PUCCH Resource Segmentation for URLLC HARQ-ACK Latency
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Solution Overview
Problem
Current frameworks for reporting HARQ-ACK information in LTE and NR are not suitable for ultra-reliable and low-latency communications (URLLC) due to stringent latency and reliability requirements, as they only allow for one uplink opportunity for HARQ feedback bits in a slot, which is not sufficient for URLLC's sporadic and short traffic patterns.
Innovation Solution
Proposing schemes that allow multiple PUCCH resources to be transmitted in an uplink slot for URLLC services, enabling the UE to use the nearest PUCCH resource to transmit HARQ feedback bits instantaneously, thereby reducing latency and improving reliability by potentially transmitting URLLC HARQ feedback bits in separate PUCCH resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only one PUCCH resource is scheduled per slot for HARQ feedback transmission, then device complexity is reduced and resource management is simplified, but latency increases and reliability decreases for URLLC transmissions
Solution Approach 1:
The patent segments the single PUCCH resource into multiple PUCCH resources within the same slot. Specifically, it divides the uplink slot into multiple opportunities for HARQ feedback transmission, allowing the UE to select from multiple PUCCH resources (e.g., different time positions or frequency resources) rather than being constrained to a single resource. This segmentation directly improves reliability by providing redundant transmission opportunities while maintaining manageable complexity through standardized resource selection rules.
Solution Approach 2:
The patent introduces dynamic PUCCH resource selection where the UE can adaptively choose the most appropriate PUCCH resource from multiple available options based on current channel conditions and traffic requirements. The network dynamically configures multiple PUCCH resources with different time-frequency characteristics, and the UE dynamically selects the optimal resource for each HARQ feedback transmission, enabling flexibility to meet varying URLLC requirements without permanent system complexity.
2Loss of time
If multiple PUCCH resources are transmitted in an uplink slot for URLLC services, then latency is reduced and reliability is improved, but device complexity and resource management overhead increase
Solution Approach 1:
The patent applies preliminary action by pre-configuring multiple PUCCH resources with different time-frequency characteristics before URLLC transmission occurs. The network provides the UE with a set of candidate PUCCH resources in advance through RRC signaling or DCI indication, so that when HARQ feedback needs to be transmitted, the UE can immediately select from the pre-prepared options without delay. This eliminates resource setup latency while maintaining the benefits of multiple resources.
Solution Approach 2:
The patent employs simplified, standardized PUCCH resource configurations that can be quickly selected and discarded. Each PUCCH resource is designed with simple time-frequency structure and basic selection criteria, making them computationally inexpensive for the UE to evaluate and select from. The resources are transient, used only for the immediate HARQ feedback transmission, then replaced by new configurations, avoiding the need for complex long-term resource management.
3Productivity
If HARQ feedback bits are accumulated over multiple previous transmissions in a single PUCCH resource, then resource efficiency is improved, but latency increases and reliability decreases for URLLC
Solution Approach 1:
The patent segments the accumulated HARQ feedback bits into separate transmission groups, each transmitted on its own PUCCH resource within the same slot. Instead of multiplexing all feedback bits into a single delayed transmission, the system divides them into multiple smaller groups that can be transmitted in parallel or sequence on different PUCCH resources. This segmentation reduces the waiting time for feedback acknowledgment while maintaining efficient resource utilization through parallel transmission paths.
Data Source
AI summary
Various solutions for reporting hybrid automatic repeat request-acknowledgement (HARQ-ACK) information for ultra-reliable and low latency communications (URLLC) with respect to user equipment and network apparatus in mobile communications are described. An apparatus may receive a downlink control information (DCI) format comprising a resource indication. The apparatus may choose a physical uplink control channel (PUCCH) resource from a plurality of PUCCH resources according to the resource indication. The apparatus may transmit HARQ-ACK information in the PUCCH resource. The resource indication may indicate timing information of the PUCCH resource by a unit of symbol.