An Internship Study submitted in partial fulfillment of the requirements for the degree of Master of Science in Computer Science

Internship Report (M. Sc.) - Asian Institute of Technology, 2025

Low-Power Wide-Area Networks using standard LoRaWAN struggle with coverage gaps due to single-hop topology limitations. While mesh networking addresses this through multi-hop relay, existing LoRa mesh protocols face scalability barriers from broadcast-based routing and fixed-interval control overhead. Flooding protocols create exponential tra!c violating duty cycle constraints, while table-driven protocols waste airtime with unnecessary periodic control packets regardless of network stability. This research implements a gateway-aware cost routing protocol combining three mechanisms: (1) Trickle adaptive scheduling reducing HELLO overhead through exponential backo" and redundancy suppression, (2) multi-metric cost function integrating signal quality and gateway load for path selection, and (3) proactive fault detection with safety mechanisms preventing over-suppression while enabling rapid convergence.The research makes six novel contributions: (1) first complete Trickle adaptive scheduler integrated with LoRaMesher firmware achieving 85-90% suppression e!ciency, (2) discovery that Trickle operates as local per-node decisions rather than network-wide cascades, limiting fault impact regionally, (3) zero-overhead ETX tracking via sequence-gap detection eliminating ACKoverhead, (4) active gateway load sharing with real-time load encoding enabling dynamic traffic distribution, (5) safety HELLO mechanism preventing over-suppression while enabling rapid fault detection, and (6) proactive health monitoring reducing fault detection time versus library baseline.Hardware validation on ESP32-S3 nodes demonstrates approximately 30% HELLO overhead reduction, 96-100% packet delivery ratio in indoor scenarios, and successful dual-gateway load distribution. Multi-hop routing capability is validated with relay nodes forwarding traffic and cost-based routing selecting quality-aware paths unavailable in hop-count protocols. The adaptive overhead reduction and fault-tolerant design enable scalable LoRa mesh deploy ments for resource-constrained applications including agricultural monitoring, industrial IoT, and environmental sensing requiring duty cycle compliance and network resilience. The local fault isolation discovery and zero-overhead ETX tracking represent fundamental contributions to LPWAN mesh protocol research.