System-wide Energy Efficiency Key Performance Indicator (EE KPI) for both LTE/EPC Evolution and Next Generation Mobile System/5G shall be defined with references to the standard specifications in other SDO's such as ETSI. Energy efficiency shall be considered in architecture and functions, in 3GPP standards including LTE/EPC evolution and Next Generation Mobile Systems/5G. 3GPP standards should support energy saving control to maximize energy efficiency under different network loads varying from zero to fully loaded network conditions. 3GPP standards shall aim to ensure that enhancements of standard functions increase the system capacity and coverage, and improve energy efficiency. Energy efficiency control and the associated management (statistics collection, monitoring, and report etc) should not adversely affect the system capacity and performance as well as the QoE/QoS. In order to provide a holistic view of energy efficiency, this study may consider aspects such as extending the operation conditions, e.g. larger ranges of temperature and humidity in equipment rooms (i.e. the operation conditions in which performance and equipment life duration are not affected) to reduce power consumption due to air conditioning.

The architecture definition and evolution should consider supporting energy saving capabilities. Energy saving at three levels: network, site and equipment should be enabled. System-wide energy saving standards should consider the coexistence of multi-radio access technologies 2G/3G/4G and NextGen New Radio as well as non-3GPP accesses to improve energy efficiency. Resource sharing and network collaborations shall be allowed and necessary enhancements shall be made to improve energy efficiency. Energy saving operations in different network nodes/sub-systems (e.g. base stations, backhaul networks, core network, backbone as well as UE's) shall be enabled in a coordinated manner. Energy efficiency shall be able to acquire spatial and temporal knowledge of the radio network environment to enable energy efficient control of the available radio resources to meet the demand.

Energy efficiency control and the associated management (statistics collection, monitoring, and report etc) should not adversely affect the system capacity and performance as well as the QoE/QoS. The energy efficiency control may be localized to a specific network entity and limited to a set of functions to achieve an energy saving target. Balance between distributed and centralized energy efficiency control operations should be made to avoid extra network complexity and signalling. Energy efficiency control should be performed based on:

• operators' policy to meet the targeted energy efficiency KPI;
• the desired level of QoE/QoS network capability in terms of capacity and coverage;
• spatial resolution and the resulting acquisition of measurements data including the deployment scenarios (dense urban, urban, hotspot, indoor, rural areas), network load, traffic density, connection density as well as the types of services.

The extra complexity and signalling to enable energy efficiency control shall be minimized.

Leverage, when possible or applicable (e.g. for UEs in networks supporting dual connectivity) the separation of control plane and user plane traffic (e.g. carried over separate bearers or even network elements/entities) to enhance energy efficiency by enabling separate handling of signalling traffic from data traffic e.g. signalling traffic on long-range low-bandwidth transmission on macro cells while user data on short distance and high-throughput transmission such as small cells. Consider applying separate energy efficiency improvement mechanisms in consideration of the different traffic profiles, patterns , network/link load and deployment scenarios (dense urban/urban/hotspot/indoor/rural). Leverage simplification of control functions such as access control, session, mobility/handover, location management etc to reduce signalling traffic to improve energy efficiency. Consider "on-demand" power saving y by enabling energy saving operations such as switch off or enabling "energy saving mode" (e.g. sleep mode) of those "redundant" network nodes with no or low data traffic load. Dynamic Management of "Energy" Resource:

• Classification of Energy Efficiency (CoE) levels and association of CoE with services types of traffic (common channel signalling, data session management signalling, user data etc), network functions/components and deployment scenarios.
• On-demand allocation of "energy" depending on the network status (deployment scenarios network capacity and load conditions , data vs. signalling traffic, and the energy consumption status) and the user status (traffic/connection density, services/applications).
• Operators Policies Control based on CoE: allocate network resources based on QoS and CoE, e.g. macro cell for less stringent CoE traffic such as common control signalling traffic (broadcast channels, synchronization signals) and small cells for session management signalling traffic and data traffic.

Synchronize and coordinate the energy saving operations in different network nodes/sub-systems (e.g. base stations, backhaul networks, core network, backbone).