Experimental Evaluation of a Noise-Resilient Factorial-Coding Protocol for Low-Rate UAV-to-Ground Emergency Telemetry in Wireless Sensor and Actuator Networks

This paper addresses the problem of improving the reliability of backup UAV telemetry in wireless sensor and actuator networks under degraded radio-channel conditions. A highly redundant protocol with low effective payload throughput is proposed for noise-resilient emergency telemetry from a UAV to a ground control station. The protocol was implemented on a hardware platform comprising an SX1278 transceiver and an STM32G474RE microcontroller. It operates in the 434 MHz band and uses continuous GFSK, non-separable factorial coding, a dedicated synchronization block, majority-vote processing, and software decoding performed by the microcontroller. The proposed protocol is experimentally benchmarked against the standard SX1278 packet-mode GFSK protocol with CRC-16 under identical hardware conditions, a data rate of 100 kbps, and transmitter output powers of +2, +3, and +4 dBm. Ground-based field experiments using two stationary nodes to emulate a UAV-GCS telemetry link with distance-induced attenuation demonstrate that the proposed protocol substantially increases the communication range at fixed PDR thresholds, where PDR is defined in this paper as the delivery rate of protocol transmission units. The 90% PDR threshold shifts from 30–35 m for the baseline protocol to 90–100 m for the proposed protocol, while the 50% PDR threshold increases from 45–60 m to 100–110 m. At a distance of 80 m, the baseline protocol achieved a PDR of 0%, whereas the proposed protocol maintained a PDR of 98–99%. These results confirm the suitability of the proposed protocol as a low-rate backup communication channel under low-RSSI reception conditions. Controlled AWGN, CW, burst-noise, and jamming experiments are left for future validation.