Istituto di Scienza e Tecnologie dell'Informazione     
Conti M., Gregori E. Bandwidth allocation for the transmission of scalable MPEG video traffic with deterministic guarantees. In: Real-Time Imaging, vol. 7 pp. 237 - 253. 2001.
his 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.
Subject VBR traffic
C.2.1 Computer communication-networks

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