Queueing Methods for Analysis and Scheduling of Transport Rings

University Of Texas At Austin, Austin TX

Investigators

Abstract

This project will study stochastic transport rings, using modern multiclass queueing network models and methods to perform analysis and scheduling of these systems. The first part of the research involves classifying scheduling policies which can achieve the highest possible production rate in the system. Such policies are called throughput optimal. In the second stage, the intent is to identify good scheduling policies which are near optimal under some performance measure like average WIP, delay, or holding cost. In the last stage, the plan is to work with International SEMATECH, a research consortium in Austin, Texas, to build realistic and detailed simulation models of the automated material handling system (AMHS) used in 300mm wafer fabs. The goal is to see if the insights and results obtained from the queueing analysis can carry over to more realistic systems. This research has the potential for broader impact in several areas. The first is in the semiconductor wafer fabrication industry. Scheduling jobs in wafer fabs requires formulating efficient dispatch, setup, and batching policies and addressing a host of other issues. In the newest generation of wafer fabs, processing 300mm wafers, material handling is completely automated. Providing insight into the design of efficient scheduling rules for the AMHS is one major motivation for the project. A key to broader impact is working with SEMATECH, which sets standards and provides benchmark testing of research for a large portion of the global semiconductor industry. Hence, if the simulation stage of the research is successful, collaboration with SEMATECH creates an excellent opportunity to convince currently operating wafer fabs to implement the results in AMHS software. A second motivation arises in the design of Local Area Networks linking computers, which can also be modeled by the systems proposed in this study. Algorithms developed with the aid of queueing theory have been implemented in actual internet routing software in a number of instances. This previous success indicates that broad dissemination in the telecommunications arena is quite feasible.