NR V2X Multi-Source Synchronization for Reliable Sidelink
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Solution Overview
Problem
In sidelink communication, UEs may face challenges in establishing communication due to differing synchronization timings when selecting synchronization sources based on different priority rules, leading to communication failures between UEs that are in-coverage and out-of-coverage or have different recognized neighboring synchronization sources.
Innovation Solution
A method and device for selecting multiple synchronization sources based on a sidelink synchronization priority, where UEs maintain multiple synchronization timings and select additional sources with a time gap greater than a threshold, allowing efficient communication by configuring separate PSFCH regions for different synchronization timings in the time, frequency, and code domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a UE selects a single synchronization source based on pre-configured priority rules, then the synchronization selection is simple and deterministic, but communication may fail when UEs have different synchronization timings due to different in-coverage/out-of-coverage status or different recognized neighboring sources
Solution Approach 1:
The patent segments the synchronization source selection into multiple independent candidates (first synchronization source and second synchronization source) with different timing characteristics. Instead of selecting a single synchronization source, the UE maintains multiple candidates and selects appropriate SSB transmission timings based on each candidate's timing, thereby ensuring communication reliability across different coverage scenarios while managing complexity through structured segmentation.
Solution Approach 2:
The patent introduces dynamic adaptability by allowing the UE to flexibly switch between different synchronization source candidates based on current communication needs and conditions. The UE can dynamically adjust which synchronization candidate to use for SSB transmission depending on the target UE's likely synchronization source, transforming a static single-source selection into a dynamic multi-candidate system that adapts to varying network conditions.
2Adaptability or versatility
If UEs use different synchronization timings based on their coverage status and recognized sources, then each UE optimizes for its local conditions, but sidelink communication between UEs with different timings becomes impossible
Solution Approach 1:
The patent resolves the timing conflict by introducing an additional dimension - multiple SSB transmission timings corresponding to different synchronization source candidates. Instead of forcing all UEs to use a single timing, the system allows SSB transmissions at multiple distinct timings, each aligned with a different synchronization source. This dimensional expansion enables UEs with different synchronization timings to successfully communicate by matching their respective timing preferences.
3Ease of operation
If a UE transmits SSB based on a single synchronization timing, then the transmission is simple and consistent, but it cannot effectively communicate with UEs that have different synchronization timings
Solution Approach 1:
The patent makes the SSB transmission system universal by enabling it to function with multiple synchronization timing references. The UE is configured to determine multiple SSB transmission timings based on different synchronization source candidates, allowing the same SSB transmission mechanism to effectively reach UEs regardless of which synchronization source they are using. This multi-functionality ensures broad compatibility and reliable communication establishment across diverse synchronization scenarios.
Data Source
AI summary
A method by which a first apparatus performs wireless communication is proposed. The method may comprise the steps of: selecting a first synchronization source, on the basis of a sidelink synchronization priority; obtaining a first synchronization, on the basis of the first synchronization source; receiving a plurality of synchronization signals from a plurality of synchronization sources; obtaining a plurality of synchronizations, on the basis of the plurality of synchronization signals; selecting a second synchronization source from among the plurality of synchronization sources, on the basis of a gap between a time related to the first synchronization and a time related to a second synchronization being greater than or equal to a threshold value, wherein the second synchronization is obtained on the basis of the second synchronization source; and transmitting, to a second apparatus, a sidelink-synchronization signal block (S-SSB), on the basis of the first synchronization or the second synchronization. For example, the first synchronization source and the second synchronization source may comprise at least one of a global navigation satellite system (GNSS), a base station, or user equipment. For example, the S-SSB may comprise a sidelink primary synchronization signal (S-PSS), a sidelink secondary synchronization signal (S-SSS), and a physical sidelink broadcast channel (PSBCH).