3.5.4 and that carries only the video traffic to be scheduled. The because the packet loss rate is nearly zero, the heuristic video encoding used is the same as that described in scheme, which uses time-out triggered retransmissions Section 3.5.4. The preroll delay for the experiments is with the time-out set to 2 (estimated RTT), performs 600 ms. Figure 3.5-9 plots luminance PSNR versus av- nearly optimally at high transmission bit rates. erage end-to-end delay for the CoDiO and the RaDiO schemes. The various points on the curves were gener- ated by varying A, which trades-off congestion-distortion 3.5.6 Congestion-distortion in the case of CoDiO and rate distortion in the case of RaDiO. The graphs show that the CoDiO scheme optimized scheduling resulted in end-to-end delays that were approximately half of those measured for the RaDiO scheme at the RaDiO streaming and its various extensions described do same PSNR. Transmission rates versus PSNR for both not consider the effect that transmitted media packets schemes are almost identical (Figure 3.5-10). may have on the delay of subsequently transmitted CoDiO outperforms RaDiO because it distributes packets. Delay is modeled as a random variable with transmissions in time and attempts to send packets as a parameterized distribution; parameters are adapted late as safely possible. This reduces the backlog in the slowly according to feedback information. In the case bottleneck queue and hence the average end-to-end when the media stream is transmitted at a rate that is delay. Other applications sharing the network experience negligible compared to the minimum link speed on the less congestion. RaDiO, however, is less network- path from server to client, this may be an acceptable friendly. As the scheduler only considers average rate, its model. In the case where there is a bottleneck link on the traffic tends to be more burst, relying more on the path from server to client, however, packet delays can be buffering in the network itself. strongly affected by self-cong