An Online Scheduling Algorithm for Variable Bit Rate Interactive Video Streaming in UMTS Networks

Variable Bit Rate (VBR) video transmission over UMTS networks is assuming an ever growing importance. To face the problem of high quality interactive video streaming over wireless channels, the online Interactive Video Scheduling Algorithm (IVSA) is proposed. It dynamically regulates transmitted bit rate according to the user actions at client side that can modify the real free buffer space if compared with the buffer space calculated by the server during the schedule computation. Real Time Control Protocol (RTCP) information is periodically sampled at client side and brought back to the server to adjust the schedule. IVSA is innovative for two reasons. First, it tries to keep as long as possible the free buffer space at 50% of its size, to equally prevent buffer overflows and underflows. Second, RTCP sampling rate is dynamically varied to follow at best external user actions. Numerical results show the effectiveness of the proposed algorithm in different simulation scenarios.