Modeling Latency and Reliability of Hybrid Technology Networking

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<p>Operational safety and security are key concerns within the North American railroad industry. Of growing importance is the ability for real-time identification, monitoring and fault alerting of freight railcars. Operators are enabled to track devices and components of trains, as well as other equipment and personnel, within this system. This vision of an Internet of Things (IoT) applied to the transportation industry has widespread benefits and applications. Wireless Sensor Networks (WSNs) have been extensively utilized for addressing such measurement and monitoring problems. However, the nature of a train’s arrangement requires the sensor nodes to be placed in a long almost-linear network topology. Given ZigBee’s limitations in radio transmission range and network depth, it is infeasible to be used for this and similar applications. Furthermore, due to its low throughput, severe packet loss and high latency may occur, which is unacceptable, especially for equipment failure alert messages. Therefore, we have proposed a heterogeneous multi-hop network approach called Hybrid Technology Networking (HTN), which employs WiFi together with ZigBee. In this paper, we derive a mathematical model to express HTN’s superiority in performance compared to conventional ZigBee-based WSNs. Specifically, we analyze and compare the delay and reliability of HTN and ZigBee networks and also verify the analytical results against our simulations.</p>