Channel Matrix Feedback for Long-Distance Precoding Accuracy
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Solution Overview
Problem
The existing method of determining a precoding matrix based on a PMI indicator is not applicable to long-distance communication due to errors in beam direction, which affect communication quality, especially in scenarios where uplink and downlink channels are not reciprocal.
Innovation Solution
A terminal device feeds back limited channel elements, such as those with maximum signal strength or specific time-frequency resources, to a network device, allowing the network device to determine a more accurate precoding matrix, reducing feedback overheads and improving beam sweeping precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the network device determines the precoding matrix based on the PMI indicator, then the feedback overhead is reduced, but the beam direction accuracy deteriorates
Solution Approach 1:
The patent extracts only the essential channel elements (those with maximum signal strength or on specific time-frequency resources) from the complete channel matrix for feedback. By selecting and transmitting only these critical elements rather than the entire channel matrix, the system reduces feedback overhead while maintaining sufficient accuracy for beam direction determination.
Solution Approach 2:
The patent applies local quality by treating different channel elements differently based on their importance. Channel elements with maximum signal strength or those on specific time-frequency resources are identified as having higher quality/importance and are selected for feedback, while other less critical elements are omitted. This selective approach optimizes the balance between feedback overhead and beam direction accuracy.
2Measurement precision
If the terminal device feeds back all channel elements, then the beam direction accuracy is improved, but the feedback overhead increases
Solution Approach 1:
The patent extracts only the essential channel elements (those with maximum signal strength or on specific time-frequency resources) from the complete channel matrix for feedback. By selecting and transmitting only these critical elements rather than the entire channel matrix, the system reduces feedback overhead while maintaining sufficient accuracy for beam direction determination.
Solution Approach 2:
The patent applies partial action by feeding back only a subset of channel elements that are most relevant for beam direction accuracy, rather than all channel elements. This partial feedback approach is sufficient to achieve the required beam direction precision without the excessive overhead of complete channel matrix feedback.
3Device complexity
If the network device uses the PMI indicator for precoding matrix determination, then the system complexity is reduced, but the communication quality in long-distance scenarios deteriorates
Solution Approach 1:
The patent extracts only the essential channel elements needed for accurate beam direction determination in long-distance scenarios. By selecting and feeding back only these critical elements, the system maintains relatively low complexity while significantly improving communication quality compared to using the PMI indicator alone.
Solution Approach 2:
The patent changes the feedback parameter from the PMI indicator (which provides limited spatial beam direction information) to actual channel elements (which provide more accurate and detailed channel state information). This parameter change enables better precoding matrix determination and improves communication quality in long-distance scenarios while maintaining acceptable system complexity.
Data Source
AI summary
Embodiments of this application provide a channel matrix determining method, an apparatus, and a system, relating to the field of communication technologies, to resolve a technical problem that a manner in which a network device determines a precoding matrix based on an existing PMI indicator is not applicable to long-distance communication. The method includes: A terminal device obtains a plurality of reference signals, determines a first channel matrix based on the plurality of reference signals, and feeds back, to a network device, first information indicating some channel elements in the first channel matrix. The terminal device may further receive a downlink signal determined based on the first information and sent by the network device. A channel element in the some channel elements is determined based on signal strength and/or a time-frequency resource of the reference signal.