Duan-Shin Lee

Queueing analysis of a threshold based priority scheme for ATM networks

A threshold-based priority scheme in which a tuning parameter is used to provide adequate quality of service to real-time traffic while providing the best possible service to the non-real-time traffic is proposed. The priority scheme is a generalization of the static priority scheme and the one-limited scheme and is more flexible than both. For this scheme, the authors carry out a queueing analysis and obtain the joint distribution of the queue-lengths. They show by numerical examples how the parameter of this scheme can be tuned dynamically, so that the tuning function can be integrated with the call admission policy. >

TES modeling for analysis of a video multiplexer

Abstract The transport of video images is likely to be a major application of high-speed networks of the future. These applications are capable of utilizing the high bandwidths that will become available with the advent of B-ISDN. In this paper, we propose a new methodology (called TES) for modeling the frame bitrate stream generated by compressed video sources. The main characteristic of this method is that it can model an arbitrary marginal distribution and approximate the autocorrelation structure of the random bitrate process generated by compressed frames. We present a modeling example utilizing this method, based on data from a video coding algorithm employing a layering technique. Using the source model, we develop a simulation model of a multiplexer of video sources. We show that this model can be used to address a number of design issues that arise in this class of problem. In particular, we show that for a layered video coding algorithm, it is possible to have a gain in the number of sources multiplexed at the cost of some loss of low priority packets.

Transient analysis of multi-server queues with Markov-modulated Poisson arrivals and overload control

Abstract This paper studies the transient behavior of a Markov-molulated Poisson arrival queue under overload control. The queue has finite or infinite buffer capacity with multiple exponential servers. A Markov-modulated Poisson process is used to represent an aggregated voice or video packet arrival process in integrated service networks. By overload control, we mean to properly adapt the arrival process once the buffer contents exceed a designated level. The probability distribution of queue length as a function of time is obtained. The temporal effect of the overload control is measured in two forms. While in overload, we measure the amount of time for the queue to fall into underload. While in underload, we measure the amount of time for the queue to rise to overload. A proper design of the control will not only reduce the fall time but also increase the rise time. We also explore the transient queueing behavior as affected by time stochastic properties of the underlying Markov chain for the arrival process.

Design and analysis of a congestion-free overlay on a high-speed network

Current designs of high-speed networks assume that all customers are tolerant of some amount of losses. However, it is possible that some applications may require very high reliability, and would be willing to pay more for it, if such a service were available. Motivated by this, we propose a design of a hybrid network which can guarantee zero cell loss probability for type 1 traffic while allowing some losses for type 2 traffic. This paper has three contributions. Our first contribution in this paper is to propose a service discipline (which can be implemented easily on a specific switch architecture) which guarantees zero losses for type 1 traffic. Our second contribution is to propose an algorithm for a scheduling strategy which reduces the number of buffers required at the output pods of the switches to zero for type 1 traffic. Our last contribution is to solve a difficult queueing problem involving service interruptions, which characterizes the performance of type 2 traffic.

Policies for temporal placement control of video frames in B-ISDN networks

Proposes a new method of traffic smoothing for frames of different video sources. The authors assume that each video source transmits frames at fixed intervals and that the network is free to decide the relative temporal spacing of video frames from different sources. They propose three control policies (two heuristic and one based on an optimization problem via some Fourier analysis). These are compared against the case in which the video frames from different sources are randomly distributed (i.e., no control is exercised). They show that significant performance advantages accrue if one controls the temporal placement of the video frames from different sources.

An adaptive pipeline polling protocol for packet satellite communications

An adaptive pipeline polling protocol for packet satellite communications is introduced. The main feature of the protocol is that a frame containing a particular number of slots is shared unequally among the active ground stations. The sharing is done in a manner so that a ground station which has a large number of packets waiting to be transmitted is assigned a large number of slots in the frame. By extensive simulations, it is shown that the performance of the protocol is substantially better than that of a protocol in which the transmission medium is shared among the ground stations in a window-based scheme (i.e. without an adaptive scheme). The analysis includes both steady-state and transient results.<<ETX>>

An architecture for lossless service on a packet switched network

Current designs of high-speed networks assume that the all customers are tolerant of some amount of losses. However, it is possible that some applications may require very high reliability and would be willing to pay more for it, if such a service was available. Motivated by this, we propose two methods of designing a hybrid network which can guarantee zero cell loss probability for type 1 traffic while allowing some losses for type 2 traffic. Our first contribution in this paper is to propose a service discipline (which can be implemented easily on a specific switch architecture) which guarantees zero losses for type 1 traffic (the first method). Our second contribution is to propose an algorithm for a scheduling strategy which reduces the amount of buffers required at the output ports of the switches to zero for type 1 traffic (the second method).

A reservation based cyclic server queue with limited service

In this paper, we examine a problem which is an extension of the limited service in a queueing system with a cyclic server. In this service mechanism, each queue, after receiving service in cycle j, makes a reservation for its service requirement in cycle j + 1. In this paper, we consider symmetric case only, i.e., the arrival rates to all the queues are the same. The main contribution to queueing theory is that we propose an approximation for the queue length and sojourn-time distributions for this discipline. Most approximate studies on cyclic queues, which have been considered before, examine the means only. Our method is an iterative one, which we prove to be convergent by using stochastic dominance arguments. We examine the performance of our algorithm by comparing it to simulations and show that the results are very good.