HARQ ACK/NACK Bundling for Missed Downlink Subframes
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Solution Overview
Problem
In wireless communication systems, particularly in TDD mode, the inefficiency in transmitting ACK/NACK signals due to the limited number of uplink resources available for feedback, leading to restricted packet loss and reduced recovery capability when the number of ACK/NACK signals is less than the number of downlink packets.
Innovation Solution
A method where a user equipment (UE) receives a bundling indicator for downlink subframes, determines if any are missed, and generates a representative ACK/NACK signal for successful or unsuccessful reception, transmitting it on an uplink channel, potentially using Physical Uplink Control Channel (PUCCH) or Physical Uplink Shared Channel (PUSCH), to maximize recovery capability and minimize packet loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of ACK/NACK signals is reduced to match the limited uplink feedback resources, then the resource utilization efficiency is improved, but the packet loss increases and recovery capability is reduced
Solution Approach 1:
Multiple ACK/NACK signals corresponding to different downlink subframes are merged into a single representative ACK/NACK signal for transmission on the uplink channel. This combining approach allows multiple feedback signals to be transmitted using a single uplink resource, thereby improving resource utilization efficiency while maintaining the ability to convey comprehensive feedback information about packet reception status across multiple subframes.
2Reliability
If representative ACK/NACK signals are generated by logical AND operation, then the recovery capability is maximized, but the complexity of signal generation increases
Solution Approach 1:
The base station automatically determines the representative ACK/NACK signal by applying logical AND operation to multiple ACK/NACK signals without requiring explicit configuration or complex processing. The system self-adjusts the feedback mechanism to ensure that the representative signal accurately reflects the reception status of all downlink subframes, maximizing recovery capability while keeping the implementation straightforward.
Data Source
AI summary
A method of performing HARQ performed by a user equipment (UE) is provided. The method includes receiving a bundling indicator which indicates the number of bundled downlink subframes, determining whether at least one bundled downlink subframe is missed by comparing the bundling indicator with the number of detected bundled downlink subframes, generating a representative ACK/NACK signal when no bundled downlink subframe is missed, and transmitting the representative ACK/NACK signal on an uplink channel. Recovery capability is maximized and the packet loss is reduced in such a situation that less number of ACK/NACK signals are fed back than that of downlink packets.