Ching-Hung Wang, Tzung-Pei Hong*, and Shian-Shyong Tseng+
Chunghwa Telecommunication Laboratories
Chungli, Taiwan 326, R.O.C.
E-mail: amidofu@cht.com.tw
*Department of Electrical Engineering
National University of Kaohsiung
Kaohsiung, Taiwan 840, R.O.C.
E-mail: tphong@nuk.edu.tw
+Institute of Computer and Information Science
National Chiao Tung University
Hsinchu, Taiwan 300, R.O.C.
E-mail: sstseng@cis.nctu.edu.tw