Turbo-Code Interleaver Layout for Puncturing-Aware Error Correction
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Solution Overview
Problem
Current turbo-codes face limitations in encoding performance, particularly at low error rates, due to the cumbersome process of finding interleaving parameters and the suboptimal performance of standardized interleavers across various encoding rates, leading to inefficient error correction and high error rates in certain communication standards.
Innovation Solution
A novel encoding method for turbo-encoders that incorporates a two-level interleaving function, where information symbols are distributed across Q layers based on a puncturing pattern, allowing for the adjustment of inter-layer and intra-layer positions to enhance encoding and decoding performance, and an interleaver design that adapts to each encoding rate, eliminating catastrophic patterns and improving minimum Hamming distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If standardized interleavers are used across various encoding rates, then device complexity is reduced, but encoding performance deteriorates at low error rates
Solution Approach 1:
The interleaver parameters (P, Q, S(l)) are made adaptive to the encoding rate rather than fixed. The system dynamically selects interleaving parameters based on the puncturing pattern and encoding rate, allowing optimal performance across different rates while maintaining a unified interleaver structure.
Solution Approach 2:
The invention changes the parameters of the interleaving function (specifically P, Q, and S(l)) according to the encoding rate and puncturing pattern. This allows the same interleaver structure to achieve optimal performance for different encoding rates by adjusting its parameters rather than using different interleaver designs.
2Productivity
If puncturing patterns are applied to increase encoding rate, then productivity is improved, but manufacturing precision deteriorates due to catastrophic patterns
Solution Approach 1:
The system performs preliminary selection of puncturing patterns and corresponding interleaving parameters before encoding. By pre-determining compatible pairs of puncturing patterns and interleaver parameters, the system avoids catastrophic patterns and ensures optimal minimum Hamming distance is maintained while achieving the desired encoding rate.
Solution Approach 2:
The invention establishes a feedback mechanism where the puncturing pattern selection influences and determines the interleaver parameter selection. This interdependent selection process ensures that the combination of puncturing and interleaving maintains optimal error correction properties while achieving the target encoding rate.
3Ease of operation
If the search space for interleaving parameters is reduced, then ease of operation is improved, but adaptability deteriorates across different encoding rates
Solution Approach 1:
The invention uses parameter changes to maintain adaptability across different encoding rates. By defining the interleaving parameters (P, Q, S(l)) as functions of the puncturing pattern and encoding rate, the system can adapt to different rates while operating within a constrained and systematic parameter selection framework.
Solution Approach 2:
The unified interleaver structure with adjustable parameters serves multiple encoding rates and puncturing patterns. Rather than requiring different interleaver designs for each rate, this universal interleaver can be configured through parameter adjustment to optimize performance across the full range of encoding rates.
Data Source
AI summary
A method is provided for encoding an input digital message bearing K information symbols using a turbo-encoder forming a turbocode, the turbo-encoder including an interleaver and first and second encoders for encoding according to at least one elementary code and delivering the information symbols and redundancy symbols. With a puncturing of the symbols delivered by the turbo-encoder being done according to at least one periodic puncturing pattern of a length N, defining the puncturing period N, the interleaver distributes the information symbols of the input message into Q layers of the interleaved input message in complying with an interleaving function defined from the at least one puncturing pattern, according to the relationship: π(i)=Pi+S(i mod Q)mod K=Pi+(Tl+AlQ)mod K.