Beijing Key Laboratory of Network System Architecture and Convergence, Beijing University of Posts and Telecommunications, Beijing 100876, P. R. China;
Beijing Key Laboratory of Network System Architecture and Convergence, Beijing University of Posts and Telecommunications, Beijing 100876, P. R. China;
Research Institution of China Mobile, Beijing 100053, P. R. China;
Beijing Key Laboratory of Network System Architecture and Convergence, Beijing University of Posts and Telecommunications, Beijing 100876, P. R. China;
Microsoft Corporation, Redmond, USA;
New Jersey Institute of Technology, Newark, USA;