SPS HARQ-ACK Timing Condition for PUCCH Resource Ambiguity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communication systems, particularly in 3GPP Release-15 and Release-16 NR, there is an ambiguity in HARQ-ACK codebook size for SPS PDSCHs without corresponding PDCCHs, leading to uncertainty in transmitting HARQ-ACKs for SPS configurations, which affects the efficient use of PUCCH resources and can result in HARQ-ACK codebook size ambiguity and bit collisions.
Innovation Solution
The proposed solution involves defining timing conditions for the reception of DL channels to determine when to cancel UL channels, specifically requiring that the second DL channel (PDCCH) is received no later than the first DL channel (SPS PDSCH) and that the last symbol of the PDCCH is not after the last symbol of the SPS PDSCH, to clarify when HARQ-ACKs should be transmitted for SPS PDSCH releases, thereby eliminating ambiguity and avoiding codebook size issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple SPS configurations are configured to support TSN flows, then the system can support multiple TSN flows simultaneously with reduced PDCCH overhead, but HARQ-ACK codebook size ambiguity occurs when SPS PDSCH releases are received
Solution Approach 1:
The patent applies preliminary action by defining timing conditions in advance that determine when UL channels should be canceled upon receiving SPS PDSCH releases. The timing condition specifies that if the second DL channel (PDCCH) is received no later than the first DL channel (SPS PDSCH) and the last symbol of the PDCCH is not after the last symbol of the SPS PDSCH, then the UL channel (PUCCH) should be canceled. This pre-defined rule eliminates HARQ-ACK codebook size ambiguity by providing clear criteria for when HARQ-ACK feedback should be transmitted or canceled, ensuring both UE and base station have the same understanding of active SPS configurations.
2Reliability
If HARQ-ACK feedback is transmitted for SPS PDSCH without corresponding PDCCH, then complete acknowledgment coverage is achieved, but PUCCH resource determination becomes complex due to codebook size dependencies
Solution Approach 1:
The patent applies preliminary action by establishing timing conditions in advance that determine when UL channels should be canceled. The condition specifies that if the second DL channel (PDCCH) is received no later than the first DL channel (SPS PDSCH) and the last symbol of the PDCCH is not after the last symbol of the SPS PDSCH, then the UL channel (PUCCH) should be canceled. This pre-defined rule simplifies PUCCH resource determination by providing clear criteria for when HARQ-ACK feedback should be transmitted or canceled, eliminating the need for complex codebook size calculations.
3Speed
If the smallest periodicity of SPS configuration is reduced to slot level, then TSN flows with short periodicity are better supported, but timing synchronization between DL channels and UL channel becomes more critical
Solution Approach 1:
The patent applies preliminary action by defining specific timing conditions in advance that must be satisfied for UL channel cancellation. The timing condition requires that the second DL channel (PDCCH) be received no later than the first DL channel (SPS PDSCH) and that the last symbol of the PDCCH be not after the last symbol of the SPS PDSCH. This pre-defined timing rule ensures precise synchronization between DL channels and UL channel even at slot-level periodicity, eliminating ambiguity about when HARQ-ACK feedback should be transmitted.
Data Source
AI summary
A method performed by a base station (BS) is provided. The method transmits, to a user equipment (UE), a radio resource control (RRC) message that carries a configuration for a configured downlink (DL) transmission on a first DL channel and a configured uplink (UL) transmission on a UL channel. In a case a timing condition between the first DL channel and a second DL channel is satisfied, the method transmits, to the UE, the second DL channel; cancels the configured DL transmission on the first DL channel; and cancels the configured UL transmission on the UL channel. The UL channel includes a physical uplink control channel (PUCCH) for a hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback.