CSI Bitwidth Configuration for Massive MIMO Feedback Reduction
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Solution Overview
Problem
Existing MIMO technologies face challenges in efficiently reducing the amount of uplink feedback for channel state information, particularly in massive MIMO scenarios, where the large number of network device antennas leads to significant resource consumption.
Innovation Solution
Implementing AI/ML-based CSI generation and reconstruction processes, with configuration information to set bitwidths for CSI, allowing terminal equipment to transmit and network devices to receive CSI more efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of antennas of the network device is increased to provide higher channel capacity, then the channel capacity is improved, but the amount of feedback on channel state information becomes very large
Solution Approach 1:
The patent extracts only the essential channel state information parameters needed for precoding from the complete channel state, rather than feeding back all channel details. The terminal equipment feeds back a precoding matrix indicator (PMI) that points to a recommended precoding matrix from a codebook, instead of feeding back the entire channel matrix. This extraction approach maintains the benefit of high channel capacity while significantly reducing feedback overhead.
Solution Approach 2:
Instead of the terminal equipment directly measuring and feeding back the downlink channel state information, the system inverts the approach by having the terminal equipment recommend precoding parameters (PMI, CQI, RI) that indirectly represent the channel state. The network device then uses these recommended parameters to determine the actual precoding, effectively inverting the direct feedback relationship into an indirect parameter recommendation relationship.
2Reliability
If the terminal equipment feeds back detailed downlink channel state information, then the network device can perform accurate precoding, but the uplink resource consumption increases significantly
Solution Approach 1:
The patent changes the parameters being fed back from detailed channel state information (amplitude, phase, spatial correlation) to compressed precoding parameters (PMI, CQI, RI). The PMI is an index that selects a precoding matrix from a predefined codebook, reducing the feedback from potentially hundreds of complex channel coefficients to just a few integer indices. This parameter transformation maintains precoding accuracy while dramatically reducing uplink resource consumption.
Solution Approach 2:
The patent introduces a codebook as an intermediary between the channel state measurement and the feedback process. Instead of directly feeding back channel measurements, the terminal equipment compares the measured channel with precoding matrices in the codebook and feeds back the index (PMI) of the best-matching matrix. This intermediary codebook structure enables accurate precoding selection while minimizing feedback overhead.
Data Source
AI summary
An apparatus for transmitting channel state information, applicable to a terminal equipment, includes first processor circuitry, wherein the terminal equipment, by the first processor circuitry controlling the terminal equipment, is configured to: receive, by the terminal equipment, first configuration information transmitted by a network device, at least a part of the first configuration information being information of a bitwidth of second information; and transmit channel state information at least based on the information of the bitwidth.