Sidelink Synchronization Reference Signal for Connected UEs
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Solution Overview
Problem
Conventional sidelink synchronization procedures in wireless communications systems are inefficient and result in unreliable synchronization due to the infrequent updating of transmit and receive beam pairs, leading to outdated time and frequency synchronization between user equipment (UEs), especially when network conditions change or UEs move.
Innovation Solution
Implementing a method where UEs perform a beam sweep procedure to identify optimal beams for sidelink communication, and then use sidelink synchronization reference signals transmitted periodically or semi-persistently to maintain time and frequency synchronization, allowing for more frequent updates and reduced resource usage compared to synchronization signal blocks (SSBs).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional synchronization procedures are used, then resource utilization is simplified, but synchronization reliability deteriorates due to infrequent beam pair updates
Solution Approach 1:
The patent introduces dynamic synchronization reference signals that can be transmitted periodically or on-demand, allowing the synchronization mechanism to adapt to changing network conditions and UE movements. This dynamic approach enables more frequent synchronization updates without requiring continuous beam sweeping, thereby improving reliability while optimizing resource usage.
Solution Approach 2:
The patent changes the transmission parameters of synchronization signals by introducing a new type of reference signal with flexible periodicity and timing characteristics. This allows the system to adjust synchronization update frequency based on actual needs, resolving the contradiction between reliable synchronization and efficient resource utilization.
2Reliability
If beam sweeping is performed frequently to maintain synchronization, then synchronization reliability improves, but device complexity and resource consumption increase
Solution Approach 1:
The patent extracts the essential synchronization function from the complex beam sweeping procedure. By introducing dedicated synchronization reference signals that can be transmitted using established beam pairs, the system separates synchronization tasks from beam management tasks, reducing overall procedure complexity while maintaining reliability.
Solution Approach 2:
The patent performs preliminary beam pair establishment during the connection setup phase, and then uses pre-configured reference signals for subsequent synchronization. This preliminary action avoids the need for repeated beam sweeping during normal operation, reducing complexity while ensuring reliable synchronization.
3Measurement precision
If synchronization reference signals are transmitted frequently, then time and frequency synchronization accuracy improves, but signaling overhead increases
Solution Approach 1:
The patent employs periodic transmission of synchronization reference signals with adjustable periods, allowing the system to balance synchronization accuracy with overhead reduction. The periodicity can be adapted based on UE mobility and network conditions, providing precise synchronization when needed while minimizing unnecessary transmissions.
Solution Approach 2:
The synchronization reference signals utilize the existing beam pairs and transmission resources already established for sidelink communication. This self-service approach allows frequent synchronization updates without requiring additional dedicated resources, as the system leverages its own existing infrastructure for synchronization purposes.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. Sidelink UEs may be configured with a synchronization reference signal that may be used by the UEs to synchronize time and frequency resources. A first and second UE may perform a beam sweeping procedure to identify transmit and receive beams to use for communications between the UEs. A synchronization reference signal procedure may be initiated and the first UE may receive a sidelink synchronization reference signal from the second UE using the established receive beam. The UEs may align time and frequency resources for communications between the UEs and the UEs may communicate via the sidelink channel based on the time synchronization, frequency synchronization, or both, determined using the sidelink synchronization signal. In some cases, a sidelink UE may receive multiple synchronization reference signals from multiple sidelink UEs simultaneously, where each synchronization reference signal may include a UE identifier.