OFDM Code Word Interleaving for Frequency-Selective Channels
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Solution Overview
Problem
In frequency selective channels, the communication quality is deteriorated due to insufficient study of interleave patterns for code words fragmented into multiple OFDM symbols, leading to poor distribution across a wide frequency domain.
Innovation Solution
A transmission apparatus and method that interleaves code words into OFDM signals, allocating them in ascending order and starting from the second code word, allowing for efficient distribution across a wide frequency domain, thereby enhancing communication quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If code words are fragmented into multiple OFDM symbols and allocated using conventional interleaving, then the transmission structure is simplified, but the communication quality deteriorates in frequency selective channels due to insufficient frequency domain distribution
Solution Approach 1:
The patent applies inversion by changing the conventional interleaving approach. Instead of writing code words sequentially and reading in the same order, the invention writes code words in ascending order of code word index but starts reading from the second code word (code word index 1) and reads backwards to the first code word. This reverse reading approach redistributes the code words across OFDM symbols in a pattern that achieves wide frequency domain distribution without increasing system complexity
Solution Approach 2:
The patent introduces a new dimension to the interleaving process by changing the reading direction. The conventional approach processes code words in a single forward direction, while this invention adds a backward reading dimension by starting from the second code word and reading backwards. This dimensional change in the processing sequence enables better frequency domain distribution of code words across multiple OFDM symbols, improving communication quality in frequency selective channels
2Ease of manufacture
If code words are allocated sequentially in ascending order, then the interleaving process is simple, but the distribution across wide frequency domain is insufficient
Solution Approach 1:
The patent maintains the simple ascending order writing process but applies inversion to the reading operation. By reading code words in reverse order (starting from the second code word backwards to the first), the invention achieves wide frequency domain distribution while keeping the writing process simple and easy to implement
Solution Approach 2:
The patent performs preliminary arrangement by writing all code words in ascending order first, then applies the reverse reading operation. This preliminary writing in ascending order simplifies the process setup, and the subsequent reverse reading automatically achieves the desired wide frequency domain distribution without complex real-time calculations
Data Source
AI summary
The interleaver 104 interleaves first to Nth code words. The OFDM modulation circuit 105 converts the interleaved first to Nth code words into OFDM signals. The transmission RF circuit 106 transmits the OFDM signals. The number of data symbols included in the first code word is less than the number of data symbols included in the second code word. The interleaver 104 writes the first code word to the Nth code word in ascending order and starts reading from the second code word.