MAC Entity Suspension for SCG Deactivation Energy Savings

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Solution Overview

Problem

In wireless networks, particularly in multi-connectivity scenarios like NR-DC, the energy consumption of user equipment (UE) is significantly higher when connected to multiple cell groups, especially when one cell group is in a deactivated state, leading to inefficiencies in energy management and increased battery drain.

Innovation Solution

The method involves specific operations on the MAC entity during cell group deactivation and reactivation, including canceling ongoing procedures, maintaining buffer status reporting, resetting timers, and initiating procedures for efficient resource management to reduce energy consumption and minimize latency during reactivation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE maintains connection to multiple cell groups simultaneously, then connection robustness and network capacity are improved, but UE energy consumption increases significantly

Engineering Contradiction:
Improveconnection robustnessVSAvoidUE energy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic state transitions for the MAC entity, allowing it to switch between active and suspended states based on cell group activation status. When a cell group is deactivated, the MAC entity transitions to a suspended state, dynamically adjusting resource usage to match current operational needs while maintaining the ability to quickly resume when the cell group is reactivated.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent applies the discarding and recovering principle by suspending MAC entity procedures during cell group deactivation and recovering them upon reactivation. Instead of completely discarding MAC entity state, the patent preserves essential information (like buffer status reports and ongoing procedures) while discarding active resource allocations, enabling fast recovery without full reinitialization.

Inventive Principle:
Principle #34Discarding and recovering

2Use of energy by moving object

If the MAC entity is fully reset during cell group deactivation, then energy consumption is reduced, but reactivation latency increases due to procedure reinitialization

Engineering Contradiction:
Improveenergy consumptionVSAvoidreactivation latency
Core Design Contradiction:
Use of energy by moving objectVSLoss of time

Solution Approach 1:

The patent performs preliminary actions by suspending rather than fully resetting MAC entity procedures during deactivation. Buffer status reports, ongoing random access procedures, and other MAC entity state are preserved in a suspended state, preparing them for quick resumption. This preliminary preservation avoids the need for complete reinitialization during reactivation, reducing latency while still achieving energy savings.

Inventive Principle:
Principle #10Preliminary action

3Use of energy by moving object

If ongoing MAC procedures are canceled during deactivation, then energy consumption decreases, but data transmission continuity is disrupted

Engineering Contradiction:
Improveenergy consumptionVSAvoiddata transmission continuity
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies beforehand cushioning by preserving buffer status reports and ongoing procedure state before deactivation occurs. This cushioning of critical information ensures that when the cell group is reactivated, data transmission can resume with minimal disruption. The preserved state acts as a buffer that protects against complete procedure interruption, maintaining transmission continuity while still allowing energy savings during the deactivated period.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentEP4381868B1Handling of medium access control (MAC) entity during secondary cell group (SCG) deactivation/reactivation
Publication Date: 2024.09.04 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP4381868B1 patent drawingFigure 1~2
  • EP4381868B1 patent drawingFigure 3~4
  • EP4381868B1 patent drawingFigure 5~6

AI summary

Embodiments include methods for a user equipment (UE) configured to communicate with a wireless network via a plurality of cell groups (e.g., MCG and SCG). Such methods include, upon deactivating one of the cell groups (e.g., SCG), suspending a medium access control (MAC) entity associated with the deactivated cell group and performing one or more first operations on the MAC entity upon the suspension of the MAC entity. Such methods also include, while the MAC entity is suspended, performing one or more second operations related to reporting of uplink (UL)data available for transmission via the deactivated cell group. Such methods also include, upon reactivating the deactivated cell group, performing one or more third operations on the MAC entity and resuming the MAC entity based on the one or more third operations. Other embodiments include UEs configured to perform such methods.