D2D User Apparatus Synchronization via External Sources
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Solution Overview
Problem
In D2D communications, user apparatuses outside coverage areas face challenges in maintaining synchronization accuracy due to the lack of defined techniques for using external synchronization sources other than D2D synchronization signals.
Innovation Solution
A user apparatus equipped with a receiver for external synchronization sources, such as GPS signals, and a synchronization processor that prioritizes radio frame and frequency synchronization using signals from a base station or other user apparatuses, allowing for enhanced synchronization accuracy by switching between multiple synchronization sources based on priority information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If D2D synchronization signals are used for synchronization, then synchronization can be maintained within coverage areas, but synchronization accuracy degrades when user apparatuses are located outside coverage areas
Solution Approach 1:
The user apparatus is designed to support multiple synchronization sources (external synchronization sources like GPS and internal D2D synchronization signals) to perform synchronization functions. This multi-functionality allows the apparatus to operate effectively both within and outside coverage areas, resolving the contradiction between maintaining synchronization reliability and adapting to different coverage conditions.
Solution Approach 2:
External synchronization sources serve as an intermediary mechanism that provides a common reference for multiple user apparatuses outside coverage areas. By using this external reference, the apparatuses can achieve accurate synchronization without relying on base station infrastructure, thus resolving the coverage area limitation while maintaining synchronization accuracy.
2Reliability
If multiple synchronization sources are supported, then synchronization accuracy is enhanced both inside and outside coverage areas, but device complexity increases
Solution Approach 1:
The synchronization apparatus dynamically selects and switches between different synchronization sources based on current operational conditions (within or outside coverage areas). This dynamic adaptation allows the system to maintain high synchronization accuracy by using the most appropriate source for the current context, while avoiding the need to permanently maintain complex multi-source synchronization capabilities in all operating modes.
Data Source
AI summary
There is provided a user apparatus of a radio communication system supporting D2D communication, the user apparatus including a receiver configured to receive a signal of an external synchronization source, a synchronization signal transmitted from a base station, or a synchronization signal transmitted from another user apparatus; and a synchronization processor configured to execute, in accordance with priority information indicating priority order of signals used for synchronization, radio frame synchronization and frequency synchronization using any one of the signal of the external synchronization source, the synchronization signal transmitted from the base station, or the synchronization signal transmitted from the other user apparatus, which is received by the receiver.