Out-of-Network D2D Synchronization via Discovery Signal Master Selection
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Solution Overview
Problem
Existing D2D communication systems face challenges in establishing efficient out-of-network device-to-device (D2D) communications, particularly in scenarios where devices are out of network coverage, requiring effective methods to determine a master controller for synchronization and resource allocation.
Innovation Solution
The proposed solution involves a method where user equipment (UE) receives a discovery signal, determines the transmitter, and synchronizes or transmits a second discovery signal to establish a timing reference for time synchronization between devices, with the ability to designate a timing master and resource master based on signal quality and network coverage status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If devices establish D2D communication out of network coverage, then communication autonomy is improved, but synchronization reliability deteriorates
Solution Approach 1:
The patent uses discovery signals as intermediaries to establish timing relationships between devices. When out of network coverage, devices cannot directly access network timing references, so they use transmitted and received discovery signals as mediator references to achieve mutual synchronization and maintain reliable communication autonomously.
Solution Approach 2:
The patent performs preliminary timing relationship establishment through discovery signal exchange before actual data communication. Devices exchange discovery signals to determine timing offsets and establish synchronization relationships in advance, ensuring that when out of network coverage, the synchronization foundation is already laid and communication can proceed reliably.
2Measurement precision
If devices transmit discovery signals frequently, then proximity discovery accuracy is improved, but energy consumption increases
Solution Approach 1:
The patent implements periodic transmission of discovery signals at predetermined intervals rather than continuous transmission. This periodic action allows devices to maintain proximity discovery accuracy by regularly exchanging timing information while significantly reducing energy consumption compared to continuous transmission.
Solution Approach 2:
The patent transmits discovery signals with sufficient frequency to achieve accurate timing offset determination, but not excessively frequent. The transmission frequency is optimized to provide just enough measurements for accurate proximity discovery and synchronization without wasting energy on redundant transmissions.
3Measurement precision
If devices synchronize to network timing reference, then time synchronization accuracy is improved, but device complexity increases
Solution Approach 1:
The patent extracts the essential timing reference information from network synchronization signals and uses only the necessary timing offset data for D2D communication. Instead of implementing full network synchronization protocols, devices extract and use only the timing reference elements needed for mutual synchronization, reducing device complexity while maintaining synchronization accuracy.
4Productivity
If devices establish master-slave relationship, then resource allocation efficiency is improved, but system complexity increases
Solution Approach 1:
The patent introduces asymmetric master-slave relationships where one device is designated as master and the other as slave for resource allocation purposes. This asymmetry simplifies resource management by creating clear roles: the master device determines timing and resource parameters, while the slave device follows these parameters. This role differentiation improves resource allocation efficiency while the standardized master-slave protocol keeps implementation complexity manageable.
Data Source
AI summary
Embodiments are provided herein for determining a synchronizing master for device-to-device (D2D) communication in a cellular network environment. In an embodiment, a user equipment (UE) receives a discovery signal comprising a timing reference, and determines a transmitter of the discovery signal. In accordance with the determination of the transmitter of the discovery signal, the UE performs one of synchronizing to the timing reference in the discovery signal and transmitting a second discovery signal. The UE performs the synchronizing to the timing reference if the transmitter of the discovery is a cellular network. Alternatively, the UE transmits the second discovery signal upon determining that the transmitter of the discovery signal is a second UE that is out of coverage of a cellular network.