OFDM Interleaving for Fragmented Code Words in Wideband Channels
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Solution Overview
Problem
In wireless communication systems, particularly those adhering to the IEEE 802.11ay standard, fragmented code words allocated across multiple OFDM symbols experience poor communication quality due to inadequate interleaving patterns in wide frequency domains, leading to performance degradation.
Innovation Solution
A communication apparatus and method that employs a specific interleaving process, where data symbols are rearranged and distributed across a wide frequency domain, using a two-dimensional array interleaving scheme to optimize the allocation of code words across OFDM symbols, ensuring improved communication quality in frequency selective channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data symbols are allocated consecutively in OFDM symbols without proper interleaving, then the allocation process is simple, but communication quality deteriorates in frequency selective channels
Solution Approach 1:
The patent applies two-dimensional array-based interleaving where data symbols are arranged in rows and columns, with rows corresponding to code words and columns to OFDM symbols. This dimensional transformation distributes symbols across both time (OFDM symbols) and frequency (subcarriers) domains, achieving wide frequency domain allocation while maintaining systematic structure for manageable complexity
Solution Approach 2:
The patent segments the code word into multiple code word segments, each allocated to different OFDM symbols through the interleaving process. This segmentation allows the code word to be distributed across multiple time slots and frequency resources, improving frequency diversity without requiring complete retransmission
2Productivity
If code words are fragmented across multiple OFDM symbols, then more data can be transmitted, but communication quality deteriorates without sufficient interleaving
Solution Approach 1:
The patent uses two-dimensional array interleaving to distribute code word segments across multiple OFDM symbols in the time dimension and across subcarriers in the frequency dimension. This dual-dimensional distribution ensures that fragmented code words achieve wide frequency domain allocation, improving both transmission efficiency and communication quality in frequency selective channels
Solution Approach 2:
The patent performs interleaving operations before OFDM modulation and transmission. By pre-distributing data symbols across multiple OFDM symbols and subcarriers in the two-dimensional array structure, the system prepares the signal to inherently resist frequency selective fading, rather than attempting correction after transmission
3Reliability
If conventional interleaving methods are used for fragmented code words, then implementation is straightforward, but wide frequency domain allocation is not achieved
Solution Approach 1:
The patent introduces a systematic two-dimensional array interleaving method where code word segments are arranged in rows and OFDM symbols in columns. This structured approach achieves wide frequency domain allocation by distributing symbols across multiple columns (OFDM symbols) and rows (code word segments), providing both performance improvement and implementation clarity
Solution Approach 2:
The patent changes the interleaving parameters by defining specific relationships between the number of rows (code word segments), columns (OFDM symbols), and the interleaving pattern. By adjusting these parameters, the system can adapt to different code word lengths and OFDM symbol configurations while maintaining the wide frequency domain allocation property
Data Source
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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.