MIMO Precoding Codebook Segmentation for Lower Feedback Overhead

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Solution Overview

Problem

As the number of transmission antennas increases in MIMO systems, the size of the codebook grows, leading to increased feedback data and varying reception capabilities, necessitating a more efficient codebook design and feedback scheme to reduce data overhead and enhance reception performance.

Innovation Solution

A method and apparatus for configuring precoding matrices in a wireless communication system, where a user equipment transmits codebook indices at different intervals to a base station, allowing for reduced feedback overhead and improved data transmission efficiency with multiple transmission antennas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the number of transmission antennas is increased, then the beamforming gain and diversity gain are improved, but the codebook size increases and feedback overhead increases

Engineering Contradiction:

Improvebeamforming gain and diversity gainVSAvoidcodebook size and feedback data

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The codebook is divided into multiple subcodebooks, each corresponding to a specific transmission rank. The receiving end selects appropriate subcodebooks based on channel conditions and feeds back only the necessary subcodebook indices, rather than selecting from a single large codebook containing all possible precoding matrices for all ranks.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The codebook configuration is made dynamic by allowing the receiving end to adaptively select and indicate specific subcodebooks based on current channel conditions and transmission requirements. This dynamic selection enables the system to use smaller, more efficient codebook portions when full codebook capability is not needed.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If the codebook size is increased to support more antennas, then the precoding options are improved, but the feedback overhead increases

Engineering Contradiction:

Improveprecoding optionsVSAvoidfeedback overhead

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The large codebook is segmented into multiple smaller subcodebooks organized by transmission rank. Each subcodebook contains precoding matrices appropriate for a specific rank, allowing the receiving end to select and feedback only the relevant subcodebook indices rather than searching through or feedback information about the entire large codebook.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The receiving end performs partial codebook evaluation by selecting and indicating only the necessary subcodebooks corresponding to current channel conditions and transmission rank, rather than evaluating or feedback information about the entire codebook. This partial action reduces feedback overhead while maintaining adequate precoding options.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentEP2545657B1Method and user equipment for transmitting precoding matrix information, and method and base station for configuring precoding matrix

Publication Date: 2022.10.19 QUALCOMM INC

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AI summary

An apparatus and method for a precoding matrix are disclosed. A codebook used for selecting a precoding matrix is comprised of m subgroups each including n precoding matrices. A user equipment indicates a specific precoding matrix selected from the codebook by transmitting to a base station a first codebook index indicating one of the m subgroups and a second codebook index indicating one of n precoding matrices in a subgroup. The base station configures the specific precoding matrix from the codebook based on the first and second codebook indexes.