Issue link: https://read.uberflip.com/i/1545219
9 Balanced SF distribution For frequency plans using SF7-12, such as EU868, exceeding 10% of SF12 from total SF usage is not recommended. When too many devices operate on SF12, their transmissions occupy the channel for long durations leading to network congestion. SF12 is used for join requests which are rare and critical. Monitoring of SF12 usage is necessary for overall efficiency. For frequency plans where the lowest data rate is SF10, such as US915, exceeding 15– 20% of SF10 from total SF usage is not recommended. While SF10 is used for join requests and deep coverage, its excessive use can reduce overall network capacity. Balancing traffic toward faster data rates (SF7–SF9) helps maintain network efficiency. Dynamic allocation based on real-time network conditions (e.g., congestion levels, packet error rates) is far superior to static allocation because it adapts to the actual operating environment rather than theoretical link budgets. This ensures that SF assignment is both fair and performance-driven. Capacity-aware device provisioning It's always important to monitor usage of high SF and use network statistics to ensure effective distribution of SF. This approach accounts for both device density and existing channel utilization, avoiding overload on particular SFs. Optimize for air-time, not just delivery A common misconception is that the highest spreading factors inherently guarantee the best message delivery. In practice, a small number of retransmissions at a lower level SF (e.g., SF10) often impose significantly less airtime and energy cost than a single long transmission at SF12. Retransmissions allow to benefit from time and frequency diversity, mitigating fading and interference (SF10 airtime is ~4 times smaller than SF12 in EU868). By prioritizing airtime efficiency over theoretical link margin, the network can sustain higher throughput and serve more devices without unnecessary collisions or delays. The guiding principle is that network health depends on minimizing airtime consumption, not maximizing the success rate of individual packets in isolation. Thus, the general recommendation would be, for e.g. lightweight downlink mode, when a device does not meet the target PER: First increase the transmission power; Then increase NbTrans to 8 if there is not much macro diversity (keeping max power); Increase SF by one step (keeping NbTrans to 8). LoRa Alliance ® WHITEPAPER