CSI-RS Triggering via DL Control Signaling
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Solution Overview
Problem
The existing methods for channel state information (CSI) reference signal (CSI-RS) in LTE systems face issues such as high overhead and resource waste due to periodic sending, limited port reduction, and increased complexity with more antennae, leading to inefficiencies in spectrum usage and CSI calculation.
Innovation Solution
A method and device are introduced to determine non-periodic CSI-RS transmission resource configuration information, allowing flexible location and port configuration, and triggering CSI feedback through DL control signaling, reducing overhead and resource waste by dynamically configuring CSI-RS transmission and feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If periodic CSI-RS transmission is used, then channel measurement can be performed regularly, but overhead and resource waste increase
Solution Approach 1:
The patent applies periodic action by configuring CSI-RS transmission with specific periodicities (e.g., every 5, 10, 20, 40, 80 subframes) and subframe offsets. This allows the system to perform channel measurements at regular intervals rather than continuously, reducing overhead while maintaining measurement reliability. The network can select appropriate periodicity based on channel conditions and QoS requirements.
Solution Approach 2:
The patent enables dynamic CSI-RS transmission through aperiodic triggering mechanisms where CSI-RS is transmitted only when needed based on scheduling decisions. The network can dynamically activate or deactivate CSI-RS resources via downlink control information (DCI), allowing adaptive resource allocation that reduces overhead during periods when channel measurement is not required while maintaining reliability when needed.
2Productivity
If more antenna ports are configured, then MIMO performance improves, but system complexity increases
Solution Approach 1:
The patent segments the CSI feedback process into multiple independent components: Rank Indication (RI), Precoding Matrix Indication (PMI), and Channel Quality Indication (CQI). This segmentation allows the terminal to calculate and report each component separately, reducing the overall complexity of CSI calculation while supporting multiple antenna ports. The segmented feedback can be reported at different timings and with different granularities.
Solution Approach 2:
The patent applies local quality by allowing different CSI feedback configurations for different terminal groups or different time periods. The network can configure wideband CSI feedback for some terminals and subband CSI feedback for others, or adjust feedback granularity based on terminal capability and channel conditions. This reduces overall system complexity while maintaining high MIMO performance where needed.
3Measurement precision
If CSI feedback is triggered frequently, then channel state accuracy improves, but uplink resource consumption increases
Solution Approach 1:
The patent implements periodic CSI feedback where terminals report CSI at regular intervals configured by the network (e.g., every 5, 10, 20 subframes). This periodic feedback mechanism ensures the network receives updated channel state information regularly while controlling uplink resource consumption through configurable periodicity. The network can adjust the periodicity based on channel variability and QoS requirements.
Solution Approach 2:
The patent employs feedback mechanisms where the network receives CSI from terminals and uses this information to adjust downlink transmission parameters. The feedback loop allows the network to optimize resource allocation based on actual channel conditions, improving CSI accuracy when needed while reducing feedback frequency when channel conditions are stable, thereby balancing accuracy and resource consumption.
4Adaptability or versatility
If aperiodic CSI-RS is configured, then resource flexibility improves, but terminal processing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring multiple aperiodic CSI-RS resource sets with different parameters (time locations, frequency locations, antenna ports) before actual transmission. The terminal stores these pre-configured resources and simply activates the appropriate set based on downlink control information triggers. This approach provides resource flexibility while minimizing terminal processing complexity during actual operation.
Solution Approach 2:
The patent creates universal CSI-RS resource configurations that can serve multiple purposes. The same aperiodic CSI-RS resource set can be triggered for different measurement scenarios (e.g., beam management, channel quality estimation, interference measurement) by simply changing the trigger conditions or resource parameters. This multi-functionality reduces terminal processing complexity while maintaining high adaptability.
Data Source
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AI summary
Provided are a method and device for triggering CSI feedback, and method and device for feeding back CSI. The method for triggering CSI feedback includes: sending, by a NodeB, CSI feedback triggering instruction information and resource allocation information of a Physical Downlink Shared Channel, PDSCH, to a terminal in the same control signalling format of Downlink, DL, control signalling, wherein the CSI feedback triggering instruction information is used for instructing the terminal to feed back CSI.