Unlicensed Carrier CSI Measurement via Dynamic Feedback
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Solution Overview
Problem
The existing LTE system faces challenges in measuring Channel State Information (CSI) on unlicensed carriers due to the Listen Before Talk (LBT) mechanism, leading to failures in PUSCH transmission due to channel contention.
Innovation Solution
A method and device where a base station notifies a terminal to feedback CSI measurement results of a carrier set, including unlicensed carriers, using Physical Downlink Control Channel (PDCCH) or high-layer RRC signaling, with specific indication information to manage CSI measurement and feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LBT mechanism is used on unlicensed carriers, then channel access control is improved, but CSI measurement reliability deteriorates due to channel contention failures
Solution Approach 1:
The patent segments the carrier set into multiple subsets, where each subset contains carriers with similar LBT conditions or characteristics. This allows the terminal to perform CSI measurement on individual subsets independently, so that failure on one subset does not affect measurement on other subsets, thereby improving overall CSI measurement reliability in the presence of LBT mechanism
Solution Approach 2:
The patent changes the parameter of carrier indication by introducing a subset indicator that points to different carrier subsets. This allows dynamic selection of which carrier subset to measure based on LBT conditions, enabling the system to adapt to changing channel environments and maintain reliable CSI measurement despite channel contention
2Adaptability or versatility
If periodic CSI feedback mechanism is used, then feedback regularity is improved, but adaptability to LBT mechanism deteriorates due to fixed subframe requirements
Solution Approach 1:
The patent transforms the static periodic feedback mechanism into a dynamic one by introducing trigger-based feedback. The terminal performs CSI measurement and feedback only when triggered by the network side, allowing flexible timing that adapts to LBT outcomes. This dynamic approach maintains feedback regularity through scheduled triggering while adapting to the uncertain nature of LBT-based channel access
3Productivity
If nonperiodic CSI feedback is triggered by DCI format 0/4, then feedback flexibility is improved, but measurement coverage deteriorates when PUSCH transmission fails
Solution Approach 1:
The patent segments the carrier set into multiple subsets and associates each subset with different PUSCH resources or alternative feedback paths. When PUSCH transmission fails on one subset, the terminal can still provide CSI feedback for other subsets or use alternative resources, thereby maintaining measurement coverage and improving feedback efficiency simultaneously
Data Source
AI summary
Disclosed are a channel state information measuring method and apparatus. The method includes: a base station informs a terminal to feed back a channel state information (CSI) measuring result of a carrier set, wherein the carrier set comprises an unlicensed carrier; and the base station receives the CSI measuring result, fed back by the terminal, of the carrier set.