6G    

 

 

 

TDoc Tracking - Energy Efficiency

Energy efficiency in 6G is set as a day-one design objective. The work starts with identifying candidate technologies and defining models, metrics, and scenarios for evaluation. This gives a clear structure for how energy saving will be built into the system from the beginning.

The focus covers both network energy saving and UE power saving. Network side discussions include leaner carriers, extended or default SSB periodicity, on-demand SS/PBCH/SIB1, Cell DTX/DRX, TRP on/off, and SCell dormancy with fast activation and deactivation. UE side discussions include low-power wake-up signal and receiver, duty-cycled DRX, relaxed measurement procedures, and bandwidth or MIMO layer adaptation. Joint mechanisms are also considered to coordinate BS and UE behavior for better overall efficiency.

The work is structured into idle-mode and connected-mode tracks. Main topics include PDCCH monitoring reduction, cWUS and LP-WUS operation, and power-domain enhancement in line with waveform design.

Across companies, there is strong support to define a core set of energy-saving features from the first 6GR release. The goal is to avoid fragmented or optional deployments seen in 5G. The plan is to balance energy gain with complexity and to use common BS and UE power models with clear KPIs for evaluation.

Work plan & study structure

The 6GR energy efficiency study is structured with a clear three-meeting plan. The goal is to identify, evaluate, and agree on key energy-saving technologies for the first phase of the 6G Radio SI in a systematic way.

The first step happens at RAN1 #122. The main target is to define the scope. Common power consumption models, evaluation metrics, and baseline scenarios are agreed here. Network, UE, and joint energy saving areas are identified at a broad level.

The second step is at RAN1 #122bis. This meeting refines the scope into concrete candidate technologies. Industry brings contributions. Technical discussions and initial evaluations are made. Promising solutions are expected to reach preliminary agreement.

The last step is at RAN1 #123. The focus is on consolidating the candidate technologies. The evaluation framework is finalized. A clear set of mechanisms is locked in to guide the follow-up detailed studies.

In this context, a candidate technology is not just a concept. It must have a clear problem statement, a defined baseline, expected or measured energy gains, and measurable KPIs.

This structured approach ensures that energy-saving technologies are not only theoretical but also practical. It supports verifiable evaluation, real deployment, and alignment with day-one 6GR design principles. It also aims to avoid the fragmented and optional structure that limited energy efficiency improvements in 5G.

  • Three-meeting arc for EE — #122 defines scope/models/metrics; #122bis converges on candidate technologies; #123 refines candidates and locks evaluation.
  • “Candidate technology” definition — A concrete mechanism with problem statement, baseline, expected gains, measurable KPIs, suitable for first-phase 6GR SI.

Day-1 focus & guardrails

A central principle of the 6GR energy efficiency study is to make energy saving a Day-1 design priority. This is different from 5G, where many energy-saving features came later and were adopted unevenly.

The goal is to integrate energy-saving mechanisms from the first 6G release. These mechanisms must deliver strong and stable energy savings in real deployments. They should work across vendors, operators, and device types. This avoids the fragmented and optional structure that limited the impact of energy-saving features in 5G.

The study focuses on simplicity, architectural coherence, and forward-looking compatibility. Existing NR elements such as synchronization structure, control signaling, and power adaptation will be reused or adapted when it helps reduce complexity and speed up deployment.

At the same time, the study tries to avoid backward-compatibility traps that can block future evolution or force the system to keep legacy signaling overhead.

By setting clear Day-1 guardrails around simplicity, robustness, and efficiency, the 6GR energy efficiency framework aims to enable cohesive, system-wide energy optimization rather than fragmented feature additions.

  • Day-1 inclusion — Prioritize mechanisms with large, deployment-robust savings; avoid fragmented optionality.
  • Simplicity & compatibility — Reuse NR structures where possible, minimize options, and avoid backward-compatibility traps.

