DRX Desynchronization Detection in LTE

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Solution Overview

Problem

In LTE architecture, long discontinuous reception (DRX) desynchronization occurs due to miscommunications and errors in DRX period changes, leading to inefficient battery usage and data loss, as the enhanced Node B (eNB) and user equipment (UE) may not accurately synchronize their DRX periods.

Innovation Solution

The method involves using timers, heartbeat messages, and piggybacking DRX period information on periodic messages to detect and correct desynchronization by comparing DRX periods and adjusting them accordingly, ensuring accurate synchronization and recovery from desynchronization events.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If long DRX is implemented to allow UE to turn off transmitter and receiver for battery saving, then battery life is improved, but DRX desynchronization occurs between eNB and UE leading to data loss and inefficiency

Engineering Contradiction:

Improvebattery lifeVSAvoidDRX synchronization

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent implements feedback mechanisms where the UE sends uplink messages at specific intervals (e.g., every 4, 8, or 16 DRX cycles) to confirm its DRX state to the eNB. This feedback allows the eNB to verify whether the UE has correctly applied DRX period changes and to detect desynchronization conditions, thereby maintaining reliable DRX operation while preserving battery life benefits.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent employs preliminary actions by implementing proactive desynchronization detection mechanisms before actual data loss occurs. The eNB monitors for missed uplink messages and detects potential DRX desynchronization early, allowing it to reset the UE's DRX configuration and re-establish synchronization before critical data transmission errors occur.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If DRX period changes are signaled to UE to adapt to data activity patterns, then adaptability is improved, but miscommunications cause desynchronization between eNB and UE

Engineering Contradiction:

ImproveDRX period adaptationVSAvoidDRX period synchronization information

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent uses feedback through periodic uplink messages from UE to eNB that confirm DRX period application. When the eNB signals a DRX period change, it expects to receive feedback messages at calculated intervals based on the new DRX period. If feedback is missed, the eNB detects desynchronization and resets the DRX configuration, ensuring both parties maintain consistent DRX state information.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent introduces an intermediary verification mechanism where the UE's uplink messages serve as confirmation that DRX period changes were correctly received and applied. This intermediary feedback loop ensures that information about DRX period synchronization is reliably transmitted and verified between eNB and UE, preventing miscommunication-induced desynchronization.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by moving object

If implicit DRX changes are programmed in eNB or UE to extend DRX duration when no data activity occurs, then battery life is improved, but errors in configuration cause desynchronization

Engineering Contradiction:

Improvebattery lifeVSAvoidDRX period timing accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The patent implements feedback mechanisms where the UE sends uplink messages at intervals calculated based on the implicit DRX period. The eNB monitors for these messages to verify that the UE has correctly applied the extended DRX timing. If messages are missed or arrive at unexpected times, the eNB detects timing inaccuracies and resets the implicit DRX configuration, ensuring precise synchronization while maintaining extended battery-saving intervals.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent employs preliminary verification by having the UE send confirmation messages before the eNB assumes implicit DRX extension is active. This preliminary feedback ensures that timing configurations are correctly applied before the system transitions to extended DRX operation, preventing desynchronization caused by configuration errors while preserving battery life benefits.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8131310B2Method and system for discontinuous reception de-synchronization detection

Publication Date: 2012.03.06 BLACKBERRY LTD

AI summary

A method and apparatus for detecting loss of discontinuous reception synchronization, the method comprising the steps of: finding the shorter of a new discontinuous reception period and an old discontinuous reception period; and sending a message at a multiple of the shorter of the new discontinuous reception period and the old discontinuous reception period, wherein the message is utilized for detecting loss of discontinuous reception synchronization.