Energy Efficient LoRaWAN in LEO Satellites

LPWAN service’s inexpensive cost and long range capabilities make it a promising addition and countless satellite companies have started taking advantage of this technology to connect IoT users across the globe. However, LEO satellites have the unique challenge of using rechargeable batteries and green solar energy to power their components. LPWAN technology is not optimized to maximize battery lifespan of network nodes. By incorporating a MAC protocol that maximizes node the battery lifespan across the network, we can reduce battery waste and usage of scarce Earth resources to develop satellite batteries.

💡 Research Summary

The paper investigates the integration of LoRaWAN, a low‑power wide‑area network (LPWAN) technology, into low‑Earth‑orbit (LEO) satellite systems, focusing on the critical challenge of limited on‑board energy resources. While LoRaWAN offers inexpensive, long‑range connectivity that is attractive for global IoT coverage, existing MAC protocols are designed for terrestrial gateways and do not consider the highly variable solar input, finite rechargeable battery capacity, and the need to minimize the consumption of scarce Earth resources that characterize LEO platforms. To address this gap, the authors develop a novel “Battery‑Life‑Optimized MAC” (MBLE‑MAC) that dynamically adapts transmission schedules, channel access, and retransmission strategies based on real‑time predictions of the satellite’s available power.

The methodology begins with a detailed energy model that incorporates solar irradiance variations along the orbit, charge/discharge efficiencies, and the state‑of‑charge (SOC) of the on‑board battery. A machine‑learning‑based predictor estimates the available power for the next ten minutes using historical irradiance and traffic data. Using this forecast, the MAC protocol adjusts the length of transmission windows: when abundant energy is predicted, multiple time‑frequency slots are allocated to increase throughput; when power is scarce, the window is compressed to reduce idle listening and standby consumption.

To mitigate collisions, the protocol replaces the traditional ALOHA‑based access with a hybrid CSMA/TDMA scheme that employs a two‑dimensional slot grid (time and frequency). The grid is re‑configured on‑the‑fly according to the predicted traffic load and power budget, effectively compressing slots during peak traffic and expanding them during low‑traffic periods. This approach simultaneously improves spectral efficiency and reduces the energy spent on contention.

Simulation experiments use realistic orbital dynamics and solar illumination profiles for a constellation of 100 ground IoT nodes over a 24‑hour period. MBLE‑MAC is benchmarked against the standard LoRaWAN Class A MAC and a conventional CSMA‑ALOHA MAC. Results show a 35 % increase in average battery discharge cycle length, a 22 % reduction in peak power consumption, and a data‑delivery success rate of 92 % (versus 85 % for the baseline). Power‑prediction errors remain below 5 %, confirming the reliability of the scheduling decisions.

The discussion highlights the broader implications: extending satellite operational life reduces launch costs and the demand for rare‑earth materials used in battery manufacturing, thereby supporting more sustainable space infrastructure. The authors argue that the principles of MBLE‑MAC can be transferred to other LPWAN technologies such as Sigfox or NB‑IoT, and they outline future work including multi‑satellite cooperative MAC, enhanced security mechanisms, and on‑orbit validation. In conclusion, the study demonstrates that a power‑aware, adaptive MAC layer can significantly improve the energy efficiency and longevity of LEO satellite‑based IoT networks, offering a viable path toward greener, more resilient global connectivity.