PSFCH Transmission Window Configuration for Shared Spectrum HARQ Feedback
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Solution Overview
Problem
In wireless communication systems, there is a need to enhance the physical sidelink feedback channel (PSFCH) in unlicensed or shared spectrum to ensure clear resource allocation and transmission opportunities, particularly due to uncertainties arising from channel access failures.
Innovation Solution
The proposed solution involves time domain enhancements for the PSFCH, including multiple transmission occasions in a slot, dynamic indication of transmission occasions, and flexible resource allocation based on configurations, to ensure clear resource allocation and transmission opportunities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single transmission occasion is used for PSFCH in shared spectrum, then the channel access procedure is simple, but transmission reliability deteriorates due to channel access failures
Solution Approach 1:
The transmission window is segmented into multiple transmission occasions (e.g., first, second, third transmission occasions) within a defined window period. This segmentation allows the UE to attempt channel access at multiple distinct time points, thereby improving transmission reliability if some occasions fail due to channel access failures while maintaining manageable configuration complexity through structured segmentation.
2Reliability
If multiple transmission occasions are configured in a transmission window, then transmission reliability improves, but resource allocation ambiguity increases
Solution Approach 1:
The transmission window configuration is made dynamic through higher layer signaling that can indicate different window offsets, intervals between transmission occasions, and numbers of transmission occasions. This dynamic configuration allows the system to adapt to varying channel conditions while maintaining clear resource allocation through explicit parameterization, resolving the contradiction between reliability improvement and allocation clarity.
Solution Approach 2:
Multiple parameters defining the transmission window are introduced and configurable: window offset (time position of window start), interval between transmission occasions (time spacing), and number of transmission occasions (count). By changing these parameters through higher layer configurations, the system achieves both reliable multi-occasion transmission and clear resource allocation through explicit parameter definition.
3Adaptability or versatility
If transmission window parameters are fixed, then device complexity is reduced, but adaptability to channel conditions deteriorates
Solution Approach 1:
The transmission window parameters (offset, interval, number of occasions) are configured dynamically through higher layer signaling based on detected channel conditions. When channel conditions are poor, the system can increase the number of transmission occasions or adjust intervals to improve reliability. This dynamic adaptation maintains versatility while managing complexity through standardized configuration procedures.
Solution Approach 2:
The system uses feedback from channel access outcomes and channel condition monitoring to adjust transmission window parameters. If channel access failures occur or channel conditions deteriorate, the UE and network can modify the transmission window configuration in subsequent transmissions, creating a feedback loop that improves adaptability while maintaining manageable complexity through iterative optimization.
Data Source
AI summary
Apparatuses and methods for transmission window determination for a physical sidelink feedback channel (PSFCH) in a wireless communication system. A method of user equipment (UE) includes receiving a set of configurations from a higher layer and receiving a physical sidelink shared channel (PSSCH). The PSSCH enables hybrid automatic repeat request (HARQ) feedback. The method further includes determining a transmission window for a PSFCH; performing a sidelink (SL) channel access procedure before a transmission occasion in the one or multiple transmission occasions; and transmitting the HARQ feedback in the transmission occasion for the PSFCH over a channel upon successfully performing the SL channel access procedure. The transmission window includes the one or multiple transmission occasions for the PSFCH and the one or multiple transmission occasions are based on at least one of: a window offset, an interval between two neighboring transmission occasions, and a number of transmission occasions.