Pi-Chung Wang, Chia-Tai Chan* and Yaw-Chung Chen
Department of Computer Science and Information Engineering
National Chiao Tung University
Hsinchu, Taiwan 300, R.O.C.
E-mail: pcwang@csie.nctu.edu.tw
*Telecommunication Lab.
Chunghwa Telecom Co., Ltd.
Hsinchu, Taiwan 300, R.O.C.