Bounds for the Scalability of TLS over LoRaWAN

This work evaluates the scalability limits of TLS-secured communication over LoRaWAN networks, focusing on duty cycle constraints in license-exempt bands. The study introduces a modeling tool to calculate airtime requirements for TLS handshakes and data transfers, revealing that gateways supporting mutual TLS authentication can handle up to 7,000 handshakes every two days under ideal conditions. Practical limitations from collisions and interference suggest significantly lower real-world scalability, highlighting the tension between security requirements and LPWAN constraints. The analysis considers fragmentation challenges due to LoRaWAN’s 250-byte payload limit and demonstrates how TLS overhead impacts network capacity through airtime calculations verified via software-defined radio measurements. The open-source tool enables network planners to assess deployment-specific constraints for secure IoT applications in smart metering and critical infrastructure.