Shuji Tasaka Yusuke Watanabe Real-Time Estimation of User-Level QoS in Audio-Video IP Transmission by Using Temporal and Spatial Quality. 2661-2666 2007 GLOBECOM http://dx.doi.org/10.1109/GLOCOM.2007.505 conf/globecom/2007 db/conf/globecom/globecom2007.html#TasakaW07