DTLS Handshake Optimization with SCHC in LPWAN: Testbed Implementation and Performance Analysis

Secure end-to-end communication is essential for IoT deployments, yet Transport Layer Security (TLS) proves unsuitable for Low Power Wide Area Network (LPWAN) networks due to high overhead and connection-oriented design. Datagram Transport Layer Security (DTLS) addresses these limitations through datagram-based secure communication over UDP, but constrained networks require additional optimizations to achieve practical performance. This paper presents an implementation and evaluation of DTLS version 1.2 with Static Context Header Compression (SCHC) over commercial LoRaWAN infrastructure using severely constrained hardware with 256 kB flash memory and 64 kB random-access memory. The implementation employs context-based compression for IPv6, UDP, and DTLS headers. Controlled testbed experiments quantify handshake duration, compression efficiency, energy consumption, and resource utilization across spreading factors, acknowledgment modes, and authentication methods. Results demonstrate that header compression reduces handshake duration by 41.7%. Certificatebased authentication requires 146.9 s at spreading factor 12 compared to 73 s for pre-shared keys, while requiring 95.7% of available flash memory. Spreading factor choice has the largest performance impact, causing a 65.2% variation between SF7 and SF12. The work quantifies performance limits for secure LPWAN applications, showing that real hardware introduces extra handshake delays beyond those predicted by simulation.