Publications

The use of mobile devices is often limited by the lifetime of their batteries. For devices that have multiple batteries or that have the option to connect an extra battery, battery scheduling, thereby exploiting the recovery properties of the batteries, can help to extend the system lifetime. Due to the complexity, work on battery scheduling in literature is limited to either small batteries or to very simple loads.

The Analytical Software Design (ASD) method of the company Verum has been designed to reduce the number of errors in embedded software. However, it does not take performance issues into account, which can also have a major impact on the duration of software development. This paper presents a discrete-event simulator for the performance evaluation of ASD-structured software as well as a compositional numerical analysis method using fixed-point iteration and phase-type distribution fitting.

Synchronous dataflow graphs (SDFGs) are used extensively to model streaming applications. An SDFG can be extended with scheduling decisions, allowing SDFG analysis to obtain properties like throughput or buffer sizes for the scheduled graphs. Analysis times depend strongly on the size of the SDFG. SDFGs can be statically scheduled using static-order schedules.

In this paper we address the problem of sink placement for Gossip-based Wireless Sensor Networks (GWSN). Sink placement plays an important role in planning and deployment of sensor networks. It is an efficient means to improve performance and achieve design objectives. Sink deployment requires an optimization strategy to search a space of possible placement options, and a performance evaluation method to assess the quality of different sink placements.

Evolvability, the ability to respond effectively to change, represents a major challenge to today's high-end embedded systems, such as those developed in the medical domain by Philips Healthcare. These systems are typically developed by multi-disciplinary teams, located around the world, and are in constant need of upgrading to provide new advanced features, to deal with obsolescence, and to exploit emerging enabling technologies.

Model-driven Design-Space Exploration (DSE) for embedded systems has proven to speed up system design and improve quality. Parameterized Partial Orders (PPOs) are a simple yet powerful conservative extension of classical partial orders. They serve as an intermediate representation in our Octopus toolset, allowing to capture applications from different domains and enabling analysis with various tools.

The inherently unreliable communication infrastructure compel WSN protocols to employ error control mechanisms. Traditionally, error control is achieved by a retransmission scheme using acknowledgment mechanisms. WSN architectures are severely resource constrained and the additional energy expense of transmitting error control messages can seriously degrade network lifetime.

Wireless Body Area Networks (WBANs) have characteristic properties that should be considered for designing a proper network architecture. Movement of on-body sensors, low quality and time-variant wireless links, and the demand for a reliable and fast data transmission at low energy cost are some challenging issues in WBANs.

Warehouses play a critical role in supply chains: they are responsible for the distribution of goods of many suppliers to many customers. Because of increasing customer demands, warehouse processes are becoming too complex to be controlled optimally by their traditional centralised control systems. Several results in the literature show that decentralised controllers are a viable alternative.