## 6 Open Challenges, Future Prospects and Research Directions
### Capacity-Approaching Probabilistic Amplitude Shaping
#### 6.4.6 Cooperative Relaying  
The future directions of cooperative relaying in FSO communication are centered on enhancing network performance, reliability, and efficiency to address the requirements of increasingly demanding use cases. This involves advancements in relay selection algorithms, integration with emerging technologies, energy-efficient designs, and innovative cooperative relaying strategies.  
One of the key areas of future research is the development of intelligent relay selection algorithms that utilize ML to dynamically optimize the selection of relay nodes based on real-time network conditions. These algorithms can analyze data such as signal quality, node locations, and atmospheric conditions to make informed decisions on the best relay nodes to use at any given time. This dynamic optimization helps to maintain robust communication links, reduce latency, and improve overall network performance. ML techniques like reinforcement learning and neural networks can be particularly effective in predicting and adapting to changing conditions in real-time, ensuring optimal relay performance.  
Integration with Emerging Technologies  
Future research also focuses on integrating relay-assisted transmission with innovative technologies like 5G and future advancements. This integration will enable ultra-reliable low-latency communication (uRLLC) and massive machine-type communications (mMTC), which are crucial for applications like autonomous vehicles, smart cities, and industrial automation. By combining the low-latency and high data rates of 5G with the robust, high-capacity links provided by FSO, these hybrid systems can deliver seamless and reliable connectivity. This approach also supports the dense deployment of IoT devices and ensures that critical applications maintain connectivity even in challenging environments.  
Energy-Efficient Relay Designs  
Energy efficiency is gaining increasing importance in communication networks. Consequently, future research is expected to concentrate on exploring sustainable network operations and the development of green communication protocols.  
Sustainable Network Operations: Future research will explore energy-efficient relay designs to extend network coverage and improve energy sustainability. This includes the development of low-power relays and the utilization of renewable energy sources like solar power for relay nodes. Energy-efficient algorithms that minimize power consumption while maintaining high performance will be critical for ensuring the sustainability of large-scale FSO networks. These advancements are crucial for lowering the carbon footprint of communication networks and for deploying FSO systems in remote or off-grid locations [511; 512].  
Green Communication Protocols: The development of green communication protocols that prioritize energy efficiency without compromising performance will be another focus area. These protocols can manage the power usage of relay nodes and optimize data transmission to reduce energy consumption, contributing to the overall sustainability of the network [511; 512].