D2D Synchronization via UE Relay in Off-Base Station Coverage
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Solution Overview
Problem
In device-to-device (D2D) operations in wireless communication systems, synchronization between user equipment (UE) is challenging when one or both UE are outside the coverage of a base station, as they cannot receive the synchronization signal transmitted by the base station, which is essential for reliable D2D communication, particularly in public safety networks.
Innovation Solution
A method where UE detects a synchronization signal and reports it to another UE, enabling synchronization between UE, even when they are outside the coverage of a base station, by using an uplink channel and specific synchronization sequences, allowing for reliable D2D operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If D2D operation is performed between UE outside base station coverage, then direct communication reliability is improved, but synchronization capability deteriorates because base station synchronization signals cannot be received
Solution Approach 1:
The patent introduces an intermediary synchronization signal transmission mechanism where UE acts as a relay. Instead of directly receiving synchronization from the base station, UE outside coverage receives synchronization signals from other UE that have synchronization capability, thereby mediating the synchronization function in the absence of direct base station access
Solution Approach 2:
The patent extends the synchronization signal transmission from a single dimension (base station to UE) to multiple dimensions by enabling UE-to-UE synchronization signal transmission. This creates a multi-hop synchronization path that operates independently of direct base station coverage
2Measurement precision
If UE reports synchronization signal information to another UE, then synchronization accuracy between UE is improved, but communication complexity increases due to additional reporting procedures
Solution Approach 1:
The patent implements a feedback mechanism where UE reports synchronization signal detection information to other UE. This feedback loop enables receiving UE to adjust its synchronization based on reported information from transmitting UE, thereby improving synchronization accuracy through iterative refinement
Solution Approach 2:
The patent uses copying by having UE transmit copies of synchronization signal information to other UE. Instead of requiring direct base station signals, UE receives and forwards synchronization information copies, enabling synchronization propagation through the network of UE devices
Data Source
AI summary
Provided are a device-to-device (D2D) operation method performed by a terminal in a radio communication system and an apparatus using the method. The method detects a synchronization signal transmitted by a first network node and transmits a report for the detected synchronization signal to a second network node.