Aperiodic Tracking Reference Signal for DRX Synchronization

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Solution Overview

Problem

In wireless communication systems, user equipment (UE) may not have an updated tracking loop during discontinuous reception (DRX) or connected mode DRX (CDRX) cycles due to misalignment of reference signals with the DRX or CDRX cycle, leading to suboptimal synchronization and power consumption issues.

Innovation Solution

The implementation of an aperiodic tracking reference signal (A-TRS) is positioned within a transmission frame between a grant indicator and the DRX cycle, allowing the UE sufficient time to update its tracking loop before the on-duration of the DRX cycle, ensuring synchronization and reducing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If periodic tracking reference signals are used in conventional DRX/CDRX, then the UE can maintain tracking loop, but the reference signal occurrence may not be aligned with DRX/CDRX cycle causing suboptimal synchronization

Engineering Contradiction:

Improvesynchronization qualityVSAvoidtracking loop update timing

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The aperiodic TRS is transmitted in advance before the DRX/CDRX on-duration, allowing the UE to update its tracking loop提前 (in advance) so that synchronization is already established when the on-duration begins. This preliminary action ensures the tracking loop is ready without requiring continuous periodic signals during the sleep period.

Inventive Principle:

Principle #10Preliminary action

2Use of energy by moving object

If UE sleeps during off-duration to conserve power, then power consumption is reduced, but tracking loop may not be updated causing synchronization issues

Engineering Contradiction:

Improvepower consumptionVSAvoidtracking loop update

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The aperiodic TRS is transmitted before the DRX/CDRX on-duration while the UE is still awake, allowing the tracking loop update to be completed提前 (in advance). This way, the UE can safely enter sleep mode during off-duration without compromising tracking loop synchronization, as the update has already occurred during the preceding awake period.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

While the TRS itself is aperiodic (transmitted only when needed), the solution maintains a periodic pattern of wake-up -> TRS reception -> sleep cycle that aligns with DRX/CDRX configuration, allowing power saving while ensuring tracking updates occur at appropriate intervals.

Inventive Principle:

Principle #19Periodic action

3Reliability

If aperiodic TRS is transmitted before DRX/CDRX on-duration, then tracking loop is updated in time, but additional transmission time is required

Engineering Contradiction:

Improvetracking loop update timingVSAvoidtransmission frame structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The aperiodic TRS transmission is made dynamic and flexible, allowing the network to configure the exact timing and duration of TRS transmission before each DRX/CDRX cycle. This dynamic adjustment enables optimization of the time gap between TRS and on-duration to ensure sufficient processing time while minimizing overall overhead and adapting to different UE capabilities and network conditions.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentEP3669611B1Advanced grant indicator and aperiodic tracking reference signal in discontinuous reception

Publication Date: 2022.09.14 QUALCOMM INC

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AI summary

Aspects of the disclosure relate to wireless communications utilizing discontinuous reception (DRX). Disclosed methods and apparatus include providing a grant indicator in a transmission from a base station to a user equipment (UE), where indicator notifies the UE of a grant of data during a subsequent discontinuous reception (DRX) cycle in the at least one UE. Additionally, a tracking reference signal (TRS), which may be aperiodic (A-TRS), is transmitted prior to an on-duration time of the DRX cycle, where the TRS is usable by the UE for updating a tracking loop and also can be referenced by the indicator. In this manner, the combination of the grant indicator and the TRS affords a UE sufficient time for updating a UE tracking loop before the DRX cycle. Other aspects, embodiments, and features are also claimed and described.