Dual-Radio BLE-LoRa Hierarchical Mesh for Infrastructure-Free Emergency Communication

TL;DR

This paper introduces a dual-radio mesh architecture combining BLE and LoRa for emergency communication, achieving high scalability, low latency, and significant energy savings by offloading traffic to BLE.

Contribution

It presents the first architecture integrating BLE advertising mesh routing with a multi-hop LoRa backbone on standard hardware, optimizing traffic offloading and energy efficiency.

Findings

82-90% of traffic kept on BLE reducing LoRa energy use by 79%

Supports 10 km+ network diameter and 250-562 nodes

Achieves sub-50 ms intra-cluster latency on 3.0 KB RAM

Abstract

We present a dual-radio hierarchical mesh architecture for infrastructure-free emergency communication that exploits the complementary strengths of Bluetooth Low Energy (BLE) and LoRa. Nodes equipped with both an nRF52840 (BLE 5.0 Coded PHY) and an SX1262 (LoRa sub-GHz) form local clusters via BLE advertising-based AODV routing, while dynamically elected cluster heads bridge inter-cluster traffic over a LoRa backbone. We derive a formal traffic offloading model showing that with locality bias beta >= 0.76, validated against search-and-rescue communication patterns, the architecture keeps 82-90% of traffic on BLE, reducing LoRa energy consumption by 79% compared to LoRa-only mesh. Analytical evaluation demonstrates 10 km+ network diameter, 250-562 node scalability, and sub-50 ms intra-cluster latency on a 3.0 KB RAM footprint. To our knowledge, this is the first architecture combining BLE advertising-based mesh routing with a multi-hop LoRa backbone on commodity hardware.