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Geographic routing has received an increasing attention in the context of Wireless Sensor Networks since it frees the network from the energy-demanding task of building and maintaining a structure. It requires however each node to know its position, which may be a prohibitive assumption for many applications. To this end, some prior work has focused on(More)
Several wireless sensor network applications are currently appearing in various domains. Their goal is often to monitor a geographical area. When a sensor detects a monitored event, it informs a sink node using alarm messages. The area surveillance application needs to react to such an event with a finite, bounded and known delay: these are real-time(More)
Wireless sensor networks (WSNs) have witnessed a tremendous upsurge in recent years, both in academia and industry; this is mainly attributed to their unprecedented operating conditions and a variety of commercially viable applications. Because of their dependence on scarce battery power, communication protocols need to be energy efficient. However, finding(More)
—IETF ROLL has recently proposed gradient routing as a fundamental building block for data collection in Wireless Sensor Networks. This paper seconds this choice by presenting an implementation of gradient routing on current hardware, and by showing experimentally that gradient routing is robust against topological changes. To stress its self-healing(More)
Experimentation is important when designing communication protocols for Wireless Sensor Networks. Lower-layers have a major impact on upper-layer performance, and the complexity of the phenomena can not be entirely captured by analysis or simulation. In this report, we go through the complete process, from designing an energy-efficient self-organizing(More)
For energy constrained wireless sensor networks, lifetime is a critical issue. Several medium access control protocols have been proposed to address this issue, often at the cost of poor network capacity. To address both capacity and energy issues, we propose a novel medium sharing protocol for Wireless Sensor Networks named Cascading Tournament (CT-MAC).(More)
Many wireless sensor network applications are emerging nowadays. For critical, safety related applications, the network needs to provide bounded transmission delays. Hard real-time guarantees need therefore to be given by wireless sensor network communication protocols. In this paper, we propose a new hard real-time MAC protocol, and we give the time(More)