Design princeple and guideline

  • Day-1 Integration of Energy Efficiency: Prioritize mechanisms that deliver meaningful, deployment-robust energy savings from the first release of 6GR, avoiding the incremental and fragmented approach seen in 5G NR.
  • Mandatory Baseline Features: Define a core set of mandatory EE features to ensure uniform adoption across networks and UEs, avoiding optionality that leads to inconsistent real-world deployment and suboptimal energy performance.
  • Simplicity and Architectural Coherence: Reuse and adapt existing NR structures—such as synchronization signals, DRX/DTX frameworks, and PDCCH skipping—where possible to reduce complexity while enabling efficient Day-1 energy-saving operations.
  • Avoiding Backward Compatibility Traps: Design clean-slate mechanisms that are not constrained by legacy NR assumptions (e.g., fixed 20 ms SSB periodicity), enabling deep sleep opportunities and maximizing both network and UE savings.
  • Robustness Over Optionality: Prioritize mechanisms that provide consistent savings under diverse deployment scenarios (e.g., urban, suburban, low-load), minimizing the dependency on optional feature negotiation.
  • Unified Mechanism Design: Aim for integrated, minimal-overhead solutions that align network and UE power-saving strategies—such as joint DTX/DRX, LP-WUS/WUR, and flexible SSB periodicity—to maximize aggregate gains.
  • Extensibility for Future Enhancements: Ensure that Day-1 EE mechanisms are structured to support future feature evolution without requiring major architectural overhauls or introducing additional signaling burdens.
  • Deployment Practicality: Favor solutions that are simple to configure and operate, reducing operator and device-side complexity while achieving measurable energy efficiency improvements.

Network Energy Savings (NES)

Network energy saving in 6GR is built on the idea of minimizing unnecessary activity. The target is to create an ultra-lean baseline carrier that lets the network stay in deep sleep when traffic is low or not present.

In 5G, periodic transmissions like SSB and system information made it difficult to save energy. In 6GR, on-demand operation becomes the default. The bandwidth and periodicity of synchronization signals are reduced. Transmission intervals become flexible or extended. Two-step search and on-demand SS/PBCH/SIB1 are used to keep accessibility while lowering the energy cost of always-on signals.

Cell, TRP, and SCell activity are controlled dynamically. DTX/DRX and fast dormancy with quick reactivation allow the network to scale power based on actual traffic.

A key part of this lean design is the shift from periodic reference signals to aperiodic or triggered ones. This cuts down baseline energy use without hurting coverage or access performance.

These mechanisms together form the foundation of network-side energy efficiency in 6GR. The goal is to support sustainability targets while enabling cost-efficient operation.

  • Ultra-lean carriers by default — Reduce periodic signaling and shift to on-demand operation as the norm.
  • SS/initial access efficiency — Smaller SSB BW and adaptive/extended periodicity, two-step search, on-demand SS/PBCH/SIB1 for low-activity cells.
  • Cell/TRP/SCell activity control — Cell DTX/DRX, TRP on/off, SCell dormancy with fast (de)activation coordinated by traffic context.
  • On-demand reference signals — Prefer aperiodic/triggered RS over periodic RS wherever feasible.

Design princeple and guideline

  • Ultra-Lean Carrier Baseline: Establish ultra-lean carrier design as the default operational mode, minimizing always-on signaling and enabling deep network sleep states under low or zero traffic conditions.
  • On-Demand Signaling as Norm: Shift from periodic to on-demand transmission for SS/PBCH/SIB1 to reduce baseline power consumption while preserving accessibility for idle and low-activity UEs.
  • Efficient Initial Access: Support adaptive and extended SSB periodicity, reduced SSB bandwidth, and two-step search procedures to balance access performance with energy efficiency.
  • Dynamic Cell/TRP/SCell Control: Enable fine-grained power state management through cell DTX/DRX, TRP on/off control, and SCell dormancy with fast (de)activation coordinated by real-time traffic context.
  • Aperiodic Reference Signals: Favor triggered or event-based reference signal transmission over periodic patterns, reducing unnecessary RF activity during low-load periods.
  • Traffic-Aware Activation: Link cell and TRP activation to traffic triggers or wake-up signals to minimize idle energy drain while ensuring fast service resumption when needed.
  • Multi-Carrier Energy Coordination: Use anchor and NES carriers strategically to keep non-anchor carriers in deep sleep, only activating them on demand for capacity or coverage expansion.
  • Scalable Deployment Framework: Design NES mechanisms to be applicable across diverse deployment scenarios, from macro to small cells, ensuring consistent and measurable energy gains.

UE Power Saving (UEPS)

UE power saving in 6GR focuses on cutting device-side energy use through smarter control of wake-up, monitoring, and reception behavior.

In 5G, UEs relied on constant wideband monitoring and high-power decoding. In 6GR, low-power wake-up mechanisms such as common or dedicated LP-WUS patterns are introduced. These are closely tied with paging and control signaling. The goal is to reduce PDCCH monitoring overhead and keep the UE in a low-power state longer.

