Applying Weighted Finite State Machines to Protocol Performance Analysis

This work proposes the use of a weighted Finite State Machine to serve as a computational model for analyzing the performance of communication protocols. The new model´s use is demonstrated by concentrating on web-based services, Internet level-5 protocols in particular, because when the latter are ported onto mobile handsets, fail to meet performance expectations. The same modeling technique can also be used for lower layers, and for other communication protocols. Utilizing the new model, this work analyzes one of the most important use cases found in the agenda of the Internet Engineering Task Force, that of presence. More specifically, the new model is used in the measurement of the Session Initiation Protocol for Instant Messaging and Presence Leveraging Extensions protocol suite performance in two different scenarios. Investing on the application of the new model the paper outlines the benefits of using Presence Event Packages for Session Initiation Protocol in the analysis and enhancement of performance. Mathematical rigor and modeling accuracy improve the precision of protocol performance evaluation and offer an improved understanding on the way various web-based services function.