NR Sidelink SCI for Unlicensed COT Sharing and Shorter CCA
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Solution Overview
Problem
In unlicensed new radio (NR) networks, efficient and reliable sidelink communication between vehicles (V2X devices) is hindered by the need for complete clear channel assessment (CCA), which can lead to inefficiencies in channel occupancy time (COT) sharing and resource allocation.
Innovation Solution
Implementing sidelink control information (SCI) with additional fields for channel occupancy time (COT) indications, such as channel access priority, power indication, and duration, allowing for shorter CCA and efficient COT sharing between vehicles, including configurations for hybrid automatic repeat request (HARQ) and multi-slot scheduling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complete clear channel assessment (CCA) is performed for channel access, then channel access reliability is improved, but channel occupancy time (COT) sharing efficiency deteriorates
Solution Approach 1:
The patent segments the COT sharing process into two distinct phases: (1) a first COT acquired through complete CCA for initial channel access, and (2) subsequent COT extensions achieved through shorter CCA procedures. This segmentation allows the system to maintain reliability for the initial access while improving efficiency for subsequent transmissions by reducing the CCA duration in the extension phase.
Solution Approach 2:
The patent applies preliminary action by performing the complete CCA procedure in advance to acquire the initial COT, then utilizing this pre-acquired channel access for subsequent transmissions with reduced CCA procedures. The SCI messages carry COT extension indicators that enable receiving UEs to perform shorter CCA, leveraging the preliminary channel access already established.
2Productivity
If shorter CCA procedures are implemented for COT sharing, then COT sharing efficiency is improved, but channel access reliability deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the CCA procedure duration based on the specific transmission context. The first COT acquisition uses complete CCA for high reliability, while subsequent COT extensions use shorter CCA for efficiency. The SCI messages carry COT extension indicators that locally adapt the CCA duration to the specific sharing scenario, optimizing the balance between reliability and efficiency for each transmission phase.
3Productivity
If SCI messages include additional COT indication fields, then resource allocation efficiency is improved, but message complexity increases
Solution Approach 1:
The patent extracts the COT indication information into separate, dedicated fields within the SCI message structure. Rather than embedding COT information within existing fields, the invention introduces specific COT extension indicators and duration fields that clearly delineate the channel occupancy parameters. This extraction approach improves resource allocation efficiency by providing explicit COT information while managing complexity through structured field separation.
4Reliability
If complete CCA is performed for each transmission, then channel access reliability is improved, but communication latency increases
Solution Approach 1:
The patent enables continuity of useful action by allowing COT extensions without requiring complete CCA procedures for each transmission. Once a UE acquires initial channel access through complete CCA, subsequent transmissions within the extended COT can proceed with shorter CCA procedures. This maintains the continuous flow of communication while reducing the time loss associated with repeated complete CCA procedures, thereby lowering latency while preserving reliability.
Data Source
AI summary
A user equipment (UE), including a vehicle to everything (V2X) device, a baseband processor or other network device can operate in an unlicensed network to acquire a channel occupancy time (COT) for sidelink (SL) transmission and provide sidelink control information (SCI) with a first stage SCI in a physical sidelink control channel (PSCCH) and a second stage SCI in a physical sidelink shared channel (PSSCH). The first stage SCI or the second stage SCI can provide COT indications to a receiving UE device that enable COT sharing in a sidelink unlicensed COT (SL-U COT) for SL communication.