UE Active Time Calculation for Extended DRX Cycles

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Solution Overview

Problem

In Machine-Type Communication (MTC) scenarios, extended DRX cycles longer than the System Frame Number (SFN) cycle pose challenges for User Equipment (UE) to accurately calculate active times, leading to potential loss of paging messages and degraded Quality of Service (QoS).

Innovation Solution

The UE calculates active times by receiving the sequence number of the current SFN cycle in an extended DRX cycle from the network, using a preset length to determine the correct active time, ensuring timely activation and data reception, even when the extended DRX cycle exceeds the SFN cycle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the DRX cycle is extended to reduce power consumption, then power saving is improved, but the UE cannot calculate accurate active time, leading to potential loss of paging messages

Engineering Contradiction:
Improvepower consumptionVSAvoidpaging message reception
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The network side pre-calculates and notifies the UE of the sequence number of the current SFN cycle in the extended DRX cycle before the UE needs to calculate its active time. This preliminary provision of reference information enables the UE to accurately determine its active time position without needing to independently track multiple SFN cycle boundaries, thus preventing paging message loss while maintaining extended DRX for power saving

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The sequence number of the current SFN cycle acts as an intermediary parameter that bridges the network side's extended DRX cycle timing and the UE's local SFN cycle counting. This intermediary reference information allows the UE to correctly map its position within the extended DRX cycle without directly tracking the entire extended cycle duration, resolving the timing calculation accuracy issue

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the UE monitors paging continuously to ensure accurate reception, then paging message reception reliability is improved, but power consumption increases

Engineering Contradiction:
Improvepaging message receptionVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The UE monitors paging periodically according to the extended DRX cycle rather than continuously. By using the notified sequence number of the current SFN cycle as a reference, the UE can accurately determine when to wake up and monitor paging within the extended DRX cycle, achieving reliable paging reception while consuming less power through periodic rather than continuous monitoring

Inventive Principle:
Principle #19Periodic action

3Use of energy by moving object

If the UE uses existing DRX calculation methods with extended DRX cycles, then power saving is improved, but active time calculation accuracy deteriorates

Engineering Contradiction:
Improvepower consumptionVSAvoidactive time calculation accuracy
Core Design Contradiction:
Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The invention changes the parameter that the UE uses for active time calculation from relying on independent SFN cycle counting to using the network-notified sequence number of the current SFN cycle. This parameter change allows the UE to maintain accurate active time calculation even when the DRX cycle is extended beyond a single SFN cycle, as the sequence number provides a direct reference to the current position in the extended cycle

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2983395B1Method and device for computing activation time
Publication Date: 2020.03.11 CHINA ACAD OF TELECOMM TECH
  • EP2983395B1 patent drawingFigure 1~2
  • EP2983395B1 patent drawingFigure 3~4
  • EP2983395B1 patent drawingFigure 5~6

AI summary

The present invention relates to DRX technology and disclosed are a method and device for computing an activation time, which are used for solving the problem that a UE cannot enter an active state at an accurate time when using an extended DRX cycle. The method is: a network side notifying a UE of a serial number of a current SFN cycle in an extended DRX cycle, and the UE computing an activation time of the UE by combining the length of a preset extended DRX cycle in accordance with the serial number. In this way, when the extended DRX cycle is greater than the SFN cycle, the UE can still compute a correct paging time and/or a time of receiving service data, thereby entering the active state at an accurate time, effectively avoiding the situation where paging messages or service data are lost due to computation errors of the UE, then guaranteeing the service QoS of the UE and improving the service performance of the system.