Especificação e implementação de um protocolo tolerante a falhas e de baixa latência para redes de sensores sem fio.
Resumen
Wireless sensor networks are increasingly being deployed for fine-grain monitoring of
physical environments subjected to critical conditions such as fire, leaking of toxic gases
and explosions. A great challenge to these networks is to provide a fast, reliable and fault
tolerant channel for event propagation. The protocol has to meet the requirements of querybased,
event-driven and periodic sensor network application scenarios, even in the presence
of emergency conditions that can lead to node failures and path disruption to the sink that
receives those events. This paper presents a fault tolerant and low latency routing protocol
that meets the sensor networks requirements for critical condition monitoring applications.
The algorithm uses the publish/subscribe mechanism and the concept of event driven
delivery, a technique that selects the shortest path for the notification of events, reducing
latency. Fault tolerance is achieved through the triggering of a local path repair mechanism
to find new paths with minimal number of transmissions. The protocol was implemented
and simulated in the ns-2 network simulator and compared to the Directed Diffusion
paradigm. Relevant metrics, such as end-to-end delay, energy dissipation, and delivery
ratio, were evaluated showing that the proposed algorithm can be an adequate solution to
meet the strict requirements of information propagation in real-time monitoring
applications. An extension of the proposed protocol is also presented. This extension is in
phase of implementation and simulation and it is expected to reduce data traffic and,
consequently, reduce the energy dissipation. This new solution follows a hierarchical
approach to propagate data through the network.