RTP transport in IoT MQTT topologies

Media transmission in the context of constrained IoT devices is of critical importance to support several solutions that enable interaction with the physical environment. This includes solutions that range from scenarios of occupancy estimation in building automation to traditional audio and image processing in remote sensing. Many modern access side IoT networks follow Event Driven Architecture (EDA) topologies that rely on brokers to forward messages between endpoints. The Message Queuing Telemetry Transport (MQTT) is one such protocol that can be used to encapsulate well known Real Time Protocol (RTP) audio and media packets. Unfortunately, MQTT relies on TCP transport that is not well suited in IoT constrained environments. This paper introduces a scheme that leverages some of the MQTT features to enable the reliable transmission of media in the context of Lossy Low Power Networks (LLNs). Specifically, this scheme is presented, analyzed, optimized and compared against other state-of-the-art mechanisms.