  Frequent power failures can introduce significant packet losses during
communication among energy harvesting batteryless wireless sensors. Nodes
should be aware of the energy level of their neighbors to guarantee the success
of communication and avoid wasting energy. This paper presents TRAP
(TRAnsiently-powered Protocol) that allows nodes to communicate only if the
energy availability on both sides of the communication channel is sufficient
before packet transmission. TRAP relies on a novel modulator circuit, which
operates without microcontroller intervention and transmits the energy status
almost for free over the radiofrequency backscatter channel. Our experimental
results showed that TRAP avoids failed transmissions introduced by the power
failures and ensures reliable intermittent communication among batteryless
sensors.
