# Future Is Unlicensed: Private 5G Unlicensed Network for Connecting Industries of Future
## 2 Background  
### Industry 4.0  
The advent of modern emerging industrial technologies, known as Industry 4.0, is an evolutionary trend of automation and data exchange in industrial technology after mechanization (First Industry), electrification (Second Industry), and digitalization (Third Industry) [20; 21]. The fourth industrial revolution focuses on incorporating IoT (Industrial IoT or IIoT [22]) and cyber-physical technologies in the domain of industrial automation with the key purpose of increasing the competitiveness of industrial automation verticals such as manufacturing, energy, utilities, oil and gas refineries, and transportation [23]. For example, in manufacturing systems, we need reliable communication for smart production, maintaining sustainable supply chain networks, and real-time process monitoring, as presented in [4; 24]. Communication for automated and connected industries needs strict criteria in terms of latency, availability, throughput, and the number of devices for diverse Industry 4.0 equipment, as shown in Table 2[25]. Such vital communications needs in Industry 4.0 generate the opportunity for the communication to handle mobile robots, autonomous guided vehicles, and specialized head-mounted displays' application for employees. In support, 5G NR access technology is actively working on ultra-reliable low-latency communications (URLLC), enhanced mobile broadband (eMBB) for use cases like extended reality (XR), connectivity for massive machine-type communications (mMTC), time sensitive networks (TSN) and Ethernet replacement, and expansion to the unlicensed spectrum for the Industry 4.0 applications [26].  
The 3 rd Generation Partnership Project (3 GPP) introduced NR-U in the unlicensed sub-7 GHz bands in 3 GPP Release 16[6] to provide a necessary technology supporting the future industry and society. NR-U is a groundbreaking transformation of LTE in the Unlicensed band (LTE-U) [28]/Licensed Assisted Access (LAA) [29] from 4G LTE to 5G NR and provides an alternative to mitigate the bandwidth scarcity problem by leveraging the unlicensed spectrum in NR operations. Due to its high availability and relatively easy access to the unlicensed spectrum, NR-U is expected to play a crucial role in future cellular networks. Figure 1 shows the evolution of NR-U from early 2013 as LTE-U, which eventually will lead to the integral part of NR in the future.  
\begin{table}
\begin{tabular}{l l l l l} \hline \hline
**Industrial Devices** & **Latency** & **Availability** & **Throughput** & **Number** \\ \hline
**Industrial robot** & \textless{}1 ms & \textgreater{}99.9999\% & Kbps & \textgreater{}100 \\ \hline
**Mobile robot** & \textless{}1 ms & \textgreater{}99.9999\% & Mbps & \textgreater{}100 \\ \hline
**Sensors** & \textless{}100 ms & \textgreater{}99.999\% & Kbps & \textgreater{}200 \\ \hline
**Head-mounted display** & \textless{}10 ms & \textgreater{}99.9999\% & G-Mbps & \textgreater{}50 \\ \hline
**Handheld terminals** & \textless{}10 ms & \textgreater{}99.9999\% & M-Kbps & \textgreater{}50 \\ \hline
**Automated guided vehicles** & \textless{}10 ms & \textgreater{}99.9999\% & Mbps & \textgreater{}10 \\ \hline
**Security camera** & \textless{}100 ms & \textgreater{}99.999\% & G-Mbps & \textgreater{}10 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Key performance requirement (KPI) of Industry 4.0 devices [27].