Multicast HARQ Feedback on PUCCH for Reliable NR Broadcast
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Solution Overview
Problem
In New Radio (NR) systems, there is no feedback mechanism for multicast or broadcast services, which is a challenge for services requiring high reliability, such as Vehicle to Everything (V2X) or industrial Internet, as they necessitate multicast transmission.
Innovation Solution
A wireless communication method is introduced where a terminal device determines Hybrid Automatic Repeat Request (HARQ) feedback information corresponding to a Group Radio Network Temporary Identifier (G-RNTI) and sends NACK-included HARQ feedback on configured Physical Uplink Control Channel (PUCCH) resources, and a network device receives this feedback to determine retransmission needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multicast or broadcast services are transmitted without feedback mechanism, then transmission complexity is reduced and resource overhead is decreased, but service reliability is insufficient for high-reliability scenarios like V2X or industrial Internet
Solution Approach 1:
The feedback mechanism is segmented into two distinct modes: a first feedback mode for normal multicast/broadcast services without feedback, and a second feedback mode for high-reliability services requiring HARQ feedback. This segmentation allows the system to maintain simplicity for常规 services while enabling reliability for critical services without universally complicating the feedback mechanism.
Solution Approach 2:
The feedback mode is made dynamic and configurable through RRC signaling, allowing the network to flexibly switch between the first feedback mode (no feedback) and the second feedback mode (HARQ feedback with NACK-only or ACK/NACK) based on service requirements. This dynamic adaptation resolves the contradiction by making the feedback mechanism complexity adjustable rather than fixed.
2Reliability
If HARQ feedback is implemented for multicast services, then service reliability is improved, but uplink control channel resource overhead increases
Solution Approach 1:
The patent extracts only the essential feedback information (NACK-only or ACK/NACK) required for high-reliability multicast services, rather than implementing full-duplex feedback mechanisms used in unicast. By taking out only the critical feedback elements needed for reliability improvement, the uplink control channel resource overhead is minimized while still achieving the desired reliability enhancement.
Solution Approach 2:
The feedback information parameters are changed from traditional ACK/NACK bits to optimized formats such as NACK-only feedback or group-based ACK/NACK feedback. This parameter change reduces the number of uplink control resources required while maintaining the ability to achieve retransmission for unreliable receptions, thus improving reliability without proportionally increasing resource overhead.
3Quantity of substance
If NACK-only HARQ feedback mode is used, then uplink control resource consumption is reduced, but the ability to provide complete feedback information is compromised
Solution Approach 1:
The patent implements a feedback mechanism where the network device receives NACK-only feedback from terminal devices and uses this information to trigger retransmissions. The feedback loop is completed through network-side retransmission decisions, compensating for the reduced information content in uplink feedback. This resolves the contradiction by maintaining resource efficiency while preserving functional feedback capability through network-side action.
Data Source
AI summary
Provided in the embodiments of the present disclosure are a wireless communication method, a terminal device and a network device. The method includes: a terminal device determining Hybrid Automatic Repeat Request (HARQ) feedback information corresponding to a first Group Radio Network Temporary Identifier (G-RNTI), wherein the first G-RNTI is associated with one or multiple Physical Uplink Control Channel (PUCCH) resources configured for a first feedback mode, and the first feedback mode includes an HARQ feedback mode only feeding back Non-Acknowledgement (NACK)-included HARQ feedback information; and the terminal device sending, on one of the one or multiple PUCCH resources, NACK-included HARQ feedback information corresponding to the first G-RNTI. By the solution provided in the present disclosure, feedback can be provided for multicast or broadcast, such that a network may determine, according to the feedback, whether data retransmission is needed, thereby ensuring the reliability of service transmission.