Unlicensed Carrier Synchronization Reference Configuration
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Solution Overview
Problem
Current wireless communication systems face challenges in configuring synchronization references for time/frequency tracking in unlicensed carriers, particularly in 3GPP LTE systems, where efficient use of unlicensed spectrum like the 5GHz U-NII band is essential due to increasing data rate demands and coexistence with other radio access technologies.
Innovation Solution
A method and apparatus for user equipment (UE) to receive a configuration for a time/frequency tracking reference carrier, enabling time/frequency tracking in an unlicensed carrier, which involves receiving a reference signal from LTE-U eNBs and performing tracking based on this configuration, allowing for efficient operation in unlicensed bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If time/frequency tracking is performed in unlicensed carriers without configuration, then tracking functionality cannot be established, but system complexity and interference management become problematic
Solution Approach 1:
The patent applies preliminary action by configuring the time/frequency tracking reference carrier before actual tracking operations in unlicensed carriers. The network pre-configures which carrier (licensed or unlicensed) should be used as the reference for time and frequency synchronization, so that the UE has clear guidance on which signals to use for tracking without having to perform complex autonomous decisions during operation.
2Productivity
If unlicensed spectrum is utilized for higher data rates, then capacity increases, but coexistence interference with other radio access technologies worsens
Solution Approach 1:
The patent uses the configured time/frequency tracking reference carrier as an intermediary mechanism to enable coexistence. By allowing the network to configure whether a licensed or unlicensed carrier serves as the tracking reference, the system can mediate between LTE-U operations and other radio access technologies sharing the unlicensed band, reducing harmful interference through coordinated reference signal usage.
3Reliability
If synchronization reference configuration is implemented, then tracking reliability improves, but signaling overhead increases
Solution Approach 1:
The patent applies universality by using the existing carrier configuration signaling framework to convey time/frequency tracking reference information. Rather than introducing entirely new dedicated signaling messages, the solution leverages existing RRC signaling structures that can be repurposed to indicate which carrier should serve as the tracking reference, thereby reducing additional signaling overhead.
Data Source
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AI summary
A method and apparatus for performing time/frequency tracking in a wireless communication system is provided. A user equipment (UE) receives a configuration of a frequency or a carrier for a time/frequency tracking reference carrier, and performs time/frequency tracking in an unlicensed carrier based on the received configuration.