Channel State Information Upsampling for 5G Precoder Gain

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Solution Overview

Problem

In 5G wireless communication systems, the downsampling of resource block (RB) level precoders to subband (SB) level precoders leads to severe precoder gain degradation due to aliasing effects, especially in channels with large delay spreads.

Innovation Solution

A physics-inspired learning-based approach is introduced to recover RB-level precoders from SB-level precoders by leveraging side information such as uplink CSI and historical CSI, which helps suppress aliasing effects and enhance precoder gain.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If downsampling of RB level precoders to SB level precoders is performed to reduce feedback overhead, then feedback overhead is reduced, but precoder gain degradation occurs due to aliasing effects

Engineering Contradiction:

Improvefeedback overheadVSAvoidprecoder gain

Core Design Contradiction:

Loss of substanceVSManufacturing precision

Solution Approach 1:

The system performs preliminary downsampling at the UE side to generate SB level precoders before feedback, which reduces feedback overhead. The base station then recovers RB level precoders from these downsampled SB level precoders using upsampling and aliasing suppression techniques, effectively reversing the downsampling effect to maintain precoder gain.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

SB level precoders serve as an intermediary representation that reduces feedback overhead while preserving essential channel information. The base station uses this intermediary form and combines it with side information (UL CSI, historical CSI) to reconstruct the full-resolution RB level precoders, achieving both reduced overhead and maintained precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of substance

If downsampling to SB level precoders is performed, then feedback overhead is reduced, but aliasing effects increase in channels with large delay spreads

Engineering Contradiction:

Improvefeedback overheadVSAvoidaliasing effects

Core Design Contradiction:

Loss of substanceVSObject-generated harmful factors

Solution Approach 1:

The system acknowledges that downsampling inherently creates aliasing effects, but converts this harmful factor into a manageable challenge by developing specific aliasing suppression techniques. These techniques use side information and sophisticated signal processing to identify and remove aliasing components, effectively transforming the downsampling-induced distortion into a solvable problem rather than a system limitation.

Inventive Principle:

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

Solution Approach 2:

The base station changes the resolution parameter of precoders from SB level to RB level through upsampling operations. By adjusting this parameter and combining it with aliasing suppression algorithms that leverage side information, the system recovers the high-resolution precoder details that were lost during downsampling, thereby reducing aliasing effects while maintaining low feedback overhead.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If RB level precoders are used directly, then precoder gain is maintained, but feedback overhead increases

Engineering Contradiction:

Improveprecoder gainVSAvoidfeedback overhead

Core Design Contradiction:

Manufacturing precisionVSLoss of substance

Solution Approach 1:

The feedback information is segmented into two parts: SB level precoders (downsampled form) and side information (UL CSI, historical CSI). This segmentation allows the system to transmit compressed precoder data while using the side information to reconstruct the full-resolution RB level precoders at the base station, thereby maintaining precoder gain while reducing feedback overhead.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system transitions from a single-dimension approach (direct RB level precoder feedback) to a multi-dimensional approach by incorporating time dimension (historical CSI) and frequency dimension (UL CSI) as additional resources. These side information dimensions enable the reconstruction of high-resolution precoders from low-resolution feedback, achieving reduced overhead without sacrificing precision.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS20250088228A1Channel state information upsampling in wireless communication network

Publication Date: 2025.03.13 SAMSUNG ELECTRONICS CO LTD

AI summary

Methods and apparatuses for an operation for a channel state information upsampling in a wireless communication system. A method of BS includes: receiving, from a UE, feedback information including at least one SB level precoder; identifying, based on the at least one SB level precoder, a mapping function to perform an up-sampling operation; performing, based on the mapping function, the up-sampling operation to the at least one SB level precoder; and identifying, based on the up-sampling operation, at least one RB level precoder from the at least one SB level precoder for a precoder gain of the BS.