NR-U SSB Transmission Timing for LBT-Constrained Synchronization
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Solution Overview
Problem
In NR-U, the gNB may not be able to transmit SSB burst sets on pre-defined locations due to LBT failures, leading to issues in UE detection of SSBs, which are crucial for synchronization and functionality in the NR system.
Innovation Solution
Implement mechanisms for SSB transmission in NR-U that include configuring a SSB Transmission Timing Configuration (STTC) with plural locations, performing LBT checks, and transmitting SSBs only when the channel is available, along with beam-based LBT and flexible index ordering to enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SSB transmission is performed on pre-defined locations in NR-U, then the transmission schedule is fixed and simple, but LBT failure may occur causing unreliable transmission
Solution Approach 1:
The patent applies dynamics by making the SSB transmission location flexible rather than fixed. The gNB can dynamically select transmission locations within a time window based on LBT outcomes, allowing the system to adapt to changing channel conditions while maintaining reliable transmission.
Solution Approach 2:
The patent changes the parameter of transmission location from a fixed pre-defined position to a variable position within a configured time window. This parameter change enables the system to handle LBT failures by allowing location flexibility while maintaining transmission reliability.
2Reliability
If LBT check is performed before SSB transmission, then channel availability is ensured, but transmission timing flexibility is reduced
Solution Approach 1:
The patent applies preliminary action by performing LBT checks at multiple predetermined time instances before the actual SSB transmission. This allows the system to prepare for transmission by checking channel availability in advance, ensuring reliability while maintaining timing flexibility through multiple check opportunities.
Solution Approach 2:
The patent implements periodic action by conducting LBT checks at multiple periodic time instances within a configured window. This periodic checking mechanism ensures channel availability is assessed multiple times, balancing reliability requirements with timing flexibility.
3Reliability
If multiple SSBs are transmitted in a burst set, then synchronization information is provided, but transmission time window increases
Solution Approach 1:
The patent applies segmentation by dividing the SSB transmission into multiple discrete SSBs within a burst set, each transmitted at different time instances. This segmentation allows the system to provide comprehensive synchronization information across multiple time points while managing the overall transmission time window through structured organization.
Data Source
AI summary
An apparatus including a non-transitory memory including instructions stored thereon for monitoring synchronous signals and physical broadcast channels (SSBs) from a network node. The apparatus also includes a processor, operably coupled to the non-transitory memory, configured to execute a set of instructions. The instructions include configuring the apparatus for a STTC (SSB Transmission Timing Configuration). The STTC is a time interval with plural locations accommodating transmission of the SSBs. The instructions also include monitoring the STTC for the SSBs. The instructions further include determining a first one of the SSBs in a first slot of a subframe in a scheduled SSB transmission in the STTC has been transmitted at a first scheduled location, where the transmission of the first one of the SSBs is based upon confirmation of a successful Listen Before Talk (LBT) available channel prior to the scheduled SSB transmission in the STTC.