Quantized Beamforming Feedback for MIMO Multicarrier Systems

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Multicarrier communication systems face challenges in adapting to changing channel conditions due to differing channel conditions across subcarriers, particularly in MIMO systems, which requires significant feedback and consumes bandwidth and energy.

Innovation Solution

The use of quantized transmit beamforming coefficients, applied before inverse Fourier transform, reduces feedback by generating a quantized beamforming matrix that accounts for channel conditions, allowing for adaptive beamforming and efficient data transmission across multiple spatial channels without increasing frequency bandwidth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If feedback is used to adapt transmissions to changing channel conditions in multicarrier MIMO systems, then transmission adaptability is improved, but bandwidth consumption and energy usage increase significantly

Engineering Contradiction:

Improvetransmission adaptabilityVSAvoidenergy consumption

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent extracts only the essential channel state information needed for beamforming adaptation, specifically the beamforming feedback matrix, rather than transmitting complete channel state information for all subcarriers. This selective extraction reduces feedback overhead while maintaining transmission adaptability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent segments the channel adaptation process by applying different beamforming strategies to different subcarrier groups. The feedback mechanism is segmented to provide adaptive information only where needed, reducing overall feedback requirements while maintaining system adaptability.

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If feedback is increased to adapt to changing channel conditions across many subcarriers, then transmission accuracy is improved, but bandwidth consumption increases

Engineering Contradiction:

Improvechannel condition adaptation accuracyVSAvoidbandwidth consumption

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The patent changes the parameter representation from complete channel state information to compressed beamforming feedback matrices. By transforming the channel adaptation information into a more efficient parameter format, the system maintains measurement precision while reducing feedback bandwidth requirements.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Instead of transmitting channel state information from receiver to transmitter as conventional feedback, the patent inverts the approach by having the transmitter generate beamforming matrices based on reduced feedback information, achieving accurate channel adaptation with minimal feedback overhead.

Inventive Principle:

Principle #13The other way round (Inversion)

3Productivity

If multiple antennas are used to communicate additional data streams over the same subcarriers, then data transmission capacity is improved, but feedback requirements increase

Engineering Contradiction:

Improvedata transmission capacityVSAvoidfeedback overhead

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent creates a universal beamforming feedback mechanism that serves multiple functions simultaneously: it enables spatial multiplexing for increased capacity, provides channel adaptation across subcarriers, and reduces feedback overhead through compressed representation. This multi-functional approach increases productivity without proportionally increasing feedback requirements.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS7570696B2Multiple input multiple output multicarrier communication system and methods with quantized beamforming feedback

Publication Date: 2009.08.04 TAHOE RES LTD

AI summary

A multicarrier receiver generates a quantized transmit beamformer matrix ({tilde over (V)}) for each subcarrier of a multicarrier communication channel for use by a multicarrier transmitting station. The multicarrier receiver applies a corrected receiver beamformer matrix (ŨH) to received subcarriers signals generated by signals received from the transmitting station.