# Machine Learning for Physical Layer in 5G and beyond Wireless Networks: A Survey
## 2 5G Technology
### 5G Network Architecture
Real-time intelligent edge-distributed AI and intelligent radio must be a part of 5G design to acquire autonomous services, intelligent calculation, accurate decision planning, and a real-time approach [91]. According to [92], the 5G framework demands intelligent radio (IR) instead of deploying the PHY model as it has specific hardware and transceiver algorithm traits. In contrast, DAI outperforms other approaches with regard to the security and privacy of data.In Table 3, we discuss architectures that support 5G network technologies to deliver expected services. Before moving forward, it is important to understand the trends and services of 5G. Some of the key trends provided by 5G are as follows:  
1. Increased spectrum, bits, and reliability: For proper working and operation, the sub-6 GHz spectrum must deliver increased bits, a large spectrum, and increased reliability [93]. Fifth-generation networks are a standalone approach to provide services for the latest technological applications, such as wireless brain-computer interactions, abbreviated as BCI [94; 95]; extended reality services, abbreviated as XR [96]; connected robotics and autonomous systems, abbreviated as CRAS [97]; distributed ledger technologies, abbreviated as DLT [98]; and much more. This is possible only by exploring more spectrum resources and achieving higher reliability ratios at high-frequency bands. 2. Using volumetric spectral efficiency and metamaterials: 5G demands the use of volumetric spectrum efficiency and energy efficiency, abbreviated as SEE, with bps/Hz/m\({}^{3}\)/Joules units. Along similar lines, 6G requires the support of XR, CRAS, DLT, BCI devices, and flying vehicles, which would not be possible without aerial bandwidths. Furthermore, the 3D evolutionary architecture of 6G requires active surfaces, smart, or intelligent coverings to transmit signals instead of deploying a conventional base system [99]. 3. Moving from a centralized to distributed data approach: Due to the continuous transformation of data from large, big, and centralized to a small and distributed approach, 5G must furnish its infrastructure to provide services \begin{table}
\begin{tabular}{c c} \hline
**5G Network** & **Key Aspect** & **References** \\ \hline
5G Spectrum and Frequency & 1. Multiple frequency ranges. 2. Supports higher frequencies, wide-area, outside-in coverage, deep indoor coverage, reliability, spectral efficiency, and the M2M type of communication. 3. Supports very high throughput services for eMBB, and industrial IoT. 4. Provides a balance between throughput, coverage, quality, and latency. \\ \hline \end{tabular}
\end{table} 
Table 2: _Cont._for current centralized and future distributed data. This is one of the most crucial trends of 5G required for ML, and small data analytics [100]. * Implementing wearable devices: 5G creates a space for smart body implementation, wearable devices, and integrated handsets. All these devices operate through human sensory inputs [101]. * Focusing self-sustaining networks: The technologies upheld by 5G and beyond demand intuitive networks instead of self-organizing networks, supported by previous cellular generations. These self-sustaining networks bring instantaneous sources, network operations, and optimization traits. Furthermore, the network can perform and explore dynamic environmental conditions, states, and key performance indicators [102]. Thus, beyond 5G networks (B5G) create artificial learning, quantum computing (QC), and quantum machine learning (QML) skill sets [103]. * Enhancing communication premises: From 1G to 4G, the primary purpose of these generations is to serve wireless communication, but 5G has slightly different premises. 3 CLS stands for communication, computing, control, localization, and sense, which is potentially given by 6G, allowing it to become a multi-purpose generation. The design of 5G must evolve in a way to achieve all the 3 CLS services and bring something valuable for real-time applications [104].