Sidelink COT Maintenance Across PSFCH Gaps in Unlicensed Bands
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communication networks, maintaining channel occupancy time (COT) for sidelink communications in shared or unlicensed frequency bands is challenging due to gaps caused by physical sidelink feedback channel (PSFCH) resources, leading to inefficiencies and increased collision and interference risks.
Innovation Solution
Mechanisms are introduced to maintain COT by indicating a second wireless device to transmit a signal in a gap symbol before PSFCH, using cyclic prefix extensions or filler signals, and rate-matching sidelink data to extend over these gaps, ensuring continuous communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PSFCH resources are allocated for sidelink feedback communication, then feedback capability is improved, but channel occupancy time continuity deteriorates due to required gaps
Solution Approach 1:
The patent applies this principle by filling the gap symbols between PSSCH and PSFCH with extended cyclic prefixes from the PSSCH transmission. This allows the channel occupancy to continue without interruption, maintaining the useful action of data transmission while accommodating the necessary PSFCH feedback resources. The gap symbols that would normally break continuity are repurposed to extend the cyclic prefix, enabling seamless transmission continuation.
2Ease of operation
If gap symbols are inserted before PSFCH for processing, then feedback processing capability is improved, but channel utilization deteriorates due to idle time
Solution Approach 1:
The patent eliminates idle gap symbols by extending the cyclic prefix to cover the entire gap period between PSSCH and PSFCH. This transforms what would be unused idle time into productive transmission time, maintaining channel utilization at 100% while still providing the necessary processing interval for feedback preparation. The cyclic prefix extension absorbs the gap duration without creating actual idle time on the channel.
Solution Approach 2:
The patent changes the parameter of cyclic prefix length, extending it from its normal duration to cover the gap symbols between PSSCH and PSFCH. This parameter modification allows the transmission to occupy the gap time that would otherwise be idle, converting non-productive time into useful transmission time while maintaining the required processing capability for feedback.
3Productivity
If COT is maintained across PSFCH resources, then spectral efficiency is improved, but collision and interference risks increase in unlicensed bands
Solution Approach 1:
The patent maintains continuous channel occupancy across PSFCH resources by filling gap symbols with extended cyclic prefixes. This continuity improves spectral efficiency by eliminating idle time while the LBT mechanism monitors the channel during this continuous occupancy to detect and respond to external interference or collisions from other systems in the unlicensed band.
Solution Approach 2:
The patent employs LBT (Listen Before Talk) feedback mechanisms that continuously monitor the channel during the maintained COT. This feedback system detects external signals or interference in real-time, allowing the transmitting device to adjust or terminate transmission when collisions are detected, thus managing the risks of operating in unlicensed bands while maintaining spectral efficiency.
Data Source
AI summary
A method of wireless communication performed by a first wireless communication device may maintain a channel occupancy time (COT) in a shared frequency band during at least one physical sidelink feedback channel (PSFCH) instance. In some aspects, the method includes transmitting, in a first portion of a COT based on a listen-before talk (LBT), a first sidelink (SL) communication comprising SL communication information (SCI), the SCI indicating a second wireless communication device to transmit a signal in at least one gap symbol preceding a PSFCH resource. The method further includes receiving, from the second wireless communication device, the signal during the at least one gap symbol. The method further includes transmitting, in a second portion of the COT based on the LBT, a second SL communication, wherein the second portion of the COT is subsequent to the PSFCH resource.