HARQ Feedback for Downlink SPS Decoding Failures
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently handling semi-persistent scheduling (SPS) in downlink (DL) scenarios, particularly in 5G and beyond, leading to decoding failures and inefficiencies in HARQ-ACK feedback mechanisms.
Innovation Solution
A method and apparatus for user equipment (UE) and base stations to manage HARQ-ACK feedback by receiving configuration information for PDSCH and identifying DL SPS, transmitting a negative acknowledgement (NACK) when decoding fails, thereby improving the HARQ-ACK feedback mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If semi-persistent scheduling (SPS) is used in downlink scenarios, then resource allocation efficiency is improved, but decoding failures occur and HARQ-ACK feedback mechanisms become inefficient
Solution Approach 1:
The patent inverts the traditional HARQ-ACK feedback approach by introducing NACK-only feedback for SPS scenarios. Instead of requiring full HARQ-ACK feedback (both ACK and NACK), the system only transmits NACK when decoding fails, while successful decodings remain silent. This inversion resolves the contradiction by maintaining SPS resource efficiency while improving decoding reliability through selective feedback.
Solution Approach 2:
The patent extracts only the necessary feedback component (NACK) from the complete HARQ-ACK mechanism for SPS scenarios. By removing unnecessary ACK transmissions and retaining only error indication signals, the system achieves both resource allocation efficiency and decoding reliability, as the extracted NACK feedback is sufficient for SPS retransmission management.
2Reliability
If traditional HARQ-ACK feedback mechanism is used, then decoding failures can be detected, but feedback overhead and system complexity increase
Solution Approach 1:
The patent extracts only the essential error detection function from the traditional HARQ-ACK feedback mechanism. By implementing NACK-only feedback where only negative acknowledgments are transmitted for SPS, the system maintains decoding failure detection capability while significantly reducing feedback mechanism complexity and overhead.
Solution Approach 2:
The patent employs a simplified, lightweight feedback approach using disposable NACK signals instead of persistent full HARQ-ACK mechanisms. Each NACK transmission is a simple, low-complexity signal that serves its purpose immediately, reducing overall system complexity while maintaining necessary reliability for decoding failure detection.
Data Source
AI summary
A method performed by a user equipment (UE) in a wireless communication system is provided. The method includes receiving, from a base station, first configuration for a physical downlink shared channel (PDSCH) and second configuration information for a hybrid automatic repeat request (HARQ) acknowledgement (ACK), receiving, from the base station, scheduling information for receiving the PDSCH, receiving, from the base station, the PDSCH, identifying whether the scheduling information is associated with a downlink (DL) semi-persistent scheduling (SPS), and transmitting, to the base station, a negative acknowledgement (NACK) message, in case that the scheduling information is associated with the DL SPS and decoding of the received PDSCH fails.