Sidelink PSSCH HARQ Feedback to Reduce Latency and Overhead
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Solution Overview
Problem
In sidelink communication, the conventional use of a physical sidelink feedback channel (PSFCH) for HARQ feedback results in excessive system overheads when all slots are configured with resources, and fails to meet ultra-low latency requirements when not all slots are configured, leading to potential half-duplex problems and reduced reliability.
Innovation Solution
The method involves sending HARQ feedback information through a physical sidelink shared channel (PSSCH) instead of PSFCH, utilizing newly defined or existing SCI to carry feedback information, allowing simultaneous transmission of data and feedback in the same time unit, and reducing decoding complexity and power consumption by targeting specific terminal devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If PSFCH resources are configured in all slots, then feedback can be sent timely, but system overheads become excessively high
Solution Approach 1:
The patent merges the feedback transmission function into the PSSCH by carrying HARQ feedback information in the SCI or data portion of the PSSCH. This combination eliminates the need for separate PSFCH resources, reducing system overhead while maintaining the capability for timely feedback transmission.
Solution Approach 2:
The PSSCH is designed to perform multiple functions: transmitting data, control information (SCI), and HARQ feedback information. This multi-functionality allows the channel to serve as both a data channel and a feedback channel, eliminating the need for dedicated feedback resources and reducing overall system overhead.
2Quantity of substance
If PSFCH resources are not configured in all slots, then system overheads are reduced, but feedback latency increases and ultra-low latency requirements cannot be met
Solution Approach 1:
By combining feedback transmission with data transmission in the PSSCH, the system can provide feedback in every slot without requiring dedicated PSFCH resources in each slot. This approach reduces overhead while ensuring low latency feedback is always available.
Solution Approach 2:
The PSSCH carries feedback information continuously in every slot where data is transmitted, ensuring uninterrupted feedback capability. This continuous operation maintains ultra-low latency requirements without the need for periodic PSFCH resources.
3Reliability
If feedback is sent through PSFCH, then dedicated feedback resources are provided, but half-duplex problems occur and reliability is reduced
Solution Approach 1:
The patent combines data transmission and feedback transmission in the same PSSCH resources. Since the terminal device transmits both data and feedback in the same direction (uplink or sidelink) during the same time period, the half-duplex conflict is eliminated while maintaining feedback reliability.
Solution Approach 2:
The system dynamically adjusts the PSSCH to carry both data and feedback information based on channel conditions and traffic requirements. This dynamic approach allows flexible resource utilization and eliminates the rigid half-duplex constraints of separate dedicated feedback channels.
4Device complexity
If new SCI is defined to carry feedback information, then feedback can be embedded in PSSCH, but protocol complexity increases
Solution Approach 1:
The existing SCI structure is extended to carry feedback information, making it a multi-functional control element. This approach minimizes protocol changes while enabling feedback transmission, as the SCI format is enhanced rather than completely redesigned.
Solution Approach 2:
The SCI parameters are modified to include feedback information fields. By changing the parameter structure of existing SCI rather than creating new message types, the protocol complexity is minimized while achieving the goal of embedded feedback transmission.
Data Source
AI summary
This application provides a communication method and an apparatus, which are applicable to a sidelink communication scenario. A method includes a first terminal device receives data sent by a second terminal device, and sends feedback information to the second terminal device through a PSSCH based on a receiving status of the data.