Aperiodic CSI Feedback Triggering in CoMP Transmission
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Solution Overview
Problem
The existing CoMP transmission systems in LTE-A face challenges with high feedback overhead due to the need for accurate CSI reporting from multiple transmitting points and interference assumptions, which increases signaling load and reduces system performance.
Innovation Solution
A method combining dynamic DCI and high-layer RRC signaling is used to trigger aperiodic feedback, allowing for flexible CSI reporting by preconfiguring feedback sets based on transmitting points, CSI-RS resources, and interference types, reducing the need for full CSI reporting from all points and assumptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full CSI reporting from all transmitting points and interference assumptions is implemented, then measurement precision is improved, but feedback overhead increases
Solution Approach 1:
The patent segments the feedback mechanism by introducing a trigger-based aperiodic reporting system. Instead of continuous full CSI reporting, the system divides feedback into periodic (basic) and aperiodic (triggered detailed) reports. The aperiodic reports are segmented by trigger type (e.g., trigger 00, 01, 10, 11) that selectively activates reporting for specific transmitting points or interference assumptions based on current channel conditions, thus reducing overall feedback overhead while maintaining measurement precision when needed.
Solution Approach 2:
The patent implements dynamic feedback control through the aperiodic triggering mechanism. The eNB dynamically decides when detailed CSI reporting is needed based on channel state changes, user equipment position, or scheduling requirements. This dynamic approach allows the system to adapt feedback granularity in real-time, providing full measurement precision only when necessary rather than continuously, thereby optimizing the trade-off between accuracy and overhead.
2Productivity
If aperiodic feedback is triggered via DCI with multiple bits, then feedback capacity is improved, but device complexity increases
Solution Approach 1:
The patent makes the DCI triggering mechanism universal by designing it to handle multiple feedback scenarios with a single unified structure. The same DCI format and triggering logic are used whether the system is in CoMP mode, carrier aggregation mode, or single-carrier mode. The trigger bits serve multiple functions: indicating aperiodic report activation, specifying which CSI processes to report, and adapting to different transmission modes without requiring separate mechanisms, thus improving feedback capacity while controlling complexity.
Solution Approach 2:
The patent utilizes parameter changes in the DCI triggering mechanism to achieve flexible feedback control. By changing the interpretation of trigger bit values (e.g., 00, 01, 10, 11) based on system configuration and current state, the same physical mechanism can provide different levels of feedback capacity. The system dynamically adjusts parameters such as the number of CSI processes to report and the triggering conditions based on these parameter changes, optimizing feedback capacity without proportionally increasing device complexity.
3Adaptability or versatility
If flexible CSI reporting is implemented for CoMP and CA scenarios, then adaptability is improved, but signaling load increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring multiple CSI processes and associated parameters through higher-layer signaling (RRC) before actual transmission. The system pre-establishes CSI process IDs, resource configurations, and reporting settings that can be quickly activated or deactivated via simple DCI triggers. This preliminary configuration reduces the need for dynamic signaling during operation, as the detailed CSI reporting parameters are already in place and only simple activation triggers are needed, thus improving adaptability while controlling signaling load.
Data Source
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AI summary
Embodiments of the present invention provide a method and apparatus for triggering aperiodic feedback in coordinated multipoint transmission. The method includes: transmitting, by an eNB to UE, dynamic control information (DCI) and preconfigured feedback sets corresponding to the DCI, so that the UE aperiodically feeds back corresponding channel state information (CSI) according to the DCI and the feedback sets corresponding to the DCI; wherein the preconfigured feedback sets corresponding to the DCI are classified according to a triggered transmitting point or a CSI-RS of non-zero power, or are classified according to configured CSI, or are classified according to an interference type. With the method and apparatus of the embodiments of the present invention, a relatively good tradeoff between flexibility of aperiodic CSI feedback and signaling load in a CoMP transmission process or a joint transmission process of CoMP and CA may be achieved.