Duty-cycled operation becomes more efficient with deeper and longer DRX cycles. Smarter wake-up strategies and relaxed or conditional measurements let the UE sleep longer without breaking service continuity.

Dynamic bandwidth and MIMO layer adaptation align active RF and baseband resources with real traffic and coverage conditions. This avoids unnecessary power use during low-throughput or idle periods.

Lightweight control procedures reduce blind decoding and processing. The power consumed by the UE scales with actual activity instead of staying high all the time.

These mechanisms make UE power saving a core Day-1 design pillar in 6GR. The design works across different device types, from ultra-low-power IoT to high-performance XR, while delivering strong energy savings.

  • Low-power wake-up — Common WUS/cWUS/LP-WUS patterns to reduce wide PDCCH monitoring; align with paging design.
  • Duty-cycled operation — Deeper/longer DRX with smarter wake-ups and relaxed/conditional measurements.
  • Bandwidth/MIMO adaptation — Dynamically scale UE active bandwidth and MIMO layers to traffic/coverage needs.
  • Lightweight control — Reduce blind detections and avoid heavy procedures in low-throughput modes.

Design princeple and guideline

  • Low-Power Wake-Up as Default: Introduce common and configurable LP-WUS/cWUS mechanisms to minimize wideband PDCCH monitoring, tightly integrating wake-up signaling with paging design for low-energy UE operation.
  • Deeper Duty-Cycled Operation: Extend DRX cycles with smarter wake-up strategies, allowing UEs to remain in low-power states longer while maintaining service reliability through relaxed or conditional measurement configurations.
  • Adaptive Bandwidth Usage: Dynamically scale UE active bandwidth according to traffic demand and coverage conditions, enabling efficient RF/baseband operation without full-carrier monitoring during low activity.
  • MIMO Layer Adaptation: Reduce the number of active MIMO layers in low-throughput or coverage-stable scenarios to minimize power consumption without degrading essential connectivity.
  • Lightweight Control Plane: Minimize blind decoding, reduce PDCCH monitoring density, and streamline control procedures to lower power draw in idle and low-throughput states.
  • Unified Power State Management: Align UE power-saving features—such as DRX, LP-WUS, and bandwidth adaptation—into a cohesive framework to maximize energy efficiency without increasing signaling complexity.
  • Traffic-Aware Wake-Up: Trigger wake-up events based on traffic context or on-demand signaling, avoiding unnecessary monitoring cycles when no data activity is expected.
  • Support for Device Diversity: Ensure that UEPS mechanisms are scalable and applicable across a wide range of device classes, from ultra-low-power IoT to high-performance XR, enabling consistent power-saving benefits.

UE-Network Joint coordination

UE power saving in 6GR aims to minimize device energy use through intelligent control of wake-up, monitoring, and active reception.

5G devices relied on wideband monitoring and continuous high-power decoding. 6GR moves to low-power wake-up mechanisms such as common or dedicated LP-WUS patterns. These integrate with paging and control signaling to cut PDCCH monitoring overhead and keep the UE in low-power states longer.

Duty-cycled operation improves through deeper and longer DRX cycles. Smarter wake-up strategies and conditional measurement rules allow longer sleep without losing service continuity.

Dynamic bandwidth and MIMO-layer adaptation align active RF and baseband use with real traffic demand. This limits power draw when data is sparse or the UE is idle.

Lightweight control procedures further reduce blind decoding and processing. As a result, UE power scales with actual activity.

Together, these principles make UE power saving a Day-1 foundation of 6GR design. The same approach applies to all device classes, from ultra-low-power IoT to high-performance XR, while achieving large energy gains.

  • Scheduling aligned to energy — Burst-friendly allocations, rapid (de)activation of carriers/cells/TRPs, traffic-aware timing to maximize sleep windows.
  • Reference-signal governance — Joint policies for when/where RS are sent so network/UE savings reinforce each other.
  • Mobility & measurements — Event-conditioned, on-demand measurements; sleep-preserving beam/mobility actions.

