PUCCH Resource Switching for Delayed HARQ-ACK Feedback
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Solution Overview
Problem
In wireless communications systems, the overlap of uplink control resources with downlink or flexible resources due to reconfiguration can prevent user equipment (UE) from transmitting hybrid automatic repeat/request acknowledgement (HARQ-ACK) feedback messages, leading to potential PDSCH retransmissions even if the original transmission was successfully received.
Innovation Solution
The UE identifies a second uplink control resource, such as a next configured PUCCH resource or RRC-configured resource, to transmit HARQ-ACK feedback messages when the initial resource overlaps with downlink or flexible resources, ensuring timely feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the UE uses the initially configured uplink control resource for HARQ-ACK feedback transmission, then the feedback can be transmitted according to the original scheduling, but the resource may overlap with downlink or flexible resources preventing successful transmission
Solution Approach 1:
The patent implements dynamic uplink control resource allocation by allowing the UE to switch from an initially configured resource to an alternative resource when overlap with downlink or flexible resources is detected. This dynamic adjustment ensures reliable feedback transmission while maintaining efficient resource utilization, resolving the contradiction between original scheduling efficiency and transmission reliability.
2Adaptability or versatility
If the uplink control resource is reconfigured as a downlink or flexible resource at symbol and/or slot level, then the system can optimize resource allocation for downlink transmissions, but the UE cannot transmit HARQ-ACK feedback messages on the reconfigured resource
Solution Approach 1:
The patent applies preliminary action by having the UE check for resource overlap before attempting feedback transmission. When overlap is detected, the UE proactively identifies and switches to an alternative uplink control resource in advance, ensuring feedback transmission can proceed without interruption. This preliminary detection and switching mechanism maintains ease of operation while accommodating flexible resource reconfiguration.
3Loss of time
If the UE transmits HARQ-ACK feedback on an overlapping resource, then the transmission follows the original schedule, but the transmission may be blocked causing unnecessary PDSCH retransmissions
Solution Approach 1:
The patent implements a feedback mechanism where the UE monitors the availability of its configured uplink control resource and provides implicit feedback by switching to an alternative resource when overlap is detected. This ensures timely HARQ-ACK feedback transmission is maintained while preventing blocked transmissions that would trigger energy-consuming PDSCH retransmissions, thus resolving the contradiction between transmission timing and energy efficiency.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may receive a configuration message indicating a semi-persistent scheduling configuration. The UE may monitor for a downlink data transmission based at least in part on the semi-persistent scheduling configuration. The UE may determine that an uplink feedback message corresponding to the downlink data transmission is scheduled to be transmitted by the UE in a first uplink control resource that at least partially overlaps with a downlink resource, a flexible resource, or both. The UE may identify, based at least in part on the overlap, a second uplink control resource to use for transmitting the uplink feedback message.