Enabling Human-Machine Interfaces with 5G RedCap: Architecture, Key Requirements, and Challenges

G wireless communication protocols introduce a new paradigm for Human Machine Interface (HMI), allowing for a seamless user experience everywhere. HMI applications require low latency, balanced data rate, low energy consumption, and cost efficiency. The recent development of 3GPP-based $\mathbf{5 G}$ NR Reduced Capability (RedCap) may serve as the solution to fulfill this objective. This article focuses on the compatibility of the RedCap protocol with developing HMI. We have studied numerous previous research works by other authors related to the requirements of various HMI use cases and conducted a secondary study on how the capabilities of RedCap can satisfy these requrements. We examine the application cases of HMI, such as virtual reality (VR), augmented reality (AR), industrial collaborative robotics (Cobots), and wearables, as well as the RedCap requirements for HMI deployment. Furthermore, we discuss potential technological architectures and characteristics. Comparing the HMI link level requirements with the RedCap link level performance offerings, we observe that RedCap can be a suitable solution to meet the HMI communication demands. Finally, we discuss challenges and potential research directions for accomplishing this goal such as security, privacy, scalability, interoperability, and large level integration.