Hybrid LoRaWAN–MQTT Architecture for Portable Smart Greenhouses: Cross-Layer Validation of Latency, Energy, and ADMR Trade-Offs

Abstract

This paper presents a novel hybrid LoRaWAN–MQTT connectivity framework for smart portable greenhouses, explicitly designed to meet stringent sub-2 s actuation deadlines under regulatory duty-cycle constraints. By integrating adaptive spreading factors, randomized retransmissions, and broker-level resilience mechanisms, the proposed system ensures deterministic latency guarantees while maintaining high Actuation Deadline Miss Ratio (ADMR) stability. Comprehensive experiments, i.e. the evaluation combines MATLAB R2023b simulations and field tests, were conducted across diverse scenarios, including stress conditions with broker failures, dense node deployments, and energy-lifetime profiling. Results show that more than 95% of downlink transmissions complete within 1.7 s, directly sustaining ADMR above 94% across all conditions. Statistical analyses, including ANOVA, Kruskal–Wallis, and GLMM modelling, confirm the robustness of these findings with error margins below 0.5%. Additional contributions include full latency cumulative distribution functions (CDFs), broker queue dynamics, and end-to-end packet trace validation, all provided in public repositories for reproducibility. These results establish a reproducible and regulatory-compliant communication architecture that advances reliable IoT-enabled smart farming, positioning hybrid LoRaWAN–MQTT as a first-class solution for portable greenhouse applications.