  Over the last decade, society and industries are undergoing rapid
digitization that is expected to lead to the evolution of the cyber-physical
continuum. End-to-end deterministic communications infrastructure is the
essential glue that will bridge the digital and physical worlds of the
continuum. We describe the state of the art and open challenges with respect to
contemporary deterministic communications and compute technologies: 3GPP 5G,
IEEE Time-Sensitive Networking, IETF DetNet, OPC UA as well as edge computing.
While these technologies represent significant technological advancements
towards networking Cyber-Physical Systems (CPS), we argue in this paper that
they rather represent a first generation of systems which are still limited in
different dimensions. In contrast, realizing future deterministic communication
systems requires, firstly, seamless convergence between these technologies and,
secondly, scalability to support heterogeneous (time-varying requirements)
arising from diverse CPS applications. In addition, future deterministic
communication networks will have to provide such characteristics end-to-end,
which for CPS refers to the entire communication and computation loop, from
sensors to actuators. In this paper, we discuss the state of the art regarding
the main challenges towards these goals: predictability, end-to-end technology
integration, end-to-end security, and scalable vertical application
interfacing. We then present our vision regarding viable approaches and
technological enablers to overcome these four central challenges. Key
approaches to leverage in that regard are 6G system evolutions, wireless
friendly integration of 6G into TSN and DetNet, novel end-to-end security
approaches, efficient edge-cloud integrations, data-driven approaches for
stochastic characterization and prediction, as well as leveraging digital twins
towards system awareness.
