Measurement Based Optimal Source Shaping with a Shaping+Multiplexing Delay Constraint - INFOCOM 2000. Nineteenth Annual Joint Conference of the IEEE Computer and Communications Societies

Most on-line (i.e., not stored) Variable Bit Rate sources would find it difficult to a priori declare the traffic parameters required by a connection admission control strategy. There is thus the problem of measurement based on-line estimation of source parameters. In this paper we address the problem of selection of source parameters based on minimising a bufferbandwidth cost function in the network, for a specified delay QoS Violation Probability. We consider the shaping delay plus first hop multiplexing delay; this is adequate, for example, for n statistically identical packet voice sources being multiplexed at a PBX, or in approaches where the end-to-end delay bound is broken into per hop delay bounds. Our approach yields a leaky bucket rate parameter p’ , and the sum of the shaper buffer and leaky bucket depth (B, + a). We show that, for a fluid source model, for a linear buffer-bandwidth cost function, and for lossless multiplexing, a sustainable rate parameter of p* and burst parameter of 0 yields the minimum cost. We propose and study a stochastic approximation algorithm for on-line estimation of p*. We then use buffer-bandwidth cost considerations to arrive at an optimal leaky bucket depth 0’ > 0 for lossy multiplexing of several statistically identical sources. The computation of o* must be done at the network node. We show, by an example, the improvement in cost that is possible by lossy multiplexing and a positive U*. Keywords-optimal leaky bucket, renegotiation, stochastic approxhation