Adaptive Execution Timing for Offline First Quorum Coordination in LoRa Mesh Networks

Emergency, remote, and infrastructure-constrained environments cannot always rely on cellular networks or continuous Internet connectivity. LoRa offers an alternative for direct, long-range communication between low-power devices without depending on nearby cellular infrastructure, but its low data rate and variable transmission time create new coordination challenges. When multiple LoRa nodes must agree on information, fixed timing can either introduce unnecessary delay or cause missed deadlines as radio conditions change. This paper introduces a cross-layer controller that adapts mesh coordination timing to LoRa time-on-air at runtime. A MAPE-K loop maps estimated airtime into transmission-slot spacing S(c) and deadlines D(c), coupled with quorum or full-participation finalisation and a bounded single-retry mechanism. The framework was implemented on four SX1276 nodes at 915 MHz and evaluated over 2514 coordination rounds under crash and omission faults. Three-of-four quorum coordination achieved a median latency of 2.1 s, compared with 5.3 s for full participation. Overall, 88.6% of rounds met the first adaptive deadline, 11.4% required one retry, and none exhausted the retry budget or violated the evaluated safety invariants. A replay-derived fixed-SF12 schedule produced a median completion time of 11.3 s, compared with 3.4 s for adaptive execution. These results show that LoRa airtime can serve as a practical runtime signal for adaptive coordination on constrained mesh nodes.