Hybrid-ARQ Code-Rate Adaptation Using BER/SER Estimation
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Solution Overview
Problem
Conventional incremental-redundancy schemes in digital communication systems fail to adjust code rates effectively in response to improving channel conditions, leading to suboptimal throughput and redundancy levels.
Innovation Solution
The implementation of techniques for determining retransmission parity size based on instantaneous bit error rate (BER) or symbol error rate (SER) estimation using Gaussian mixture-modeling, allowing for dynamic adjustment of code rates in response to changing channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional incremental-redundancy schemes use fixed code rates, then transmission reliability is maintained, but data throughput is reduced due to excessive redundancy when channel conditions improve
Solution Approach 1:
The patent implements dynamic code rate adjustment by estimating instantaneous BER/SER and adapting the code rate accordingly. The system transitions from fixed code rates to variable code rates that dynamically respond to channel conditions, increasing code rate when channel quality improves and decreasing it when conditions deteriorate, thereby optimizing throughput while maintaining reliability
Solution Approach 2:
The patent introduces feedback mechanisms where the receiver estimates instantaneous BER/SER and feeds this information back to the transmitter. The transmitter uses this feedback to adaptively adjust the code rate for subsequent transmissions, creating a closed-loop system that continuously optimizes performance based on actual channel conditions
2Productivity
If code rates are increased to improve throughput, then data transmission efficiency improves, but error rate increases under deteriorating channel conditions
Solution Approach 1:
The system dynamically adjusts code rates based on real-time channel conditions by estimating instantaneous BER/SER. When channel conditions deteriorate, the code rate is automatically decreased to maintain acceptable error rates, and when conditions improve, the code rate is increased to maximize throughput, creating an adaptive balance between efficiency and error performance
Solution Approach 2:
The patent changes the code rate parameter adaptively based on estimated error rates. By monitoring instantaneous BER/SER and adjusting the code rate parameter in response, the system optimizes the trade-off between transmission efficiency and error performance, selecting appropriate code rates from a family of rate-compatible codes
Data Source
AI summary
The disclosure proposes bit-error-rate (BER) and symbol-error-rate (SER) estimation techniques and its application to incremental-redundancy and rate-adaptation for modern-coded hybrid-ARQ systems. In particular, BER/SER estimators are proposed based on iterative refinement of mixture-density modeling of the bit/symbol decision metrics. For hybrid-ARQ systems, rate-adaptation functions are proposed based on BER/SER estimators for failed transmissions. Methods are disclosed for code-rate selection based on successfully decoded blocks as well as incremental parity size selection for retransmission of failed blocks Techniques disclosed here apply to forward-error-correction codes employed for digital data communication systems.