Design and Implementation of a COAP-Based Broker for Heterogenous M2M Applications

In the Internet of Thing (IoT) vision, Machineto-Machine (M2M) applications will be able to communicatewith remote physical devices, being continuously updated as thestatus of things and monitored phenomena change. However,IoT environments have strict constraints concerning limitedenergy, low bandwidth, and limited computing capabilities.Thus, network congestion and scalability issues arise if manysensing applications with heterogeneous requirements demandstate updates for the same resource too frequently. To addressthis problem, in this work we propose, implement and evaluatean application broker for heterogenous M2M applications. Inparticular, our application broker acts as the proxy betweenremote applications and constrained devices. Then, it dynamicallyregulates the frequency of resource state updates leveraging themeasured transmission reliability of update notifications fromthat resource. A key feature of our proposed approach is the useof a max-min fair allocation procedure to obtain a more efficientutilisation of the limited network resources, without starvingsome applications. A prototype of our application broker has beendeveloped for COAP, a standard web-based transfer protocolfor IoT environments. The proposed approach is extensivelyevaluated through emulation and compared to a conventionalproxy that is unaware of network congestion. Our results showthat our solution can provide a significant improvement regardingnetwork utilisation and energy consumption, as well as to bettermeet applications' requirements.