## 3 Application Fields of Smart Manufacturing and Tactile Internet Powered by 5G
### Virtual Reality and Augmented Reality  
A taxonomy for TI deployment in real-time ultra-reliable low latency (URLL) applications such as Healthcare 4.0, Industry 4.0, virtual reality and augmented reality (VR/AR), and smart education is illustrated in Figure 11. TI is used in all these applications to improve communication, minimize latency, increase bandwidth and reduce overall operational and capital expenditures [53].  
The tactile internet will benefit virtual reality (VR) by enabling'shared haptic virtual environments', in which several users are physically coupled via a VR simulation to perform tasks that require fine motor skills, as presented in Figure 12. High-fidelity interaction requires haptic feedback, which allows the user to perceive objects in VR not only through audio-visual means but also through touch. This enables delicate object manipulations, such as those required in telesurgery, micro-assembly, or other applications requiring extreme sensitivity and precision. When two users interact with the same object, the VR creates a direct force coupling, and the users can feel each other's actions. However, communication delays in today's networked VR systems are too great for stable, seamless user coordination. High-fidelity interaction is only possible with a few milliseconds of communication latency between the users and the VR. During these few milliseconds, the users' movements must be transmitted to the VR server, whic  
Figure 11: Taxonomy of TI for URLL MFG applications (adapted from [8]).  
Figure 10: Existing and future use cases aligned to 5G technical capabilities [52].  
simulation and returns the results to the users in the form of object status updates and haptic feedback. Therefore, even wired communication may be insufficient for remote users. Typical update rates for physical simulation and haptic information display are in the 1000 Hertz range, corresponding to an ideal round-trip communication latency of 1 millisecond. A consistent local view of the VR for all users is thus only possible if delays are kept to a minimum [53; 54].  
Additionally, the authors in [53] describe the statistical characteristics of control and haptic feedback signals, as well as virtual reality-based human-to-machine (H2M) experimental setup. Next, the volume of input and output data in any H2M experimental setup is determined by hardware design parameters such as sampling frequency, the number and type of sensors and actuators [55]. The slave haptic subsystem can be a physical device that interacts with a remote physical environment or a virtual pointer that operates in a virtual environment, such as a virtual hand. Simulated virtual worlds can connect multiple users in a virtual space over a local network. Therefore, a VR-based H2M experimental setup, was developed to investigate the characteristics of control signals from a master device and the corresponding haptic signals from a slave device. The master device consists of a pair of VR gloves, each with two 9-degrees-of-freedom orientation sensors on the thumb and wrist, as well as five flexible sensors on the five fingers for tracking movements and applied forces.  
To summarize, in order to establish a truly immersive VR user experience, there is still a lot of work to be done. The VR quality of experience is greatly reliant on strict latency and reliability standards. Motion sickness is caused by high message transfer part (MPT) delays of 20 milliseconds or more, as well as distortions caused by low data rates and the consequent quality of projected images. As a result, an immersive VR experience requires end-to-end delay and reliability. Figure 13 depicts the expected requirements as well as the key technological enablers for single and multiple user VR scenarios. Then, as two primary thrusts of the future interconnected VR, the envisioned roles of mmWave communications and mobile edge computing (MEC) are also highlighted.