Design princeple and guideline

  • Traffic-Aware Scheduling: Align UL/DL scheduling with bursty traffic patterns to minimize active time for both network and UE, enabling longer and more predictable sleep windows.
  • Coordinated (De)Activation: Enable rapid activation and deactivation of carriers, cells, and TRPs in coordination with UE activity, ensuring energy savings are synchronized between both ends.
  • Reference Signal Governance: Establish joint policies to control when and where reference signals are transmitted, favoring triggered or aperiodic signaling that minimizes unnecessary UE monitoring and network transmissions.
  • Shared Power State Awareness: Ensure network and UE exchange state information or follow shared timing structures to align sleep and wake cycles for maximum efficiency.
  • Event-Conditioned Measurements: Replace rigid periodic measurement frameworks with event-based or on-demand measurement triggering to reduce continuous monitoring overhead.
  • Sleep-Preserving Mobility: Adapt beam and handover procedures to minimize UE wake-up time, using prediction or context-based triggers rather than constant scanning.
  • Energy-Synchronized Control Plane: Design control signaling such that energy-saving actions on the network side directly translate to UE power reduction, ensuring both ends benefit from each operation.
  • Low-Latency Resume: Maintain efficient and low-overhead mechanisms for fast reactivation after sleep periods to balance energy savings with performance and user experience.

Idle-mode feature

In 6G, idle-mode operation is a key factor for overall device energy efficiency. Most UEs spend much of their life in idle or low-activity states, so reducing energy use in this mode gives the largest long-term impact.

The main goal is to cut down “always-on” signaling. Synchronization, paging, and system information delivery are redesigned to be lighter and more adaptive. Instead of frequent and rigid transmissions, 6G focuses on flexible triggering and lower repetition.

Larger SSB periodicities and adaptive synchronization scheduling reduce unnecessary UE wake-ups. On-demand delivery of system information such as SIB1 further lowers idle-time overhead.

Paging becomes more efficient through lightweight wake-up signal (WUS) variants, which reduce PDCCH monitoring load. Idle-mode measurements are also optimized. The cadence is lowered while keeping mobility robustness, allowing the device to save energy without losing responsiveness.

These combined changes make idle operation lean, efficient, and scalable. The approach fits different device classes and deployment types while keeping accessibility and mobility intact.

  • Problem focus — Idle dominates time; optimize sync, paging, and system information delivery to minimize “always-on.”
  • Concrete levers — Larger SSB periodicity, adaptive SS scheduling, on-demand SIB1, lightweight paging with WUS variants, reduced measurement cadence.

Design princeple and guideline

  • Minimize always-on activity: Optimize idle-mode operation to significantly reduce unnecessary signaling, since devices spend most of their time in idle state. This is key to improving UE energy efficiency and network resource usage.
  • Extend synchronization periodicity: Support larger SSB periodicities and adaptive SS scheduling to lower the frequency of idle-mode wake-ups while maintaining robust coverage and reliable access.
  • Deliver system information on demand: Transition from frequent broadcast of SIB1 toward on-demand delivery, reducing control-plane overhead while ensuring availability when needed.
  • Use lightweight paging mechanisms: Introduce and enhance WUS (Wake-Up Signal) variants to minimize UE monitoring time and enable more energy-efficient paging procedures.
  • Reduce measurement cadence: Optimize idle-mode mobility handling by lowering the frequency of measurements without compromising reliability, improving device battery life.
  • Ensure flexible adaptation: Allow operators to configure idle-mode signaling behavior based on deployment scenarios and device tiers, ensuring scalability across IoT, eMBB, and future use cases.

Connected-mode feature

In 6G, connected-mode operation is designed with energy efficiency as a core objective. This is different from past systems where power saving came later.

Connected mode must balance low power operation with maintaining quality of service. Unlike idle mode, it cannot rely only on long sleep intervals. It needs more flexible timing and signaling to create short, controlled sleep opportunities.

Micro-sleep allows the UE to power down receiver chains briefly without losing sync or missing control information. Longer sleep windows are created by scheduling PxSCH and PUCCH more efficiently. Unnecessary wake-ups are avoided while keeping latency and reliability targets intact.

Reference signal and control plane trimming are also critical. CSI-RS, SRS, and TRS can be reduced or shifted to aperiodic operation. Control channel structures are simplified. This lowers forced activity cycles that keep UEs awake in NR.

With these strategies, 6G can maintain strong performance while cutting power use during connected-mode operation. This makes energy efficiency an integral part of the design, not an optional add-on.

  • Micro-sleep opportunities — Allow PxSCH/PUCCH and control timing that create longer contiguous sleep windows without breaking QoS.
  • RS & control trimming — Favor aperiodic CSI/SRS/TRS; simplify control structures that force frequent UE wake-ups.

