DRX Timing De-synchronization Recovery in LTE

Solution Overview

Problem

In LTE networks, DRX timing de-synchronization between user equipment (UE) and the eNB leads to increased downlink message delivery latency and wastage of radio resources, especially for critical control messages, due to misinterpretation of HARQ feedback and automatic incrementation of DRX periods.

Innovation Solution

A method where the UE automatically increases the DRX period based on predetermined rules signaled by the eNB, with efficient DRX configuration and reconfiguration using MAC-PDU headers, and indication of DRX timing de-synchronization through system information, ensuring synchronized DRX operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the UE automatically increments DRX length according to a rule, then power saving is improved, but DRX timing de-synchronization occurs between UE and eNB

Engineering Contradiction:

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The eNB sends a feedback message to the UE indicating that the UE is out of synchronization. This feedback mechanism allows the UE to recover from de-synchronization by adjusting its DRX timing, thus maintaining reliability while preserving power saving benefits.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system pre-configures DRX parameters and synchronization mechanisms before data transmission begins. By establishing synchronized DRX operation in advance and providing feedback when de-synchronization occurs, the system maintains both power efficiency and timing accuracy.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If the UE misses the DLSCCH scheduling indication, then data reception is improved, but HARQ feedback is lost and data may be lost

Engineering Contradiction:

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The eNB transmits the scheduling indication on the DLSCCH before the actual data transmission begins. This preliminary signaling ensures that the UE is prepared to receive and process data correctly, maintaining both efficiency and reliability of the communication.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the eNB sends probing messages to determine UE DRX timing, then DRX timing de-synchronization is resolved, but downlink message delivery latency increases

Engineering Contradiction:

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

Instead of using probing messages to determine UE DRX timing, the system uses a feedback mechanism where the eNB directly informs the UE of its synchronization status. This eliminates the need for multiple probing attempts and reduces the time required to resolve de-synchronization.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP3687092B1Method and system for recovering from DRX timing de-synchronization in LTE-active

Publication Date: 2021.09.08

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AI summary

A method for Discontinuous Reception ('DRX') operation, comprising waking up a receiver at a radio frame if the radio frame number is equal to a radio frame offset plus N times a DRX interval, wherein N is an integer greater than or equal to zero is described.