# A Review-Unguided Optical Communications: Developments, Technology Evolution, and Challenges
## 6 Contemporary Developments with UOC Technology
### AI in UOC  
AI is an emerging field that performs computations to resolve problems by emulating human biological (cognitive) processes such as learning, thinking, and adapting. This section provides a broad review on the implementation of AI in FSO communication systems aiming to enhance quality and the performance of data transmission and reception. AI is successfully implemented into almost all the scientific fields and is currently entering into optical communication systems, in particular to establish optimal optical data transportation, system characterization, system operation/performance monitoring, optical network planning/control/management, mitigation of nonlinearities, modulation format recognition, transmission quality estimation, etc. [444]. Over the past few decades, research on the incorporation of AI mechanisms in optical communication for the applications of photonic device (source and detector) control, data transmission, and switching, and network management have become increasingly popular. AI general design techniques and their optimization algorithms that are being applied in optical communication networks nowadays, are shown in Figure 39a [445]. The design of optical path routing/establishment and network planning has been conducted based on several search algorithms and theories of different optimization techniques. All those classical algorithms/techniques are now being replaced by several AI and machine learning (ML) algorithms such as genetic algorithms, simulated annealing, local search techniques, improved grey wolf optimization, swarm optimization, etc. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Context** & **Type of Application** & **Ref.** & **Description** & **Hybrid Network Type** \\ \hline \multirow{6}{*}{Outdoor} & Cellular networks & [421] & Rate analysis and Coverage & RF/VLC \\  & eHealth & [422, 423] & Remote patient monitoring & OCC/Bluetooth \\  & Positioning and navigation & [424, 425, 426] & Space–air-ground–ocean-integrated communication & FSO/VLC, and RF/OCC \\  & Vehicular communication & [427, 428, 429, 430, 431] & V2V, V2I communication, & WiFi/VLC, VLC/RF, V2X, RF/OCC, and RF/FSO \\  & Link reliability, high data rate, ocean monitoring, and Internet of Underwater Things (IoUT) & [432, 433, 434, 435] & Link range, type of water, environment & RF/FSO, and acoustic/FSO \\  & High-data-rate & & & \\  & communication, the IoT, and 5G/6G & & & \\  & High-data-rate & & & \\  & communication, IoUT, ocean monitoring, and underwater wireless optical sensor & [439, 440, 441, 442, 443] & Multiple hops are used to connect & FSO-UWOC, UWOC-FSO, and RF-UWOC \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._  
Figure 39: (**a**) AI design subfields and techniques, and (**b**) schematic of turbulence mitigation feedback network with CNN and GDO. Game theory, where different intelligent agents involved in a decision-making process, was proposed for multimode hybrid RF/FSO networks in [446; 447]. In this intelligent technique, actions taken by one agent have an impact on others. Intelligent agents keep a knowledge base about environmental changes, and the impact of their actions, and use these data when they take decisions to act to adapt the network to the changing conditions. In FSO networks, non-deterministic events will occur frequently due to the lack of thorough studies and accurate predictions of environmental changes over time. Therefore, the incorporation of AI systems/techniques in FSO communications becomes highly significant to operate the data link in a robust way, even under bad weather conditions. Bayesian models have been used to build robust agents to handle the uncertainty as well [448]. The Markov technique is preferred to handle decision making when the current state of the agent solely defines its further actions [449]. Apart from these AI algorithms, several ML techniques are also coming up nowadays and are entering into FSO communication systems.