Jiandong Li is a vice president and professor at Xidian University, Xi'an China. He received his B.S., M.S. and Ph.D. in communication and electronic systems from Xidian University Min Sheng is currently a professor at the Broadband Wireless Communications Laboratory at the School of Telecommunications Engineering, Xidian University, Xi'an China. She received her M.S. and Ph.D. degrees in communication and information systems from Xidian University, Xi,an, China. Xijun Wang is an associate professor in the School of Telecommunications Engineering, Xidian University, Xi'an China. He received his B.S. degree in telecommunications engineering from Xidian University, Xi'an China and his Ph.D. degree in electronic engineering from Tsinghoa University, Bejjing, China. Hongguang Sun is currently a lecturer with the school of telecommunications Engineering, Xidian University, Xi'an China. He received his B.S. degree in electronic and information engineering from Northeastern University and his Ph.D. degree in telecommunications engineering from Xidian University, Xi'an China