Sidelink Absolute Time Distribution for Out-of-Coverage UE Sync
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Solution Overview
Problem
Existing wireless communication systems lack efficient mechanisms for distributing absolute time information over sidelink communications, particularly for UEs outside network coverage areas.
Innovation Solution
The system employs sidelink messages and medium access control (MAC) control elements to distribute absolute time information between UEs, using PC5 radio resource control (RRC) signaling or MAC control elements (MAC-CEs), with reference to global standards like UTC or GPS time, and supports request-response or unilateral time distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If sidelink communication is used for time distribution, then UEs outside network coverage can achieve time synchronization, but the system lacks established mechanisms for absolute time distribution over sidelink
Solution Approach 1:
The patent introduces sidelink messages as an intermediary mechanism to transfer absolute time information between UEs. The time distribution is achieved through MAC-CEs or RRC signaling carried over the sidelink interface, enabling UEs to act as time sources for other UEs without requiring direct network coverage.
Solution Approach 2:
The patent copies the absolute time information from the source UE to target UEs through standardized message formats. The time information is extracted from the source UE's clock and replicated in sidelink messages with appropriate timing references, allowing accurate time distribution across the sidelink interface.
2Measurement precision
If absolute time information is distributed through sidelink messages, then time synchronization accuracy is improved, but the complexity of message formatting and processing increases
Solution Approach 1:
The patent segments the time distribution function into standardized message formats (MAC-CEs and RRC messages) with defined information elements. The absolute time information is structured with specific fields for time values, timing references, and validity indicators, making processing systematic and reducing implementation complexity.
Solution Approach 2:
The patent creates universal message formats that can carry absolute time information through multiple interfaces (MAC-CE and RRC). These standardized formats can be used for different time distribution scenarios, reducing the need for multiple specialized message types and simplifying overall system complexity.
3Adaptability or versatility
If time distribution is performed unilaterally or through request-response signaling, then flexibility in time distribution is improved, but the signaling overhead and processing delay increase
Solution Approach 1:
The patent enables unilateral time distribution where the source UE can proactively send absolute time information without waiting for requests. This preliminary action allows target UEs to receive time synchronization information immediately when needed, reducing delays compared to purely request-response mechanisms.
Solution Approach 2:
The patent supports periodic time distribution where source UEs can send absolute time information at regular intervals. This periodic action ensures continuous time synchronization without requiring constant request-response exchanges, reducing overall signaling overhead while maintaining synchronization accuracy.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A wireless communications system may establish sidelink messages and information elements (IEs) that may be used to distribute absolute time information from a first user equipment (UE) to a second UE. Participating UEs (e.g., the first UE or the second UE) may be mobile or stationary (e.g., a roadside unit (RSU) ). The first UE may provide an absolute time to the second UE with ten nanosecond resolution, and the absolute time may be referenced to a global standard (e.g., universal time coordinated (UTC) time or global positioning system (GPS) time). Time messages may be exchanged (e.g., between the leapSeconds first UE and the second UE) using PC5 radio resource control (RRC) signaling or medium access control (MAC) control elements (MAC-CEs). Time distribution may be based on a request-response signaling or unilaterally provided by a participating UE (e.g., the first UE).