Turbo-Code HARQ Feedback for Low-Latency Radio Retransmission
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Solution Overview
Problem
Current HARQ processes in mobile radiocommunication systems for transportation vehicle communication face challenges in achieving high reliability with minimal latency, particularly in safety-critical scenarios, due to inefficiencies in error protection and retransmission mechanisms.
Innovation Solution
The proposed method, referred to as HARQ+, includes additional feedback information to identify which decoder is more challenged during decoding, allowing for targeted retransmission of error protection data, thereby optimizing incremental redundancy and reducing latency by adapting the error protection strategy based on decoder performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional HARQ processes are used with standard error protection mechanisms, then data transmission reliability is maintained, but transmission latency increases and decoding efficiency decreases
Solution Approach 1:
The patent implements enhanced feedback mechanisms where the receiving unit provides detailed decoding status information back to the transmitting unit. This feedback includes identification of which specific decoders are struggling and the nature of decoding difficulties, enabling the transmitting unit to adaptively adjust retransmission strategies and error protection levels, thereby reducing unnecessary retransmissions and latency while maintaining reliability
Solution Approach 2:
The error protection strategy is made dynamic rather than static. The system adapts the level and type of error protection based on real-time decoder performance feedback. When decoders encounter difficulties, the system dynamically adjusts the error protection mechanism to provide targeted assistance, optimizing the balance between reliability and transmission speed
2Reliability
If incremental redundancy is applied uniformly to all decoders, then error protection is provided, but transmission efficiency decreases due to unnecessary retransmissions
Solution Approach 1:
Instead of applying uniform error protection to all decoders, the patent implements localized error protection strategies. The system identifies specific decoders that are experiencing difficulties and applies error correction measures targeted at those particular decoders. This localized approach ensures that error protection resources are allocated only where needed, improving transmission efficiency while maintaining the necessary level of reliability
Solution Approach 2:
The system changes the parameters of error protection based on decoder-specific needs. Rather than using a fixed error protection scheme, the patent dynamically adjusts error protection parameters such as redundancy level and correction algorithm selection based on the specific challenges faced by each decoder, thereby optimizing both reliability and efficiency
3Reliability
If multiple decoding attempts are performed with increased error protection, then decoding reliability improves, but the number of retransmissions increases and latency increases
Solution Approach 1:
The patent implements preliminary actions by providing forward error correction capabilities that prevent decoding failures before they occur. By incorporating robust error correction codes and predictive error protection mechanisms, the system addresses potential decoding issues in advance, reducing the need for multiple retransmission attempts and simplifying the overall retransmission mechanism
Data Source
AI summary
Modern mobile communication systems transfer data by error protection measures including the use of a forward error correction code for the channel coding and a HARQ (hybrid automatic repeat request) system for the repeated transfer of incorrect transport blocks in response to the error protection mechanisms failing. When a turbo code is used as an error protection code, two decoders work on the decoding of the turbo code. Disclosed is an expanded HARQ system wherein the receiving side determines which of the decoders was more greatly challenged in the decoding of the turbo code and reports this to the transmitting side. Instead of uniformly providing more redundancy data to both decoders, more redundancy data are targetedly provided to the more greatly challenged decoder in the expanded HARQ process than in the case of the repetition operation according to the typical HARQ process reducing the latency of the data transfer.