1. Computer Science Department, Government Postgraduate Jahanzeb College Swat, Khyber Pakhtunkhwa 19130, Pakistan
2. Department of Computer Science, University of Swat, Saidu Sharif, Khyber Pakhtunkhwa 21300, Pakistan
3. Graduate School of Information & Communication Engineering, Inha University, 253 Yonghyun-dong, Nam-gu, Incheon 402-751, Republic of Korea
4. CISTER Research Unit, Polytechnic Institute of Porto, 4200-072 Porto, Portugal