affic with similar energy consumption. The network energy efficiency was not a target when 3G or 4G technologies were defined; the focus was only on the device power efficiency. The thinking was that the network energy effi- ciency is just an implementation topic. As the implementation technology becomes 5G boost for mobile broadband LTE 20+20 5G 100 MHz LTE 20+20 5G 100 MHz User data rate [Mbps] Sector capacity [Mbps] Figure 10.62 Mobile broadband data rate and capacity boost with 5G at 3.5 GHz. 10 5G Performance more efficient, the energy efficiency is improved. But this evolution is too slow com- pared to the traffic increase. Therefore, 5G networks need to include more efficient system-level solutions to reduce the power consumption. The focus has been especially on the energy efficiency during low loading. The learning from LTE networks has been that the average network level utilization is typically 10-25% over 24/7 for the whole network. The relatively low utilization can be explained by the fact that the traffic is unequally distributed over a 24-hour period and unequally distributed over the geo- graphical area. The loading is low in the network during the night time, and there are number of cells in the network that are needed for coverage and carry only low traf- fic volumes. All this means that base stations send nothing 75-90% of the time even in high-loaded networks. The LTE base station power consumption is relatively high also during the idle times because of the transmission of common reference symbols. 5G does not have common reference symbols, and 5G can better utilize power sav- ing techniques in the base station. See Chapter 3 for more details on the technology components. If the low load power consumption can be minimized with 5G, there is a major potential for improving the network-level energy efficiency. Figure 10.63 shows the share of off-time in the base station transmission without any data transmission. The off-time share varies between 91% and 99% depending on the size of Synchro- ni