Enhanced LoRa-Based Underground Communication Using Repeaters for Range Extension

This paper proposes a low-cost underground communication system that uses LoRa radios (ESP32 and SX1276 modules at 433 MHz) with a repeater node to relay sensor data from mining tunnels to a distant receiver that displays readings and triggers alerts. According to the abstract, the repeater design is intended to improve coverage, reduce packet loss, and increase reliability in non-line-of-sight conditions, with performance assessed via RSSI, SNR, packet delivery efficiency, and range.