Turbo Decoder Early Termination Using LLR Sign Transitions

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Solution Overview

Problem

Existing wireless communication systems face challenges in achieving low-power decoding with high accuracy due to decoding failures indicated by sign differences in log likelihood ratios, leading to unnecessary power consumption.

Innovation Solution

A modem chip with a turbo decoding circuit that generates log likelihood ratios and uses a decoding control circuit to stop decoding based on counting values exceeding a threshold, indicating potential decoding failure, thereby reducing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If decoding is performed repeatedly to ensure high decoding accuracy, then decoding reliability is improved, but power consumption increases

Engineering Contradiction:

Improvedecoding accuracyVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic decoding by adaptively adjusting the number of iterative loops based on the decoding state. The decoding control circuit monitors log likelihood ratios and dynamically determines when to terminate decoding, rather than using a fixed number of iterations. This dynamic approach allows the system to achieve high decoding accuracy when needed while reducing power consumption when the decoding state indicates early termination is appropriate.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent employs feedback mechanisms where the decoding control circuit continuously monitors the decoding state through log likelihood ratios and extrinsic information. Based on this feedback, the system determines whether to continue or terminate decoding. The feedback loop enables intelligent decision-making about resource allocation, stopping decoding when reliability thresholds are met or when further iterations are unlikely to improve results, thus optimizing the balance between decoding accuracy and power consumption.

Inventive Principle:

Principle #23Feedback

2Reliability

If decoding continues for a predetermined number of times to ensure accuracy, then decoding reliability is improved, but unnecessary power consumption occurs when decoding failure is expected

Engineering Contradiction:

Improvedecoding accuracyVSAvoidunnecessary power consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies preliminary action by performing early termination checks during the decoding process. The decoding control circuit monitors log likelihood ratios and extrinsic information at intermediate stages to predict whether decoding will succeed. When the monitoring indicates that decoding failure is expected, the system terminates decoding early, avoiding the waste of energy that would occur by continuing unnecessary iterative loops.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements partial action by performing only the necessary number of iterative loops required to achieve decoding success, rather than always executing a fixed predetermined number of loops. The system performs partial decoding when the decoding state indicates success is achieved early, and performs full decoding only when necessary. This partial execution strategy eliminates excessive power consumption while maintaining decoding reliability.

Inventive Principle:

Principle #16Partial or excessive action

3Use of energy by moving object

If early termination is implemented to reduce power consumption, then power efficiency is improved, but decoding accuracy may deteriorate

Engineering Contradiction:

Improvepower efficiencyVSAvoiddecoding accuracy

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent uses feedback mechanisms to monitor decoding state through log likelihood ratios and extrinsic information. The decoding control circuit continuously evaluates whether termination conditions are met, ensuring that early termination only occurs when decoding accuracy is sufficiently high. This feedback-based decision-making prevents premature termination that would compromise accuracy while enabling energy-efficient termination when appropriate.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces blind mechanical iteration with intelligent control based on information-theoretic metrics. Instead of simply counting iterations, the system uses log likelihood ratios and extrinsic information to make informed decisions about termination. This substitution of intelligent control for mechanical repetition ensures that power efficiency improvements do not come at the cost of decoding accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS20250247113A1Modem chip for low-power decoding based on transition of log likelihood ratio and operating method of turbo decoder

Publication Date: 2025.07.31 SAMSUNG ELECTRONICS CO LTD

AI summary

A modem chip may include a turbo decoding circuit configured to receive a plurality of channel log likelihood ratios respectively corresponding to a plurality of bits included in a symbol, generate a plurality of first posteriori log likelihood ratios respectively corresponding to the plurality of bits in an Nth iterative loop based on the plurality of channel log likelihood ratios, wherein N is greater than or equals to 1, and generate a first input/output counting value by counting a number of first posteriori log likelihood ratios, among the plurality of first posteriori log likelihood ratios, that differ in sign from the corresponding channel log-likelihood ratios, and a decoding control circuit configured to stop decoding for the plurality of bits in the turbo decoding circuit based on the first input/output counting value being greater than or equal to a first threshold.