Sidelink HARQ-ACK Timing in Unlicensed COT Transmission
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Solution Overview
Problem
Sidelink transmissions on unlicensed spectrums face frequent interruptions due to periodic physical sidelink feedback channel (PSFCH) occasions, leading to channel loss, non-compliance with regulatory requirements, and inefficient channel access procedures.
Innovation Solution
Determine PSFCH occasions based on a PSFCH periodicity with reference to a resource pool, and perform channel access procedures or leave gap symbols blank to manage HARQ-ACK feedback transmissions within a channel occupancy time (COT), ensuring continuous transmissions and reducing channel loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If periodic PSFCH occasions are implemented for HARQ-ACK feedback transmission, then feedback reliability is improved, but channel occupancy is reduced due to frequent interruptions
Solution Approach 1:
The patent dynamically determines whether to transmit PSFCH in periodic occasions based on whether the feedback timing falls within the current COT. The system transitions from static periodic transmission to dynamic conditional transmission, maintaining reliability only when channel occupancy is preserved
Solution Approach 2:
The patent changes the transmission parameter of PSFCH from always transmitting to conditionally transmitting based on timing parameters relative to COT boundaries. This parameter change allows the system to adapt transmission behavior to maintain both reliability and channel occupancy
2Reliability
If channel access procedures are performed at each PSFCH occasion, then regulatory compliance is improved, but transmission efficiency deteriorates
Solution Approach 1:
The patent performs channel access procedure once at the beginning of COT to secure channel occupancy, rather than repeating it at each PSFCH occasion. This preliminary action maintains regulatory compliance while eliminating redundant procedures that reduce transmission efficiency
Solution Approach 2:
The patent enables continuous transmissions within the secured COT by avoiding repeated channel access procedures. The useful action of data transmission continues uninterrupted through multiple PSFCH occasions without efficiency degradation from repeated LBT
3Reliability
If gap symbols are left blank for PSFCH occasions, then channel loss is reduced, but transmission continuity is interrupted
Solution Approach 1:
The patent dynamically decides whether to leave gap symbols blank or transmit continuously based on whether PSFCH timing falls within COT. This dynamic approach resolves the contradiction by adapting the transmission pattern to maintain both channel occupancy and continuity where applicable
Data Source
AI summary
Embodiments of the present disclosure relate to methods and apparatuses for determining sidelink HARQ-ACK feedback transmission occasions over unlicensed spectrums. According to some embodiments of the disclosure, a UE may: perform a first channel access procedure to initiate a first COT; determine a first PSFCH occasion inside of the first COT; determine whether there is HARQ-ACK feedback to be transmitted in the first PSFCH occasion; and in response to determining that there is HARQ-ACK feedback to be transmitted in the first PSFCH occasion, leave gap symbols for the first PSFCH occasion within the first COT blank, or in response to determining that no HARQ-ACK feedback is to be transmitted in the first PSFCH occasion, perform continuous transmissions in the first PSFCH occasion.