DMRS Placement in Shortened TTI to Cut UE Processing Delay

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Solution Overview

Problem

The adoption of a shortened Transmission Time Interval (TTI) in 5G communications leads to a major processing delay for User Equipment (UE) due to the De Modulation Reference Signal (DMRS) being located further back, which is not effectively addressed in existing technologies.

Innovation Solution

The method involves determining and altering the location of the DMRS within the time-frequency resource in the TTI according to specific preset conditions, such as port of the antenna sending a Cell-specific Reference Signal (CRS) or cell identification, to minimize processing delays for UE.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If the TTI is lowered to 0.5ms to reduce latency, then the transmission time is reduced, but the processing delay for UE increases due to DMRS being located further back

Engineering Contradiction:

ImproveTTI durationVSAvoidprocessing delay

Core Design Contradiction:

Duration of action of moving objectVSLoss of time

Solution Approach 1:

The patent inverts the conventional DMRS placement by positioning it at the beginning of the TTI rather than at the end or middle. This inversion allows the DMRS to be available immediately at the start of the TTI, eliminating the processing delay issue that occurs when DMRS is placed further back in the TTI structure.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent applies preliminary action by placing the DMRS at the very beginning of the TTI, before any data transmission occurs. This allows the UE to perform channel estimation and other processing operations in advance, before the actual data reception begins, thereby reducing overall processing delay in the shortened TTI scenario.

Inventive Principle:

Principle #10Preliminary action

2Loss of time

If the DMRS is placed at the beginning of the TTI to reduce processing delay, then the processing time is reduced, but the conflict with CRS placement increases

Engineering Contradiction:

Improveprocessing delayVSAvoidreference signal placement complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The patent segments the TTI into distinct time intervals: a first time interval for DMRS and a second time interval for CRS. This segmentation allows both reference signals to be placed without overlapping, with DMRS in the first interval and CRS in the second interval, thereby resolving the placement conflict while maintaining both signals' functionality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces dynamic configuration where the base station can flexibly determine the exact timing and resources for DMRS and CRS based on system conditions. This dynamic approach allows the system to adapt the reference signal placement to avoid conflicts while optimizing for minimal processing delay, rather than using fixed rigid positioning.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentEP3996446B1Reference signal transmitting method and device, and reference signal receiving method and device

Publication Date: 2026.02.25 ADVANCED STANDARD COMM LLC

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AI summary

The present disclosure relates to a method for sending a reference signal, comprising: determining a location of a time-frequency resource for sending a reference signal in a Transmission Time Interval, TTI; and sending the reference signal according to the location of the time-frequency resource, wherein a symbol in the TTI is included in a neighbor TTI, and wherein the symbol included in the neighbor TTI comprises the reference signal.