Sidelink Feedback Channel Occasion Procedures
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Solution Overview
Problem
In wireless communication systems, sidelink feedback channels face inefficiencies due to repetitive and interfering feedback transmissions, leading to decreased communication efficiency and increased latency, particularly in scenarios like vehicle-to-everything (V2X) systems where UEs directly communicate without base station relay.
Innovation Solution
Implementing multiple sidelink feedback channel occasion procedures that allow UEs to transmit acknowledgments (ACK) or negative acknowledgments (NACK) based on reception, with the option for NACK-only feedback and prioritization of transmissions, using a set of preconfigured Physical Sidelink Feedback Channel (PSFCH) slots to improve reliability and reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UEs transmit feedback in every available slot, then feedback reliability is improved, but channel interference and signaling overhead increase
Solution Approach 1:
The feedback channel resources are segmented into multiple PSFCH slots, allowing UEs to distribute feedback transmissions across different time slots rather than concentrating all feedback in one slot. This segmentation reduces instantaneous channel interference while maintaining feedback reliability through diverse transmission opportunities.
Solution Approach 2:
Feedback transmissions are organized in periodic slots rather than continuous transmission. UEs transmit feedback in specific periodic PSFCH slots, which reduces channel interference compared to continuous feedback transmission while ensuring reliable delivery through regular transmission opportunities.
2Loss of time
If multiple UEs transmit feedback simultaneously, then feedback latency is reduced, but channel overload and interference increase
Solution Approach 1:
The patent introduces a spatial dimension to feedback transmission by assigning different UEs to different PSFCH slots or frequency resources. This dimensional separation allows multiple UEs to transmit feedback without overwhelming the channel, reducing overload while maintaining low latency through parallel transmission paths.
3Loss of information
If UEs transmit both ACK and NACK feedback, then complete feedback information is provided, but signaling overhead and channel usage increase
Solution Approach 1:
The patent extracts only the essential feedback information (NACK-only feedback) in certain scenarios, removing unnecessary ACK transmissions. When channel conditions are good or retransmission is not critical, UEs transmit only NACK when needed, reducing signaling overhead while maintaining sufficient feedback information for reliable communication.
4Productivity
If feedback transmissions are prioritized and queued, then channel efficiency is improved, but system complexity increases
Solution Approach 1:
UEs perform preliminary actions by queuing and prioritizing feedback transmissions before actual transmission. Feedback messages are organized in advance based on urgency and channel conditions, allowing efficient channel utilization without requiring complex real-time decision-making during transmission, thus balancing productivity and complexity.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. One or more user equipments (UEs) may communicate in a wireless communications system by transmitting and receiving sidelink messages from other UEs. The UEs may transmit acknowledgement (ACK) or negative acknowledgment (NACK) feedback based on reception of sidelink messages for other UEs. The UEs may identify a sidelink feedback resource set including a set of feedback transmission slots for transmitting sidelink feedback. The UEs may perform NACK-only feedback, and may streamline feedback transmissions based on monitoring for other NACKs from other UEs. The UEs may prioritize feedback transmissions when the UE has multiple feedback transmissions queued, and when a UE has feedback to transmit and to receive in overlapping transmission time intervals (TTIs).