Network on or Off? Instant Global Binary Decisions over UWB with Flick

In many low-power wireless systems, a condition occurring at some nodes (e.g., an anomalous sensor sample, an aperiodic packet to transmit, a new joining node) determines whether the entire network should be awake (e.g., to react to the anomaly, deliver the packet, update the node group) or enter sleep. State-of-the-art protocols exploit periodic network-wide floods based on concurrent transmissions (e.g., via Glossy) to establish the global decision quickly, reliably, and efficiently. Still, time is of the essence: the faster the network agrees, the faster it either reacts or enters sleep. Flick achieves this global decision with order-of-magnitude latency improvements and 5-nines reliability by detecting and disseminating a binary on/off vote via the preamble of a packet instead of its full content. The actual realization of this simple idea entails several techniques on the ultra-wideband (UWB) radios we use. We evaluate Flick over a 78-node network in the Cloves testbed showing that, e.g., a single node can globally flick the switch to on across a 10-hop diameter in < 500&#U+03BC;s , i.e., roughly the time for a Glossy packet to go across a single hop, and with 4.4 × less energy. We demonstrate the potential of Flick by integrating it into staple protocols and evaluating the performance improvements it enables.