OQAM Modulator Partial Fourier Transform Complexity
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Solution Overview
Problem
OFDM/OQAM modulation techniques require higher operational complexity and spectral efficiency compared to OFDM, due to the need for inverse discrete Fourier transformations and prototype filtering, which increases computational load and reduces spectral efficiency.
Innovation Solution
A partial Fourier transform is applied to reduce the number of operations required, calculating only part of the outputs and deducing the rest, thereby reducing complexity and maintaining spectral efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OFDM/OQAM modulation is used to improve spectral efficiency by avoiding guard intervals, then spectral efficiency is improved, but operational complexity increases due to required inverse discrete Fourier transformations and prototype filtering
Solution Approach 1:
The patent applies partial Fourier transform instead of complete inverse discrete Fourier transformation, calculating only the necessary portion of transformed symbols. This reduces the number of computational operations while still achieving the required signal transformation for OFDM/OQAM modulation, thereby lowering operational complexity while maintaining spectral efficiency.
2Reliability
If complete inverse discrete Fourier transformation is performed on M real data symbols, then all M transformed symbols are obtained, but the number of operations is doubled compared to OFDM modulation
Solution Approach 1:
The patent extracts and utilizes the symmetry properties of the Fourier transform of real data symbols. By recognizing that transformed symbols exhibit conjugate symmetry, the method obtains only the necessary independent transformed symbols (M/2 unique values) and derives the remaining symbols from these, effectively halving the computational load while maintaining complete signal reconstruction capability.
Data Source
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AI summary
The invention relates to a modulation method outputting an OQAM multi-carrier signal. According to the invention, such a method implements a step of transforming, from the frequency domain to the time domain, a set of M symbols of real data so as to output M transformed symbols, said complete transformation (22) including the following sub-steps: applying a partial Fourier transform (221) to said set of M symbols of real data, outputting a first subset of C transformed symbols, where C is strictly less than M; and obtaining (222), from said first subset, a second subset of (M-C) transformed symbols that is complementary to said first subset.