On the Uplink Repetitions in LoRaWAN

Ensuring reliable data delivery in LoRaWAN is challenging due to interference and path loss. This paper analyzes the trade-off between using acknowledgments (ACKs) and successive uplink retransmissions without ACKs. While ACKs confirm reception, they consume downlink capacity and suffer from low delivery ratios due to duty cycle limits and half-duplex hardware. Retransmissions avoid downlink use but increase collision risk. Through probabilistic modeling and simulations, we show that repeated uplinks improve reception probability by 11% compared to using ACKs, even though the latter case offers better reliability in some cases. Moreover, ACKs increase energy consumption by about 14.6% on average in the selected simulated scenarios.