D2D Synchronization Signal Transmission Hierarchy
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Solution Overview
Problem
Current Device to Device (D2D) communication in wireless systems faces challenges in resource allocation and synchronization signal management, particularly in licensed bands, leading to inefficiencies and interference issues.
Innovation Solution
A method and apparatus for transmitting a synchronization signal in D2D communication systems, where user equipment (UE) receives and prioritizes synchronization signals from different sources, determining a root index and synchronization timing reference to efficiently manage synchronization and resource allocation, thereby enhancing D2D communication efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If D2D communication uses non-licensed band (Wi-Fi, Bluetooth), then device complexity and ease of operation are improved, but reliability and resistance to interference deteriorate
Solution Approach 1:
The patent introduces an eNodeB as an intermediary to manage and coordinate D2D communication resources in licensed bands. The eNodeB allocates synchronization signals, time-frequency resources, and manages interference coordination, thereby providing network-controlled reliability while maintaining D2D direct communication capabilities. This mediator resolves the contradiction by bringing licensed-band reliability to D2D communication.
2Adaptability or versatility
If multiple synchronization sources are used in D2D communication, then adaptability and coverage are improved, but synchronization precision and timing alignment deteriorate
Solution Approach 1:
The patent segments synchronization sources into hierarchical levels: Level 1 (eNodeB-based synchronization) and Level 2 (UE-based synchronization). UEs first attempt to synchronize with eNodeB (Level 1), and only when out of coverage do they become Level 2 synchronization sources for other UEs. This segmentation maintains synchronization precision by establishing a clear hierarchy while improving adaptability to different coverage scenarios.
Solution Approach 2:
The patent implements preliminary synchronization actions where UEs first try to acquire synchronization from eNodeB before attempting D2D communication. The system pre-establishes synchronization references and timing alignment through eNodeB before D2D data transmission begins, ensuring precision is maintained even when multiple sources are eventually used.
3Measurement precision
If synchronization signals are frequently transmitted to maintain accuracy, then synchronization precision is improved, but resource utilization efficiency and energy consumption worsen
Solution Approach 1:
The patent implements periodic synchronization signal transmission where UEs transmit synchronization signals at regular intervals rather than continuously. The synchronization period is configured based on channel conditions and mobility patterns, allowing the system to maintain acceptable synchronization precision while significantly reducing resource consumption compared to continuous transmission.
Solution Approach 2:
The patent applies partial action by transmitting synchronization signals only when necessary - such as when UEs enter out-of-coverage areas, experience synchronization failure, or based on configured periodic intervals. This avoids excessive synchronization transmissions during stable connected states, optimizing the balance between precision and resource efficiency.
Data Source
AI summary
Exemplary embodiments provide a method and apparatus for transmitting a synchronization signal for Device-to-Device (D2D) communication in a wireless communication system. With respect to a D2D synchronization source to transmit a synchronization signal for D2D communication, the method includes: generating a D2D Synchronization Signal (D2DSS); and transmitting, by a synchronization source, the D2DSS to a D2D reception (Rx) UE, wherein the D2DSS includes a Primary D2D Synchronization Signal (PD2DSS) generated based on information associated with the synchronization source.