Energy-Efficient Multicast Service Delivery Exploiting Single Frequency Device-To-Device Communications in 5G New Radio Systems  
[PERSON]  
1 DIIES Department, University Mediterrane of Reggio Calabria, 89100 Reggio Calabria, Italy;  
1 [EMAIL_ADDRESS] (S.P. ); [EMAIL_ADDRESS] (F.R. ); [EMAIL_ADDRESS] (A.M.); [EMAIL_ADDRESS] (A.I)  
[PERSON]  
1 DIIES Department, University Mediterrane of Reggio Calabria, 89100 Reggio Calabria, Italy;  
1 [EMAIL_ADDRESS] (S.P. ); [EMAIL_ADDRESS] (F.R. ); [EMAIL_ADDRESS] (A.M.); [EMAIL_ADDRESS] (A.I)  
[PERSON]  
1 DIIES Department, University Mediterrane of Reggio Calabria, 89100 Reggio Calabria, Italy;  
1 [EMAIL_ADDRESS] (A.I)  
1 sara. * enhanced Mobile Broadband (eMBB) coping with the significant increase of data volumes, overall data capacity, and user density;
* massive Machine Type Communications (mMTC) requiring low power consumption for a huge number of connected devices;
* Ultra-Reliable and Low Latency Communications (URLLC) providing safety-critical and mission critical applications. The service heterogeneity imposed by the need to effectively manage the coexistence of Human-Type Communication (HTC) and Machine-Type Communication (MTC) requires that the 5G technology puts in place appropriate changes and improvements, at both application and customer levels, to manage resources efficiently at higher data-rates, lower latency and higher reliability, and to support effectively a huge number of connected devices. MTC [5], also known as Machine-to-Machine communication (M2M), refers to data exchange among MTC devices and foresees a wide range of applications and services. Generally, MTC devices require high power consumption during a wireless communication. Thus, energy efficiency represents a very important concern in 5G networks that foresee the presence of a massive number of devices (i.e., sensor nodes) deployed for gathering environmental information, health-care monitoring, improving security, and so on. 5G shifts the focus on energy efficiency rather than throughput. That is why network operators are working hard with the aim to offer more and more efficient solutions in energy for 5G New Radio (NR) systems. The change of the point of view, from throughput-optimized to energy-efficiency-optimized solutions, is due to several reasons. On one hand, 5G has to face to the management of the wide and always-increasing diffusion of low-power MTC devices (i.e., sensor/machine nodes). Indeed, energy efficiency is a decisive feature for MTC devices, for example, when sensing and monitoring in disperse areas where it is difficult to regularly replace the battery. On the other side, the problem of the environment impact became more and more serious in the last decade. In particular, the Information and Communications Technology (ICT) industry is also responsible of the global power consumption by generating a hundred million tons of CO\({}_{2}\). For these reasons, one of the main bets of 5G is to reduce energy consumption by ensuring longer battery life of sensor/machine nodes. By doing so, the forthcoming next generation technology not only aims to enhance the overall network performance, but it will also ensure a sustainable environmental development and to boost the system autonomy. Hence, Energy-Efficiency has actually become a key performance indicator for future 5G networks. In order to enhance the network capacity and to boost the energy efficiency of 5G networks, offloading techniques, i.e., Device-to-Device (D2D) [6] communications, could be the key. D2D communications allow devices in close proximity to activate side-links (D2D links) by exploiting cellular radio resources. Supporting direct communications among neighboring devices reduces the cell-edge effect and increases the coverage extension, the Aggregate Data Rate (ADR), and the system energy efficiency, thanks to the lower transmit power compared to that needed for communication to the gNodeB (the new 5G base station).