Unleashing the potential of Real-time Internet of Things

Abstract

With the recent surge in the interest for the Internet of Things (IoT) and an increased deployment of cyber-physical systems (CPS) in commercial and indus- trial applications, distributed systems have gained a significance influence on modern civilization and are performing increasingly complex tasks. Building such platforms in a reliable manner is challenging, as they include concurrent tasks on the application and the communication layers. As the majority of such devices features a single processor, tasked with both communicating over the network as well as sensing and computing, real-time scheduling conflicts arise as the resource separation of the applications in software is difficult to manage. To achieve such independence, we propose a platform consisting of dedicated application (AP) and communication (CP) processors which are completely de- coupled in terms of resource access, clock speeds and power management using BOLT. Leveraging this hardware separation, we then use the Distributed Real-time Protocol (DRP) to provably provide end-to-end real-time guaran- tees for the communication between distributed applications over a multi-hop wireless network. By establishing a set of contracts at run-time, DRP ensures that all messages reaching their destination meet their hard deadline. To demon- strate this, we implement the BLINK scheduler directly on the AP and adapt the LWB round structure to use DRP as a control layer protocol. We show that our system is capable of supporting several hundred simultaneous streams and can respond to requests in maximally 3 stream periods over up to 10 hops.