Wideband CSI Reporting in Unlicensed Band LBT Sub-bands
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Solution Overview
Problem
Current methods for reporting channel state information in unlicensed bands are inefficient, particularly in Listen Before Talk (LBT) sub-bands, where the transmission of channel state information-reference signals (CSI-RS) is not effectively managed, leading to suboptimal communication performance.
Innovation Solution
A method and device for reporting wideband channel state information (CSI) by receiving CSI-RS through multiple LBT sub-bands, measuring CSIs, and generating a wideband CSI for all sub-bands, which can be reported to a base station, even skipping CSI-RS transmission in sub-bands with high probability of skipping, to optimize communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If CSI-RS transmission is performed in all LBT sub-bands, then channel state information can be obtained for the entire bandwidth, but transmission time and energy consumption increase
Solution Approach 1:
The bandwidth is divided into multiple LBT sub-bands, and CSI-RS transmission is performed selectively in sub-bands where LBT succeeds. This segmentation allows the system to obtain channel state information for the most relevant frequency portions without attempting to transmit across the entire bandwidth, thereby reducing overall transmission time while maintaining measurement precision for the active sub-bands.
Solution Approach 2:
Instead of attempting to transmit CSI-RS in all sub-bands (excessive action), the system performs partial action by only transmitting in sub-bands where LBT indicates the channel is available. This partial approach reduces transmission time and energy consumption while still providing sufficient channel state information for effective communication in the active sub-bands.
2Loss of time
If CSI-RS transmission is skipped in LBT sub-bands, then transmission time is reduced, but channel state information becomes incomplete
Solution Approach 1:
The system applies different transmission strategies to different LBT sub-bands based on their individual channel conditions and LBT outcomes. For sub-bands where LBT succeeds, CSI-RS is transmitted to obtain complete channel state information. For sub-bands where LBT fails, transmission is skipped. This local differentiation ensures that time is not wasted on inaccessible sub-bands while maintaining information completeness for the sub-bands that are actually accessible.
Solution Approach 2:
The system dynamically changes the transmission parameter (CSI-RS transmission) based on the LBT outcome parameter. When LBT indicates the channel is available, transmission occurs; when LBT indicates the channel is occupied, transmission is skipped. This parameter change strategy optimizes the balance between transmission time and information completeness by adapting to real-time channel conditions.
3Reliability
If wideband CSI is generated from multiple LBT sub-bands, then communication performance is improved, but processing complexity increases
Solution Approach 1:
The CSI processing is segmented by handling each LBT sub-band independently, measuring CSI for each sub-band where LBT succeeds, and then combining the results to generate wideband CSI. This segmentation approach reduces the complexity of processing each individual sub-band while still achieving comprehensive wideband coverage, making the overall process more manageable and efficient.
Solution Approach 2:
The system merges the CSI measurements from multiple LBT sub-bands to generate a comprehensive wideband CSI. By combining the results from the individual sub-bands, the system achieves improved communication performance that reflects the overall channel conditions across the entire bandwidth, while the merging process is performed efficiently by leveraging the structured data from the segmented measurements.
Data Source
AI summary
Disclosed is a method for a terminal to report channel state information (CSI) in an unlicensed band. In particular, this disclosure includes: receiving a channel state information-reference signal (CSI-RS) through at least one listen before talk (LBT) sub-band among a plurality of LBT sub-bands; measuring a plurality of pieces of CSI for each of the plurality of LBT sub-bands; generating wideband CSI for all of the plurality of LBT sub-bands on the basis of the plurality of pieces of CSI; and reporting the generated wideband CSI to a base station.