Recursive Discrete Fourier Transform Device Throughput Optimization

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Solution Overview

Problem

Traditional recursive discrete Fourier transform (RDFT) devices have high time complexity and computation cycles, making them unsuitable for real-time processing in broadband communication systems like OFDM transmission systems.

Innovation Solution

The implementation of an RDFT device using input-decimation technology, where M pre-processors divide N input signals into M aggregated signals, reducing the number of inputs for a recursive-filter and minimizing computation cycles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If traditional recursive discrete Fourier transform is used, then the transform operation can be performed, but the computation cycle is long and time complexity is high

Engineering Contradiction:
ImprovethroughputVSAvoidcomputation cycle
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent applies segmentation by dividing the N-point input sequence into M separate subsequences, each containing N/M points. This allows the recursive filter to process M aggregated signals in parallel or with reduced sequential steps, reducing the computation cycle from O(N) to O(N/M) while maintaining the same transform functionality.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements preliminary action through pre-processing steps where M pre-processors compute aggregated signals from the input sequence before the main recursive filter operation. This pre-computation of aggregated signals reduces the workload during the main transform phase, thereby reducing the overall computation cycle and improving throughput.

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If traditional recursive discrete Fourier transform is used, then the transform operation can be performed, but the time complexity is high making it unsuitable for real-time processing

Engineering Contradiction:
Improvereal-time processing capabilityVSAvoidcomputation complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

By segmenting the input sequence into M subsequences and processing them through M pre-processors followed by a recursive filter, the patent reduces the effective computation complexity from O(N²) to O(N·N/M) = O(N²/M). This segmentation enables real-time processing capability while managing device complexity through distributed computation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the processing parameter by introducing the decimation factor M, which transforms the computational approach from processing N individual points to processing N/M aggregated points. This parameter change reduces the time complexity and enables real-time processing adaptability without fundamentally changing the recursive filter structure.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS11416579B2Recursive discrete Fourier transform device
Publication Date: 2022.08.16 NAT CENT UNIV
  • US11416579B2 patent drawing
  • US11416579B2 patent drawing
  • US11416579B2 patent drawing

AI summary

A recursive discrete Fourier transform (RDFT) of this invention uses an input-decimation technique to reduce the number of input sequences for a recursive-filter so as to decrease the computation cycle of the recursive-filter. Therefore, the time complexity of the RDFT can be minimized, namely, increasing the throughput of the RDFT.