D2D Reference Signal Mapping for Synchronization
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Solution Overview
Problem
In device-to-device (D2D) communication, synchronization mismatch between user equipment performing cellular network communication and those performing D2D communication can cause interference, and establishing fine synchronization between D2D user equipment is challenging due to hardware limitations and mobility issues.
Innovation Solution
A method involving the transmission of a reference signal by one D2D user equipment to another, mapped to a predetermined symbol in a resource allocated for D2D communication, to acquire synchronization, which can be used for channel estimation and synchronization correction, potentially using a demodulation reference signal (DMRS) across a full or partial frequency band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If D2D communication shares resources with cellular network, then resource utilization is improved, but synchronization mismatch and interference between D2D and cellular users occurs
Solution Approach 1:
The patent segments the resource allocation by establishing dedicated D2D communication resources separate from cellular network resources. The eNodeB allocates specific time-frequency resources for D2D pairs, isolating them from cellular user resources to prevent interference while maintaining efficient resource utilization.
Solution Approach 2:
The patent introduces the eNodeB as an intermediary that coordinates between D2D users and the cellular network. The eNodeB receives synchronization information from the serving cell and transmits it to D2D user equipment, acting as a mediator to ensure proper synchronization without requiring direct D2D-to-D2D synchronization signaling.
2Productivity
If D2D communication is performed directly between user equipment without base station, then communication efficiency is improved, but synchronization establishment becomes challenging due to hardware limitations and mobility
Solution Approach 1:
The patent uses the eNodeB as an intermediary to simplify synchronization establishment. Instead of D2D users directly establishing synchronization with each other (which would be complex), the eNodeB receives synchronization information from the serving cell and distributes it to D2D users, significantly reducing the complexity of synchronization establishment.
Solution Approach 2:
The patent enables D2D users to automatically utilize existing cellular network synchronization resources without requiring additional synchronization signaling between themselves. The D2D users leverage the already-established synchronization of the cellular network through the eNodeB, making the system self-sufficient in terms of synchronization.
3Measurement precision
If reference signal is mapped to predetermined symbol in allocated resource, then synchronization accuracy is improved, but resource allocation flexibility is reduced
Solution Approach 1:
The patent applies preliminary action by pre-configuring the reference signal mapping pattern in the resource allocation. The eNodeB indicates in advance which symbols within the allocated resources will be used for reference signals, allowing D2D users to prepare their receivers accordingly while maintaining flexibility in the overall resource allocation.
Data Source
AI summary
In the present invention, disclosed are a method for transceiving a reference signal in a wireless access system supporting device-to-device communication, and apparatus for same. More particularly, comprised are the steps of: a first device transmitting the reference signal for aligning device-to-device synchronization with a second device; and the first device performing device-to-device communication with the second device performing device-to-device synchronization with the second device after obtaining synchronization with the second device, wherein the reference signal is mapped on a predetermined symbol inside a resource that is allocated for device-to-device communication with the second device.