DRX State Transition Control in Mobile Communication Systems

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Solution Overview

Problem

In LTE and LTE-Advanced systems, mobile stations cannot flexibly change their DRX states, particularly transitioning to the Short-DRX state unnecessarily even when configured to do so by the radio base station, limiting battery savings and operational flexibility.

Innovation Solution

A mobile communication system where the radio base station can instruct the mobile station to transition directly to a Long-DRX state using a new MAC-CE (Long-DRX MAC-CE) or interpret existing DRX-command MAC-CE to bypass the Short-DRX state, allowing flexible DRX state management based on traffic and device type, enabling direct transition to Long-DRX without going through Short-DRX.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the mobile station transitions to the Short-DRX state as configured by the radio base station, then the mobile station can maintain relatively short delay for data transmission/reception, but the battery saving effect is limited and the mobile station cannot achieve significant power efficiency improvement

Engineering Contradiction:
Improvedata transmission/reception restart speedVSAvoidbattery saving effect
Core Design Contradiction:
SpeedVSUse of energy by moving object

Solution Approach 1:

The patent applies dynamics by making the DRX state transition flexible and adaptive. The mobile station can dynamically switch between Short-DRX and Long-DRX states based on real-time conditions such as traffic patterns, device type, and power status. The radio base station can instruct the mobile station to transition directly to Long-DRX state when appropriate, rather than following a fixed transition path through Short-DRX state. This dynamic adaptability resolves the contradiction by allowing the system to optimize between speed and energy consumption based on current operational context.

Inventive Principle:
Principle #15Dynamics

2Stability of the object's composition

If the mobile station is configured to transition through Short-DRX state before Long-DRX state, then the system maintains a standardized state transition process, but the mobile station lacks operational flexibility and cannot directly transition to Long-DRX state when beneficial

Engineering Contradiction:
Improvestate transition process stabilityVSAvoidDRX state transition flexibility
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent makes the state transition process dynamic by allowing both fixed and flexible transition paths. The standardized Short-DRX to Long-DRX transition remains available for stability, but the patent adds the capability to transition directly from Active state to Long-DRX state when instructed by the radio base station. This dynamic structure resolves the contradiction by providing both procedural stability and operational flexibility.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent applies inversion by reversing the conventional transition sequence. Instead of requiring transition through Short-DRX state as an intermediate step, the patent allows direct transition to Long-DRX state under certain conditions. This inverted approach challenges the traditional hierarchical transition model and enables more efficient state changes when the system determines that the intermediate Short-DRX state is unnecessary.

Inventive Principle:
Principle #13The other way round (Inversion)

3Reliability

If the mobile station monitors PDCCH and reports feedback information in the Active state, then the system maintains reliable communication control, but the mobile station consumes more power compared to DRX states

Engineering Contradiction:
Improvecommunication control reliabilityVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies periodic action through DRX (Discontinuous Reception) cycles where the mobile station alternates between Active state (monitoring PDCCH and reporting feedback) and Inactive state (sleep mode). During Inactive state, the mobile station periodically wakes up to check for incoming data or control signals. This periodic operation resolves the contradiction by maintaining communication reliability during Active periods while significantly reducing power consumption during Inactive periods, achieving a balance between reliability and energy efficiency.

Inventive Principle:
Principle #19Periodic action

Data Source

PatentEP2903351B1User equipment and radio base station
Publication Date: 2022.08.17 NTT DOCOMO INC
  • EP2903351B1 patent drawingFigure 1~2
  • EP2903351B1 patent drawingFigure 3
  • EP2903351B1 patent drawingFigure 4

AI summary

A DRX state of a mobile station UE is flexibly changed. In a mobile station UE according to the invention, in a case where a reception state of the mobile station UE is managed as a continuous reception state, and even in a case where the reception state of the mobile station UE is configured to be capable of transitioning to a Short-DRX state, a control unit 22 transitions the reception state of the mobile station UE to a Long-DRX state without transitioning the reception state to the Short-DRX state when an instruction to transition the reception state of the mobile station UE to the Long-DRX state is made via MAC-CE by a radio base station.