CSI Feedback Method Reducing Uplink Overhead via PMI Extraction
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Solution Overview
Problem
Conventional CSI feedback methods in cellular systems require significant uplink feedback overhead, as User Equipment (UE) needs to transmit multiple pieces of information, including Rank Indicator (RI), Pre-coding Matrix Indicator (PMI), and Channel Quality Indicator (CQI), which limits system performance and increases complexity for network side devices.
Innovation Solution
The proposed CSI feedback method reduces uplink feedback overhead by allowing the UE to transmit only the first PMI information to the network side device, enabling beamforming operations based on this information, while the network side device receives CQI information from the UE to adjust links directly, thereby simplifying the feedback process and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE feeds back multiple pieces of CSI information (RI, PMI, CQI) for both horizontal and vertical dimensions, then the network side device can perform comprehensive beamforming operations, but the uplink feedback overhead becomes relatively large
Solution Approach 1:
The patent extracts only the essential PMI information from the complete CSI feedback set, allowing the UE to feed back only PMI while the network side device derives other necessary information (RI, CQI) from this extracted PMI information through pre-configured codebooks and channel measurements, thereby reducing feedback overhead while maintaining beamforming accuracy
Solution Approach 2:
The PMI information serves multiple functions simultaneously: it enables the network side device to determine both the horizontal dimension precoding matrix and the vertical dimension beamforming vector, and also allows derivation of RI and CQI information, making a single feedback parameter universally useful for comprehensive beamforming operations
2Productivity
If the network side device performs three-dimensional beamforming operations based on CSI from both horizontal and vertical dimensions, then system performance is enhanced, but the device complexity increases
Solution Approach 1:
The network side device performs preliminary configuration of codebooks for both horizontal and vertical dimensions before actual beamforming operations. These pre-configured codebooks contain all necessary precoding matrices and beamforming vectors, allowing the device to quickly derive complete beamforming parameters from the received PMI without complex real-time calculations, thus reducing operational complexity while maintaining 3D beamforming capability
Data Source
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AI summary
The present disclosure provides a CSI feedback method, a CSI feedback device and a CSI feedback system. The CSI feedback method includes steps of: configuring, by a network side device, a first downlink channel measurement pilot for a UE; and receiving, by the network side device, first PMI information fed back by the UE. The first PMI information is acquired by the UE based on measurement of the first downlink channel measurement pilot and second PMI information. A dimension represented by the first PMI information is different from a dimension represented by the second PMI information.