Design princeple and guideline

  • Enable micro-sleep opportunities: Design scheduling and control timing to create longer, contiguous sleep windows for UEs, reducing active receiver time without degrading latency or reliability.
  • Optimize PxSCH and PUCCH placement: Allow scheduling flexibility so that data and control transmissions can be grouped efficiently, minimizing unnecessary wake-ups and transitions between active and sleep states.
  • Reduce forced wake-ups: Trim down periodic or rigid signaling structures that prevent UEs from entering sleep states, prioritizing leaner connected-mode operation.
  • Favor aperiodic RS usage: Shift CSI-RS, SRS, and TRS toward more aperiodic or on-demand transmission to lower energy consumption without compromising measurement quality.
  • Simplify control structures: Avoid overly frequent control monitoring requirements that increase UE power draw, keeping only the minimum signaling needed for stable link performance.
  • Preserve QoS guarantees: Ensure that energy-saving mechanisms are fully compatible with latency and reliability requirements for diverse 6G services, including URLLC, eMBB, and IoT.

Power-domain & RF-aware optimizations

In 6G, power-domain and RF-aware optimization plays a key role in improving energy efficiency and overall system performance.

A major focus is on more efficient CSI handling. The goal is to reduce the granularity and frequency of channel state reporting while keeping it adaptive. This lets the network make smarter power allocation decisions in real time without adding extra measurement or signaling overhead at the UE.

Downlink power control becomes more granular. Power allocation is adjusted dynamically depending on context. For example, the network can prioritize coverage during access and mobility, and shift to capacity during data-heavy phases. This avoids static and inefficient power profiles.

Adaptive emission and EVM targets are also part of the strategy. When the link is good, devices can relax RF performance to save power. When needed, they can tighten it again. This keeps link quality high while cutting power in both transmission and reception.

These mechanisms create a more context-aware and power-efficient 6G radio system. High performance is maintained, but energy waste is minimized.

  • Efficient CSI for power control — Streamlined CSI granularity/cadence for power-domain adaptation.
  • Granular DL power control — Context-aware allocation for coverage versus capacity phases.
  • Adaptive emission/EVM targets — Context-based EVM and emission masks to avoid unnecessary power spend.

Design princeple and guideline

  • Streamline CSI for power control: Use leaner CSI reporting in both granularity and cadence to enable effective power-domain adaptation without imposing excessive measurement or signaling overhead on UEs.
  • Enable context-aware DL power control: Adapt downlink power allocation dynamically based on operational context—emphasizing coverage during access and mobility, and capacity during data-heavy phases.
  • Reduce unnecessary power spend: Avoid static or over-provisioned power settings; tailor power levels to actual channel and traffic conditions for both energy efficiency and interference control.
  • Adopt adaptive emission targets: Allow emission masks and EVM requirements to scale with link conditions, relaxing RF constraints when feasible to lower power consumption without compromising service quality.
  • Support fine-grained control loops: Design power control mechanisms with sufficient flexibility to react quickly to link dynamics, enabling robust yet power-efficient operation across device classes and frequency ranges.
  • Balance performance and efficiency: Ensure that RF optimizations preserve link reliability and coverage while achieving tangible reductions in UE and network energy consumption.

Spatial-Domain Enhancement Directions

In 6G, power-domain and RF-aware optimization becomes a core part of energy efficiency design. These mechanisms aim to improve both device power use and overall network performance.

A key focus is on more efficient CSI handling. Channel state information reporting is simplified in both granularity and cadence. This supports smarter power-domain decisions without adding unnecessary measurement or signaling load. The network can adapt power allocation in real time while keeping UE processing light.

Granular downlink power control is another important element. The system can adjust power dynamically based on context. It can prioritize coverage during access or mobility and increase capacity during data-heavy phases. This removes the need for static power settings that waste energy.

Adaptive emission and EVM targets give another layer of flexibility. Devices can relax RF performance in good link conditions and tighten it only when needed. This avoids wasting power in both transmission and reception while keeping link quality stable.

These techniques together enable a more power-efficient and context-aware 6G radio. The system maintains robust performance without overspending on RF power resources.

  • BS antenna/port adaptation (Tx chain pruning): Dynamically reduce active TRx units, antenna ports, or layers during low load; wake them only when needed for coverage/capacity spikes.
  • MIMO rank & beam adaptation: Adapt rank (layers) and beamwidth/beamcount per traffic/coverage state; prefer narrow beams only when required; simplify beam sweeping to cut idle scanning energy.
  • Multi-TRP / multi-carrier sleep coordination: Allow secondary TRPs or carriers to enter deep sleep while an anchor remains minimal-active for coverage and wake-ups.
  • NES-aware CSI/SRS: Lighter, less frequent CSI acquisition and SRS patterns aligned with NES states; avoid full-band, full-beam measurements when traffic is sparse.
  • SSB/PG beams rationalization: Support SSB-less SCells or “two-stage/condensed” SSB to limit wide beam sweeps when the cell is dormant; coordinate SI/paging beams with sleep windows.

