NR Tracking Reference Signals for DRX Synchronization Accuracy

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Solution Overview

Problem

User equipment (UE) experiences frequency and/or timing errors when transitioning between active and sleep modes, impacting the processing of control information and data, which existing technologies fail to adequately address.

Innovation Solution

Implementing enhanced tracking reference signal (TRS) transmission and reception techniques, including periodic, aperiodic, and semi-persistent configurations, along with a DCI trigger mechanism, to ensure accurate frequency and timing tracking during power-saving operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the UE enters sleep mode to conserve power, then power saving is improved, but frequency and timing accuracy deteriorates

Engineering Contradiction:
Improvepower consumptionVSAvoidfrequency and timing accuracy
Core Design Contradiction:
Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by transmitting the tracking reference signal (TRS) before the UE enters sleep mode and before the next active period begins. This allows the UE to perform frequency and timing tracking in advance while still in active mode, so that when the UE wakes up from sleep mode, it already has accurate synchronization information, thereby resolving the contradiction between power saving and frequency/timing accuracy.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The tracking reference signal (TRS) acts as an intermediary element between the network and the UE. It provides the necessary synchronization information that enables the UE to maintain accurate frequency and timing estimation without requiring continuous active processing. The TRS serves as a mediator that bridges the gap between power-saving sleep mode and the need for accurate signal processing upon wake-up.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If the UE performs continuous active processing to maintain frequency and timing accuracy, then measurement precision is improved, but power consumption increases

Engineering Contradiction:
Improvefrequency and timing accuracyVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic action by configuring the UE to receive and process the tracking reference signal at specific periodic intervals rather than continuously. The UE can be configured with periodic TRS reception patterns that align with its active/sleep cycle, allowing the UE to maintain frequency and timing accuracy only when needed (during active periods or when TRS is transmitted), thereby reducing overall power consumption while preserving measurement precision.

Inventive Principle:
Principle #19Periodic action

3Reliability

If the network transmits tracking reference signal continuously to maintain synchronization, then frequency and timing tracking is improved, but network overhead and energy consumption increase

Engineering Contradiction:
Improvesynchronization accuracyVSAvoidnetwork energy consumption
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies dynamics by making the TRS transmission pattern adaptable rather than fixed. The network can dynamically adjust the TRS transmission timing and periodicity based on UE capabilities, active/sleep cycle configuration, and channel conditions. This dynamic approach allows the network to transmit TRS only when necessary for maintaining synchronization, optimizing the balance between synchronization accuracy and energy consumption.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent utilizes parameter changes by allowing flexible configuration of TRS transmission parameters such as periodicity, offset, and timing. The network can modify these parameters to match the UE's operational characteristics, enabling TRS to be transmitted at optimal intervals that maintain synchronization reliability while minimizing unnecessary network energy consumption and overhead.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4211986B1Tracking reference signal enhancements for new radio
Publication Date: 2026.02.11 APPLE INC
  • EP4211986B1 patent drawingFigure 1
  • EP4211986B1 patent drawingFigure 2
  • EP4211986B1 patent drawingFigure 3A

AI summary

A user equipment (UE) receives reference signals during a discontinuous reception (DRX) cycle to perform frequency and timing tracking or automatic gain control (AGC). The UE receives configuration information corresponding to a reference signal that is to be transmitted to a user equipment (UE) when the UE is in a first operating state, receives the reference signal from a cell of a network when the UE is in the first operating state, performs one of frequency and timing tracking or automatic gain control (AGC) using the reference signal and receives a signal from the cell during a time window that the UE is scheduled to utilize an active mode of data exchange processing.