Using SCHC for an optimized protocol stack in multimodal LPWAN solutions

Abstract

Low Power Wide Area Networks (LPWANs) are formed out of cheap, small, interconnected devices which operate in the sub-GHz domain. The last couple of years, many communication technologies arose in this domain, each with its own characteristics. In order to satisfy more diverse requirements, devices are now equipped with multiple LPWAN radio technologies, which requires the use of a unified protocol stack independent of the underlying LPWAN technology. With its 2128 addresses available and its ability to operate over different link layer technologies, the IPv6 protocol stack would be the ideal candidate. However, many LPWAN configurations do not allow standardized IP/UDP communication, sometimes acquiring more header overhead than there is room for the actual payload. Recently, a new initiative to directly connect constrained devices over IP was initiated by the LPWAN working group of the Internet Engineering Task Force (IETF). This work resulted in the Static Context Header Compression or SCHC mechanism. This header compression mechanism is able to compress the overhead of these internet protocols up to 95%. In order to comply with the IPv6 Maximum Transfer Unit (MTU) of 1280 bytes, a fragmentation mechanism is also included. In this work, we validate the benefits of using SCHC for multimodal LPWAN solutions and show its implementation feasibility on such constrained devices.