CSI Feedback Overhead Reduction via Spatial Domain Basis Vectors
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Solution Overview
Problem
Current wireless communication systems face challenges in reducing the channel state information (CSI) feedback overhead, which is essential for efficient data transmission and support for new applications in 5G and beyond communication systems.
Innovation Solution
The proposed solution involves a user equipment (UE) and a base station (BS) that utilize a processor and transceiver to determine and transmit CSI reports with reduced overhead. This is achieved by determining spatial domain basis vectors, inter-polarization coefficient values, and channel quality indicators based on specific information about CSI reports, and transmitting these reports on specific physical uplink control channel formats.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional CSI feedback methods are used, then accurate channel state information is obtained, but feedback overhead increases
Solution Approach 1:
The patent extracts and reports only the most significant CSI components (spatial domain basis vectors and inter-polarization coefficient values) while omitting less critical information. This selective extraction reduces feedback overhead while maintaining sufficient accuracy for effective channel state representation and precoding optimization.
Solution Approach 2:
The patent applies different reporting precision levels to different CSI components. Spatial domain basis vectors are reported with higher precision as they capture the dominant channel characteristics, while inter-polarization coefficient values use reduced precision since they represent secondary polarization relationships. This differential precision approach optimizes the balance between accuracy and overhead.
2Measurement precision
If detailed CSI reports are transmitted, then channel state accuracy is improved, but uplink control channel resources increase
Solution Approach 1:
The patent extracts only the essential CSI parameters needed for effective precoding and channel adaptation, transmitting them through PUCCH format 2, 3, or 4. By removing redundant or less critical CSI components, the feedback message size is reduced, thereby conserving uplink control channel resources while maintaining sufficient channel state accuracy.
Solution Approach 2:
The patent changes the parameter representation by using compact encoding schemes for spatial domain basis vectors and inter-polarization coefficient values. Instead of reporting full-channel matrices, the system transforms channel state information into a compressed parameter set that requires fewer bits for transmission, thus reducing PUCCH resource requirements.
3Reliability
If comprehensive CSI information is reported, then precoding performance is optimized, but processing complexity increases
Solution Approach 1:
The patent extracts the dominant spatial domain characteristics and essential inter-polarization relationships, reporting only these key components to the base station. This extraction approach provides sufficient information for effective precoding optimization while significantly reducing the computational complexity of CSI processing at both UE and base station.
Solution Approach 2:
The patent applies higher processing precision to spatial domain basis vectors which are critical for precoding, while using reduced precision for inter-polarization coefficient values. This differential processing approach maintains precoding performance for the most important channel dimensions while reducing overall processing complexity through selective precision management.
Data Source
AI summary
Apparatuses and methods for reduced channel state information (CSI) feedback overhead. A method performed by a user equipment (UE) includes receiving information about a channel state information (CSI) report. The information indicates an antenna port group, wideband (WB) or sub-band (SB) reporting, and a physical uplink control channel (PUCCH) format X, where X=2, 3, or 4. The method further includes determining, based on the information, a spatial domain (SD) basis vector bl for each layer and determining, based on the information, an inter-polarization coefficient value cl for each layer. The method further includes determining, based on the information, a channel quality indicator (CQI) and transmitting the CSI report on the PUCCH format X. The CSI report includes a rank indicator (RI), a precoding matrix indicator (PMI), and the CQI. The PMI indicates the SD basis vector and the inter-polarization coefficient value. The RI indicates a rank value.