Signal Processing for Selective Soft-Decision Turbo Product Decoding
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Solution Overview
Problem
Current signal processing devices for optical transmission face challenges in achieving high error-correcting performance while maintaining low power consumption, particularly as the multi-level modulation method increases, leading to higher error rates and reduced effectiveness in improving error-correcting performance due to increased redundancy.
Innovation Solution
The implementation of a signal processing device that uses a turbo product code for encoding and decoding, combining soft decision coding with turbo product codes for both outer and inner codes, allowing for improved error-correcting performance by selectively performing soft decisions on bit strings and decoding with log-likelihood ratios, thereby enhancing the accuracy of bit string values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-level modulation method is used to increase transmission capacity, then data transmission rate is improved, but error rate increases and error-correcting performance deteriorates
Solution Approach 1:
The patent segments the error correction process into two distinct stages: outer code correction (using BCH or Reed-Solomon codes) and inner code correction (using soft decision Viterbi decoding). This segmentation allows each code to be optimized for its specific function, with the outer code handling burst errors and the inner code handling random errors, thereby achieving high error correction performance for multi-level modulation without sacrificing transmission rate
Solution Approach 2:
The patent employs a composite coding structure combining two different error correction codes (outer code and inner code) with complementary characteristics. The outer code provides robust protection against burst errors while the inner soft decision Viterbi code provides protection against random errors, creating a synergistic effect that achieves high error correction performance for high-order modulation schemes
2Reliability
If redundancy is increased to improve error-correcting performance, then reliability is improved, but transmission efficiency decreases
Solution Approach 1:
The patent applies partial redundancy by using different code rates for outer and inner codes based on channel conditions and modulation order. The soft decision Viterbi decoding with configurable path metric thresholds allows adaptive redundancy application, performing full soft decision decoding only when needed while using simpler hard decision decoding otherwise, thereby optimizing the balance between error correction performance and transmission efficiency
3Reliability
If soft decision decoding is performed on all bit strings, then error-correcting performance is improved, but power consumption increases
Solution Approach 1:
The patent performs soft decision decoding selectively rather than on all bit strings. The outer code decoding is performed first, and only when uncorrectable errors remain does the system perform additional soft decision Viterbi decoding on specific portions of the data. This partial application of computationally intensive soft decision decoding significantly reduces power consumption while maintaining high error correction performance
Data Source
AI summary
A signal processing device includes: a memory; and a processor coupled to the memory and configured to: perform soft decision of a value of, among bit strings, a predetermined bit string encoded with a soft decision code from a symbol assigned to, according to each value of the bit strings, the bit strings having been subject to encoding of an outer code with a turbo product code and encoding of an inner code with the soft decision code; decode the predetermined bit string with the soft decision code on a basis of a result of the soft decision; individually perform, from the symbol, the soft decision of a value of each bit string other than the predetermined bit string among the bit strings; and decode the bit strings with the turbo product code on a basis of a result of the decoding and a result of the soft decision.