D2D Synchronization via Hop Count and Reference Selection
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Solution Overview
Problem
In device-to-device (D2D) communication, existing synchronization mechanisms, such as those used in LTE systems, are not suitable for distributed networks as they rely on a single base station, leading to instability in time and frequency synchronization among devices, making it difficult for devices to establish communication without a network infrastructure.
Innovation Solution
A device synchronization method that involves receiving and processing D2D synchronization information, including a synchronization source identifier and a forwarding hop count, to synchronize with a corresponding synchronization source and update the forwarding hop count when it falls below a threshold, allowing for the transmission of updated synchronization information to facilitate synchronization between devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If each UE randomly transmits a synchronization signal in D2D communication, then devices can initiate communication without network infrastructure, but receiver UE will be unable to determine a synchronization reference and communication cannot be established
Solution Approach 1:
The patent introduces a synchronization reference device (which can be a UE or base station) that acts as an intermediary to provide stable time and frequency references. This mediator device transmits synchronization signals that other UEs can reliably use for synchronization, solving the problem of unable to determine synchronization reference while maintaining the ability to communicate without network infrastructure.
Solution Approach 2:
The patent implements preliminary synchronization actions where UEs first acquire synchronization signals from a reference device before establishing actual communication. The synchronization process includes preliminary steps of detecting synchronization signals, determining time and frequency offsets, and aligning transmission timing before data communication begins, ensuring reliable synchronization reference determination.
2Adaptability or versatility
If UEs use different time and frequency references in D2D communication, then devices can operate independently, but stability of time and frequency of user equipment is poorer than that of a base station
Solution Approach 1:
The patent merges the independent operation capability with centralized synchronization by having UEs combine their local oscillators with references from a designated synchronization reference device. Multiple UEs merge their synchronization efforts by selecting a common reference device, achieving both independent operation (choosing their own reference) and improved stability (using a dedicated reference source).
Solution Approach 2:
The patent applies local quality by allowing different UEs to have different synchronization reference devices based on their local conditions (coverage, signal quality), while each UE optimizes its local time and frequency stability through careful selection and tracking of its designated reference. This enables independent operation with locally optimized stability.
3Adaptability or versatility
If multiple UEs transmit synchronization signals in D2D scenario, then distributed network structure is formed, but LTE two-step synchronization mechanism does not suit such distributed network structure
Solution Approach 1:
The patent inverts the traditional LTE approach by instead of having a single base station transmit synchronization signals to all UEs, it allows multiple UEs to potentially become synchronization reference devices. The inversion is that ordinary UEs can be elevated to reference device status, and the synchronization mechanism works backwards from multiple potential sources rather than from a single centralized source, simplifying the distributed structure.
Solution Approach 2:
The patent makes the synchronization mechanism universal by designing it to work in both centralized (base station as reference) and distributed (UE as reference) modes. The same synchronization signal structure and processing methods are used regardless of whether the reference is a base station or a UE, allowing the system to adapt to different network configurations without requiring separate mechanisms.
4Area of stationary object
If forwarding hop count is not controlled in D2D synchronization, then synchronization information can propagate widely, but communication complexity increases
Solution Approach 1:
The patent implements dynamic hop count management where the maximum forwarding hop count is not fixed but can be adjusted based on network conditions, device capabilities, and synchronization requirements. The system dynamically determines appropriate hop count limits to balance coverage area with complexity control, allowing flexible adaptation to different deployment scenarios.
Solution Approach 2:
The patent incorporates feedback mechanisms where UEs monitor synchronization signal quality, timing offset stability, and propagation delay as they increase hop count. When feedback indicates degradation or excessive complexity, the system adjusts the maximum hop count downward. This feedback-driven approach ensures that synchronization coverage expands only as far as complexity and quality thresholds allow.
Data Source
AI summary
A device synchronization method in D2D communication implements synchronization between devices. One such method includes receiving first device-to-device (D2D) synchronization information sent by a first device in a D2D communication, including a secondary D2D synchronization signal (SD2DSS). The method further includes determining a synchronization source identifier and a forwarding hop count according to preset correspondences between the SD2DSS and the synchronization source identifier and between the SD2DSS and the forwarding hop count. A synchronization source which corresponds to the synchronization source identifier is synchronized with. The forwarding hop count in the first D2D synchronization information is updated in response to determining that the forwarding hop count in the first D2D synchronization information is less than a set threshold, to obtain second D2D synchronization information, and the second D2D synchronization information is sent.