3GPP TR 26.510 Change Request - Summary

Document Information

• CR Number: 0015, Revision 03
• Specification: TR 26.942 (Release 20)
• Work Item: FS_Energy_Ph2_MED (Energy Efficiency Phase 2 for Media)
• Category: B (Addition of feature)
• Source: Nokia

Main Purpose

This CR adds Solution #12 addressing Key Issue #6: "Client-driven management of media delivery service energy optimisation". The solution enables the Media AF to manage energy-saving operations that may cause QoS and QoE degradation through coordination between the 5GC, Media Application Providers, and UE.

Technical Contributions

1. NWDAF Interactions for QoE Insights (Clause 4.2.2.6 - New)

Overview

• Enables Media AF to request Observed Service Experience analytics from NWDAF
• Provides predictive insights on service performance and network conditions affecting QoE
• Allows proactive decisions on media profiles, buffering, and delivery modes before quality deteriorates

Interaction Patterns

The solution defines three interaction models between AF and NWDAF:

1. Via NEF (N33 reference point):
2. Most common approach for external AF
3. AF accesses NEF using Nnef_* APIs (TS 29.522)

4. NEF interacts with NWDAF on AF's behalf

5. Via PCF (N5 reference point):

6. AF influences policy decisions using Npcf_PolicyAuthorization (TS 29.514)
7. PCF obtains analytics from NWDAF via N23

8. PCF passes results back to AF

9. Direct service-based interaction:

10. For trusted AFs within operator domain
11. Direct consumption via Nnwdaf services
12. Not a numbered reference point

Data Flow

1. AF determines need for network analytics
2. Intermediate NF (PCF/NEF) handles AF request
3. Intermediate NF requests analytics from NWDAF via Nnwdaf_AnalyticsInfo_Request/Subscribe
4. NWDAF collects data from SMF using Smf_EventExposure service
5. NWDAF provides QoE insights to consuming NF
6. Consuming NF makes policy decisions and instructs SMF
7. Results shared with AF for application-level adaptation

Note: No direct AF-SMF interface exists in 3GPP specifications.

2. Solution #12 Architecture and Functional Description (Clause 7.14 - New)

Key Issues Addressed

1. How to determine user tolerance for reduced QoS/QoE
2. How Media AF proposes strategies to minimize QoE impact when QoS is restricted
3. How Media Client prioritizes strategies to minimize QoE impact

Core Principles

Energy Policy Provisioning:
- Media Application Provider provisions energy policies in advance
- Policies aligned with contracts (e.g., green streaming agreements)
- Define acceptable QoS/QoE ranges for media delivery

Energy Saving Triggers:
- 5G Core triggers: Network decides to reduce QoS (e.g., bandwidth allocation)
- Media Application Provider triggers: Based on cloud provider contracts or resource status
- Mix of real-time triggering and pre-provisioned policies

User Tolerance Assessment:
- Energy Information AF assesses QoE impact when triggered
- Compares requested QoE with predefined thresholds
- May query SMF for user subscription QoE levels (from UDM)
- If within agreed levels → proceed without approval (collect feedback)
- If exceeds levels → request user approval via notification

UE QoE Control:
- Energy Information Client in Media Session Handler assesses status
- Determines if Media-aware Application can tolerate degradation
- Manages QoE to stay above pre-defined thresholds

Architecture Mapping

Energy Information AF Responsibilities:
- Validates Energy Information Exposure Specifications
- Subscribes to NF Energy Information from EIF (E12)
- Subscribes to AS Energy Information from Application Server (E3)
- Collates and exposes Network Energy Information to Energy Information Collector (E5)
- Interacts with NWDAF via NEF (N33), PCF (N5), or direct service-based interface

Energy Information Collector Responsibilities:
- Acquires collection configuration from Energy Information AF
- Collects energy information at different granularities (UE, PDU Session, QoS flow)
- Per TS 23.501 clause 5.51.2.3

3. Energy-Related Information Elements

Energy Policy Parameters (Table 7.14.5.2-1)

Provisioned by Media Application Provider to guide Media AF behavior:

• Energy efficiency policy: Overall policy for energy consideration during QoS degradation
• Energy vs. media quality preference: Trade-off preference
• Energy consumption budget: Abstract budget for session/service
• Energy-aware adaptation priority: Prioritized list of adaptation actions
• Maximum allowed processing complexity: Upper bounds on encoding complexity
• Energy-based suspension policy: Conditions for component/session suspension
• Energy recovery policy: Conditions for increased consumption when QoS improves
• Service energy differentiation indicator: Energy efficiency category
• Validity time: Applicable time period for policy information

QoE Reduction Notification Parameters (Table 7.14.5.3-1)

Conveyed by Media AF to Media Session Handler upon QoS degradation:

• QoS degradation indication: Detection/notification of degradation
• QoS degradation severity: Classified severity (minor/moderate/severe)
• Affected media components: Impacted components identification
• Recommended media adaptation actions: Mitigation actions
• Media parameter adjustment constraints: Min/max values for bitrate, resolution, frame rate
• Media component priority information: Relative priority for selective adaptation
• Session continuity indication: Continuity vs. quality preference
• Adaptation urgency indication: Immediate or gradual timing
• Media suspension/termination indication: Recommendation for component/session handling
• Media quality recovery indication: Conditions for quality recovery
• Reporting trigger indication: Conditions for reporting back to AF
• Validity time: Applicable time period

