CSI Reporting Method Using Relative Values to Reduce Overhead
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Solution Overview
Problem
In multi-antenna technologies like MIMO, high CSI reporting overheads occur due to the need to report all CSI parameters, especially in TDD, FDD, and carrier aggregation systems, leading to reduced system throughput.
Innovation Solution
The method involves reporting a relative value between CSI parameters measured by user equipment and the base station, allowing the base station to determine a precoding matrix without needing all CSI parameters, thereby reducing the number of bits required for quantization and improving system throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all CSI parameters are reported by user equipment to base station, then the base station can obtain accurate channel state information for precoding, but the CSI reporting overhead increases significantly
Solution Approach 1:
The patent extracts and reports only the differential part of CSI parameters rather than complete CSI information. Specifically, the user equipment calculates the difference between measured CSI parameters and predicted CSI parameters, then reports only this differential information to the base station, thereby reducing reporting overhead while maintaining necessary accuracy
Solution Approach 2:
The patent uses a prediction mechanism where the base station predicts CSI parameters based on previously reported information and channel characteristics. This prediction serves as a reference that reduces the amount of actual CSI data that needs to be transmitted, as only deviations from the prediction need to be reported
2Measurement precision
If complete CSI parameters are reported for multiple frequency bands in carrier aggregation, then accurate channel state information is obtained, but the reporting overhead increases
Solution Approach 1:
The patent segments CSI reporting by frequency band and applies differential encoding within each band. Instead of reporting complete CSI for all bands, the system divides the reporting into separate segments for each frequency band and reports only the differential values relative to predicted values for each segment, reducing overall reporting overhead
3Ease of operation
If user equipment feeds back W1 codebook and W2 codebook in TDD system, then the base station can perform precoding, but high CSI reporting overhead is caused due to inability to perform complete reciprocity calibration
Solution Approach 1:
The patent changes the reporting parameter from complete codebook indices to differential values representing deviations from predicted CSI. This parameter transformation reduces the number of bits required for reporting while still enabling the base station to reconstruct accurate CSI for precoding operations
Data Source
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AI summary
The present invention provides a method for reporting channel state information. The method includes: receiving, by a base station, a first reference signal sent by user equipment; sending, by the base station, a first parameter set and a second reference signal to the user equipment, where the first parameter set is obtained by the base station by measuring the first reference signal; and receiving, by the base station, a third parameter set sent by the user equipment, where the third parameter set includes a relative value between a parameter in a second parameter set and a parameter in the first parameter set, the second parameter set is obtained by the user equipment by measuring the second reference signal, and the third parameter set and the first parameter set are used by the base station to determine a precoding matrix.