HARQ-ACK Reporting for Multicast PDSCH in Wireless Systems
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Solution Overview
Problem
In wireless communication systems, accurately interpreting HARQ-ACK information transmitted on physical uplink control channels (PUCCHs) is challenging, especially when multiple HARQ-ACKs are transmitted in the same slot, leading to ambiguity and incorrect interpretation by base stations.
Innovation Solution
A method and apparatus for configuring HARQ-ACK reporting for multicast PDSCH reception, where ACK/NACK-based or NACK-only based HARQ-ACK reporting is configured for each UE identifier, allowing for accurate transmission and reception of HARQ-ACK information on PUCCHs by multiplexing, dropping, bundling, or deferring transmission of HARQ-ACKs to prevent ambiguity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple HARQ-ACKs are transmitted on the same PUCCH slot, then the feedback efficiency is improved, but the base station cannot accurately interpret the HARQ-ACK information due to ambiguity
Solution Approach 1:
The patent segments HARQ-ACK information by associating different PUCCH resources with different serving cells or component carriers. Each PUCCH resource is configured to carry HARQ-ACK feedback for specific downlink carriers, allowing the base station to distinguish and accurately interpret feedback from multiple sources without ambiguity.
Solution Approach 2:
The patent introduces PUCCH resource indicators (PRI) and downlink carrier indicators as intermediary elements that mediate between the UE and base station. These indicators serve as tags or labels that enable the base station to correctly identify which HARQ-ACK feedback corresponds to which downlink transmission, resolving the interpretation ambiguity.
2Reliability
If HARQ-ACK feedback is transmitted for all received PDSCHs, then the reliability of data transmission is improved, but the uplink control channel resources are wasted when ACK is always transmitted
Solution Approach 1:
The patent implements NACK-only feedback mechanism where the UE transmits uplink control information only when a NACK is generated (indicating decoding failure). When ACK is generated (successful decoding), no transmission occurs. This partial action approach maintains transmission reliability by ensuring feedback is sent when needed while avoiding resource waste when feedback would be positive.
Solution Approach 2:
The patent discards the transmission of redundant ACK feedback by implementing selective feedback based on decoding outcomes. The base station recovers the necessary information by receiving only NACK transmissions, allowing it to identify which downlink transmissions require retransmission without the overhead of transmitting all ACKs.
Data Source
AI summary
Disclosed are a method and a device for transmitting and receiving HARQ-ACK information in a wireless communication system. A method of transmitting HARQ-ACK information according to one embodiment of the present disclosure may comprise the steps of: receiving, from a base station, configuration information related to a HARQ-ACK report on a multicast physical downlink shared channel (PDSCH), wherein, on the basis of the configuration, an ACK/negative ACK (NACK)-based HARQ-ACK report or a NACK-only-based HARQ-ACK report is configured for each of one or more identifiers configured in a terminal; receiving, from the base station, downlink control information (DCI) including a cyclic redundancy check (CRC) scrambled by a specific identifier form among the one or more identifiers; receiving, from the base station, the multicast PDSCH on the basis of the DCI; and transmitting, to the base station, HARQ-ACK information on the multicast PDSCH on a first physical uplink control channel (PUCCH) on the basis of the NACK-only-based HARQ-ACK report configured for the specific identifier.