CSI Feedback Assumptions Reduce Signaling Overhead

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Solution Overview

Problem

The radio resource management signaling for configuring non-PMI feedback in wireless communication systems is heavy, posing challenges in reducing uplink control signaling without increasing signaling overhead.

Innovation Solution

A wireless device is configured to make assumptions for CSI feedback reporting under certain circumstances, eliminating the need for explicit signaling of port indication parameters. These assumptions reflect default configurations, allowing flexible association between CSI-RS ports and transmission ranks, especially when CSI-RS resources are shared or rank-nested precoding is used.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If explicit port indication parameters are signaled to the wireless device, then the configuration of CSI feedback reporting becomes more precise and adaptable, but the radio resource management signaling overhead increases

Engineering Contradiction:

Improveconfiguration precisionVSAvoidsignaling overhead

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The wireless device autonomously determines the association between CSI-RS ports and transmission ranks using pre-defined rules and assumptions, eliminating the need for explicit port indication parameters to be signaled from the network. This self-service approach maintains configuration precision while dramatically reducing signaling overhead.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent changes the parameter representation from explicit port indication values to implicit assumptions based on transmission rank. Instead of signaling specific port associations, the system uses the transmission rank parameter itself to imply the port association through pre-defined mapping rules, thereby reducing signaling requirements.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If port indication parameters are configured for each CSI-RS resource, then flexible association between CSI-RS ports and transmission ranks is enabled, but the radio resource management signaling becomes heavier

Engineering Contradiction:

ImproveflexibilityVSAvoidsignaling complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent creates a universal mapping rule that applies across all CSI-RS resources and transmission ranks. The same pre-defined association rules are used universally to determine port indications, eliminating the need for resource-specific port indication parameters while maintaining flexibility through the transmission rank parameter.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent extracts the port indication information from explicit signaling and embeds it implicitly within the transmission rank parameter. By taking out the separate port indication parameters and incorporating their function into the existing transmission rank signaling, the system maintains flexibility without increasing signaling complexity.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS20250132789A1Channel State Information Feedback in a Wireless Communication System

Publication Date: 2025.04.24 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A wireless device (14) is configured for reporting channel state information, CSI, feedback (18) based on a CSI reference signal, CSI-RS, (16) received on a CSI-RS resource (11) of one or more CSI-RS ports. If the wireless device (14) is not configured with a parameter that indicates, for the CSI-RS resource (11), which sets of one or more CSI-RS port indices (17) are associated with which transmission ranks (15), the wireless device (14) is configured to assume, for the CSI-RS resource (11), that certain sets of one or more CSI-RS port indices (17) are associated with certain transmission ranks (15).