Dual Carrier Modulation Precoding for 16QAM Frequency Diversity

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Solution Overview

Problem

Conventional dual carrier modulation (DCM) precoding techniques in OFDM systems fail to achieve full frequency diversity when using higher-order modulation schemes like 16QAM, leading to degraded channel performance and limited data rate capabilities.

Innovation Solution

An improved DCM precoding technique using a unitary precoding matrix with integer elements ensures frequency diversity of at least order 2, even with 16QAM modulation, by precoding symbols and distributing them across different subcarriers, while maintaining power spectrum density characteristics and simplifying decoding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional DCM precoding is used with higher-order modulation schemes (16QAM), then data rate is increased, but frequency diversity is lost and channel performance degrades

Engineering Contradiction:

Improvedata rateVSAvoidfrequency diversity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the parameters of the precoding matrix from conventional complex-valued matrices to unitary matrices with integer elements. This parameter transformation enables the system to maintain frequency diversity order of 2 while supporting higher-order modulation schemes like 16QAM, thereby resolving the contradiction between achieving high data rates and maintaining frequency diversity.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If conventional DCM precoding is used, then implementation is simple, but it cannot achieve full frequency diversity with higher-order modulation

Engineering Contradiction:

Improveimplementation simplicityVSAvoidfrequency diversity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent transforms the precoding matrix parameters to use unitary matrices with integer elements, which maintains implementation simplicity while achieving full frequency diversity. The unitary property with integer elements provides both computational efficiency and the mathematical guarantees needed for frequency diversity, resolving the contradiction between ease of implementation and reliability.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If higher-order modulation (16QAM) is used to increase data rate, then productivity improves, but channel performance is determined by the worst subcarrier

Engineering Contradiction:

Improvedata rateVSAvoidchannel performance limitation

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary precoding using unitary matrices with integer elements before transmission. This preliminary action redistributes the signal energy across subcarriers in a way that prevents the worst subcarrier from dominating the channel performance. The precoding matrix is designed to ensure that all subcarriers contribute effectively to the overall transmission reliability, thereby enabling higher data rates without being limited by the worst subcarrier.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP2269356B1Improved Dual Carrier Modulation Precoding

Publication Date: 2018.07.25 KONINKLIJKE PHILIPS NV

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AI summary

A method (300) for performing dual carrier modulation (DCM) precoding. The method comprises generating data sub-blocks (S320), independently interleaving the sub-blocks (S330), generating bit vectors by grouping bits of the interleaved sub- blocks (S350), mapping the bit vectors into data symbols (S360), and precoding the data symbols using a precoding matrix to generate precoded symbols (S370).