Bounds for the Scalability of TLS over LoRaWAN

Inhalt:
Reliable and secure communication is needed to further digitize public infrastructure. LPWANs operating in license-exempt bands are a promising candidate. This work address the concept of a secure LPWAN by evaluating TLS over LoRaWAN. The overhead induced by TLS in combination with the duty cycle restrictions make this combination challenging. In this work, upper bounds of the usage are compiled by estimating the number of full TLS handshakes under various conditions. An airtime model is verified and integrated into a tool to estimate possible bounds on the duty cycle. The results reveal that a bottleneck exist in the downlink which depends on the Spreading Factor of LoRa and the selected cipher suite.