# Millimeter-Wave Smart Antenna Solutions for URLLC in Industry 4.0 and Beyond
## 6 Conclusions  
The increasing demand for URLLC as a result of burgeoning sophisticated and mission-critical applications in Industry 4.0 and beyond necessitates more spectrum and new technologies. The mmWave communications appear to be the key to delivering the solution. As a result, future 5G networks and WLANs are paying close attention to mmWave communications to enable the full potential of Industry 4.0. First, we presented an overview of Industry 4.0 and the stringent communication requirements. We then highlighted the issues associated with existing sub-6 GHz industrial wireless standards and their limitations in the industrial context. Unfurling the challenges of communication at sub-6 GHz ISM bands, we then unfolded the prospects of mmWave communication in an industrial setting. We highlighted the potential advantages, prospects, and challenges of the 60 GHz mmWave ISM band for URLLC in factory automation from the viewpoint of Industry 4.0 and beyond. The WiGig consortium has been working to widespread 60 GHz unlicensed spectrum worldwide, which can be leveraged for smart industrial communication and operations. A detailed dis cussion on IEEE 802.11 ad and 802.11 ay standards for multi-gigabits-per-second data rate communication is also presented. We also identified the prospects of the 60 GHz spectrum for mission-critical and low-latency applications in smart factory automation. Moreover, the propagation challenges at the 60 GHz band were also elucidated. Furthermore, it is expounded that beamforming is a crucial requirement at 60 GHz communication to ensure directional communication. In this view, smart beamforming array antennas as PHY candidates are of paramount importance. We present the review of various state-of-the-art 60 GHz mmWave antenna antennas suitable for Industry 4.0 and beyond. Moreover, several challenges of mmWave antenna design are also highlighted. Various future directions and opportunities are highlighted in this review. The design challenges of mmWave array antennas are presented along with the need for robust RF frontend circuity. The challenges of on-chip antennas and integrated system design are highlighted to devise solutions for them. Novel research aspects of efficient MIMO and beamforming techniques associated with mmWave communication are explored. Moreover, the potential of THz communication and THz antennas, along with their challenges, is presented for the next generation of wireless communication. Moreover, light is shed on the capabilities of distributed antenna systems to provide seamless connectivity at mmWave bands. The role of machine learning to design smart antennas is emphasized, which is a demanding area of research. Furthermore, the irrefutable potential of IRS as a key enabler for the next generation of wireless communication is looming. In this view, we accentuated the promising potential of IRS-assisted smart factories to ensure URLLC in Industry 4.0 and beyond. As a final remark, the 60 GHz mmWave communication with smart antennas holds a promising potential for future industrial automation systems. The use of the huge bandwidth of the mmWave spectrum can pave the way for a wide range of capabilities for Industry 4.0 and beyond. For instance, smart robots, cognitive machines, and other industrial automation systems enable them to actively interact with objects and safely navigate their surroundings using wireless cameras and vision technology. This will facilitate them to become accustomed to changing manufacturing-line conditions, thus unfolding a whole new world of industrial automation possibilities in Industry 4.0 and beyond. Conceptualization, A.J., M.U.R., N.A. and T.K. ; resources, M.U.R., Q.H.A., M.A.I, N.R., S.A. and O.P.F. ; writing--original draft preparation, A.J. and M.U.R. ; writing--review and editing, M.U.R., N.A., T.K., N.R., P.M.R.-u.-S., S.A. and O.P.F. ; visualization, A.J. and M.U.R. ; supervision, M.U.R., Q.H.A. and M.A.I. ; project administration, M.U.R., N.R. and S.A.; funding acquisition, M.U.R., N.R., S.A., P.M.R.-u.-S., O.P.F.