Bandwidth allocation for the transmission of scalable MPEG video traffic with deterministic guarantees

This paper studies bandwidth allocation schemes for the transmission of VBR video traffic with deterministic guarantees, i.e. no packets lost and no missed deadlines. Speci®cally, we propose and investigate a policy named quasi-constant policy. A VBR encoder attempts to keep the quality of video output constant by varying the transmission rate (constant quality); on the other hand, with a quasi-constant policy the video quality transmission is reduced when congestion occurs. We assume that this reduction is obtained by exploiting source scalability. By characterizing the trac of a source with a constraint function, we de®ne the relationship between the amount of bandwidth assigned to a VBR source and the maximum delay the application may experience. By applying this relationship to long MPEG 2 traces (more than one hour) we show that the quasi-constant policy is a very promising direction for providing, in an ecient way, a deterministic QoS to VBR video trac. Speci®cally, the results presented indicate that with the quasi-constant quality approach we can achieve a utilization greater than 50% with a deadline of one second with only eight reduced-quality frames out of 1000. On the other hand, previous works ([1, 2]) indicate that with a constant quality transmission, a 50% network utilization can be achieved only by tolerating a seven-second deadline.