The present document captures the findings from the study item of "Study on network energy savings for NR" [2]. The study includes how to model network energy consumption especially for a base station, and evaluations of network energy saving gains as well as impact to network and user performance, by reusing existing KPI whenever applicable or new KPIs as needed. The study is also to identify techniques on gNB and UE side that can improve the network energy savings in various domains, potentially with UE feedback/assistance information and information exchange over network interfaces. The study prioritizes idle/empty and low/medium load scenarios, allow different loads among carriers and neighbor cells, allows legacy UEs to be able to continue accessing a network implementing Rel-18 network energy savings techniques, with the possible exception of techniques developed specifically for greenfield deployments. The study does not include aspects related to IAB.

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Network energy saving is of great importance for environmental sustainability, to reduce environmental impact (greenhouse gas emissions), and for operational cost savings. As 5G is becoming pervasive across industries and geographical areas, handling more advanced services and applications requiring very high data rates (e.g. XR), networks are being denser, use more antennas, larger bandwidths and more frequency bands. The environmental impact of 5G needs to stay under control, and novel solutions to improve network energy savings need to be developed. Energy consumption has become a key part of the operators' OPEX. According to the report from GSMA [3], the energy cost on mobile networks accounts for ~23% of the total operator cost. Most of the energy consumption comes from the radio access network and in particular from the AAU, with data centres and fibre transport accounting for a smaller share. The power consumption of a radio access can be split into two parts: the dynamic part which is only consumed when data transmission/reception is ongoing, and the static part which is consumed all the time to maintain the necessary operation of the radio access devices, even when the data transmission/reception is not on-going. Therefore, there is a need to study and develop a network energy consumption model especially for the base station (a UE power consumption model was already defined in TR38.840), KPIs, an evaluation methodology and to identify and study network energy savings techniques in targeted deployment scenarios. The study investigates how to achieve more efficient operation dynamically and/or semi-statically and finer granularity adaptation of transmissions and/or receptions in one or more of network energy saving techniques in time, frequency, spatial, and power domains, with potential support/feedback from UE, potential UE assistance information, and information exchange/coordination over network interfaces. The study not only evaluates the potential network energy consumption gains, but also assesses and balances the impact on network and user performance, e.g. by looking at KPIs such as spectral efficiency, capacity, UPT, latency, UE power consumption, complexity, handover performance, call drop rate, initial access performance, SLA assurance related KPIs, etc. The techniques studied could avoid having a large impact to such KPIs.