Traffic engineering for multipoint videoconferencing under basic route-configuration assignment

We study a special kind of video conference system in which only the video of the current speaker is broadcast to other conferees. We allow statistical multiplexing for many conferences to share a link. This introduces the possibility of an undesirable video freeze effect when there is a temporary shortage of bandwidth. The probability of experiencing a video freeze is chosen as a measure of the conference quality. A conference model is constructed and conference calls are classified. A conference of a particular type can ride on a number of route-configurations. According to the location of the current speaker, a conference has different modes of operation. Two network management functions are discussed: call admission ensures a preset QOS requirement by blocking new calls that causes congestion and route-configuration assignment determines the multicast tree for distributing the video of the current speaker. For basic route-configuration assignment, the same route-configuration is maintained throughout the conference session. The traffic carrying capacity of a conferencing network is derived. This capacity is required for conference call admission decisions. The conference call blocking probability is also derived. It allows us to compare the performance of different route-configuration assignment schemes