Differential Channel Feedback for Complete Downlink Information
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Solution Overview
Problem
In TDD systems, network devices struggle to obtain complete downlink channel information due to terminal devices with limited capabilities, unable to send sounding reference signals through all antennas, leading to suboptimal resource scheduling and reduced downlink transmission performance.
Innovation Solution
The terminal device determines first channel information based on downlink reference signals and sends feedback information including identifiers of spatial channel components and channel differential information, allowing the network device to reconstruct complete channel information using partial uplink measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If terminal devices send sounding reference signals through all antennas, then complete downlink channel information can be obtained, but terminal devices with limited capabilities cannot fulfill this requirement
Solution Approach 1:
The patent segments the channel information feedback into two parts: first channel information obtained by the terminal device through downlink reference signals, and second channel information obtained by the network device through uplink reference signals. The feedback information includes only the difference between these two segments, allowing terminals with limited capabilities to provide useful feedback without needing to transmit through all antennas.
Solution Approach 2:
The patent introduces feedback information as an intermediary mechanism that bridges the capability gap. This feedback contains differential information between the terminal's actual antenna measurements and the complete channel information, allowing the network device to reconstruct complete downlink channel information without requiring the terminal to transmit through all antennas.
2Measurement precision
If terminal devices feed back complete channel information, then the network device obtains accurate channel data, but measurement and reporting overheads increase
Solution Approach 1:
The patent extracts only the essential differential information from the complete channel information and includes it in the feedback. Instead of transmitting the full channel information matrix, the terminal device transmits only the difference between its measured first channel information and the complete second channel information, significantly reducing feedback overhead while maintaining accuracy.
Solution Approach 2:
The patent changes the representation of channel information from absolute values to differential values. By expressing channel information as differences between measured and complete channel data, the system reduces the amount of information that needs to be transmitted while preserving the necessary precision for accurate channel estimation.
Data Source
AI summary
Example channel information determining methods and apparatus are provided. One example method includes: after determining first channel information between a terminal device and a network device based on a downlink reference signal from the network device, the terminal device may determine feedback information based on the first channel information, and send the feedback information to the network device. The feedback information includes difference information between second channel information and third channel information, the second channel information is channel information that is in the first channel information and that corresponds to P antennas in M antennas of the terminal device, and the third channel information is channel information that is in the first channel information and that corresponds to M-P antennas in the M antennas.