No abstract

No abstract

This paper introduces a new concept of spectral representation of packet loss rate to characterize the transient behavior of information loss during system congestion. It is found that esseiitial characteristics of loss rate spectrum in congestion is captured by the inherent excess input rate spectrum of the arriving process, less dependent on buffer size. In principle, each individual traffic stream can have substantially different requirement on its loss rate spectrum for services. Through selective packet discarding we show that one can properly redistribute the overall loss rate spectrum among individual sources to significantly iinprove the service quality of each. The spectral representation of packet loss thus provides us a great convenience to measure the network transmission quality of multimedia services. Further, with design of multi-level buffer overload control one can tune the loss rate steady state distribution of different priority streams to a piece wise step function, which minimizes the damage of packet loss on service qualities.

No abstract

In this paper we propose and implement a generalized Folding-algorithm for sojourn time analysis of finite QBD processes. It is a numerical method for the direct computation of xP = a where P is the QBD generator matrix in block tri-diagonal form. Define the QBD state space in two dimensions with N phases and K levels, so that P G 7 Z N K x N K and x . a E 7ZNK. The time and space complexity of the Foldingalgorithm for solving x P = a is O(N310gz K) and O(N210g2 IT). In contrast, a direct application of the block Gaussian elimination will yield a time and space complexity of O(N3K) and O(N2K) (see [2]). The algorithm is found to be highly stable with superior error performance. In numerical studies we provide comprehensive numerical examples with emphasis on transient queueing behavior with correlated arrivals.