Departmental Papers (CIS)

Date of this Version

July 2006

Document Type

Conference Paper

Comments

Postprint version. Copyright ACM, 2006. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version will be published in 6th ACM International Conference on Embedded Software (EMSOFT 2006).
Publisher URL: http://portal.acm.org/browse_dl.cfm?linked=1∂=series&idx=SERIES11219&coll=portal&dl=ACM

Abstract

Distributed real-time systems require a predictable and verifiable mechanism to control the communication medium. Current real-time communication protocols are typically independent of the application and have intrinsic limitations that impede customizing or optimizing them for the application. Therefore, either the developer must adapt her application and work around these subtleties or she must limit the capabilities of the application being developed.

Network Code, in contrast, is a more expressive and flexible model that specifies real-time communication schedules as programs. By providing a programmable media access layer on the basis of TDMA, Network Code permits creating application-specific protocols that suit the particular needs of the application. However, this gain in flexibility also incurrs additional costs such as increased communication and run-time overhead. Therefore, engineering an application with network code necessitates that these costs are analyzed, quantified, and weighted against the benefits.

In this work, we propose a framework to analyze network code programs for commonly used metrics such as overhead, schedulability, and average waiting time. We introduce Timed Tree Communication Schedules, based on timed automata to model such programs and define metrics in the context of deterministic and probabilistic communication schedules. To demonstrate the utility of our framework, we study an inverted pendulum system and show that we can decrease the cumulative numeric error in the model’s implementation through analyzing and improving the schedule based on the presented metrics.

Keywords

real-time networking, scheduling, TDMA, network code

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Date Posted: 20 August 2006

This document has been peer reviewed.