<> "The repository administrator has not yet configured an RDF license."^^ . <> . . . "Energy efficiency in 5G systems: A systematic literature review"^^ . "To ensure Energy Efficiency (EE) and better Quality of service (QoS), it is necessary to analyze the energy saving possibilities for low resource utilization in the current networks caused by rigorous QoS requirements and implementing EE approach in the planned model for performance improvement. Distributed Denial of Service (DDoS) attacks aim to exhaust the network's processing and communication capacity by saturating it with packets and generating malicious traffic. There are numerous advantages that make Digital Twin (DT) and Intrusion Detection technique (ID) an effective remedy for a range of (fifth generation) 5G problems. A DDoS attack must be immediately detected and stopped before a legitimate user can access the target of the attacker for the 5G network to provide an efficient energy service. Although they clearly show promise in assisting with the creation and implementation of the challenging 5G environment, Digital Twins is still a relatively new technology for 5G networks but will increase EE. In this research, a thorough examination of the materials was carried out to identify the most cutting-edge DT and ID methods. The purpose of this study was to comprehend the problems with Energy Efficiency, the need for DT, and the methods for dealing with large-scale attack by DDoS on Energy Efficient networks. Only 94 of the 1555 articles produced by the procedure were determined to be relevant using inclusion and exclusion criteria. The outcome demonstrates that in 5G networks, DT, and its fundamental approaches, like QoS and DDoS attack mitigation, can be used to regulate the network's Energy Efficiency. Numerous practical applications focusing on 5G Systems use their own principles. The effectiveness of these strategies was evaluated using several assessment criteria, including DT, Intrusion Detection, QoS, Energy Efficiency, and 5G Systems. Each study issue is thoroughly explained, along with typical methods, advantages, disadvantages, and performance metrics. Energy economy, network reliability, privacy, and cost reduction are all considerably increased by the implementation of intrusion detection technology in 5G systems. The decision is supported by the technology's demonstrated efficacy, scalability, real-time detection capacities, low error level, and personalized learning attributes, all of which contribute to the long-term viability of 5G networks as an entire system. © 2024 - IOS Press. All rights reserved."^^ . "2024" . . "28" . "1" . . "International Journal of Knowledge-Based and Intelligent Engineering Systems"^^ . . . . . . . . . . . . . . . . . . . . . . . "A."^^ . "Sarlan"^^ . "A. Sarlan"^^ . . "A."^^ . "Taiwo"^^ . "A. Taiwo"^^ . . "U.D."^^ . "Maiwada"^^ . "U.D. Maiwada"^^ . . "K.U."^^ . "Danyaro"^^ . "K.U. Danyaro"^^ . . "M.S."^^ . "Liew"^^ . "M.S. Liew"^^ . . "U.I."^^ . "Audi"^^ . "U.I. Audi"^^ . . . . . "HTML Summary of #19801 \n\nEnergy efficiency in 5G systems: A systematic literature review\n\n" . "text/html" . .