Open Loop SU MIMO Precoding via Codebook Cycling
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Solution Overview
Problem
Existing methods for open-loop precoding in high-speed wireless communication systems, particularly in MIMO systems, face challenges in selecting a reliable precoding matrix without Precoding Matrix Indication (PMI) feedback, especially in scenarios with high antenna correlation and less than full rank cases.
Innovation Solution
The method involves selecting the precoding matrix W(k) based on a SU-MIMO codebook or DFT submatrix, cycling through codebook subsets or submatrices, and applying the same matrix across scheduled subbands, ensuring reliable precoding even without PMI feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PMI feedback is used for precoding matrix selection, then precoding accuracy is improved, but system complexity increases and reliability decreases in high-speed open-loop scenarios
Solution Approach 1:
The patent extracts the essential function of precoding matrix selection from the PMI feedback mechanism and implements it through open-loop methods using predefined codebooks and DFT-based matrices. This removes the dependency on feedback channels while maintaining precoding functionality, thereby improving reliability in high-speed scenarios where feedback may be unreliable or unavailable.
Solution Approach 2:
The system performs self-service by selecting precoding matrices autonomously without external feedback. The transmitter independently chooses matrices from predefined codebooks based on system state, eliminating the need for receiver feedback and thus improving reliability in open-loop high-speed operations while maintaining adequate precoding accuracy.
2Device complexity
If codebook cycling method is used for precoding matrix selection, then implementation complexity is reduced, but precoding adaptability deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-defining codebooks and DFT-based precoding matrices before transmission. These predefined structures enable simple cycling selection at runtime while maintaining adaptability through the diverse set of pre-computed matrices that cover various channel conditions, thus resolving the contradiction between low implementation complexity and adequate precoding adaptability.
3Reliability
If same precoding matrix is applied across scheduled subbands, then frequency diversity is improved, but frequency-selective optimization is lost
Solution Approach 1:
The patent segments the frequency spectrum into subbands and applies different precoding matrix selection strategies to each segment. Within each subband, the same matrix provides frequency diversity, while varying matrices across subbands maintains frequency-selective optimization. This segmentation approach resolves the contradiction by operating at multiple hierarchical levels.
Data Source
AI summary
A method for data transmission, comprises the steps of modulating data to be transmitted via a transmitter into a plurality of modulated symbols, generating a codebook comprising a plurality of codewords, selecting a codeword from the codebook as a precoding matrix by a predetermined cycling selection, precoding the modulated symbols with the precoding matrix selected, and transmitting the precoded modulated symbols.