D2D Initial Access via Base Station Mediated Synchronization
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Solution Overview
Problem
In Device-to-Device (D2D) communication, existing methods struggle to establish initial access between mobile stations without a base station, as they rely on synchronization signals and response signals that are not directly applicable between mobile stations.
Innovation Solution
A radio communication method where a first mobile station transmits a synchronization-use signal to a second mobile station based on control information from its connected cell, and the second mobile station determines transmission power and timing for a response signal, enabling direct communication between the two mobile stations without a base station.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing base station synchronization methods are applied to D2D communication, then initial access establishment between mobile stations becomes possible, but the method cannot be directly applied due to lack of base station involvement
Solution Approach 1:
The base station acts as an intermediary by providing control information (synchronization sequence index, cyclic shift, radex) that enables mobile stations to perform synchronization without direct base station involvement in the actual D2D communication. This mediator approach allows the adaptation of base station-based synchronization methods to D2D scenarios.
Solution Approach 2:
The mobile station copies the synchronization sequence from the base station using the provided control information (sequence index, cyclic shift, radex) and transmits it as a synchronization signal to other mobile stations. This copying mechanism enables replication of base station synchronization functionality in peer-to-peer communication.
2Productivity
If mobile stations perform direct communication without base station, then cellular traffic is offloaded, but initial access establishment becomes difficult
Solution Approach 1:
The base station performs preliminary action by providing control information containing synchronization parameters (sequence index, cyclic shift, radex) before the mobile stations engage in direct communication. This preliminary configuration enables seamless initial access establishment without requiring base station involvement during the actual D2D communication setup.
3Measurement precision
If synchronization signal is transmitted between mobile stations, then timing synchronization is achieved, but transmission power and timing determination becomes complex
Solution Approach 1:
The receiving mobile station provides feedback by measuring the received synchronization signal and determining the appropriate transmission power and timing for its response signal. This feedback mechanism enables automatic adjustment of transmission parameters based on actual signal conditions, simplifying the determination process while maintaining synchronization accuracy.
Data Source
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AI summary
Provided are a radio communication method, a radio communication system, and a mobile station, by which it is possible to easily establish initial access between mobile stations in D2D 5 communication. A mobile station 200A transmits a synchronization-use signal to be used for establishment of initial access with a mobile station 200B toward the mobile station 200B on the basis of control information received from a cell to which the mobile station 200Ais connected. The mobile station 200B receives 10 the synchronization-use signal on the basis of the control information received from the cell. Moreover, the mobile station 200B determines transmission power and a transmission timing of a response signal on the basis of the received synchronization-use signal, and transmits the response signal toward the mobile station 200A. The mobile station 15 200A and the mobile station 200B start D2D communication on the basis of the synchronization-use signal and the response signal.