PUCCH Carrier Switching and Repetition for Low-Latency HARQ-ACK
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Solution Overview
Problem
Current frameworks for HARQ-ACK information transmission in mobile communications, particularly in URLLC, face challenges with high latency and reliability due to limitations in PUCCH resource allocation and cross-carrier scheduling, which are not optimized for latency-critical applications.
Innovation Solution
Implementing PUCCH carrier switching and repetition mechanisms, including dynamic and semi-static configurations, to enhance UCI transmission by aligning PUCCH resources across different carriers with varying TDD patterns, reducing alignment delay and improving transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple PUCCH resources are allocated for HARQ-ACK feedback transmission, then transmission reliability is improved, but latency increases due to additional processing time and resource coordination
Solution Approach 1:
The patent segments the PUCCH transmission into multiple repetitions across different slots, where each repetition carries the same HARQ-ACK feedback. This allows the feedback to be transmitted multiple times (improving reliability) while each individual transmission occurs in its designated slot (managing latency through structured timing rather than continuous blocking).
Solution Approach 2:
The patent applies preliminary action by pre-configuring multiple PUCCH resources and their corresponding slots before the actual feedback transmission. The UE is provided with configuration information that specifies which PUCCH resources can be used for feedback, allowing the network to optimize resource allocation in advance while ensuring low-latency transmission when needed.
2Productivity
If cross-carrier scheduling is implemented to increase system capacity, then transmission efficiency is improved, but PUCCH resource alignment complexity increases when carriers have different TDD patterns
Solution Approach 1:
The patent applies local quality by allowing different TDD patterns to be configured for different carriers (primary cell and secondary cells). Each carrier can have its own uplink-downlink configuration optimized for local traffic characteristics, while the UE handles the complexity locally by tracking which carrier has which pattern and selecting appropriate PUCCH resources accordingly.
Solution Approach 2:
The patent implements dynamic PUCCH resource selection where the UE can switch between different PUCCH resources based on the active carrier and its TDD pattern. The network dynamically indicates which PUCCH resource should be used for feedback transmission, allowing the system to adapt to different carrier configurations and maintain efficiency without fixed complex alignment.
3Loss of time
If dynamic PUCCH carrier switching is configured to reduce alignment delay, then transmission latency is reduced, but UE capability requirements and configuration complexity increase
Solution Approach 1:
The patent applies preliminary action by providing the UE with advance configuration information about which PUCCH resources are available and their associated carriers. This pre-configuration allows the UE to quickly determine the correct resource without complex real-time calculations, reducing alignment delay while keeping UE processing requirements manageable through structured information provision.
Data Source
AI summary
Various solutions for PUCCH carrier switching and PUCCH repetition with respect to user equipment and network apparatus in mobile communications are described. An apparatus may receive downlink control information (DCI) on a physical downlink control channel (PDCCH) configuring a carrier switching indication and a PUCCH repetition indication. The apparatus may receive downlink data on a physical downlink shared channel (PDSCH). The apparatus may perform a PUCCH carrier switching or a PUCCH cell switching according to the carrier switching indication when transmitting uplink control information (UCI) corresponding to the downlink data. The apparatus may perform a PUCCH repetition by retransmitting the UCI according to the PUCCH repetition indication.