MQTT-SN, CoAP, and RTP in wireless IoT real-time communications

A great number of Internet of things (IoT) applications rely on real-time communication (RTC) mechanisms for transmission of media. Essentially, applications analyze and process media to make decisions that typically affect actuation and control of embedded devices. IoT networks, however, are subjected to constrains that limit the computational and resource complexity of all entities involved. This is particularly critical when considering the traditional RTC protocols like real-time protocol (RTP) that was not designed to perform well in the context of low-power lossy networks (LLNs). This paper focuses on alternatives to media transport in IoT networks. Specially, constrained application protocol (CoAP) and the message queuing telemetry transport sensor network protocol (MQTT-SN) are presented as valid technologies for media propagation in LLNs. The paper models and compares CoAP, RTP, and MQTT-SN to determine the most efficient scenario for audio, speech, and video transmission.