Floating Sidelink S-SSB Timing for LBT Reliability
Solution Overview
Problem
Existing wireless communication systems face challenges in improving the signal strength and reliability of sidelink synchronization signal block (S-SSB) transmissions, particularly in scenarios where listen-before-talk (LBT) procedures fail, leading to incomplete S-SSB repetitions.
Innovation Solution
The implementation of a floating sidelink synchronization signal block (S-SSB) for time domain repetition, where a transmitting user equipment (UE) receives a message indicating an S-SSB timing configuration with multiple transmission occasions within a timing window, allowing for participation in LBT procedures and ensuring the completion of S-SSB repetitions despite potential LBT failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of S-SSB transmission occasions is increased to compensate for LBT procedure failures, then the reliability of S-SSB repetitions is improved, but the device complexity and timing configuration complexity increase
Solution Approach 1:
The S-SSB period is segmented into multiple timing windows, each containing multiple S-SSB transmission occasions. This segmentation allows the system to distribute the required number of repetitions across different time slots within windows, providing flexibility to compensate for LBT failures without requiring a completely reconfigured timing structure. The network can independently adjust the number of occasions per window and the number of windows within a period.
Solution Approach 2:
The system dynamically selects which S-SSB transmission occasions to use based on LBT procedure outcomes. If an LBT procedure fails at a scheduled transmission occasion, the transmitting UE can dynamically shift to use subsequent occasions within the same timing window to complete the required number of repetitions. This dynamic adaptation maintains reliability without requiring static over-provisioning of all possible transmission slots.
2Reliability
If multiple S-SSB transmission occasions are provided within a timing window, then the success rate of sidelink communications is improved, but the loss of time and scheduling overhead increase
Solution Approach 1:
The network pre-configures multiple S-SSB transmission occasions within timing windows before actual transmissions begin. This preliminary setup includes defining the number of occasions per window, the number of windows per period, and the time spacing between occasions. By preparing this structure in advance, the system avoids real-time scheduling decisions and reduces signaling overhead during actual operation, as UEs can autonomously determine which occasions to use based on pre-agreed configurations and LBT outcomes.
Solution Approach 2:
The system allows flexible adjustment of timing window parameters including the number of S-SSB occasions per window, the duration of each window, the spacing between occasions, and the number of windows within an S-SSB period. These parameter changes enable optimization of the balance between reliability (having enough retry opportunities) and time efficiency (minimizing gaps and overhead), allowing network operators to tune the system according to specific deployment scenarios and traffic conditions.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A transmitting user equipment (UE) may transmit repetitions of sidelink synchronization signal blocks (S-SSBs) in the time domain to a receiving UE to increase signal strength and reliability. The transmitting CE may receive a message from the network which indicates an S-SSB timing configuration for a timing window including multiple S-SSB transmission occasions within an S-SSB period, along with an indication of a periodicity and a duration of the timing window. The transmitting UE may then participate in at least one listen-before-talk (LBT) procedure during the timing window to access the sidelink channel. In such cases, the number of S-SSB occasions in the timing window may be numerous to compensate for possible failure of at least one LBT procedure. Based on a successful outcome of at least one LBT procedure, the UE may transmit one or more repetitions of the S-SSB.