Sidelink SCI Signaling for Unlicensed COT Structure Sharing
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently handling sidelink transmissions over unlicensed spectra due to unpredictable channel access times and the lack of clear channel occupancy structure information, leading to potential data loss and retransmission inefficiencies.
Innovation Solution
A user equipment (UE) is equipped with a transceiver and processor to perform channel access procedures and transmit sidelink control information (SCI) formats that include channel occupancy time (COT) structure indicators, providing detailed information about the COT structure to enable efficient resource sharing and synchronization among UEs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sidelink transmissions are performed on unlicensed spectrum without COT structure information, then devices can communicate directly via sidelink, but channel occupancy structure is unpredictable leading to data loss and retransmission inefficiencies
Solution Approach 1:
The transmitting UE performs channel access procedure and determines COT structure in advance before actual data transmission. The COT structure information including slot format combinations is prepared and included in SCI format 1-A, allowing receiving UEs to know the channel occupancy structure beforehand and avoid data loss during reception.
Solution Approach 2:
SCI format 1-A acts as an intermediary message that carries COT structure information from the transmitting UE to receiving UEs. This intermediate information transmission enables receiving UEs to understand the channel occupancy structure without direct observation, resolving the information asymmetry problem.
2Productivity
If detailed COT structure information is transmitted to all UEs, then resource sharing and synchronization are optimized, but signaling overhead and system complexity increase
Solution Approach 1:
The COT structure information is segmented into discrete parameters including slot format combination index, number of slots, gap configurations, and PSFCH resource allocations. Each parameter is independently encoded in the SCI format 1-A, allowing receiving UEs to process only the relevant segments for their specific needs rather than handling monolithic complex structures.
Solution Approach 2:
The patent transforms complex COT structure descriptions into compact parameter representations. Instead of transmitting detailed timing and format descriptions, the system uses indexed parameters (e.g., slot format combination index, number of slots indicator) that reference pre-defined structures, significantly reducing the information burden while maintaining full descriptive capability.
3Loss of time
If UEs perform channel access procedures individually without COT sharing information, then each UE can access channel independently, but channel access time becomes unpredictable and retransmissions increase
Solution Approach 1:
The transmitting UE provides feedback to receiving UEs about the COT structure through SCI format 1-A, including information about occupied slots, gap configurations, and shared resources. This feedback mechanism allows receiving UEs to align their channel access timing with the transmitting UE's COT, making channel access times predictable and coordinated without requiring complex inter-UE negotiation.
Data Source
AI summary
Embodiments of the present disclosure relate to methods and apparatuses for sidelink transmission over an unlicensed spectrum. According to some embodiments of the disclosure, a UE may: perform a channel access procedure for initiating a COT; and transmit an SCI format within the COT in response to the channel access procedure being successful, wherein the SCI format may include structure information of the COT.