Design princeple and guideline

  • Enable adaptive antenna and port usage: Dynamically prune or deactivate TRx chains, antenna ports, or MIMO layers during low traffic periods, and reactivate them only when required for coverage or capacity bursts.
  • Adapt MIMO rank and beam behavior: Adjust rank, beamwidth, and beam count based on traffic and coverage states, preferring simpler, wider beams in low-load conditions and activating narrow, high-rank beams only when beneficial.
  • Coordinate sleep states across TRPs and carriers: Allow secondary TRPs or carriers to enter deep sleep modes while a minimal anchor remains active for coverage, synchronization, and wake-up signaling.
  • Align CSI/SRS with NES states: Streamline CSI acquisition and SRS patterns to match network energy states—reducing beam, band, and frequency-domain overhead when traffic is sparse.
  • Rationalize SSB and paging beams: Support SSB-less SCells or two-stage/condensed SSB schemes that limit wide beam sweeps in dormant cells, aligning SI and paging beams with sleep windows to minimize unnecessary activity.
  • Optimize spatial resources for efficiency: Treat spatial resources as flexible and context-aware, balancing coverage, capacity, and power efficiency rather than operating all antenna elements at full scale continuously.

Frequency-Domain Enhancement Directions

In 6G, frequency-domain enhancements focus on making spectrum use more adaptive and power efficient. The goal is to match active spectrum to real traffic demand instead of keeping wide bandwidths always on.

Bandwidth Part adaptation is a key mechanism. A reduced portion of the carrier stays active during low-load periods. The bandwidth can expand instantly when traffic becomes bursty. This idea extends to sub-component carrier and carrier role differentiation. An anchor carrier handles essential functions like synchronization and system information, while data carriers stay dormant until needed.

A sparser synchronization raster reduces the UE search and measurement load. Default raster points are limited, and scanning is focused. This saves both network and UE energy.

Asymmetric carrier activation gives more flexibility. UL-only or DL-only operation allows the system to deactivate unnecessary bands or carriers while keeping coverage stable.

Low-PAPR and emission mask adaptation under NES mode adds another layer of efficiency. The system can relax spectral settings in dormant states and switch to efficient wideband transmission when active.

Together, these enhancements make frequency use more dynamic, scalable, and energy aware. This forms a critical part of sustainable 6G deployment.

  • BWP & bandwidth trimming: Shrink active bandwidth (BWP) and use coarse BWP granularity at low load; expand only for bursts. Permit reduced-BW common signals in dormant states.
  • Sub-CC & carrier roles: Use sub-component carriers and an Anchor/Data split: keep the Anchor narrow and sparse (SS/OD-SI), keep Data carriers dormant until scheduled activity.
  • Sparser sync raster: Limit default raster points and prioritize subsets to cut UE search/meas bandwidth and scanning time at idle.
  • UL-only/DL-only activation: Enable asymmetric (UL-only or DL-only) operation and selective deactivation of inactive bands/carriers for deeper sleep.
  • Low-PAPR & emission-mask adaptation (NES mode): Prefer wideband transmissions with low PAPR when awake, and allow tighter, NES-friendly spectral settings when dormant.

Design princeple and guideline

  • Enable adaptive bandwidth operation: Dynamically shrink active bandwidth (BWP) under low load and expand it during traffic bursts, allowing the system to scale spectrum usage with demand rather than keeping wide carriers always active.
  • Support reduced-BW common signaling: Permit reduced-bandwidth SSB, paging, and system information signaling in dormant or low-load states, minimizing energy consumption while preserving basic coverage and access.
  • Use anchor/data carrier roles: Introduce sub-component carriers with clear functional separation — a narrow anchor carrier for synchronization and minimal signaling, and data carriers that remain dormant until scheduled activity.
  • Adopt a sparser synchronization raster: Limit default raster points and prioritize a subset to reduce UE measurement bandwidth and scanning time in idle mode, improving energy efficiency.
  • Enable asymmetric carrier activation: Allow UL-only or DL-only operation and selective deactivation of inactive bands or carriers to support deeper sleep states and lower energy use.
  • Adapt spectral settings with NES states: Favor wideband transmissions with low PAPR when active, and allow tighter, NES-friendly emission masks and spectral configurations during dormant periods.
  • Promote scalable frequency usage: Treat frequency resources as elastic rather than static, enabling the network to balance energy savings, coverage, and capacity across diverse deployment scenarios.

