Terminal Device CSI Feedback Mode Selection
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Solution Overview
Problem
In MIMO communication systems, especially in TDD systems, the limited number of transmit channels in terminal devices restricts the flexibility of CSI feedback, leading to incomplete downlink channel information and increased overheads, which hampers system throughput.
Innovation Solution
A data transmission method where the terminal device determines a target mode based on channel status and transmit port correlation to selectively feed back CSI, using a combination of reference signals to optimize feedback efficiency, allowing for flexible CSI reporting and reducing overheads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the terminal device sends SRS through all receive ports to obtain complete downlink channel information, then the accuracy of downlink channel information is improved, but the overhead of uplink transmission increases and the flexibility of CSI feedback is reduced
Solution Approach 1:
The patent segments the receive ports into two groups: ports configured with transmit channels (first group) and ports without transmit channels (second group). This segmentation allows the terminal to send SRS only through the first group of ports, reducing uplink overhead while maintaining necessary channel information for precoding operations.
Solution Approach 2:
The patent applies partial action by having the terminal device send SRS only through a subset of receive ports (those with transmit channels) rather than all receive ports. This partial transmission is sufficient to obtain the necessary downlink channel information for precoding, avoiding the need to transmit through all ports and thereby reducing overhead.
2Quantity of substance
If the terminal device sends SRS through a subset of receive ports to reduce overhead, then the overhead of uplink transmission is reduced, but the completeness of downlink channel information is compromised
Solution Approach 1:
The patent introduces indication information as an intermediary that conveys the configuration of receive ports to the network device. This indication information serves as a mediator that allows the network device to understand which ports are used for SRS transmission and how to properly interpret the channel information, ensuring completeness despite using only a subset of ports.
Solution Approach 2:
The patent changes the parameter of port usage from 'all receive ports' to 'receive ports configured with transmit channels'. This parameter change is supported by configuration information that defines which ports have transmit capabilities, allowing the system to adaptively use only the necessary ports for SRS transmission while maintaining channel information completeness.
3Loss of information
If the terminal device feeds back CSI for all ports, then the completeness of channel state information is improved, but the complexity of feedback processing increases
Solution Approach 1:
The patent extracts only the necessary CSI information related to receive ports configured with transmit channels and excludes information from ports without transmit channels. This extraction process removes redundant data, reducing feedback complexity while maintaining the completeness of information needed for precoding operations at the network device.
4Adaptability or versatility
If the system configures all receive ports with transmit channels to enable flexible SRS transmission, then the flexibility of CSI feedback is improved, but the cost and complexity of the transmit channel increases
Solution Approach 1:
The patent implements a dynamic configuration where receive ports are selectively assigned transmit channel capabilities based on operational needs. The configuration information dynamically defines which ports have transmit channels, allowing the system to adapt flexibility to actual requirements without permanently equipping all ports with transmit capabilities, thus avoiding unnecessary complexity.
Data Source
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AI summary
This application provides a data transmission method and apparatus. The method includes: receiving, by a terminal device, a first reference signal sent by a network device; measuring, by the terminal device, a downlink channel based on the first reference signal, to obtain a channel status of the downlink channel; determining, by the terminal device, a target mode from a plurality of modes based on the channel status of the downlink channel, where information that is used to feed back channel state information CSI and that is sent by the terminal device in different modes of the plurality of modes is different; and sending, by the terminal device, indication information to the network device, where the indication information is used to indicate the target mode. The data transmission method and apparatus in the embodiments of this application are conducive to improvement of flexibility of feeding back CSI.