Delay Estimation of Healthcare Applications Based on MQTT Protocol: A Node-RED Implementation

In many developing countries, health monitoring system is among the innovative concepts introduced in recent years. The purpose is to help individuals get proper treatment and diagnosis in a timely manner using advanced medical technologies. IoT has been widely used to connect useful clinical assets and provide patients with smart, dependable, and high-quality healthcare services. In this paper, a new platform independent approach for measuring the delay in exchanging data between publishers and subscribers is proposed. The application was developed using the node-RED flow-based programming tool due to its availability on a variety of platforms; low overhead and capability to manage three levels of QoS to ensure reliability of message transmission makes MQTT to be extensively used. For completeness, three public brokers were tested in order to accurately reflect real-world usage of messaging protocol. Wireshark packet analyzer is used to capture packets while transmitting messages through three levels of QoS with various public brokers in order to analyse end-to-end delays. Results obtained show the maximum end-to-end delay ranged from below 0.7 seconds for fully acknowledged QoS 2 to a few hundreds of milliseconds for unconfirmed QoS 0. QoS 1 appears to be the optimum compromise between low end-to-end delay and minimized variability.