Sidelink Synchronization Block Beam Sweeping in Shared Spectrum
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently transmitting sidelink synchronization signal blocks (S-SSBs) in a shared spectrum, particularly in accessing and beam sweeping to ensure effective reception by other UEs while minimizing interference.
Innovation Solution
The proposed methods involve aligning or offsetting the starting resource blocks of sidelink synchronization signal blocks within a sidelink bandwidth part, performing listen-before-talk procedures, and beam sweeping multiple S-SSBs to optimize transmission and reception in a shared spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If beam sweeping is performed for S-SSB transmissions in shared spectrum, then coverage and reception reliability are improved, but transmission overhead and time consumption increase
Solution Approach 1:
The S-SSB transmission is divided into multiple bursts, with each burst containing a subset of beam-swept S-SSBs. This segmentation allows the system to achieve comprehensive beam coverage across multiple bursts while reducing the number of S-SSBs transmitted in each individual burst, thereby balancing reliability improvement with time efficiency.
Solution Approach 2:
Beam sweeping is performed periodically across multiple S-SSB bursts, where each burst contains a sequence of S-SSBs transmitted in different beam directions. This periodic beam sweeping ensures that all necessary beam directions are covered over time while maintaining a structured, efficient transmission pattern that minimizes overhead.
2Ease of operation
If S-SSB transmissions are performed in shared spectrum with LBT procedure, then channel access fairness is improved, but transmission opportunities and productivity decrease
Solution Approach 1:
The system performs LBT procedure in advance before each S-SSB burst transmission. This preliminary channel access attempt allows the transmitting UE to secure the channel early, enabling it to plan and execute multiple S-SSB bursts within the available channel access window, thereby maximizing transmission opportunities while maintaining fairness.
Solution Approach 2:
Once channel access is obtained through LBT, the system continuously transmits multiple S-SSB bursts in succession without releasing the channel. This continuous transmission maximizes the utilization of the acquired channel access, increasing productivity while the LBT mechanism itself ensures fairness by requiring all UEs to contend for channel access.
3Productivity
If resource allocation for S-SSB is made flexible to adapt to channel conditions, then transmission efficiency is improved, but resource identification complexity and device complexity increase
Solution Approach 1:
The system changes key parameters such as the number of S-SSBs per burst, the timing between bursts, and the beam directions based on channel conditions and LBT outcomes. These parameter adjustments enable flexible adaptation to varying channel conditions and transmission opportunities, improving efficiency while maintaining a manageable level of complexity through standardized parameter sets.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. Generally, the described techniques provide for efficiently identifying resources for transmitting one or more sidelink synchronization signal blocks (S-SSBs) in the shared spectrum or efficiently beam sweeping multiple S-SSBs in the shared spectrum. In one aspect, a user equipment (UE) may transmit an S-SSB in a sidelink bandwidth part (BWP) in the shared spectrum such that a lower edge of the S-SSB is aligned with or offset from a lower edge of the sidelink BWP. In another aspect, a UE may beam sweep S-SSBs in one or more S-SSB bursts in a S-SSB period to improve the chances that another UE may receive the S-SSBs. In yet another aspect, resources allocated for S-SSB transmissions may facilitate flexible S-SSB transmissions while minimizing gaps to prevent other UEs from incorrectly determining that a sidelink BWP in a shared spectrum is clear for transmission.