Mobile Station CQI Feedback Optimization

Solution Overview

Problem

Conventional feedback methods in 4G communication systems, such as IEEE 802.16, are inefficient in terms of system capacity and fairness, particularly when used with different scheduling policies, and result in excessive feedback and resource wastage due to the need for frequent channel quality indicator (CQI) updates from Mobile Stations (MS) to Base Stations (BS).

Innovation Solution

A method where the number of subchannels for CQI feedback from MSs is determined based on a preset feedback efficiency factor, ensuring a constant ratio of fed-back subchannels to total allocated subchannels, allowing MSs to select and feed back CQIs in descending order of channel quality, thereby optimizing feedback amount and reducing signaling overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional feedback methods (Best-M, AST, NST) are used to maintain system capacity and fairness, then channel quality information is fed back, but the feedback amount becomes excessive and causes resource wastage

Engineering Contradiction:

Improvechannel quality information accuracyVSAvoidfeedback amount

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies partial action by having MSs feed back CQI information for only a subset of subchannels (M subchannels) rather than all subchannels. The number M is determined dynamically based on the MS's average data rate, channel conditions, and scheduler type, providing just enough feedback information to maintain scheduling accuracy without excessive overhead.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent makes the feedback amount dynamic by adjusting the number of subchannels M for which CQI is fed back. The base number M is calculated based on the MS's average data rate and modified according to channel conditions and scheduler type, allowing the feedback quantity to adapt to varying system conditions rather than being fixed.

Inventive Principle:

Principle #15Dynamics

2Measurement precision

If MSs feed back CQIs for all subchannels to ensure accurate scheduling, then scheduling accuracy is maintained, but signaling overhead increases excessively

Engineering Contradiction:

Improvescheduling accuracyVSAvoidsignaling overhead

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The patent applies partial action by having MSs feed back CQI information for only a subset of subchannels (M subchannels) rather than all subchannels. The number M is determined dynamically based on the MS's average data rate, channel conditions, and scheduler type, providing just enough feedback information to maintain scheduling accuracy without excessive overhead.

Inventive Principle:

Principle #16Partial or excessive action

3Quantity of substance

If the number of feedback subchannels is reduced to minimize overhead, then signaling overhead decreases, but system capacity and fairness deteriorate

Engineering Contradiction:

Improvefeedback amountVSAvoidsystem capacity

Core Design Contradiction:

Quantity of substanceVSProductivity

Solution Approach 1:

The patent makes the feedback amount dynamic by adjusting the number of subchannels M for which CQI is fed back. The base number M is calculated based on the MS's average data rate and modified according to channel conditions and scheduler type, allowing the feedback quantity to adapt to varying system conditions rather than being fixed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter M (number of subchannels for CQI feedback) based on multiple factors including the MS's average data rate, channel conditions, and scheduler type. This parameter adjustment ensures that sufficient feedback information is provided to maintain system capacity and fairness while minimizing overhead.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS7991358B2Method for reducing an amount of feedback used in a mobile communication system

Publication Date: 2011.08.02 SAMSUNG ELECTRONICS CO LTD

AI summary

A method for feeding back a Channel Quality Indicator (CQI) in a mobile communication system is provided. The method includes determining a number of subchannels for which the MS feeds back CQIs based on a preset feedback efficiency factor, selecting the determined number of subchannels in a descending order of channel quality, and feeding back the CQIs of the selected subchannels to a Base Station (BS).