Time-Domain Enhancement Directions

In 6G, time-domain enhancements focus on turning today’s scattered power-saving mechanisms into a unified framework. The goal is to enable deep and predictable sleep for both network and UE while keeping access responsive.

A central idea is to harmonize PDCCH monitoring, C-DRX, PDCCH skipping, SSSG switching, and low-power wake-up signaling into one coordinated design. These features should work together as a single power-saving structure, not as separate add-ons.

On the network side, cell DTX/DRX is treated as a baseline feature. Base stations can enter long sleep periods in all RRC states. Their sleep cycles align with UE DRX cycles, avoiding late configuration changes that waste energy.

Deeper sleep opportunities are supported by extending default SSB periodicity beyond 160 ms and introducing on-demand SSB bursts with one-shot detection. System information delivery also shifts from periodic to on-demand. Frequent SIB1 broadcasts are replaced by short SI windows followed by long inactive intervals.

Low-power wake-up signaling gives UEs and gNBs a way to coordinate minimal-power reactivation. UEs can trigger on-demand SSB or SIB1 as needed.

Time-domain scheduling itself supports sleep through cross-slot or aggregated transmissions, UL DTX, and no-late-change rules. This ensures predictable and protected sleep windows for both sides.

Together, these changes make the time-domain structure a central enabler of 6G energy efficiency while keeping latency low and coverage stable.

  • PDCCH Monitoring Adaptation: Harmonize C-DRX, PDCCH skipping, SSSG switching, and low-power WUS toward a unified time-domain power-saving design.
  • Cell DTX/DRX as Day-1 baseline: Network-level DTX/DRX to maximize BS sleep opportunities across all RRC states; coordinate with UE cDRX to avoid “late changes.”
  • Extend default SSB periodicity (e.g., →160 ms): Make longer periodicity the default for deep sleep; pair with on-demand SSB (OD-SSB) bursts and one-shot detection methods to protect access latency.
  • On-Demand System Information (OD-SIB1): Replace frequent periodic SI with UE- or NW-triggered SI; allow bursty SSB/SIB1 windows followed by long inactive intervals.
  • Low-Power Wake-Up (LP-WUS/WUR): Use a low-power wake-up signal/receiver so UEs and gNBs avoid frequent full Rx/Tx wake cycles; allow UL-WUS to request OD-SSB/OD-SIB1.
  • Scheduling for sleep: Cross-slot/aggregated transmissions, UL DTX/UL skipping, and no-late-change rules to keep predictable sleep windows for both UE and NW.

Design princeple and guideline

  • Unify time-domain power-saving mechanisms: Harmonize C-DRX, PDCCH skipping, SSSG switching, and low-power WUS into a single, coherent framework that reduces signaling fragmentation and improves energy efficiency.
  • Adopt cell DTX/DRX as a baseline: Make network-level DTX/DRX a default feature from day one to maximize base station sleep opportunities across RRC states, coordinated with UE cDRX to avoid late scheduling changes.
  • Extend default SSB periodicity: Use longer SSB periodicities (e.g., 160 ms or more) as the default for deep sleep states, paired with on-demand SSB bursts and one-shot detection to maintain access responsiveness.
  • Enable on-demand system information: Replace frequent periodic SIB1 transmission with UE- or network-triggered SI bursts, allowing long inactive intervals between signaling windows to save power.
  • Leverage low-power wake-up signaling: Introduce LP-WUS/WUR mechanisms that let UEs and gNBs wake selectively without full Rx/Tx activation; support UL-WUS triggers for OD-SSB/OD-SIB1 requests.
  • Schedule for predictable sleep: Use cross-slot or aggregated transmissions, UL DTX/UL skipping, and “no-late-change” scheduling rules to guarantee reliable, long sleep windows for both network and devices.
  • Maintain latency-performance balance: Ensure extended sleep and wake-up mechanisms preserve low access latency and responsiveness, particularly for paging, control, and initial access.

Evaluation models, metrics & scenarios

In 6G, a clear and shared evaluation framework is essential for energy and performance studies. This ensures that proposed features are measurable, comparable, and practical for real deployment.

A common power model is the foundation. It applies to both base stations and UEs. The model includes idle, light-load, and peak-load states. It also separates baseband, RF, and PA components. This allows energy impacts to be traced to specific design choices instead of being hidden in aggregate measurements.

