HARQ Retransmission Feedback Using Parity-Check Clusters
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Solution Overview
Problem
Existing hybrid automatic repeat request (HARQ) systems in wireless communication rely on final output decoding, leading to inefficient retransmissions that do not utilize decoder internal states, resulting in suboptimal throughput and increased resource usage.
Innovation Solution
A low-overhead HARQ scheme that divides parity-check matrix rows into clusters, using parity check results to determine unsatisfied checks and selectively retransmit information and parity sub-blocks, reducing feedback bits and optimizing retransmissions based on decoder internal states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional HARQ systems rely on final output decoding for retransmission decisions, then the system is simple to implement, but retransmission efficiency is poor and throughput is suboptimal
Solution Approach 1:
The parity-check matrix is divided into multiple clusters, each corresponding to a specific subset of codeword bits. This segmentation allows the system to identify and retransmit only the specific clusters with unsatisfied parity checks, rather than retransmitting entire codewords or using complex reliability metrics for individual bits, thus improving throughput while maintaining manageable complexity.
Solution Approach 2:
Instead of performing full reliability calculations on all code bits (excessive action), the system performs partial parity check operations only on clustered groups. This partial action approach provides sufficient information to make informed retransmission decisions without the computational burden of complete reliability analysis, achieving better throughput with acceptable complexity.
2Measurement precision
If reliability-based incremental redundancy HARQ measures reliability of individual code bits, then retransmission precision is high, but feedback overhead and computational complexity increase
Solution Approach 1:
Multiple individual code bits are grouped into clusters that share common parity check relationships. By merging the feedback requirement for individual bits into cluster-level parity check results, the system reduces feedback overhead while maintaining sufficient precision to identify which groups of bits need retransmission, thus reducing information loss in the feedback channel.
Solution Approach 2:
The system transitions from measuring reliability in the bit dimension to measuring parity check satisfaction in the cluster dimension. This dimensional change allows the system to achieve effective retransmission identification without requiring precise individual bit reliability measurements, thereby reducing feedback overhead while maintaining adequate measurement precision at the cluster level.
3Productivity
If HARQ systems retransmit entire codewords or use fixed redundancy versions, then implementation is straightforward, but resource utilization is inefficient
Solution Approach 1:
The codeword is segmented into multiple clusters associated with specific rows of the parity-check matrix. This segmentation enables the system to identify and retransmit only the specific clusters containing errors, rather than retransmitting entire codewords or using fixed redundancy versions. The segmented approach improves resource utilization by sending only necessary data while maintaining relatively simple control mechanisms.
Solution Approach 2:
Cluster-based parity check results serve as an intermediary between simple fixed retransmission schemes and complex bit-level reliability analysis. This intermediary approach provides sufficient granularity to improve resource utilization by targeting specific retransmission needs without requiring full codeword retransmission or complex control logic, achieving better resource efficiency with moderate complexity.
Data Source
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AI summary
Techniques are disclosed for reducing overhead during hybrid automatic repeat request (HARQ) operations performed by a user equipment (UE) during wireless communication. The UE receives a message over the wireless network and obtains a parity check matrix (PCM) associated with a received message. Rows of the PCM are assigned to respective groups of a plurality of groups, where the respective groups have corresponding one or more parity checks as determined by the PCM. The UE generates a feedback message including a plurality of bits, wherein an individual bit of the plurality of bits indicates whether a corresponding respective group of the plurality of groups include one or more unsatisfied parity checks. The UE then transmits the feedback message to a base station of the wireless network.