Mesh Network Capacity and Congestion

LoRa Channel Capacity

LoRa is a low-data-rate technology. Unlike Wi-Fi, the RF channel is shared by all nodes simultaneously using a CSMA-like approach combined with Meshtastic's flooding mesh mechanism. Understanding channel capacity helps you design a network that doesn't saturate itself.

Airtime Utilisation Metrics

Meshtastic displays Channel Utilization and Air Utilization percentages in the app. These are your primary indicators of network load.

• Channel Utilization > 25%: the network is busy. Messages may be delayed or dropped.
• Air Utilization > 15%: your specific node is contributing significant airtime. Reduce broadcast intervals.

Sources of Traffic in a Mesh

• Position / NodeInfo broadcasts: each node announces itself every N minutes. In a 50-node network with 15-minute intervals, that is one NodeInfo broadcast every ~18 seconds on average - before any user traffic.
• User messages: text traffic generated by operators.
• Telemetry: device metrics (battery, voltage) and environmental sensor readings.
• ACKs and routing overhead: mesh protocol housekeeping packets.

Traffic Reduction Strategies for Dense Networks

• Increase position broadcast interval to 30 - 60 minutes on non-mobile nodes.
• Disable telemetry on nodes where it is not needed.
• Use the Medium Slow or Medium Fast preset - the higher data rate means each packet occupies the channel for less time, even if physical range is unchanged.
• Use the REPEATER role instead of ROUTER for infrastructure nodes - less aggressive packet retransmission reduces redundant airtime.
• Limit hop count: most community networks set a maximum of 3 - 5 hops. Longer hop chains amplify traffic because each hop retransmits every packet.

The Hop Storm Problem

If many nodes retransmit the same packet, a single user message can trigger a burst of dozens of transmissions across the mesh. Meshtastic uses duplicate-packet detection to prevent routing loops, but in dense networks already near maximum airtime utilisation, a sudden burst of messages can temporarily saturate the channel and cause widespread packet loss. Keeping hop counts low and broadcast intervals long is the primary mitigation.

Monitoring Your Network

Use the Channel Utilization and Air Utilization figures in the Meshtastic app to assess local network load before and after adding new nodes. If deploying a new repeater in a dense area, monitor whether its addition increases congestion - a new high-visibility repeater with aggressive retransmission settings can increase channel load for every other node in range.