OVCDM-OFDM Coded Modulation for Wideband Transmission
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Solution Overview
Problem
Existing OFDM wideband wireless transmission systems suffer from excessive redundancy, low transmission efficiency, and complex modulation, which reduces reliability and increases system resources without effective error correction.
Innovation Solution
The integration of Overlapped Code Division Multiplexing (OVCDM) with OFDM, involving serial-to-parallel conversion, convolutional coding, superimposing, and Inverse Fast Fourier Transform (IFFT) for transmission, and Fast Fourier Transform (FFT) for reception, to improve spectrum efficiency and reduce redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional channel coding (convolutional code or Turbo code) is combined with OFDM to improve transmission reliability, then transmission reliability is improved, but transmission efficiency is decreased due to increased system redundancy
Solution Approach 1:
The patent merges channel coding and modulation into a unified coded modulation scheme where coding and modulation are performed simultaneously in the frequency domain. This integration eliminates the need for separate coding and modulation stages, reducing overall system redundancy while maintaining error correction capabilities. The coded modulation directly maps coded symbols to subcarriers, achieving both reliability improvement and efficiency preservation.
Solution Approach 2:
The invention creates a multi-functional transmission framework that simultaneously achieves error correction, spectrum spreading, and data transmission. The coded modulation scheme serves multiple purposes: it provides error correction through coding, improves spectral efficiency through frequency-domain processing, and maintains transmission reliability through iterative detection and decoding. This universal approach replaces multiple separate functions with a single integrated mechanism.
2Productivity
If OFDM is used to alleviate ISI and improve system capacity, then system capacity is improved and ISI is reduced, but no efficient error-correcting code is provided resulting in transmission errors
Solution Approach 1:
The patent combines OFDM's multicarrier capability with channel coding to create coded OFDM modulation. The coding operation is performed in the frequency domain across multiple subcarriers, integrating error correction directly into the OFDM modulation process. This merging ensures that error correction is inherent to the high-capacity transmission mechanism rather than being an add-on.
Solution Approach 2:
The invention introduces an intermediary frequency-domain processing stage that acts as a bridge between channel coding and OFDM modulation. This intermediary stage performs coded modulation by mapping coded symbols to subcarriers in the frequency domain, enabling efficient error correction without sacrificing the capacity benefits of OFDM. The intermediary processing ensures smooth integration of coding and modulation functions.
Data Source
AI summary
A method of wideband radio transmission is disclosed, the method includes the following steps: obtaining the parallel data symbols; encoding the obtaining parallel data symbols respectively; superposing the encoded data symbols; performing the fast Fourier inverse transform for the superposed data symbols and transmitting them. Applying the solution, the transmission efficiency and the transmission dependability of the OFDM system is raised. An apparatus for wideband radio transmission and a transmission system are also disclosed.