Well-defined KPIs are equally important. Energy per bit or per session, absolute power over time, and sleep ratio provide a direct view of energy behavior. Coverage, latency, and QoS metrics show the performance impact of power-saving techniques. Clear baselines are required so different solutions can be compared fairly.

The evaluation is built around a scenario matrix that reflects real-world operation. It covers FR1 and FR3 bands, macro and hotspot deployments, bursty and background traffic, different device tiers, and various mobility states.

This structured framework makes the study of energy efficiency in 6G realistic and transparent. It helps the industry focus on solutions that deliver measurable and scalable impact across deployment scenarios.

  • Common power models — Shared BS/UE models (idle/light/peak) with baseband/RF/PA breakdown for correct attribution.
  • KPIs — Energy per bit/session, absolute power/time, sleep ratio, coverage impact, latency/QoS side effects versus a clear baseline.
  • Scenario matrix — Bands (FR1/FR3), deployments (macro/hotspot), traffic profiles (bursty/background), device tiers, and mobility states.

Design princeple and guideline

  • Use common and transparent power models: Define shared BS and UE power models that include idle, light-load, and peak-load states, with clear baseband, RF, and PA power breakdowns to ensure consistent attribution of energy impacts.
  • Align on baseline assumptions: Establish standardized reference conditions and configurations so that energy-saving techniques can be compared objectively across studies, vendors, and deployments.
  • Adopt energy-centric KPIs: Evaluate solutions using key metrics such as energy per bit/session, absolute power over time, sleep ratio, and coverage impact, ensuring energy benefits are measurable and meaningful.
  • Include QoS and latency considerations: Track latency, reliability, and QoS impacts alongside energy metrics to avoid energy gains at the cost of degraded service performance.
  • Cover diverse deployment scenarios: Include a scenario matrix spanning FR1 and FR3 bands, macro and hotspot deployments, and various traffic profiles (e.g., bursty vs. background) to reflect real-world diversity.
  • Account for device tiers and mobility states: Evaluate solutions under different UE capabilities and mobility conditions, ensuring energy-saving mechanisms scale across the full device ecosystem.
  • Enable consistent cross-feature evaluation: Ensure that power and performance impacts from different feature sets (e.g., time-domain, frequency-domain, spatial-domain) can be evaluated on a common basis.

Process & alignment

In 6G, the process and alignment framework for energy efficiency and frame structure is as important as the technical content itself. Real impact depends on early coordination and clear decision making, not just feature design.

Close collaboration with RAN4 from the start is essential. RF constraints, emission limits, and power-domain assumptions must be built into the design early to keep solutions realistic. Coordination with other working groups is also critical. It avoids cross-specification mismatches that can slow down or complicate deployment.

A clear path from study to specification must be set. The goal is not to create many optional features with unclear value. Instead, the focus is on selecting a small, strong set of Day-1 candidates. These must bring measurable benefits with known complexity and deployment impact.

This structured process avoids the 5G experience where many energy-saving options remained unused. It helps standardization move faster, keeps implementations aligned, and improves interoperability. It also ensures that energy-saving features are technically solid and practically deployable at scale.

  • Cross-WG coordination — Early engagement with RAN4 for RF constraints and with other WGs to avoid cross-spec inconsistencies.
  • From study to spec — Shortlist Day-1 candidates with clear gain/complexity trade-offs and minimal optionality for broad deployment.

Design princeple and guideline

  • Ensure early cross-WG coordination: Engage with RAN4 and other relevant working groups early in the study phase to align on RF constraints, power assumptions, and avoid inconsistencies across specifications.
  • Integrate RF considerations from the start: Treat emission limits, power control, and hardware feasibility as design inputs, not afterthoughts, to ensure realistic and deployable solutions.
  • Maintain cross-spec consistency: Coordinate across multiple WGs to ensure that time-, frequency-, and power-domain features are interoperable and do not introduce conflicting behaviors in deployment.
  • Shortlist impactful Day-1 candidates: Prioritize features with clear, quantifiable energy efficiency gains and manageable complexity, avoiding excessive optionality that weakens deployment incentives.
  • Focus on practicality and scale: Favor solutions that can be widely adopted across vendors and deployment types, ensuring that energy-saving features become part of baseline deployments rather than niche options.
  • Streamline study-to-spec transition: Establish a clear, transparent process to move from study item to specification, accelerating consensus and minimizing implementation ambiguity.

Reference