Uplink Precoder Signaling Overhead Reduction

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Solution Overview

Problem

Current Long Term Evolution Advanced (LTE-A) standards face challenges in uplink MU-MIMO precoder design due to excessive signalling overhead, particularly in non-codebook based designs, where conveying uplink precoder matrices from the base station to user terminals requires significant control channel resources, exceeding current signalling standards.

Innovation Solution

The proposal involves using an additional pilot resource in the downlink to convey uplink precoder information, estimating precoder matrices from a downlink pilot signal, and transmitting the scaling factor using existing control signalling, thereby reducing signalling overhead and enabling efficient non-codebook based uplink MU-MIMO precoding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If non-codebook based uplink precoding is used, then precoding flexibility and performance are improved, but signalling overhead increases excessively

Engineering Contradiction:

Improveprecoding flexibilityVSAvoidsignalling overhead

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent extracts only the essential precoder information (scaling factor and port indicator) from the full precoder matrix, transmitting only these critical parameters while deriving the complete precoder at the receiver side using channel state information, thereby reducing signalling overhead while maintaining precoding flexibility

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces channel state information (CSI) as an intermediary that enables the receiver to reconstruct the full precoder matrix from the transmitted scaling factor and port indicator, acting as a mediator that carries the implicit precoding information without requiring direct transmission of the complete precoder

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If full precoder matrices are transmitted, then precoding accuracy is improved, but control channel resources are exhausted

Engineering Contradiction:

Improveprecoder accuracyVSAvoidcontrol channel resources

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent segments the precoder information into multiple components: transmitted parameters (scaling factor, port indicator) and derived parameters (precoder matrix reconstructed from CSI), allowing accurate precoding while using minimal control channel resources for transmission

Inventive Principle:

Principle #1Segmentation

3Loss of information

If codebook based precoding is used, then signalling overhead is reduced, but precoding flexibility is limited

Engineering Contradiction:

Improvesignalling overheadVSAvoidprecoding flexibility

Core Design Contradiction:

Loss of informationVSAdaptability or versatility

Solution Approach 1:

The patent enables dynamic precoding where the precoder can be continuously adapted based on channel conditions through the scaling factor and port indicator, moving from static codebook-based approaches to dynamic non-codebook-based precoding that maintains flexibility while controlling overhead

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS10715226B2Apparatus and method for control signalling in uplink precoding

Publication Date: 2020.07.14 NOKIA SOLUTIONS & NETWORKS OY

AI summary

An apparatus and a method for control signaling are disclosed. The method comprises communicating (402) with one or more user terminals utilising Time Division Duplexing, estimating (404) uplink precoder parameters for the one or more user terminals, the parameters comprising an uplink precoder matrix and a scaling factor and transmitting (406) the uplink precoder parameters utilising a downlink pilot signal and downlink control signalling.