Diversity Receiver Match Filter for OFDM

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Solution Overview

Problem

Conventional diversity receivers for OFDM systems face complexity and increased manufacturing costs due to the need for complicated division algorithms and lack of background noise information for decoding, which degrades decoding performance.

Innovation Solution

A diversity receiver design incorporating N Fourier transform circuits, N channel estimators, N match filters, and a channel decoder, which replaces channel equalizers with match filters to simplify operations and provides noise power estimators for background noise information, reducing the need for dividers and enhancing decoding performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If channel equalizers with division algorithms are used in conventional diversity receivers, then channel equalization can be performed, but device complexity and manufacturing costs increase

Engineering Contradiction:

Improvechannel equalization performanceVSAvoiddivision algorithm complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the conventional channel equalizer that uses division algorithms with a match filter that uses multiplication. Specifically, the match filter multiplies the received signal by the complex conjugate of the channel frequency response, which is equivalent to the equalization operation but avoids the need for division. This substitution of mathematical operation reduces computational complexity and hardware requirements while maintaining equalization functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operational parameter of the equalization process from division-based to multiplication-based. By transforming the channel equalization operation into a matching filter operation that uses multiplication instead of division, the system achieves the same equalization effect with reduced complexity. This parameter change fundamentally alters how equalization is implemented while preserving its reliability.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If conventional channel equalizers are used without noise information, then equalization can be performed, but decoding performance degrades

Engineering Contradiction:

Improveequalization functionVSAvoidbackground noise information

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent introduces noise power estimation as a feedback mechanism that provides background noise information to the channel decoder. The noise power estimator calculates the noise power from the equalized signal and feeds this information back to the Viterbi decoder. This feedback loop enables the decoder to adapt to actual noise conditions, significantly improving decoding performance while maintaining the equalization function.

Inventive Principle:

Principle #23Feedback

3Reliability

If multiple dividers are used in conventional diversity receivers, then channel equalization can be implemented, but manufacturing costs increase

Engineering Contradiction:

Improvechannel equalization capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent eliminates the need for dividers by substituting the division operation with multiplication in the match filter. Instead of using multiple dividers to implement channel equalization across different branches, the system uses multipliers that are generally cheaper and simpler to manufacture. This substitution directly reduces manufacturing costs while preserving equalization capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If complex division algorithms are used in diversity receivers, then equalization can be performed, but operation complexity increases

Engineering Contradiction:

Improveequalization performanceVSAvoiddemodulation operation complexity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent simplifies the demodulation operation by replacing complex division algorithms with simpler multiplication operations in the match filter. The match filter performs equalization through multiplication by the complex conjugate, which is computationally simpler and easier to implement than division. This reduces operational complexity while maintaining equalization performance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS7623591B2Diversity receiver

Publication Date: 2009.11.24 SILICON INTEGRATED SYSTEMS CORP

AI summary

A diversity receiver includes N number of Fourier transform circuits, N number of channel estimators, N number of match filters, N number of soft demappers, a combination/selection unit, and a channel decoder. The diversity receiver merges the square of the absolute value of estimate channel frequency response and transmission data into a demodulation signal and then outputs the demodulation signal by means of the match filter.