# 3GPP TR 26.942 CR0022r2: Application Server Energy Information

## Change Request Overview

**Type:** Category B (Addition of Feature)  
**Release:** Rel-20  
**Work Item:** FS_Energy_Ph2_MED  
**Source:** BBC, Orange  

This CR introduces a new Candidate Solution for reporting energy consumption of Application Servers in the Data Network as part of end-to-end service chain energy monitoring.

## Key Issue Mapping

This Candidate Solution addresses:

- **Key Issue #2:** Energy-related monitoring and measurement, specifically for Application Servers instantiated in the Data Network
- **Key Issue #1:** Energy-related information exposure to Media Session Handler for energy-efficient optimization

## Main Technical Contributions

### Functional Description

The solution recognizes that total energy consumption for application services must account for:
- 5G System energy (5G Core and RAN) via Energy Information Function
- **Application Server energy in the Data Network** (focus of this solution)
- UE energy consumption

Key principle: Application Servers exist in the Data Network and are **not Network Functions**, therefore outside the scope of the Energy Information Function and must be accounted for separately.

### Energy Reporting Granularities

The solution identifies critical granularities for energy optimization:

1. **Per Service Location:**
   - Enables steering application sessions to different service locations based on energy costs
   - Supports aggregated view across multiple (Edge) Application Server instances hosting the same service location

2. **Per Service Data Flow:**
   - Application Server has visibility of Application Data Unit bytes transferred (uplink/downlink)
   - Service Data Flows identified by 3-tuples or 5-tuples
   - Can also be identified by DNS host name (e.g., TLS client "hello" message)

**Important Limitation:** Application Servers cannot report energy consumption per UE (no visibility of UE identities), but the Energy Information AF can perform reverse IP address lookup in 5G Core for per-UE routing.

### AS Energy Report Structure

The solution proposes a comprehensive **AS Energy Report** with the following baseline parameters:

#### Core Parameters
- **AS instance identifier:** Unique identifier across all Data Networks
- **Timestamp:** Start of energy consumption sampling period
- **Sample period:** Duration of the sample
- **Energy consumed:** Total energy during sampling period
- **Environmental cost of energy supply:** (Optional) CO₂ equivalent emission per unit energy, with breakdown by source if multiple sources

#### Application Data Flow Parameters
For each active Application Data Flow:
- **Service Data Flow description:** IP 5-tuple identifying client and Application Server endpoints
- **Uplink data volume:** Total Application Data Units delivered to AS instance
- **Downlink data volume:** Total Application Data Units delivered from AS instance
- **AS host name:** (Optional) Application Server host name for UE connection
- **Application session identifier:** (Optional) Unique identifier for application session
- **Configuration identifier:** Unique identifier for configuration in logical Application Server
- **Service location identifier:** (Optional) Identifier for service location exposed by AS instance

### Energy Attribution Model

The solution proposes a proportional attribution model:
- Total energy consumption measured over sampling period
- Bytes transferred per Service Data Flow metered during same period
- Average energy attributed to Service Data Flows proportionally to data volume

### Supported Aggregations

The raw information enables multiple aggregation views:

1. **Per Service Data Flow:** Combine with network energy information from EIF
2. **Per UE:** Via reverse IP lookup by authorized recipients (e.g., Energy Information AF)
3. **Per Data Network/Network Slice:** Via client IP address analysis
4. **Per Media Streaming Session:** Using media delivery session identifier
5. **Per Virtual Host:** Using configuration identifier and canonical domain name
6. **Per Service Location:** Using service location identifier
7. **Per Content Hosting Configuration/Provisioning Session:** Aggregate across all Edge AS instances

### Architecture Integration

The solution integrates with the Energy Information AF architecture (from Clause 7.6) via **reference point E3**, enabling:
- Periodic AS Energy Reports from Application Server to Energy Information AF
- Generic procedure realization (step 13 in generic procedure, step 19 in 5GMS procedure)

### System-Specific Mappings

#### 5GMS System
- Content Hosting Configuration identifier maps to Provisioning Session
- Distribution Session identifier maps to canonical host name
- Media delivery session identifier for longitudinal analysis
- Correlation with QoE metrics reports (TS 26.512)

#### RTC System
- RTC AS Media Function configuration identifier maps to Provisioning Session
- Support for in-band energy-related information extraction from media

## Gap Analysis

- AS Energy Report is entirely new for Release 19
- No service-based interface currently defined at reference point E3
- Energy Information AF is also new, requiring new interface specifications

## Proposed Normative Work

### Stage 2 Requirements

1. **Generic AS Energy Report specification:**
   - New stage 2 Technical Specification
   - Service operations for subscription and notification via E3
   - Based on generic architecture from Clause 7.6.2.2

2. **5GMS instantiation (TS 26.501):**
   - Map generic properties to 5GMS concepts
   - Extensions for in-band energy information from M2d (downlink) and M4u (uplink)

3. **RTC instantiation (TS 26.506):**
   - Map generic properties to RTC concepts
   - Extensions for in-band energy information from RTC AS Media Function

### Stage 3 Requirements

1. **Generic data structures:**
   - New stage 3 Technical Specification
   - Service-based interface definitions for E3

2. **5GMS extensions (TS 26.512):**
   - 5GMS AS Energy Report data structures

3. **RTC extensions (TS 26.113):**
   - RTC AS Energy Report data structures

## Additional References

- **TS 26.512:** 5G Media Streaming (5GMS); Protocols
- **TS 26.113:** Real-Time Media Communication; Protocols and APIs

## Design Principles

- **Raw information provision:** No preconceived usage patterns, enabling flexible downstream processing
- **Privacy considerations:** Care required to avoid exposing identifiable data (client IP, GPSI, SUPI) to unauthorized consumers
- **Equal attribution assumption:** Energy per byte during sampling period for simplified calculation
- **Correlation support:** Common filters (Service Data Flow, application session identifier) enable correlation across EIF, AS, and UE data sets