With the field of wireless sensor networks rapidly maturing, the focus shifts from “easy” deployments, like remote monitoring,
to more difficult domains where applications impose strict, real-time constraints on performance. One such class of applications
is safety critical systems, like fire and burglar alarms, where events detected by sensor nodes have to be reported reliably
and timely to a sink node. A complicating factor is that systems must operate for years without manual intervention, which
puts very strong demands on the energy efficiency of protocols running on current sensor-node platforms.
Since we are not aware of a solution that meets all requirements of safety-critical systems, i.e. provides reliable data delivery
and low latency and low energy consumption, we present Dwarf, an energy-efficient, robust and dependable forwarding algorithm. The core idea
is to use unicast-based partial flooding along with a delay-aware node selection strategy. Our analysis and extensive simulations
of real-world scenarios show that Dwarf tolerates large fractions of link and node failures, yet is energy efficient enough
to allow for an operational lifetime of several years.