User Terminal Short TTI Channel State Information Reporting Control
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Solution Overview
Problem
Existing LTE systems lack a method to control communication effectively when introducing short Transmission Time Intervals (TTIs) and processing time reductions, particularly in managing channel state information reporting triggers and transmissions.
Innovation Solution
Implementing a method where user terminals can transmit channel state information at an earlier timing than defined by existing systems, using short TTIs, and controlling signal transmission/reception in subframe or short TTI units to reduce processing latency and accommodate multiple CSI reports within a single subframe or short TTI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If short TTI and processing time reduction are introduced, then latency is reduced and productivity is improved, but communication control becomes more difficult and reliability deteriorates
Solution Approach 1:
The invention applies preliminary action by having the user terminal store multiple candidate uplink timing values in advance (e.g., first uplink timing, second uplink timing, third uplink timing) before actual communication occurs. When a downlink timing is received, the terminal can immediately select the appropriate uplink timing from pre-stored options without requiring complex real-time calculations, thus reducing latency while maintaining reliable communication control.
2Speed
If short TTI is introduced, then processing speed is improved, but the complexity of managing multiple CSI reports increases
Solution Approach 1:
The invention applies segmentation by dividing the CSI report management into distinct segments: each downlink timing is associated with specific uplink timing options, and each uplink timing can be linked to particular PUSCH resources. This structured segmentation allows the terminal to efficiently manage multiple CSI reports by following clear mapping relationships rather than handling all reports uniformly, reducing management complexity while maintaining high processing speed.
Solution Approach 2:
The terminal pre-configures multiple uplink timing values and their associated PUSCH resources before actual CSI reporting occurs. This preliminary setup creates a ready-to-use mapping table that simplifies real-time CSI report management, allowing the terminal to quickly select appropriate resources based on received downlink timing without complex real-time decision-making.
3Quantity of substance
If multiple CSI reports are transmitted per subframe, then information throughput is improved, but the difficulty of detecting and measuring appropriate transmission timing increases
Solution Approach 1:
The invention applies parameter changes by introducing multiple discrete uplink timing parameters (first uplink timing, second uplink timing, third uplink timing) that can be selectively applied based on downlink timing conditions. This parameter-based approach provides clear, distinguishable timing options for multiple CSI reports within a subframe, making it easier for the terminal to detect and measure the appropriate transmission timing for each report rather than dealing with continuous or ambiguous timing values.
Data Source
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Figure 3A~3B
AI summary
Communication is appropriately performed even when a short TTI and/or processing time reduction are introduced. A user terminal that communicates with a cell that uses at least a reduced TTI shorter than a period of a subframe includes: a reception section that receives from the cell a report request that triggers channel state information (CSI) reporting; and a control section that controls the CSI reporting in a subframe unit or a short TTI unit based on the report request.