MIMO Mobile Station Channel Feedback Using Ray Extraction

Solution Overview

Problem

Multicarrier communication systems with multiple subcarriers face challenges in adapting to changing channel conditions, particularly in MIMO systems, due to the significant bandwidth consumption and energy usage required for feedback processing, which complicates battery-powered mobile units.

Innovation Solution

A method where a mobile station sends a quantized time-domain representation of the channel transfer function to a base station, reducing processing requirements and bandwidth consumption by selecting and optimizing the most significant rays of the channel impulse response for beamforming coefficients generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If full channel transfer function feedback is used to adapt to changing channel conditions in MIMO multicarrier systems, then communication performance is improved, but feedback bandwidth consumption and mobile-station processing complexity increase significantly

Engineering Contradiction:

Improvecommunication performanceVSAvoidmobile-station processing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts only the most significant rays from the full channel impulse response and feeds back their time-domain parameters (delay, amplitude, phase) to the base station. This selective extraction reduces feedback bandwidth and mobile-station processing while maintaining sufficient accuracy for beamforming coefficient generation at the base station

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The channel impulse response is segmented into individual rays, and only the most significant portions (top L rays) are selected for feedback. This segmentation allows the system to focus resources on the most impactful channel components rather than processing the entire channel response

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If full channel transfer function feedback is transmitted, then accurate channel adaptation is achieved, but feedback bandwidth consumption increases

Engineering Contradiction:

Improvechannel adaptation accuracyVSAvoidfeedback bandwidth consumption

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent extracts only the most significant rays from the full channel impulse response and feeds back their time-domain parameters (delay, amplitude, phase) to the base station. This selective extraction reduces feedback bandwidth and mobile-station processing while maintaining sufficient accuracy for beamforming coefficient generation at the base station

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If complete channel information is processed at the mobile station, then optimal beamforming coefficients are generated, but energy consumption and processing load increase

Engineering Contradiction:

Improvebeamforming coefficient accuracyVSAvoidmobile-station energy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent extracts only the most significant rays from the full channel impulse response and feeds back their time-domain parameters (delay, amplitude, phase) to the base station. This selective extraction reduces feedback bandwidth and mobile-station processing while maintaining sufficient accuracy for beamforming coefficient generation at the base station

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of having the mobile station perform heavy processing to generate beamforming coefficients directly, the patent inverts the approach: the mobile station performs lightweight parameter extraction and feedback, while the base station performs the computationally intensive beamforming coefficient generation using the received parameters

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS7649861B2Multiple antenna multicarrier communication system and method with reduced mobile-station processing

Publication Date: 2010.01.19 TAHOE RES LTD

AI summary

In a multiple-input multiple-output (MIMO) multicarrier communication system, a mobile station sends a quantized time-domain representation of the channel transfer function to a base station for use by the base station in generating beamforming coefficients for use in subsequent transmissions to the mobile station. In some embodiments, the quantized time-domain representation of the channel transfer function may be generated from selected most significant rays of an initial estimated sampled channel impulse response. Other embodiments may be described and claimed.