SPS PDSCH Release Timing for Collision-Aware HARQ-ACK Handling
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Solution Overview
Problem
In Release 15 (Rel-15) 3GPP new radio (NR) technology, there is a need for better optimization in handling collision and release of semi-persistently scheduled (SPS) PDSCH configurations, particularly due to overlapping SPS PDSCHs and the ambiguity in PDCCH and SPS PDSCH reception timing, which affects HARQ-ACK feedback and resource allocation.
Innovation Solution
The method involves receiving SPS PDSCH occasions over multiple slots, processing a PDCCH with a specific DCI format that allows for simultaneous or near-simultaneous release of SPS configurations, and determining UE behavior based on defined timelines and collision handling rules to ensure proper SPS PDSCH reception and HARQ-ACK feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple SPS PDSCH configurations are used to increase data transmission capacity, then productivity is improved, but collision among SPS PDSCHs occurs causing reliability degradation
Solution Approach 1:
The patent segments the handling of multiple SPS PDSCH configurations by introducing separate processing paths for different collision scenarios. When collisions are detected, the system segments the SPS PDSCH receptions into those that can be reliably decoded and those that cannot, applying different HARQ-ACK feedback strategies to each segment.
Solution Approach 2:
The patent introduces dynamic behavior for SPS PDSCH reception based on real-time collision detection. The UE dynamically adjusts its reception and feedback behavior by monitoring PDCCH indications and adapting HARQ-ACK feedback generation according to the detected collision state, transitioning between different operational modes.
2Reliability
If SPS PDSCH occasions are received over multiple slots to improve reliability, then reliability is improved, but ambiguity in release timing and HARQ-ACK feedback increases device complexity
Solution Approach 1:
The patent applies preliminary action by having the network pre-indicate SPS PDSCH release timing through PDCCH before the actual release occurs. This allows the UE to prepare in advance for the release, knowing when to stop expecting SPS PDSCH transmissions and when to switch to other reception modes, reducing processing complexity at the moment of release.
Solution Approach 2:
The patent introduces a feedback mechanism where the UE generates HARQ-ACK feedback for SPS PDSCH receptions and sends it to the network. This feedback loop allows the network to verify successful receptions and adjust future SPS configurations accordingly, reducing ambiguity in the release process by having explicit confirmation of reception status.
3Productivity
If PDCCH and SPS PDSCH timing are aligned to improve resource utilization, then productivity is improved, but collision handling becomes more difficult increasing device complexity
Solution Approach 1:
The patent applies local quality by treating different time locations differently in the SPS PDSCH reception process. When a PDCCH indicating release is received, the UE applies different quality requirements to SPS PDSCH occasions before versus after the PDCCH timing. SPS PDSCH occasions occurring before the PDCCH are handled with normal expectations, while those after are treated as released, creating localized quality differences in handling.
4Reliability
If HARQ-ACK feedback is required for all SPS PDSCH occasions to improve reliability, then reliability is improved, but loss of time increases due to feedback processing overhead
Solution Approach 1:
The patent applies partial action by requiring HARQ-ACK feedback only for SPS PDSCH occasions that are successfully received and decoded, rather than for all configured occasions. When collisions or releases occur, the UE selectively generates feedback only for the subset of SPS PDSCH occasions that were actually received, reducing feedback processing time while maintaining reliability for successful transmissions.
Data Source
AI summary
A method of semi-persistently scheduled (SPS) release, comprising: receiving, by a user equipment (UE), one or more occasions of SPS physical downlink shared channels (PDSCHs) over multiple slots for a transport block (TB) according to an SPS configuration; receiving, by the UE, a physical downlink control channel (PDCCH) including a downlink control information (DCI) format such that an end of a last symbol of the PDCCH is received before or at a same time as an end of a last symbol of a first occasion of a received SPS PDSCH; and releasing, by the UE, the SPS configuration in response to receiving the PDCCH.