D2D Terminal Synchronization Reference Selection
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Solution Overview
Problem
Existing D2D communication methods inaccurately select synchronization reference devices when a UE moves from in-coverage to out-of-coverage, as they fail to consider the duration of disconnection from the synchronization source, leading to inconsistent clock synchronization and improper communication.
Innovation Solution
A method where a UE, upon leaving the coverage of a synchronization source, determines its target timing by either using its own clock if the disconnection is short or selecting a synchronization reference device based on priority if a higher-priority device is found, ensuring accurate synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a UE selects a synchronization reference device based only on priority when moving from in-coverage to out-of-coverage, then the selection process is simple, but the synchronization accuracy deteriorates
Solution Approach 1:
The patent changes the selection parameters from only priority-based to a composite evaluation that includes disconnection duration, priority, and coverage status. This allows the system to maintain simple operation while improving synchronization accuracy by considering multiple factors in the selection process.
Solution Approach 2:
The patent introduces dynamic adjustment of synchronization reference selection based on the UE's current coverage status and disconnection duration. The selection criteria adapt dynamically according to whether the UE is in-coverage or out-of-coverage and how long it has been disconnected, thereby improving accuracy without overly complicating the operation.
2Ease of operation
If a UE uses its own clock when out of coverage, then the operation is simple, but the synchronization reliability deteriorates
Solution Approach 1:
The patent introduces an intermediary evaluation mechanism that assesses whether the UE's own clock can be used or if external synchronization references should be selected. This intermediary layer (the disconnection duration threshold and priority evaluation) maintains operational simplicity while improving reliability by making informed decisions about clock usage.
Solution Approach 2:
The patent performs preliminary evaluation of disconnection duration and available synchronization references before the UE actually uses its own clock or selects a reference device. This preliminary action ensures that the most reliable synchronization method is chosen in advance, balancing simplicity and reliability.
3Device complexity
If a UE considers only adjacent UEs for synchronization reference when out of coverage, then the device complexity is low, but the synchronization precision deteriorates
Solution Approach 1:
The patent makes the synchronization reference selection system universal by allowing it to evaluate both in-coverage and out-of-coverage devices, not just adjacent UEs. The selection mechanism can universally apply priority-based evaluation across different coverage scenarios, improving precision without significantly increasing device complexity.
Solution Approach 2:
The patent changes the selection parameters from limited adjacent-UE evaluation to a broader evaluation that includes disconnection duration, coverage status, and priority levels. This parameter expansion improves timing synchronization precision while keeping the device complexity manageable through systematic evaluation criteria.
Data Source
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AI summary
Embodiments of the present invention provide a device-to-device D2D communication method and a D2D terminal device. The method includes: determining, by a first device, a time the first device is out of coverage of a synchronization source after leaving the coverage of the synchronization source; determining, by the first device, target timing based on the time; and performing, by the first device, D2D communication based on the target timing. In the embodiments of the present invention, the target timing can be selected more accurately for the first device.