CARS: connection as required scheme for horizontal communications in Industry 4.0

In the rapidly evolving landscape of Industry 4.0 (I4.0), the convergence of information and operational technologies necessitates real-time communication and collaboration across cyber-physical systems and the Internet of Things (IoT). Rapid data transmission is particularly critical within enterprises (vertically) and among stakeholders (horizontally) in this complex, heterogeneous ecosystem. While current research has focused on data application, processing, and storage within the cloud-edge-device continuum, cross-edge transmission has received less attention, resulting in challenges such as suboptimal routing and excessive delays in horizontal communications. To address the above issues, this paper introduces a Connection-As-Required Scheme (CARS) specifically designed for delay-sensitive IoT and Cyber-Physical System (CPS) applications, where low-latency communication is essential for operational efficiency. CARS leverages Lyapunov optimization and backpressure algorithms to optimize traffic scheduling and routing, minimizing communication delay between entities. Benchmarking against state-of-the-art solutions, CARS reduces Round-Trip Time (RTT) to approximately 47.0% of conventional methods and decreases delay by 24.5% in TCP-based and 26.0% in UDP-based applications. These results highlight the potential of CARS to facilitate effective, low-latency collaboration in diverse I4.0 environments.