DRX Reference Signal Tracking for Wireless Power Saving

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Solution Overview

Problem

Wireless devices face challenges in efficiently managing power consumption while maintaining concurrent connections with current and next-generation radio access technologies, particularly due to the lack of 'always ON' signals in 5G NR, which affects signal tracking and power saving during dynamic traffic scenarios.

Innovation Solution

The wireless device requests and receives reference signal information from the base station associated with the DRX cycle, allowing it to perform tracking during the on-duration and remain in a sleep state during off-durations, thereby optimizing power consumption by reducing unnecessary wake-ups for signal tracking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the wireless device continuously monitors signals to maintain tracking accuracy, then signal tracking reliability is improved, but power consumption increases

Engineering Contradiction:
Improvesignal tracking reliabilityVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements Discontinuous Reception (DRX) cycles where the wireless device alternates between active monitoring periods (On Duration) and sleep periods (Off Duration). During On Duration, the device monitors reference signals for tracking; during Off Duration, it enters low-power state. This periodic action pattern allows the device to maintain acceptable tracking reliability while significantly reducing power consumption compared to continuous monitoring.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent introduces a Wake-Up Signal (WUS) mechanism where the base station sends a preliminary signal before the scheduled On Duration. If the WUS is detected, the device knows it needs to wake up for reference signal monitoring; if not detected, the device can skip the upcoming On Duration and remain in sleep mode. This preliminary action allows the device to avoid unnecessary wake-ups and further reduce power consumption while maintaining tracking reliability when needed.

Inventive Principle:
Principle #10Preliminary action

2Use of energy by moving object

If the device enters sleep state during DRX off-duration to save power, then power consumption is reduced, but signal tracking capability deteriorates

Engineering Contradiction:
Improvepower consumptionVSAvoidsignal tracking capability
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The Wake-Up Signal (WUS) serves as a preliminary indicator that prepares the device for upcoming reference signal transmissions. When WUS is detected, the device activates its receiver in time to capture the reference signals at the beginning of the On Duration, ensuring tracking capability is restored before full monitoring begins. This preliminary warning mechanism ensures the device doesn't miss critical tracking signals while still benefiting from extended sleep periods.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The WUS acts as an intermediary signal between the base station and the wireless device. It provides advance notice to the device about upcoming active periods, allowing the device to transition from sleep state in a controlled manner. This intermediary mechanism coordinates the device's power state transitions with the network's signaling schedule, ensuring tracking capability is maintained without requiring continuous power consumption.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If the device wakes up frequently for reference signal monitoring, then tracking accuracy is improved, but power saving benefit is reduced

Engineering Contradiction:
Improvetracking accuracyVSAvoidpower saving benefit
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The Wake-Up Signal (WUS) provides preliminary notification to the device about upcoming reference signal transmissions. By detecting WUS in advance, the device can plan its wake-up schedule more efficiently, waking up only when reference signals are actually transmitted. This eliminates unnecessary wake-ups where the device would wake up but find no reference signals to monitor, thereby improving power saving benefit while maintaining tracking accuracy when signals are present.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The WUS mechanism creates a feedback loop where the base station informs the device about upcoming transmission opportunities. The device uses this feedback to adjust its power state accordingly, waking up only when needed for reference signal monitoring. This feedback-driven approach optimizes the balance between tracking accuracy and power saving by aligning device activity with actual network signaling patterns.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3648514B1Apparatus, system, and method for mobile station power saving
Publication Date: 2022.04.06 APPLE INC
  • EP3648514B1 patent drawingFigure 1~2
  • EP3648514B1 patent drawingFigure 3
  • EP3648514B1 patent drawingFigure 4

AI summary

Apparatuses, systems, and methods for performing power saving for a wireless device. The wireless device may connect to abase station (BS). The wireless device may establish discontinuous reception (DRX) with the BS, where the DRX comprises a DRX cycle having a cycle length. The wireless device may receive reference signal information from the base station in association with the DRX cycle length, where the reference signal information is transmitted according to the cycle length. The wireless device may perform tracking using the reference signal information.