NexusEdge: Leveraging IoT Gateways for a Decentralized Edge Computing Platform

Edge computing enables scalability and privacy improvements for Internet of Things (IoT) systems, by shifting applications from the cloud to edge servers closer to IoT devices. Conceptually, IoT devices communicate directly with the edge, but in real-world IoT deployments often IoT gateways are needed to bridge devices and edge servers. Design decisions at this gateway layer directly contribute to the responsiveness of edge applications and scalability of the platform, yet these gateways are often overlooked and under-explored. IoT gateways have a compelling mix of features, including reasonable compute capabilities, low cost, direct contact with devices, and spatial distribution in deployments. We hypothesize that a new management layer that organizes already existing gateways can replace expensive edge servers while enabling the privacy, reliability, and performance benefits of executing IoT applications on the edge. We utilize a decentralized architecture that creates a nexus among disjoint gateways using out-of-band discovery, low-overhead abstraction layers, and runtime application scheduling. This platform supports heterogeneous devices, minimizes configuration overhead, executes applications, and provides resiliency to failure. We develop a prototype of the architecture, NexusEdge, and deploy it across several gateways and hundreds of low-power and energy-harvesting devices. When compared to Amazon's AWS IoT Greengrass, NexusEdge shows a 10x improvement in application latency, and a 2.5x reduction in network traffic, indicating better scalability and responsiveness. We demonstrate how NexusEdge supports applications without cloud support, and envision future extensions of this platform.