MIMO Precoding Codebook Design for Limited Feedback Systems
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Solution Overview
Problem
In multi-user MIMO communication systems, the limited feedback information and the need for partial channel knowledge hinder the full exploitation of multi-user diversity, as conventional codebook designs fail to maintain sufficient distance between precoding matrices, affecting performance.
Innovation Solution
A codebook is designed using a pre-set basic matrix comprising a discrete Fourier transform (DFT) matrix and a rotation matrix, where the diagonal element values of the rotation matrix are determined to maximize the minimum distance between precoding matrices, allowing for efficient data transmission and reception even with limited feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional codebook is used for multi-user MIMO communication, then the system can operate with limited feedback information, but the distance between precoding matrices is insufficient which degrades system performance
Solution Approach 1:
The patent changes the parameters of the basic matrix by introducing a rotation matrix with optimized diagonal elements. This transforms the DFT matrix into a new basic matrix that generates precoding matrices with sufficient distance, thereby improving system performance while maintaining operation with limited feedback information
2Reliability
If the codebook size is increased to improve performance, then more precoding matrices are available, but maintaining sufficient distance between matrices becomes more difficult
Solution Approach 1:
The patent segments the codebook generation process into two parts: a fixed DFT matrix providing structural foundation, and a rotation matrix with optimized diagonal elements providing distance separation. This segmentation allows systematic generation of precoding matrices with guaranteed sufficient distance even as codebook size increases
Solution Approach 2:
By changing the parameters of the basic matrix through the rotation matrix optimization, the patent enables systematic generation of precoding matrices that maintain sufficient distance regardless of codebook size, thus improving performance without proportionally increasing design complexity
3Reliability
If precoding matrices are designed to maintain sufficient distance between them, then system performance improves, but the codebook becomes less adaptable to different propagation conditions
Solution Approach 1:
The patent creates a universal basic matrix structure (DFT + rotation) that serves multiple functions: it maintains sufficient distance between precoding matrices for performance improvement, while also being adaptable to different propagation conditions through the systematic generation approach and feedback mechanism
Data Source
AI summary
Provided are a data transmitting and receiving method for a multiple-input multiple-output (MIMO) communication system, and a transmitter and a receiver using the method. Accordingly, since precoding matrices of a codebook is constituted using a rotation matrix, expansion of the codebook is easy, and since each of the precoding matrices is determined according to the number of transmit antennas, the codebook is systematically created according to a system. In addition the codebook can be applied to even a correlated channel, and the minimum distance between precoding matrices can advantageously be maximized.