CSI Feedback via Wideband and Subband Amplitude Quantization
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Solution Overview
Problem
Existing LTE FDD systems face challenges in accurately transmitting channel state information, which affects downlink communication quality due to limitations in feedback precision of state information.
Innovation Solution
The method involves determining first and second amplitude information of the precoding matrix, where the first amplitude information indicates wideband amplitude quantization and the second amplitude information indicates amplitude quantization of subbands, allowing for improved precision in channel state information feedback by adjusting amplitude values and determining the precoding matrix based on these values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional channel state information feedback methods are used, then feedback overhead is reduced, but feedback precision and accuracy deteriorate
Solution Approach 1:
The patent segments the feedback process into two distinct parts: wideband amplitude information and subband amplitude information. The wideband amplitude provides coarse-grained amplitude quantization across the entire bandwidth, while subband amplitude provides fine-grained adjustments for specific frequency subbands. This segmentation allows the system to achieve high feedback precision without transmitting complete channel state information for all frequency bands, thus reducing feedback overhead while improving accuracy.
2Reliability
If complete channel state information is fed back, then downlink communication quality is improved, but feedback overhead increases
Solution Approach 1:
The patent extracts only the essential amplitude information from the complete channel state information. Instead of feeding back full CSI including phase, spatial parameters, and complete amplitude data across all frequencies, the system extracts and feeds back only wideband amplitude quantization information and subband amplitude adjustments. This extraction approach maintains downlink communication quality by preserving the most critical amplitude characteristics while significantly reducing feedback overhead by omitting redundant information.
3Measurement precision
If amplitude quantization is performed without differential encoding, then encoding complexity is reduced, but quantization accuracy deteriorates
Solution Approach 1:
The patent applies preliminary wideband amplitude quantization before subband amplitude differential encoding. The wideband amplitude quantization establishes a baseline reference that is then used to perform differential encoding on subband amplitudes. This preliminary action reduces the dynamic range of subsequent differential encoding operations, allowing for more accurate quantization with fewer bits while keeping encoding complexity manageable through the use of differential encoding techniques.
Data Source
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AI summary
Embodiments of the present invention provide a method and an apparatus for transmitting channel state information. The method includes: receiving, by a terminal device, a reference signal sent by a network device; obtaining, by the terminal device, a precoding matrix based on the reference signal; determining, by the terminal device, first amplitude information and second amplitude information of the precoding matrix, where the first amplitude information is used to indicate amplitude quantization information of a wideband, and the second amplitude information is used to indicate amplitude quantization information of N first subbands of the wideband; and sending, by the terminal device, the first amplitude information and the second amplitude information to the network device, so as to improve feedback precision of state information.