This paper presents an approach for dynamic software reconfiguration in sensor networks. Our approach utilizes explicit models of the design space of the embedded application. The design space is captured by formally modeling all the software components, their interfaces, and their composition. System requirements are expressed as formal constraints on QoS parameters that are measured at runtime. Reconfiguration is performed by transitioning from one point of the operation space to another based on the constraints. We demonstrate our approach using simulation results for a simple sensor network that performs one-dimensional tracking.

As the complexity of computer based systems increases, designers are faced with the task of balancing a variety of design choices and parameters against conflicting optimization criteria. Design space exploration seeks to automate or partially automate the process of evaluating tradeoff decisions at design time. DesertFD is a domain-independent design space exploration tool which facilitates the representation and pruning of a design space using constraint satisfaction. DesertFD offers a formal tree-based view of a family of systems related through common structure, together with a flexible scripting language for modeling mathematical expressions governing property composition. User-specified constraints applied to the design space representation result in a pruning of the space. We discuss the reduction of the design space, property composition formulas and constraints into a constraint satisfaction problem using finite domain constraints. We examine two example design space exploration problems to evaluate DesertFD: the generation of a high level custom computer architecture for supporting H.264-based motion estimation, and the reliabilitydriven mapping of tasks to distributed embedded control units in a steer-by-wire automotive application.

No abstract

Abstract-Functional flow block diagrams (FFBDs) are a traditional tool of systems engineering and remain popular in some systems engineering domains. However, their lack of formal definition makes FFBDs imprecise and impossible to rigorously analyze. The inability to analyze FFBDs may allow specification errors to remain undetected until well into the system design process or, worse, until the system is operational. To help address these problems, we have developed a precise formal syntax and semantics for FFBDs, based on the application of metamodels and the process algebra Communicating Sequential Processes (CSP). FFBDs constructed within our formalized framework are precisely defined and amenable to analyses of properties, such as safety, progress, and conformance to required scenarios. We demonstrate some of the analyses made possible by our formalization in a simple case study of system specification and show how our formalization can be used to detect and correct subtle system errors during the specification phase.

No abstract