Precoding Matrix Design for MIMO Channel Correlation
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Solution Overview
Problem
In multiple-input multiple-output (MIMO) systems, especially in direct path conditions, channel correlation increases, leading to a decrease in channel rank and the inability to support multiple data stream transmission, particularly when antenna spacing is difficult to design and relative movements between transmit and receive ends occur, such as in mobile scenarios.
Innovation Solution
A signal transmission method and device determine a target precoding matrix V=(H)^-1 * H̃, where H is the channel matrix and H̃ is an equivalent channel matrix related to the transmission distance and antenna element spacing, to support multiple data stream transmission by effectively creating a diagonal equivalent channel matrix H̃, allowing for signal precoding and transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If antenna spacing is designed to meet a fixed relationship between antenna spacing and data transmission distance, then channel correlation decreases and multiple data stream transmission is supported, but antenna spacing becomes extremely difficult to design and cannot adapt to mobile scenarios
Solution Approach 1:
The patent changes the parameter of antenna spacing from a fixed physical constraint to a dynamically adjustable parameter. By using precoding matrices that can be adapted based on channel state information, the system effectively modifies the electrical spacing between antennas without physically moving them, thereby resolving the contradiction between maintaining reliable multi-stream transmission and avoiding complex fixed spacing design
Solution Approach 2:
The patent introduces dynamic adaptation through precoding matrices that are adjusted in real-time based on channel conditions and transmission distance. This dynamic approach allows the system to maintain optimal performance in both fixed and mobile scenarios without requiring complex pre-designed antenna spacing configurations
2Ease of operation
If direct path exists between transmit end and receive end, then signal transmission is straightforward, but channel rank decreases due to increased channel correlation and multiple data stream transmission is not supported
Solution Approach 1:
The patent introduces precoding matrices as an intermediary between the transmitted signals and the channel. These precoding matrices transform the original signals in a way that compensates for the direct path channel correlation, enabling multiple data streams to be transmitted simultaneously even in direct path conditions without complicating the basic signal transmission process
3Reliability
If antenna spacing is fixed to support multiple data stream transmission, then channel correlation is reduced, but the system cannot adapt when relative movement occurs between transmit and receive ends
Solution Approach 1:
The patent makes the antenna spacing effective value dynamic through precoding adjustments. As the relative movement between transmit and receive ends changes the channel characteristics, the precoding matrices are updated accordingly to maintain the effective electrical spacing needed for multiple data stream transmission, thereby providing adaptability to mobile scenarios
Data Source
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AI summary
Embodiments of the present invention provide a signal transmission method and device. The method includes: determining, by a sending device, a target precoding matrix V, where V=(H)-1·H̃, H indicates a channel matrix between the sending device and a receiving device, H̃ indicates an equivalent channel matrix between the sending device and the receiving device, (H̃H·H̃) or (H̃·H̃H) is a diagonal matrix, and H̃ is related to a transmission distance D between the sending device and the receiving device and an element spacing of an antenna of the receiving device; and sending, by the sending device, a signal to the receiving device according to the target precoding matrix V. Because H̃ meets a characteristic that (H̃H·H̃) or (H̃·H̃H) is a diagonal matrix, a channel corresponding to H̃ can support multiple data stream transmission. Therefore, the signal transmission method and device provided in the embodiments of the present invention can support multiple data stream transmission.