HARQ-ACK Feedback Segmentation in Multi-Cell Carrier Aggregation
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Solution Overview
Problem
Current wireless communication systems face inefficiencies in transmitting control information, particularly in carrier aggregation systems, where managing uplink control information and resources is challenging.
Innovation Solution
A method and apparatus for efficiently transmitting control information by detecting physical downlink shared channels across multiple cells, including a primary and secondary cell set, and transmitting hybrid automatic repeat request acknowledgement (HARQ-ACK) information through a physical uplink control channel (PUCCH), using different formats based on channel detection, with power control and resource indication fields in the physical downlink control channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carrier aggregation is used to increase system capacity, then data transmission rate is improved, but control information management complexity increases
Solution Approach 1:
The patent segments control information into two distinct types: Type 1 HARQ-ACK feedback for PDSCH on PCell only, and Type 2 HARQ-ACK feedback for PDSCH on SCell. This segmentation allows the system to manage control information more efficiently by applying different feedback mechanisms appropriate to each cell type, reducing overall management complexity while maintaining high data transmission rates through carrier aggregation
Solution Approach 2:
The patent implements dynamic control information feedback where the UE selectively transmits HARQ-ACK information based on which cell set detected PDSCH. The feedback type (Type 1 or Type 2) is dynamically determined by the detection status of PDSCH on different cell sets, allowing flexible adaptation to varying channel conditions and traffic requirements while managing control information efficiently
2Reliability
If HARQ-ACK feedback is transmitted for all detected PDSCH across all cells, then reliability is improved, but uplink control channel resource requirements increase
Solution Approach 1:
The patent applies different feedback quality requirements to different cell types. For PCell (first cell set), Type 1 HARQ-ACK feedback is used which provides essential reliability for primary cell communications. For SCell (second cell set), Type 2 HARQ-ACK feedback is used which provides selective reliability only when PDSCH is detected on SCell. This local differentiation ensures adequate reliability where needed while reducing overall uplink control channel resource consumption
Solution Approach 2:
The patent implements partial feedback action where HARQ-ACK information is transmitted selectively based on PDSCH detection. Instead of always transmitting full HARQ-ACK feedback for all cells, the UE transmits Type 2 feedback only when PDSCH is detected on SCell, providing just enough feedback reliability for the actual data transmission while minimizing unnecessary uplink control channel resource usage
Data Source
AI summary
The present invention relates to a wireless communication system. Specifically, the present invention relates to a method for transmitting control information, and an apparatus therefor, the method comprising: a step of detecting one or more PDSCHs on a plurality of cells, wherein the plurality of cells are divided into a first cell set including a PCell and a first SCell, and a second cell set including one or more second SCells; and a step of transmitting, as feedback for the one or more PDSCHs, HARQ-ACK information through a PUCCH, wherein if the one or more PDSCHs are detected only on the first cell set, the HARQ-ACK information includes HARQ-ACK responses only for the first cell set, and if the one or more PDSCHs are detected at least on the second cell set, the HARQ-ACK information includes HARQ-ACK responses for both the first and second cell sets.