Using SCHC for an optimized protocol stack in multimodal LPWAN solutions

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

Device discovery and context registration in static context header compression networks

Due to the limited bandwidth of Low-Power Wide-Area Networks (LPWAN), the application layer is currently often tied straight above the link layer, limiting the evolution of sensor networks distributed over a large area. Consequently, the highly efficient Static Context Header Compression (SCHC) standard was introduced, where devices can compress the IPv6 and upper layer protocols down to a single byte. This approach, however, assumes that every compression context is distributed before deployment, again limiting the evolution of such networks. Therefore, this paper presents two context registration mechanisms leveraging on the SCHC adaptation layer. This is done by analyzing current registration solutions in order to find limitations and optimizations with regard to very constrained networks. Both solutions and the current State-of-The-Art (SoTA) are evaluated in a Lightweight Machine to Machine (LwM2M) environment. In such situation, both developed solutions decrease the energy consumption already after 25 transmissions, compared with the current SoTA. Furthermore, simulations show that Long Range (LoRa) devices still have a 80% chance to successfully complete the registration flow in a network with a 50% Packet Error Ratio. Briefly, the work presented in this paper delivers bootstrapping tools to constrained, SCHC-enabled networks while still being able to reduce energy consumption