4. Detailed Procedures (Clause 7.14.6)

Initial Setup (Steps 1-8)

• Standard downlink media delivery session establishment
• Media-aware Application requests session
• Media delivered between UE Media Client and Media AS
• Based on TS 26.501 clause 5.5.3 steps 4-6

Energy Information Subscription (Steps 9-12)

1. Energy Information AF subscribes to NF Energy Information from EIF (E12), requests immediate report
2. EIF responds with NF Energy Information report
3. Energy Information AF subscribes to AS Energy Information from 5GMS AS (E3)
4. 5GMS AS responds with AS Energy Information report

QoE Reporting via QMC Framework (Steps 13-18)

Based on TS 38.300 clause 21.2.1:

1. OAM sends QoE configuration to RAN/gNodeB
2. gNodeB forwards measConfigAppLayerContainer in RRCReconfiguration to UE
3. UE sends application layer reports in MeasurementReportAppLayer to gNodeB
4. gNodeB forwards to OAM
   17-18. OAM forwards to MnS Consumer (e.g., AF) upon subscription

Energy Saving Trigger and QoE Management (Steps 9/10a/10b-31)

5GC-Initiated Trigger Process (Step 21 details):
1. UDM provisions "QoE reduction authorization" in user subscription (TS 23.502 clause 5.2.3.1)
2. SMF selects specific UE/application for QoS reduction
3. SMF subscribes to Observed Service Experience analytics from NWDAF with candidate QoS parameter sets
4. NWDAF provides predicted QoE to SMF
5. SMF optionally queries UDM for "QoE reduction authorization"
6. SMF sends energy saving trigger to AF with QoE ranges

Media Application Provider Trigger (Step 10a):
- Provider decides to reduce AS energy consumption (e.g., during peak hours 12:00-14:00)
- Can be pre-provisioned schedule or real-time trigger
- Trigger contains possible QoE ranges

EIF to EIAF Request (Step 10b/9):
- EIF informs EIAF via E12 to request UE Media Client QoE degradation
- Due to network and/or UE energy saving

EIAF Activation (Step 10/20):
- EIAF receives request and activates energy saving mode
- Determines which UEs under control to activate

QoE Reduction Request (Steps 18/22):
- EIAF requests subset of Media Clients to reduce QoE via E5
- Based on comparison with pre-defined ASP standards

Current QoE Reporting (Steps 13/22a):
- Media Session Handler requests current QoE metrics from Media Access Function (M11)

UE Decision Point (Step 14/23):

If UE does not agree:
- Does not activate buffer control
- Session continues unmodified
- Optional notification to Media AF of preference

If UE agrees (Steps 25-31):
25. Media Session Handler instructs Media Access Function to activate buffer control
26. Media Access Function activates buffer control
27. Ongoing session requires modification
28. Media Session Handler requests Media AF to modify session (new dynamic QoS policy at M5)
29/24. Media AF modifies session and acknowledges
30. Media Session Handler establishes session with new QoE
31. Media continues with possibly reduced QoE

5. Gap Analysis (Clause 7.13.7)

Identified gaps requiring specification:

1. Steps 17-18: Media AF subscribing as MnS consumer with OAM for immediate QoE reports
2. Step 19: EIF requesting EIAF to activate energy saving mode
3. Step 20: EIAF activating energy-saving mode
4. Step 21: EIAF providing energy-related indications/recommendations to Media AF
5. Step 22: EIAF requesting Media Clients to reduce QoE via E5
6. Steps 25-29: Media Session Handler instructing buffer control and requesting dynamic QoS policy modification at M5

6. Potential Normative Requirements (Clause 7.13.8)

Proposed normative work in TS 26.512:

1. Reference Point E5 Extensions:
2. Procedures and service-based interfaces for EIAF requesting EIC to activate energy saving mode

3. Specific to 5G Media Streaming System sessions

4. Reference Point M5 Extensions:

5. Procedures and service-based interfaces for MSH requesting AF to modify dynamic QoS policy
6. Specific to media streaming sessions

7. Key Differentiators

Contrast with Alternate QoS Profile Feature:
- This solution differs from TS 23.501 clause 5.7.1.2a Alternate QoS Profile feature
- Alternate QoS Profile: Network (NG-RAN) dynamically adapts QoS for network energy saving
- Solution #12: Client-driven approach with user consent and application-level adaptation

Solution Benefits:
- Dynamic coordination between Media AF, 5GC, Media Application Provider, and UE
- User-aware energy-saving decisions based on QoE tolerance
- Joint network-UE optimization of energy while maintaining service continuity
- Proactive QoE management before quality deteriorates

References Added

• TS 23.503: Policy and charging control framework for 5GS
• TS 29.522: Network Exposure Function Northbound APIs
• TS 29.514: Policy Authorization Service

Affected Clauses

• Clause 2: References (additions)
• Clause 4.2.2.6: New clause on NWDAF QoE insights
• Clause 7.1: Solution mapping table updated
• Clause 7.14: New complete solution description