D2D Synchronization Using Base Station Configured Uplink Signals
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Solution Overview
Problem
Existing device-to-device (D2D) communication systems face challenges in achieving accurate synchronization between devices, especially in scenarios where devices are out of coverage or in partial coverage areas, leading to interference and suboptimal communication performance.
Innovation Solution
The proposed solution involves using an uplink (UL) synchronization signal for D2D communication, where a base station configures a UE in an RRC_CONNECTED state to act as a synchronization source and transmit a device-to-device synchronization signal (D2DSS) using a designated synchronization resource, which can include time, frequency, or time-frequency resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If devices use traditional downlink synchronization signals for D2D communication, then synchronization can be maintained in full coverage areas, but synchronization accuracy deteriorates in out-of-coverage or partial coverage areas
Solution Approach 1:
The patent introduces an uplink synchronization signal as an intermediary mechanism between devices for direct synchronization. Instead of relying solely on the base station's downlink signals, devices transmit and detect uplink synchronization signals to each other, enabling accurate synchronization even when out of base station coverage. This intermediary approach resolves the contradiction by providing an alternative synchronization path that works independently of base station coverage.
Solution Approach 2:
The patent inverts the traditional synchronization approach by using uplink signals (device-to-device transmission) instead of downlink signals (base station-to-device transmission) for synchronization. This inversion allows devices to synchronize directly with each other using their own transmitted signals, eliminating the dependency on base station coverage and improving synchronization accuracy in out-of-coverage scenarios.
2Measurement precision
If devices transmit synchronization signals continuously to maintain synchronization accuracy, then synchronization precision is improved, but energy consumption increases
Solution Approach 1:
The patent implements periodic transmission of uplink synchronization signals instead of continuous transmission. Devices transmit synchronization signals at specific intervals and detect them during designated time windows, achieving effective synchronization while reducing energy consumption compared to continuous transmission. This periodic approach resolves the contradiction by maintaining synchronization precision through regular updates without the excessive energy cost of continuous signaling.
3Area of stationary object
If multiple devices transmit synchronization signals simultaneously to provide coverage, then synchronization coverage is improved, but interference between devices increases
Solution Approach 1:
The patent segments the synchronization resource space into distinct time-frequency resources for different devices. By allocating specific time windows and frequency resources to different transmitting devices, the system enables multiple devices to provide synchronization coverage simultaneously without causing mutual interference. This segmentation resolves the contradiction by expanding coverage through multiple transmitters while preventing interference through resource isolation.
Data Source
AI summary
A method and system for including a base station that configures a first user equipment (UE) that is in a radio resource control connected state with the base station. The UE is configured to be a synchronization source and transmit a first device-to-device synchronization signal (D2DSS) by using a synchronization resource that comprises a time resource, a frequency resource or a time and frequency resource. The base station instructs the first UE to transmit the first D2DSS using the synchronization resource. The base station signals the UE to configure the UE separately from the signal to transmit the D2DSS, and both of the signals are performed with radio resource control signaling from the base station to the UE.