Unlicensed Band Reference Signal Transmission via Dynamic Resource Selection
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Solution Overview
Problem
In communications systems using unlicensed frequency bands, the periodic transmission of reference signals is disrupted by the Listen-Before-Talk specification, leading to reduced opportunities for cell synchronization and channel state information measurement, which affects mobility performance of user equipment.
Innovation Solution
A method is introduced to determine a candidate resource set for transmitting reference signals, which includes a preset resource and flexible candidate resources, allowing for increased opportunities by translating the preset resource in time, thereby improving the success rate of signal transmission without affecting normal system communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base station performs clear channel assessment (CCA) before sending reference signals according to LBT specification, then the coexistence requirement in unlicensed spectrum is met, but the periodic transmission of reference signals is disrupted and transmission success rate decreases
Solution Approach 1:
The base station performs clear channel assessment (CCA) in advance before the scheduled reference signal transmission time. If the channel is found to be busy, the base station selects an alternative pre-configured time resource from multiple candidate resources. This preliminary channel check and proactive resource selection ensures that reference signals can be transmitted successfully while complying with LBT requirements.
Solution Approach 2:
The patent introduces multiple candidate time resources for reference signal transmission instead of a fixed periodic schedule. The base station dynamically selects from these candidate resources based on channel conditions detected through CCA. This dynamic resource selection adapts to the uncertain channel availability in unlicensed spectrum, maintaining transmission reliability while meeting coexistence requirements.
2Reliability
If the base station skips reference signal transmission when channel is busy, then LBT specification is followed, but cell synchronization and CSI measurement opportunities are reduced, affecting UE mobility performance
Solution Approach 1:
Multiple candidate time resources are pre-configured for reference signal transmission. When the primary scheduled resource is unavailable due to busy channel, the base station has alternative resources ready for immediate use. This preliminary preparation of alternative resources ensures that synchronization and measurement opportunities are maintained without delay, even when channel conditions require LBT compliance.
Solution Approach 2:
The system transitions from a static periodic reference signal transmission schedule to a dynamic selection mechanism among multiple candidate resources. The base station adaptively chooses transmission opportunities based on real-time channel assessments, ensuring that UE continuously receives reference signals for synchronization and measurement while complying with LBT requirements.
3Productivity
If multiple candidate resources are configured for reference signal transmission, then transmission opportunities increase and success rate improves, but system complexity increases
Solution Approach 1:
The patent divides the reference signal transmission resources into multiple discrete candidate time resources instead of using a single periodic schedule. Each candidate resource is independently configurable and can be selected based on channel conditions. This segmentation allows the system to increase transmission opportunities while managing complexity through modular resource configuration.
Solution Approach 2:
The system changes the parameter of resource availability by configuring multiple candidate time resources with different timing characteristics. This parameter change enables the base station to adapt to varying channel conditions and LBT outcomes, increasing transmission success rate while the resources themselves remain pre-configured to limit management complexity.
Data Source
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AI summary
The present invention discloses a method for transmitting a reference signal in a cell that uses an unlicensed frequency band and a device. The method includes: determining a candidate resource set that is used when a first reference signal is transmitted in the cell that uses the unlicensed frequency band, where the candidate resource set includes a preset resource and at least one flexible candidate resource; determining a first candidate resource that is used when the first reference signal is transmitted in the cell that uses the unlicensed frequency band, where a channel on the unlicensed frequency band corresponding to the first candidate resource is in an idle state, and the first candidate resource is the preset resource or a flexible candidate resource in the candidate resource set; and sending the first reference signal on the first candidate resource. According to embodiments of the present invention, a success rate of sending a reference signal can be improved.