NACK-Only HARQ Feedback for 5G Multicast in RRC Idle
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Solution Overview
Problem
Current 5G-NR radio access networks are not designed to reliably support multicast and broadcast communications, particularly in RRC idle and inactive states, leading to poor downlink data reception performance and increased packet latency due to blind retransmissions in point-to-multipoint communications.
Innovation Solution
Implementing NACK-only reporting in 5G-NR cellular communication networks, where user equipment (UE) generates and transmits HARQ feedback only when data packets are not decoded successfully, using pseudo-random sequences for HARQ information reports and configuring PUCCH resources to reduce unnecessary retransmissions and improve resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If blind retransmissions are implemented in multicast or broadcast communication, then data can be retransmitted to ensure delivery, but downlink data reception performance deteriorates and packet latency increases
Solution Approach 1:
The patent implements feedback mechanisms where user equipment (UE) in RRC idle and inactive states can send acknowledgments or negative acknowledgments to the base station regarding received multicast/broadcast data. This feedback allows the base station to make informed retransmission decisions, avoiding unnecessary blind retransmissions and improving overall downlink reception performance while maintaining delivery reliability.
2Reliability
If blind retransmissions are implemented in multicast or broadcast communication, then data can be retransmitted to ensure delivery, but packet latency increases
Solution Approach 1:
The feedback mechanism enables the base station to receive timely information about successful or failed data reception from UEs in idle and inactive states. This allows for selective retransmission only when necessary, significantly reducing unnecessary delays caused by repeated blind retransmissions while maintaining reliable data delivery.
3Ease of manufacture
If current NR radio specifications are used for point-to-multipoint communication, then implementation is simple, but reliable content delivery to UEs in RRC idle and inactive states cannot be achieved
Solution Approach 1:
The patent introduces dynamic mechanisms for handling multicast and broadcast communications, including configurable feedback options and adaptive retransmission strategies that activate specifically for UEs in RRC idle and inactive states. These dynamic features enhance delivery reliability without significantly complicating the overall system implementation, as they build upon existing NR radio specifications.
Data Source
AI summary
Methods and apparatus for negative acknowledgement (NACK)-only reporting in radio resource control (RRC) idle and inactive states are provided. A method implemented by a user equipment (UE) comprising: receiving, from a serving node and via a new radio (NR) radio access network (RAN), at least one physical downlink shared channel (PDSCH) transport block; determining that a first PDSCH transport block is decoded erroneously during a UE RRC idle state or a UE RRC inactive state; generating a hybrid automatic repeat request (HARQ) information report indicating NACK of the first PDSCH transport block; and performing NACK-only reporting to the serving node. When a second PDSCH transport block is decoded correctly or is not decoded, UE determines not generating a HARQ information report indicating an acknowledgement (ACK) of the second PDSCH transport block.