Interpolation-Based Uplink Subband Precoding Phase Rotation

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Solution Overview

Problem

Current wireless communication systems, particularly in 5G NR, face challenges in efficiently managing precoding for physical uplink shared channels (PUSCH) across multiple sub-bands, which affects channel utilization and interference management.

Innovation Solution

The proposed solution involves a method where a user equipment (UE) receives downlink control information (DCI) indicating different precoders for various resource grids of a PUSCH. The UE then transmits the PUSCH using a first precoder for a first resource grid and a third precoder for a second resource grid, where the third precoder is based on a phase rotation of the second precoder.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single precoder is used for the entire PUSCH bandwidth, then device complexity is reduced, but channel utilization and interference management performance deteriorate

Engineering Contradiction:

Improveprecoder management complexityVSAvoidchannel utilization and interference management

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The PUSCH bandwidth is divided into multiple sub-bands, and different precoders are applied to different sub-bands. This segmentation allows the system to optimize channel utilization and interference management for each sub-band independently while keeping the overall complexity manageable through structured precoder selection and phase rotation techniques.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different precoders are applied to different sub-bands based on local channel conditions. Each sub-band can have its own precoding characteristics optimized for its specific frequency range, allowing local optimization of channel utilization and interference management without requiring complete re-precoding of the entire bandwidth.

Inventive Principle:

Principle #3Local quality

2Reliability

If different precoders are applied to different sub-bands, then channel utilization and interference management are improved, but device complexity increases

Engineering Contradiction:

Improvechannel utilization and interference managementVSAvoidprecoder management complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system dynamically selects precoders and applies phase rotations based on channel conditions and sub-band characteristics. This dynamic approach allows the system to adapt to changing conditions while maintaining a manageable complexity level through structured selection procedures and relationships between precoders across sub-bands.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes precoder parameters (such as phase rotation values) across different sub-bands to optimize performance. By systematically varying precoder parameters rather than using completely independent precoders for each sub-band, the system achieves improved channel utilization and interference management while controlling complexity through parameter relationships.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If interpolation-based sub-band precoding is used, then precoder accuracy is improved, but phase discontinuity and out-of-band emissions increase

Engineering Contradiction:

Improveprecoder accuracyVSAvoidphase discontinuity and out-of-band emissions

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The system applies periodic phase rotations at sub-band boundaries to maintain phase continuity. By introducing controlled phase rotations at regular intervals (sub-band boundaries), the system prevents phase discontinuities that would otherwise arise from interpolation, thereby reducing out-of-band emissions while maintaining precoder accuracy within sub-bands.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system converts the potential harm of phase discontinuity into a beneficial controlled phase rotation. By deliberately applying phase rotations at sub-band boundaries, the system transforms what would be a harmful discontinuity into a controlled transition that maintains overall phase continuity and reduces out-of-band emissions while preserving the accuracy benefits of interpolation-based precoding.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS20250125841A1Interpolation based uplink subband precoding with phase rotation

Publication Date: 2025.04.17 QUALCOMM INC

AI summary

A UE receives DCI scheduling a PUSCH spanning multiple sub-bands, the DCI indicating a first precoder for a first resource grid of the PUSCH and a second precoder for a second resource grid of the PUSCH. The UE transmits the PUSCH with the first precoder at the first resource grid and with a third precoder at the second resource grid, the third precoder being based on a phase rotation of the second precoder. A base station transmits DCI scheduling a PUSCH spanning multiple sub-bands, the DCI indicating a first precoder for a first resource grid of the PUSCH and a second precoder for a second resource grid of the PUSCH. The base station receives the PUSCH with the first precoder at the first resource grid and with a third precoder at the second resource grid, the third precoder being based on a phase rotation of the second precoder.