LTE Multi-Subframe HARQ Feedback Aggregation
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Solution Overview
Problem
Multi-subframe scheduling in LTE systems poses challenges in managing HARQ ACK/NACK feedback, particularly when UEs use the same PUCCH resource across multiple subframes, leading to potential conflicts with single-subframe assignments for other UEs.
Innovation Solution
Implementing a system where HARQ processes are split into groups and used differently across subframes, with aggregated ACK/NACK feedback collected and processed to prevent resource conflicts, allowing for efficient retransmission of codewords without interfering with single-subframe scheduling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the UE uses the same PUCCH resource in every subframe of the multi-subframe assignment, then the feedback transmission is simplified, but the eNB must avoid reusing the corresponding PDCCH CCE in those subframes for single-subframe assignments to other UEs, leading to resource conflicts
Solution Approach 1:
The invention divides the feedback transmission into two separate resources: a first PUCCH resource for aggregated ACK/NACK feedback and a second PUCCH resource for individual codeword feedback. This segmentation allows the eNB to reuse PDCCH CCE resources for single-subframe assignments while maintaining simplified feedback transmission for multi-subframe assignments through the first PUCCH resource.
2Reliability
If the eNB avoids reusing PDCCH CCE resources for single-subframe assignments during multi-subframe assignment subframes, then resource conflicts are prevented, but the utilization of available PDCCH resources is reduced
Solution Approach 1:
The invention introduces a first PUCCH resource as an intermediary for aggregated ACK/NACK feedback. This intermediary allows the eNB to maintain normal PDCCH CCE resource allocation for single-subframe assignments while still providing reliable feedback transmission for multi-subframe assignments, thus preventing resource conflicts without reducing overall PDCCH resource utilization.
3Quantity of substance
If aggregated ACK/NACK feedback is received for multiple codewords in a single subframe, then feedback overhead is reduced, but the complexity of processing and identifying individual codeword status increases
Solution Approach 1:
The invention segments the feedback information into two parts: aggregated ACK/NACK feedback for multiple codewords transmitted on a first PUCCH resource, and individual codeword feedback transmitted on a second PUCCH resource. This segmentation reduces the overall feedback overhead by aggregating where possible, while maintaining manageable processing complexity by separating individual codeword status information.
Data Source
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AI summary
A communication system is provided in which a communication node can allocate resources, for another communication node, within a number of consecutive subframes using a single control message. The other communication node receives codewords transmitted over using the allocated resources, aggregates ACK/NACK feedback for the received codewords and transmits the aggregated ACK/NACK feedback to the communication node for use in controlling subsequent transmission of new codewords or retransmission of previous codewords.