NR Sidelink HARQ Feedback with LBT-Selected Code Resource Sets
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The inefficiency of Hybrid Automatic Repeat Request (HARQ) feedback in New Radio (NR) sidelink communication in unlicensed spectrum due to Listen Before Talk (LBT) failures, leading to increased resource consumption and latency in unlicensed bands.
Innovation Solution
Configuring at least two sets of code domain resources for HARQ feedback, allowing for multiple transmission opportunities based on LBT success, using different cyclic shifts of a base sequence like Zadoff-Chu, to ensure reliable and efficient HARQ feedback in unlicensed spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single set of code domain resources is used for HARQ feedback, then the device complexity is reduced, but the reliability of HARQ feedback in unlicensed spectrum deteriorates due to LBT failures
Solution Approach 1:
The patent divides the code domain resources into multiple candidate sets (first candidate set and second candidate set), each with different cyclic shifts of the base sequence. This segmentation allows the receiving device to try multiple resource sets in case LBT fails for a particular set, thereby improving HARQ feedback reliability without requiring a completely new system design.
Solution Approach 2:
The patent introduces dynamic selection between multiple code domain resource sets based on LBT outcomes. The transmitting device dynamically determines which resource set to use for HARQ feedback transmission by attempting LBT on candidate sets in a predetermined order, adapting to the actual channel conditions rather than relying on a fixed single resource allocation.
2Reliability
If multiple candidate sets of code domain resources are configured, then the reliability of HARQ feedback is improved through multiple transmission opportunities, but the device complexity increases
Solution Approach 1:
The code domain resources are segmented into multiple candidate sets with different cyclic shifts. This segmentation enables the system to divide and conquer the LBT challenge by attempting transmission on smaller, manageable resource portions (individual candidate sets) rather than all resources at once, reducing the complexity burden while maintaining high reliability.
Solution Approach 2:
The patent performs preliminary configuration of multiple candidate resource sets and their corresponding LBT procedures before actual HARQ feedback transmission. The transmitting device pre-determines the order and parameters of candidate sets, so that during actual transmission, it only needs to execute pre-planned LBT attempts rather than making real-time complex decisions, thereby reducing operational complexity.
3Productivity
If LBT procedure is performed for each candidate set, then the spectral efficiency is improved by reducing unnecessary retransmissions, but the time consumption increases due to multiple LBT attempts
Solution Approach 1:
The patent implements periodic LBT attempts on different candidate resource sets in a predetermined order. Instead of continuous or random LBT checking, the system performs LBT at specific periodic intervals on systematically selected candidate sets, which optimizes the balance between checking availability and minimizing total checking time. This structured periodic approach ensures spectral efficiency while controlling time consumption.
Solution Approach 2:
The patent performs preliminary ordering and parameter setup of candidate resource sets before actual transmission. By pre-determining the sequence and LBT parameters for each candidate set, the system eliminates the need for real-time complex calculations during LBT attempts, reducing the time overhead while maintaining high spectral efficiency through targeted resource selection.
Data Source
AI summary
Embodiments of the present disclosure relate to devices, methods, apparatuses and computer readable storage media of HARQ for NR sidelink communication in unlicensed spectrum. The method comprises receiving, from a second device, an indication of at least two candidate sets of code domain resources for the first device to transmit a feedback message for a sidelink transmission between the first device and a third device; and transmitting, to the third device, the feedback message on a target set of code domain resources determined from the at least two candidate sets of code domain resources based on a listen before talk procedure. In this way, additional code domain resources may provide more available time occasions as backup resources for HARQ feedback of sidelink transmission in unlicensed band, which may increase reliability of HARQ feedback transmission for sidelink communication in unlicensed spectrum. Hence it can eventually increase spectral efficiency by avoiding unnecessary retransmission of PSCCH/PSSCH, and can also reduce transmission latency in the meantime.