List Viterbi Decoding With Adaptive PMD Thresholds
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
List Viterbi decoders face challenges in reducing false decoding errors due to the inability to effectively restrict the path metric difference (PMD) between the best path and candidate code words, leading to increased false alarms and decreased decoding performance.
Innovation Solution
A method and apparatus are introduced that set a PMD threshold based on the input signal level and a PMD limit value, allowing for decoding failure declaration when the PMD exceeds the threshold, and generating code words only when the accumulated PMD is below a certain threshold, thereby controlling the list count and reducing false alarms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the list count is increased to improve decoding performance, then more candidate code words can be evaluated, but false decoding errors increase due to inability to restrict PMD
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the PMD threshold based on input signal level and PMD limit value. The threshold determination unit calculates the PMD threshold as a function of these parameters, allowing the system to adapt the acceptance criterion for candidate code words. This resolves the contradiction by enabling the system to maintain higher list counts for improved decoding performance while using the adaptive threshold to filter out false decoding errors, thus achieving both goals simultaneously.
2Object-generated harmful factors
If the PMD threshold is set low to reduce false alarms, then fewer false decoding errors occur, but decoding performance decreases due to restricted candidate evaluation
Solution Approach 1:
The patent implements dynamics by making the PMD threshold adaptive rather than fixed. The threshold determination unit dynamically calculates the PMD threshold based on the input signal level and PMD limit value, allowing the system to adjust the threshold according to operating conditions. This resolves the contradiction by enabling the system to maintain a lower effective threshold for reducing false alarms while compensating for restricted candidate evaluation through dynamic adjustment, thus preserving decoding performance.
3Reliability
If decoding is performed without PMD restriction to evaluate all candidates, then no false decoding errors occur, but computational complexity and processing time increase significantly
Solution Approach 1:
The patent applies preliminary action by establishing the PMD threshold before the decoding evaluation process. The threshold determination unit pre-calculates the PMD threshold based on input signal level and PMD limit value, and this threshold is then used to filter candidate code words during decoding. This resolves the contradiction by enabling the system to perform preliminary filtering based on the pre-established threshold, thus reducing the number of candidates that require full evaluation while maintaining decoding accuracy, thereby reducing processing complexity.
Data Source
AI summary
Methods and apparatuses are provided for operating a list Viterbi decoder. A path metric difference (PMD) threshold is set based on an input signal level and a PMD limit value. Decoding is performed by using the PMD threshold. Performing the decoding includes determining a PMD of a best path, comparing the determined PMD and the PMD threshold, and declaring a decoding failure and ending performing of the decoding, if the PMD is greater than or equal to the PMD threshold.