S-TTI CSI Reference Resource Determination in Wireless Terminals
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Solution Overview
Problem
In wireless communication systems, particularly in D2D operating methods for UEs, there is a challenge in efficiently deriving and reporting S-TTI-based channel state information (CSI) due to the relatively short transmission time intervals, which affects the accuracy and flexibility of CSI reporting compared to legacy L-TTI-based systems.
Innovation Solution
The method involves determining CSI reference resources within S-TTI units and performing substantial measurements in L-TTI units, allowing for the use of recent interference samples and optimizing CSI reporting by configuring CSI reference resources and measurement resources based on S-TTI-specific desired signal and interference measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If S-TTI-based wireless communication is performed with short transmission time intervals, then communication speed and responsiveness are improved, but channel state information (CSI) reporting accuracy deteriorates due to insufficient measurement time
Solution Approach 1:
The patent segments the measurement and reporting processes into distinct S-TTI units. CSI reference resources are determined within specific S-TTI boundaries, and measurements are performed on segmented time intervals. This segmentation allows the system to maintain short overall TTI durations while ensuring sufficient measurement time within each segment, thereby preserving both communication speed and CSI accuracy.
Solution Approach 2:
The patent performs preliminary determination of CSI reference resources before actual CSI reporting. By pre-identifying which resource blocks and time slots will be used for CSI measurement within S-TTI units, the system ensures that measurement activities are properly scheduled and executed with adequate time, preventing accuracy degradation while maintaining the fast response characteristics of short TTIs.
2Adaptability or versatility
If CSI reference resources are determined within S-TTI units, then CSI reporting flexibility is improved, but implementation complexity increases compared to legacy L-TTI systems
Solution Approach 1:
The patent designs the S-TTI-based CSI reference resource determination mechanism to be universal and compatible with existing L-TTI frameworks. The same fundamental principles of reference resource selection and measurement are applied across both S-TTI and L-TTI operations, allowing UEs to handle multiple TTI lengths with a unified implementation approach, thereby reducing complexity while maintaining flexibility.
Solution Approach 2:
The patent manages complexity by changing parameters such as the time unit for reference resource determination (from L-TTI to S-TTI) while keeping the overall measurement and reporting framework intact. This parameter adjustment allows flexible adaptation to different TTI lengths without requiring complete redesign of the CSI reporting mechanism, balancing flexibility and implementation complexity.
3Measurement precision
If recent interference samples are used for CSI derivation, then CSI accuracy is improved by considering current interference conditions, but measurement overhead increases
Solution Approach 1:
The patent applies local quality by determining CSI reference resources specifically within S-TTI units, allowing the system to capture local interference characteristics in recent time intervals. By focusing measurements on locally relevant S-TTI segments rather than broader L-TTI periods, the system achieves accurate representation of current interference conditions while minimizing the total measurement overhead through targeted, localized measurements.
Data Source
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AI summary
The present invention provides a channel quality indicator (CQI) transmission method carried out by means of a terminal supporting a relatively short transmission time interval (S-TTI) compared to a legacy transmission time interval (L-TTI) in a wireless communication system. The method is characterized by: determining an overhead associated with a predefined control channel in accordance with whether or not S-TTI-based communication is being carried out; and transmitting the CQI on the basis of the determined overhead associated with the predefined control channel, wherein, if the S-TTI-based communication is being carried out, the overhead, which is associated with the predefined control channel, is determined in the same way between an S-TTI comprising a legacy physical downlink control channel (PDCCH) region and an S-TTI not comprising a legacy PDCCH region.