出处
《通讯和计算机（中英文版）》
2009年第9期46-53,共8页
Journal of Communication and Computer
基金
Acknowledgments： The authors thank for Prof. ZHANG Rong＇s valuable comments that improve the readability of this paper. This work was supported by the National Natural Science Foundation of China （No. 60672071）, the Ministry of Education （No. NCET-05-0534）, the Natural Science Foundation of Zhejiang （No. D 1080807）.
