# Sixth-Generation (6G) Networks for Improved Machine-to-Machine (M2M) Communication in Industry 4.0
## 3 Results of the Review
### Target M2M Communication in 6G Networks  
The fully connected, automated Industry 4.0/5.0 smart factory powered by 6G improving production processes and efficiency must evolve from the current hierarchical model towards a fully connected vertical model. Possible gaps at the levels of industrial control systems (IT/OT ICS) and IIoT M2M communication also need to be filled. It will be advantageous to deploy the 6G networks, autonomous networks, and converged data security technologies described later in this article. It is also worthwhile to assess the impact of vulnerabilities or risks that may be exploited by attackers (Table 4). Improvements in the 6G security architecture may include:  
* In the physical layer: 6G-authentication and key agreement (AKA) protocol, physical layer authentication, novel user subscription models (eSIM), and novel authentication protocols for non-third generation partnership project (3 GPP) networks. * In the connection layer: end-to-end security services and policies and user security using biological characteristics of individuals. * In the application layer: novel security applications and novel privacy schemes [4]. 6G visible light communication technology attacks and threats include:  
* Authentication attacks;
* Access control attack;
* Jamming attacks;
* Data modification attack;
* Eavesdropping attacks [4]. \begin{table}
\begin{tabular}{l c c c} \hline \hline
**Technology** & **5G** & **5.5G** & **6G** \\ \hline Ultra-reliable and low-latency communications (URLLC) & + & + & \\ \hline Massive machine-type communications (mMTC) & + & + & \\ \hline Enhanced mobile broadband (eMBB) & + & + & \\ \hline Uplink centric broadband communication (UCBC) & & + & + \\ \hline Real-time broadband communication (RTBC) & & + & + \\ \hline Human-centric services (HCS) & & + & + \\ \hline Ubiquitous mobile ultra-broadband (uMUB) & & + \\ \hline Ultra-high data density (uHDD) & & & + \\ \hline Ultra-reliable low latency communications (uHSLLC) & & + \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparison of use cases for 5G, 5.5G, and 6G systems [3]. The high performance of MIMO mass systems will be ensured by the use of intelligent multi-surface (IMS) and IRS, AI/ML, terahertz (THz) communications, cell-free architectures, wireless location and sensing, vehicular communications, extraterrestrial communications, remote sensing, and interplanetary communications [5]. Massive MIMO increases throughput by grouping antennas at both the transmitter and receiver, providing high spectral and energy efficiency with relatively simple processing. This includes processes related to pilot contamination, channel estimation, pre-encoding, user scheduling, energy efficiency, and signal detection [6]. Factors contributing to greater growth in wireless data traffic include:  
* Smart factories;
* Smart homes;
* Smart cars;
* Unmanned aerial vehicles (UAVs);
* Smartphones, smartwatches, and smartbands;
* Wearable devices;
* Broadband access [6]. The Internet of Remote Things (IoRT) provides the opportunity to expand the Internet of Things, producing and providing services in remote and geographically isolated areas where traditional Internet connectivity is a challenge. Non-terrestrial networks (NTNs) are a solution that enables the integration of satellites and UAVs with cellular networks. The 3 GPP activities have addressed the problem of standardizing the NTN network to provide an energy-efficient IoRT environment in 6G networks (Figures 2-5) [7].