Adding a Network Coding Extension to CoAP for Large Resource Transfer

This paper presents a smooth way to include Network Coding in the Constrained Application Protocol (CoAP) for large resource transmissions. Devices in the Internet of Things usually communicate using short messages with little data. In some cases, for example, requesting firmware updates, bigger resources need to be transferred. CoAP's recently finalized blockwise transfer scheme can handle large resources, but is not efficient in lossy environments. Network Coding has proven to be more error resistant. This paper demonstrates the limitations of CoAP's existing blockwise transfer scheme and presents a new approach, based on Network Coding. The evaluation compares CoAP's regular blockwise transfer to the new Network Coding extension. Measurements on an implemented client-server application with simulated losses and delay, confirm the benefits of the extension, resulting in reduced transfer durations.