Noise Tracking Reference Signals in Wireless TTI

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Solution Overview

Problem

In wireless communications, particularly in distributed wireless networks, varying noise levels within transmission time intervals (TTIs) due to asynchronous transmissions from different devices lead to reliability and efficiency issues in receiving signals, as existing techniques fail to effectively track and compensate for these noise variations.

Innovation Solution

The method involves transmitting specific reference signals within TTIs to allow receiving devices to estimate noise levels, with different sets of symbols receiving either demodulation reference signals (DMRS) or additional noise tracking reference signals (NTRS) based on expected noise levels, enabling accurate noise estimation and compensation for demodulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If reference signals are transmitted only at specific positions (e.g., beginning of TTI), then device complexity is reduced, but noise estimation precision deteriorates because noise levels vary within the TTI due to asynchronous transmissions

Engineering Contradiction:
Improvereference signal transmission complexityVSAvoidnoise estimation precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The TTI is segmented into multiple regions based on expected noise levels, with different reference signal transmission strategies applied to each region. Low-noise regions use standard reference signal positions while high-noise regions receive additional reference signals, dividing the problem into manageable segments that can be handled differently

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different reference signal transmission qualities are applied to different regions within the TTI. Regions with higher expected noise levels receive additional reference signals (higher quality), while low-noise regions use standard reference signal configurations, making the system adaptive to local noise conditions rather than applying a uniform approach

Inventive Principle:
Principle #3Local quality

2Measurement precision

If additional reference signals are transmitted in high-noise regions, then noise estimation precision is improved, but device complexity increases due to more reference signals to manage

Engineering Contradiction:
Improvenoise estimation precisionVSAvoidreference signal management complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Additional reference signals (NTRS) are transmitted only in specific regions where high noise levels are expected, rather than uniformly across the entire TTI. This localized approach improves noise estimation precision in critical regions while avoiding the complexity overhead of adding reference signals everywhere

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system changes the transmission parameters of reference signals based on the expected noise level in different regions. By adjusting reference signal density and positioning according to noise characteristics, the system achieves better noise estimation without uniformly increasing complexity across all transmission regions

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3857788B1Noise tracking within transmission time intervals in wireless communications
Publication Date: 2022.05.11 QUALCOMM INC
  • EP3857788B1 patent drawingFigure 1
  • EP3857788B1 patent drawingFigure 2
  • EP3857788B1 patent drawingFigure 3

AI summary

Methods, systems, and devices for wireless communications are described that support noise tracking within transmission time intervals (TTIs) in wireless communications. A transmitting user equipment (UE) in direct communications with a receiving UE may transmit one or more reference signals that allow the receiving UE to estimate noise during different portions of a TTI and compensate for varying noise levels within the TTI. The transmitting UE may identify different sets of symbols within the TTI that are expected to have different noise levels, and may transmit one or more reference signals that allow for noise estimation at the receiving UE for each of the different sets of symbols.