Beamforming Channel Estimation Using Receiver Power Measurements

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Solution Overview

Problem

Conventional beamforming techniques require specialized clients for channel estimation, which are complex, prone to hardware impairments, and incur processing delays and feedback overhead, making them impractical for off-the-shelf clients like Wi-Fi devices.

Innovation Solution

Employing intelligent channel estimation schemes that use differential power measurements between antenna elements, allowing either transmitter or receiver to estimate channel phases indirectly, thereby adapting beamforming signals to multipath environments without direct amplitude and phase measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional beamforming techniques use specialized clients for channel estimation, then channel estimation accuracy is improved, but device complexity and cost increase

Engineering Contradiction:

Improvechannel estimation accuracyVSAvoidclient complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses power measurement values (which are easily obtainable from standard clients) as a substitute for direct channel coefficient measurements. By copying the power measurement capability that exists in all standard clients and using it to infer channel information, the system achieves beamforming without requiring specialized measurement hardware or capabilities in the clients.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent introduces power measurement values as an intermediary between the transmitted signal and the channel estimation process. Instead of directly measuring channel coefficients (which requires specialized clients), the system measures power (which any standard client can do) and uses this intermediate measurement to derive channel estimation information through mathematical processing at the access point.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If specialized clients are used for channel estimation, then beamforming performance is improved, but processing delays increase

Engineering Contradiction:

Improvebeamforming performanceVSAvoidprocessing delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent leverages the existing power measurement functionality that is already built into standard wireless clients. By using this self-service capability that clients already possess, the system eliminates the need for specialized processing hardware or additional processing stages, thereby reducing processing delays while maintaining beamforming performance.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If direct amplitude and phase measurement is performed at the receiver, then channel estimation accuracy is improved, but hardware impairment effects increase

Engineering Contradiction:

Improvechannel estimation accuracyVSAvoidhardware impairment effects

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent uses power measurement values, which are robust and easily obtainable without sensitive hardware requirements. Power measurements are less susceptible to hardware impairments like frequency and phase offsets compared to direct amplitude and phase measurements. This approach uses a simpler, more robust measurement type that can be performed reliably with standard hardware.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Reliability

If conventional beamforming is implemented, then multipath mitigation is improved, but feedback overhead increases

Engineering Contradiction:

Improvemultipath mitigationVSAvoidfeedback overhead

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent extracts only the necessary information (power measurement values) from the received signals and feeds back this compressed representation to the access point. By taking out only the essential power measurement data rather than transmitting full channel state information, the system reduces feedback overhead while maintaining the ability to perform multipath mitigation through beamforming.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS8380133B2Beamforming methods and systems employing measured power at a receiver to perform channel estimation

Publication Date: 2013.02.19 NEC CORP

AI summary

Beamforming methods and systems are described in which differential channel estimation can be computed based on measured power at receiver. Simultaneous activation of antennas in separate pairs can be used to determine relative phases of antennas with respect to a reference antenna based on the power measurements. In turn, the beam forming signals can be weighted in accordance with the relative phases to adapt the signals to a multipath environment. Existing power measurement capabilities of conventional receivers can be employed to achieve approximate channel estimates.