductor Electronics of RAS Moscow 117105 Russia
3. Department of Computer Science and Engineering University of Aizu Aizu-Wakamatsu 965-8580 Japan
4. Department of Electrical Engineering University at Buffalo SUNY Buffalo New York 14260 USA
5. Department of Electrical Computer and Systems Engineering Rensselaer Polytechnic Institute Troy New York 12180 USA