Downlink Reference Signal Sparsity Reporting for Channel Estimation

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Solution Overview

Problem

Existing wireless communication systems face inefficiencies in channel estimation due to the high sampling rates required by the Nyquist rate, which can be mitigated by leveraging compressive sensing techniques that rely on the sparsity of target signals.

Innovation Solution

A wireless transmit/receive unit (WTRU) determines the sparsity order of a channel based on configuration information, using parameters such as minimum and maximum channel impulse response durations, amplitude thresholds, and frequency/time-domain patterns to optimize the placement and rotation of downlink reference signals, enabling efficient channel estimation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the Nyquist rate is used for channel estimation, then measurement precision is improved, but sampling frequency and system complexity increase

Engineering Contradiction:

Improvechannel estimation accuracyVSAvoidsampling frequency

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent changes the sampling frequency parameter from the traditional Nyquist rate to a reduced rate enabled by compressive sensing. By leveraging the sparsity of channel impulse response coefficients, the system can achieve accurate channel estimation at lower sampling frequencies, thus resolving the contradiction between measurement precision and device complexity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the conventional mechanical sampling system with a compressive sensing-based system. Instead of following traditional Nyquist sampling requirements, the system uses sparse representation and optimization algorithms to reconstruct channel characteristics, substituting the mechanical sampling process with an information-theoretic approach

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If compressive sensing is used to reduce sampling frequency, then device complexity is reduced, but measurement precision may deteriorate

Engineering Contradiction:

Improvesampling frequencyVSAvoidchannel estimation accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent implements feedback mechanisms where the WTRU reports sparsity order information back to the network. This feedback enables the network to adjust reference signal configuration and sampling parameters dynamically, ensuring that channel estimation accuracy is maintained even at reduced sampling frequencies through iterative optimization

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent performs preliminary actions by configuring multiple downlink reference signals with different sparsity orders before actual channel estimation. The WTRU measures and reports sparsity order information in advance, allowing the network to pre-determine optimal sampling parameters and reference signal placements, thereby ensuring measurement precision is achieved from the start

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If sparsity order is determined based on multiple parameters, then adaptability is improved, but device complexity increases

Engineering Contradiction:

Improvechannel estimation adaptabilityVSAvoidparameter processing complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the complex sparsity order determination process into multiple independent parameter measurements. Instead of processing all parameters simultaneously, the WTRU separately measures minimum CIR duration, maximum CIR duration, amplitude threshold, and frequency-domain patterns, then combines these segmented results to determine the final sparsity order, reducing processing complexity while maintaining adaptability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies partial action by selecting and processing only the most relevant parameters for sparsity order determination. The system evaluates multiple parameters (minimum/maximum CIR duration, amplitude threshold, frequency-domain patterns) but processes them selectively based on channel conditions, avoiding unnecessary computation while maintaining sufficient adaptability for accurate channel estimation

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS20260075450A1Determining and reporting of sparsity information for a downlink reference signal

Publication Date: 2026.03.12 INTERDIGITAL PATENT HOLDINGS INC

AI summary

A wireless transmit/receive unit (WTRU) may receive first configuration information. The first configuration information may indicate a first downlink reference signal (RS) and/or parameters comprising information indicating a minimum channel impulse response (CIR) duration, a maximum CIR duration, an amplitude threshold, frequency-domain patterns, and/or time-domain patterns. The WTRU may receive downlink control information (DCI). The DCI may comprise triggering information that directs the WTRU to perform measurements and/or report a sparsity order of a channel associated with the downlink RS. The WTRU may determine the sparsity order of the channel associated with the downlink RS may be based on the parameters. The WTRU may send a report that comprises an indication of the sparsity order, an indication of a preferred frequency-domain pattern indicating RSs according to the sparsity order, and/or spatial information associated with the sparsity order.