Multi-BS Precoding Codebook for Inter-Cell Interference Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional Multiple-Input Multiple-Output (MIMO) wireless communication systems face challenges in multi-cell environments due to inter-cell interference and the complexity of channel information feedback, particularly in scenarios with power differences between base stations, limiting the effectiveness of precoding matrix generation and data transmission rates.
Innovation Solution
A method for generating a multi-BS precoding matrix codebook that includes single-BS precoding matrices and a coefficient matrix, where the product with a Hermitian matrix is unitary, and the coefficient matrix is designed to maintain orthogonality and maximize subspace distance, allowing for efficient feedback and data transmission across multiple base stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a codebook based precoding scheme is used to reduce feedback overhead, then feedback overhead is reduced, but the precision of channel information feedback is compromised
Solution Approach 1:
The patent transforms the continuous channel information into discrete parameters by quantizing the channel matrix into a codebook of unitary matrices. Each unitary matrix in the codebook is represented by a compact index, converting detailed channel state information into a simplified parameter set that reduces feedback overhead while maintaining sufficient precision for effective precoding.
Solution Approach 2:
The patent creates a codebook that contains representative channel matrices (copies of actual channel conditions) pre-computed and stored. Instead of feedbacking the actual channel information, the system feeds back indices pointing to these pre-computed copies, thereby reducing feedback overhead while preserving the essential characteristics of channel information through the representative matrices in the codebook.
2Reliability
If conventional precoding matrices are used in multi-cell environments, then single-cell performance is maintained, but inter-cell interference increases
Solution Approach 1:
The patent merges the precoding matrix selection process across multiple cells by establishing a common codebook that is shared among serving cells. This allows different base stations to coordinate their precoding decisions using the same unitary matrix set, enabling multi-cell cooperation that reduces inter-cell interference while maintaining single-cell communication reliability through coordinated precoding actions.
Solution Approach 2:
The patent creates a universal codebook of unitary matrices that serves multiple functions: it provides precoding for single-cell operations while also enabling multi-cell cooperation. The same codebook structure can be applied across different serving cells, making the system adaptable to both single-cell and multi-cell scenarios without requiring separate precoding mechanisms for each case.
3Productivity
If all channel information is fed back to the base station, then precoding performance is optimized, but system overhead increases significantly
Solution Approach 1:
The patent extracts only the essential information needed for precoding by representing channel matrices as unitary matrices with compact indices. Instead of feedbacking complete channel state information, the system extracts and feeds back only the indices of the unitary matrices from the codebook, thereby maintaining sufficient precoding performance while significantly reducing system overhead.
Solution Approach 2:
The patent segments the channel information feedback process into two parts: (1) the codebook structure that is pre-established and shared, and (2) the feedback indices that point to specific matrices in the codebook. This segmentation allows the system to maintain comprehensive precoding capability through the codebook while reducing actual feedback traffic to only the index values, separating the reference framework from the variable feedback data.
Data Source
AI summary
Disclosed are a feedback-transmitting method and data-transmitting method, and a method for generating a codebook that can be used in a system such as LTE-A. When multiple base stations operate in a cooperative mode, using a codebook generated according to the present invention, an existing codebook for single cell transmission can be used to generate a codebook for cooperative transmission.