HARQ Decoder Feedback for Low-Latency Radio Retransmission
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Solution Overview
Problem
Current HARQ processes in mobile radio technologies, such as LTE and 5G, face challenges in achieving high reliability with low latency for vehicle-to-vehicle communication, particularly in safety-critical scenarios, due to inherent latency issues in the existing HARQ method.
Innovation Solution
The proposed method, referred to as HARQ+, includes additional feedback information to identify which decoder had more difficulty decoding error protection codes, allowing for targeted retransmission of additional error protection data specifically to the challenged decoder, thereby reducing the number of decoding attempts and latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional error protection data is transmitted to improve decoding reliability, then the probability of successful decoding increases, but the data throughput decreases due to reduced user data capacity per transmission unit
Solution Approach 1:
The patent applies local quality by differentiating the error protection enhancement strategy among decoders. Instead of uniformly increasing error protection for all decoders, the system identifies which specific decoder struggles with decoding and applies additional error protection data selectively to that decoder. This targeted approach improves decoding reliability for the challenged decoder while minimizing the impact on overall data throughput, as error protection is only increased where necessary rather than applied globally to all transmissions.
2Reliability
If the number of retransmission attempts is increased to ensure complete data reception, then data completeness improves, but the transmission latency increases
Solution Approach 1:
The patent implements feedback by having the receiving unit monitor decoding outcomes and provide information about which decoder failed to decode successfully. This feedback mechanism allows the transmitting unit to make informed decisions about targeted retransmissions. Instead of blindly increasing retransmission attempts, the system uses feedback to identify specific decoding failures and sends additional error protection data only when and where needed, thereby improving data completeness while minimizing unnecessary retransmissions and reducing transmission latency.
Solution Approach 2:
The patent applies preliminary action by proactively sending additional error protection data in targeted retransmissions based on decoded feedback information. Rather than waiting for multiple failed decoding attempts before acting, the system prepares and sends corrective error protection data promptly after identifying a decoding failure, reducing the need for multiple retransmission cycles and thereby降低ing overall transmission latency while ensuring data completeness.
3Reliability
If generic error protection data is transmitted to all decoders, then decoding reliability may improve, but channel resources are wasted on decoders that do not need additional protection
Solution Approach 1:
The patent applies local quality by transitioning from a generic, uniform error protection approach to a localized, selective approach. The receiving unit identifies which specific decoder is having trouble decoding, and the transmitting unit sends additional error protection data targeted specifically to that decoder. This eliminates the waste of channel resources that would occur with generic error protection sent to all decoders, as resources are now allocated precisely where decoding failures occur rather than being distributed uniformly across all decoders regardless of need.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the error protection parameters based on actual decoding performance. Instead of using a fixed, generic error protection level for all transmissions, the system modifies the error protection parameters (amount and type of error protection data) based on feedback about which decoder failed. This adaptive parameter adjustment ensures channel resources are used efficiently by matching error protection levels to actual decoder needs rather than applying a one-size-fits-all approach.
Data Source
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AI summary
Modern mobile communication systems transfer data by means of highly effective error protection measures. These include the use of a forward error correction code for the channel coding and an HARQ (hybrid automatic repeat request) system for the repeated transfer of incorrect transport blocks if the error protection mechanisms fail. When a turbo code is used as an error protection code, two decoders (210, 220) work on the decoding of the turbo code. The invention relates to an expanded HARQ system, according to which the receiving side determines which of the decoders (210, 220) 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 (210, 220), as was previously typical, more redundancy data are provided in a targeted manner to the more greatly challenged decoder in the expanded HARQ process than provided for in the case of the repetition step according to the typical HARQ process. The latency of the data transfer is thereby reduced.