DRX Timer Control for LTE Subframe Monitoring

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Solution Overview

Problem

In LTE Release-11, the use of a single DRX starting offset for multiple UEs restricts eNB scheduling flexibility, leading to subframe overload or underload issues due to latency in ePDCCH decoding, which affects the UE's ability to start the inactivity timer and monitor control channels effectively.

Innovation Solution

Implementing a system control module with an inactivity timer and an on-duration timer to determine active times for monitoring subframes on the physical downlink control channel, allowing the UE to monitor subframes after the active time and adjust DRX cycles based on decoding latency, thereby enhancing DRX control and flexibility in resource allocation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single DRX starting offset is used for multiple UEs, then device coexistence is improved, but eNB scheduling flexibility is restricted

Engineering Contradiction:

Improvedevice coexistenceVSAvoideNB scheduling flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent segments the single DRX starting offset into multiple DRX starting offsets (first DRX starting offset and second DRX starting offset). The UE can be configured with multiple offsets and selectively use them based on whether the next subframe is active or inactive, thereby resolving the conflict between device coexistence and scheduling flexibility.

Inventive Principle:

Principle #1Segmentation

2Loss of time

If ePDCCH decoding latency is reduced, then UE response time is improved, but decoding accuracy may deteriorate

Engineering Contradiction:

ImproveePDCCH decoding latencyVSAvoiddecoding accuracy

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The patent applies preliminary action by having the UE determine the status of the next subframe (active or inactive) before attempting to start the inactivity timer. This allows the UE to prepare appropriate monitoring behavior in advance, avoiding the problem of delayed response due to decoding latency while ensuring accurate decoding through proper timing.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If the UE monitors subframes during inactive periods, then resource allocation responsiveness is improved, but power consumption increases

Engineering Contradiction:

Improveresource allocation responsivenessVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic monitoring behavior where the UE adapts its subframe monitoring based on the status of the next subframe. When the next subframe is active, the UE monitors normally; when inactive, the UE uses multiple DRX starting offsets to determine appropriate monitoring timing. This dynamic adaptation improves responsiveness while minimizing unnecessary power consumption during inactive periods.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11979768B2Discontinuous reception (DRX) enhancements in LTE systems

Publication Date: 2024.05.07 APPLE INC

AI summary

Embodiments of a system and method for providing DRX enhancements in LTE systems are generally described herein. In some embodiments, a system control module is provided for controlling communications via a communications interface. A processor is coupled to the system control module and is arranged to implement an inactivity timer and an on-duration timer for determining an active time for monitoring subframes on the physical downlink control channel for control signals, the processor further monitoring subframes after the active time.