# Energy Efficiency for 5G and Beyond 5G: Potential, Limitations, and Future Directions
## 3 Identifying Pros and Cons of Available Solutions
\begin{table}
\begin{tabular}{c c c c} \hline
**Features** & **Study 1 [23]** & **Study 2 [24]** & **Study 3 [25]** \\ \hline Metrics & Maximize SEE & Maximize SEE & Improve secrecy \\ \hline Optimization variable & Hybrid BF & Hybrid BF & BF, Alternating Optimization \\ \hline Takes into consideration imperfect CSI & Yes, for wiretap channels & Yes, for jamming and wiretap channels & Yes, for direct and cascaded channels of the legitimate and eavesdropping links \\ \hline Other constraints & SINR requirements, analog precoder power, transmit power constraints, RIS & Target rate requirements, wiretap rate & Worst case QoS constraints and the UMC of uni-modal constraint & the phase shifter \\ \hline Use of SCA & Yes & Yes & Yes \\ \hline Charnes-Cooper approach & Yes & No & No \\ \hline Use of interference & No & Yes & No \\ \hline EE improvements & NA & 0.0814 and 0.1190 bps/Hz,/Joule & NA \\ \hline \end{tabular}
\end{table} 
Table 2: Features of studies of beyond 5G new networks. \begin{table}
\begin{tabular}{c c c c} \hline
**Study** & **Strength** & **Limitation** & **Real Network Development Considerations** \\ \hline Study 1 [9] & Comprehensive, multiple techniques, green sources & Assumes allowable power source availability, complex infrastructure & Assumes ideal-size conditions, may require complex energy management systems \\ \hline Study 2 [14] & Proactive, considers mobility, minimizes wiretage from idle cells & Radius on accurate mobility prediction & Not explicitly addressed, but remains controlled control and groundlink scalability \\ \hline Study 3 [11] & Dynamic, adaptive to avoid time over behavior & High computational complexity & Not explicitly addressed, but computational complexity could be a challenging \\ \hline Study 4 [12] & Distributed, adaptable to traffic/interference & Learning phase required, potential for suboptimal policies & Regories real-time monitoring and adaptation to network conditions \\ \hline Study 5 [14] & Provides optimal (IIP) and routing (GA) solutions, considers BS & Complexity of EE, GA needs parameter tuning & Implementation complexity for joint optimization and BS-switching \\ \hline Study 6 [15] & Considers dynamic point selection (CARI, load balancing, cell scanning) & Heuristic approach may not guarantee global optimality & Regories coordination between BSs and control controller \\ \hline Study 7 [13] & Adaptive to traffic patterns, balances energy saving and QoS & Regories training, may not generalize to all scenarios & Real-time traffic estimation and BS-control needed \\ \hline Study 8 [14] & Simple, efficient, good energy-saving performance & May and be optimal for complex network topologies & Practically of frequent BSs switching, impact on QoS \\ \hline Study 9 [17] & Adaptive to traffic load, balancing energy efficiency \& data rate & Regories accurate traffic prediction, potential for handover overhead & Regories coordination between fronthand and backhaul, potential for increased complexity \\ \hline Study 10 [15] & Simple, adaptable to traffic patterns, guarantees delay constraints & Limited to low traffic periods, assumes Poisson arrivals & Regories real-time traffic estimation and prediction \\ \hline \end{tabular}
\end{table} 
Table 3: Advantages and limitations of energy efficiency studies of 5G networks. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Comparison** & **Study 1**[23] & **Study 2**[24] & **Study 3**[25] \\ \hline Advantages & Improved SEE, robust to imperfect AoD, CSI & Improved SEE, enhanced security, robust to CSI, flexible and adaptable & Improved secrecy, robust to CSI \\ Disadvantages & Limited to STIN scenarios & Increased complexity due to RIS, computation intensive for & High computational \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Studies’ comparisons of beyond 5G new networks.