D2D Synchronization Signal Transmission in RRC Connected State
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Solution Overview
Problem
In device-to-device (D2D) operations within wireless communication systems, the transmission of synchronization signals is disrupted when a terminal transitions from an RRC idle state to a connected state, causing synchronization issues for other terminals relying on these signals.
Innovation Solution
A method where a user equipment (UE) continues to transmit a D2D synchronization signal in the RRC connected state if a specific condition, such as a low RSRP threshold, is met, and includes receiving a one-bit indicator allowing continued transmission or until a setting to disable it is received from the network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal stops transmitting D2D synchronization signal after entering RRC connected state, then the terminal follows conventional control procedures, but synchronization is disrupted for other terminals relying on the D2DSS
Solution Approach 1:
The patent applies dynamics by making the D2DSS transmission state changeable based on RRC state transitions. The terminal dynamically adjusts its transmission behavior: in RRC idle state, it transmits D2DSS autonomously; upon entering RRC connected state, it transitions to a controlled state where transmission continues only if explicitly permitted by network configuration, thus adapting to different operational contexts while maintaining synchronization reliability.
Solution Approach 2:
The patent implements feedback mechanisms through network control messages that indicate whether D2DSS transmission should continue in RRC connected state. The network provides feedback configuration to the terminal, and the terminal adjusts its transmission behavior based on this feedback, ensuring that synchronization continuity is maintained when beneficial while allowing network control when needed.
2Duration of action of stationary object
If the terminal continues transmitting D2D synchronization signal in RRC connected state, then synchronization continuity is maintained, but transmission control complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the terminal with network control indications before it enters RRC connected state. The network provides configuration information in advance that specifies whether D2DSS transmission should continue, allowing the terminal to maintain synchronization continuity without complex real-time decision-making, thus reducing operational complexity while ensuring continuous transmission when needed.
3Reliability
If the terminal transmits D2D synchronization signal autonomously in RRC idle state, then D2D operation synchronization is established, but transmission may be interrupted upon state transition
Solution Approach 1:
The patent applies beforehand cushioning by preparing the terminal with network control configuration before the RRC state transition completes. This preliminary configuration acts as a cushion that prevents abrupt transmission interruption, ensuring that if the network determines continuous transmission is beneficial, the terminal is already authorized to continue, thus smoothing the transition and maintaining synchronization continuity.
Data Source
AI summary
Provided are a method for transmitting, by a terminal, a synchronization signal for a device-to-device (D2D) operation in a wireless communication system, and a terminal using the method. The method comprises the steps of: transmitting a synchronization signal for a D2D operation (D2D synchronization signal: D2DSS) in an RRC (radio resource control) idle state; entering an RRC connected state; and transmitting the D2DSS even after entering the RRC connected state if a certain condition is met.