SC-FDMA Cluster Mapping for Orthogonality Preservation

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Solution Overview

Problem

In LTE uplink communication, the division of SC-FDMA signals into clusters for frequency resource allocation leads to a loss of orthogonality in the DFT matrix, resulting in significant inter-symbol interference (ISI), especially with high-level modulation schemes like 64 QAM, due to varying equalization channel gains across discontinuous frequency bands.

Innovation Solution

A radio communication apparatus and method that divides the SC-FDMA signal into clusters using a partially orthogonal bandwidth corresponding to a partially orthogonal vector length of the DFT matrix, ensuring that clusters are mapped to discontinuous frequency bands, thereby reducing ISI by maintaining orthogonality within each cluster.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If SC-FDMA signals are divided into clusters and mapped to discontinuous frequency bands, then frequency resource allocation flexibility is improved, but orthogonality of the DFT matrix is lost causing significant ISI

Engineering Contradiction:

Improvefrequency resource allocation flexibilityVSAvoidorthogonality of DFT matrix

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent segments the frequency bands into multiple clusters, where each cluster is further divided into sub-clusters. This segmentation allows flexible allocation of frequency resources while maintaining orthogonality within each sub-cluster through careful design of the segmentation boundaries and mapping relationships.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by ensuring that within each cluster, the sub-clusters are mapped to frequency bands that maintain orthogonal relationships. This allows different parts of the frequency spectrum to have different mapping characteristics, with orthogonality preserved locally within each sub-cluster while enabling global flexibility in resource allocation.

Inventive Principle:

Principle #3Local quality

2Productivity

If SC-FDMA signals are divided into clusters for flexible frequency allocation, then frequency resource efficiency is improved, but inter-symbol interference increases due to varying equalization channel gains

Engineering Contradiction:

Improvefrequency resource efficiencyVSAvoidinter-symbol interference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent segments frequency bands into clusters with specific sub-clusters that are mapped to maintain orthogonal relationships. This segmentation strategy allows efficient frequency resource utilization while controlling ISI by ensuring that signals within each sub-cluster experience similar channel characteristics.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the mapping parameters between frequency bands and sub-clusters to ensure that orthogonal relationships are preserved. By carefully selecting mapping relationships and adjusting parameters such as frequency spacing and cluster configuration, the patent reduces variations in equalization channel gains that would cause ISI.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If high-level modulation schemes like 64 QAM are used, then data transmission efficiency is improved, but sensitivity to ISI increases significantly

Engineering Contradiction:

Improvedata transmission efficiencyVSAvoidsensitivity to ISI

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent ensures that within each sub-cluster, the frequency bands are mapped to maintain orthogonal relationships, creating local quality consistency. This allows high-level modulation schemes to be used effectively, as the orthogonal structure within sub-clusters minimizes ISI that would otherwise degrade the performance of high-efficiency modulation schemes.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20240179037A1Integrated circuit for discrete fourier transforming a time signal to a frequency signal

Publication Date: 2024.05.30 SUN PATENT TRUST

AI summary

A communication system includes a communication apparatus and a base station. The communication apparatus includes a Discrete Fourier Transform (DFT) transformer which transforms a time-domain signal into a frequency-domain signal with a DFT size that is a product of powers of a plurality of values; a mapper which maps the frequency-domain signal on a plurality of frequency bands, each frequency band being located at a position separate from position(s) of other(s) of the plurality of frequency bands; and a signal generator which generates a single carrier-frequency division multiple access (SC-FDMA) time-domain signal from the mapped signal. The base station includes a receiver which receives the SC-FDMA time-domain signal; a combiner which generates the frequency-domain signal from the SC-FDMA time-domain signal; and a transformer which transforms the frequency-domain signal into the time-domain signal with an inverse Discrete Fourier Transform (IDFT) having the DFT size.