OFDM Transmission Apparatus Precoding Matrix Subcarrier Allocation
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Solution Overview
Problem
Conventional OFDM transmission systems experience reduced transmission efficiency due to frequency-selective fading, which can lead to errors in subcarriers with low reception electric field intensity, even when using error correction methods that provide low code rates.
Innovation Solution
The proposed solution involves an OFDM transmission apparatus that employs a precoding matrix to generate multiplexed symbols, which are then allocated to subcarriers in a manner that distributes power evenly across multiple subcarriers, allowing for high code rate error correction without compromising frequency-selective fading resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If error correction methods with low code rates are used to improve transmission quality, then transmission quality is improved, but transmission efficiency is reduced
Solution Approach 1:
The patent applies different precoding matrices to different subcarriers based on their individual channel conditions. Each subcarrier receives optimized processing tailored to its specific fading characteristics, allowing efficient error correction only where needed rather than applying uniform low code rate correction across all subcarriers.
Solution Approach 2:
The system dynamically changes precoding matrix parameters based on channel state information. By adapting the precoding matrix selection to current fading conditions, the system optimizes transmission quality for affected subcarriers while maintaining high efficiency for subcarriers experiencing good channel conditions.
2Reliability
If conventional error correction methods are applied to all subcarriers, then transmission quality is improved, but transmission efficiency decreases due to unnecessary processing
Solution Approach 1:
The patent implements selective error correction processing where each subcarrier is evaluated individually. Only subcarriers experiencing frequency-selective fading receive precoding-based error correction, while subcarriers with good channel conditions transmit data without additional processing overhead.
Solution Approach 2:
Instead of applying full error correction processing to all subcarriers, the system applies partial correction only to the extent necessary for subcarriers affected by fading. This partial action approach maintains transmission quality for vulnerable subcarriers while avoiding unnecessary processing for robust subcarriers.
Data Source
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AI summary
An OFDM transmission apparatus (10a) performs transmission using an orthogonal frequency division multiplexing scheme in one or a plurality of frequency bands and includes a symbol multiplexing unit (400) to multiply a column vector containing a first number of modulated symbols generated by primary modulation in a frequency domain, by a precoding matrix having as many rows and columns as the first number to generate a multiplexed symbol group containing the first number of multiplexed symbols each containing a second number of the modulated symbols that are multiplexed, where the first number is two or more, and the second number is equal to or more than two and equal to or less than the first number; and a subcarrier allocation unit (400) to allocate the multiplexed symbols contained in the multiplexed symbol group to different subcarriers.