Multi-User Precoding by Spatial-Correlation-Based Mode Selection
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Solution Overview
Problem
Existing pre-coding methods for multi-user, multi-antenna transmitters face performance degradation with increasing user correlation and high computational complexity, particularly in non-linear pre-coding scenarios.
Innovation Solution
A method involving determining spatial correlation values between users, reducing the user plurality by discarding users with high correlation, and applying tailored pre-coding (linear for low correlation and non-linear for high correlation) to optimize performance and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-linear pre-coding is applied to address user correlation, then pre-coding performance is improved, but computational complexity increases
Solution Approach 1:
The patent segments users into different groups based on their correlation characteristics. Users are divided into a first group (high correlation) and a second group (low correlation), allowing different pre-coding strategies to be applied to each segment. This segmentation enables the system to achieve good performance for high-correlation users without applying complex non-linear pre-coding to all users, thus reducing overall computational complexity.
Solution Approach 2:
The patent applies different pre-coding qualities to different user groups: linear pre-coding is applied to the first group (high correlation) to reduce complexity, while non-linear pre-coding is applied to the second group (low correlation) to optimize performance. This local differentiation of pre-coding quality allows the system to balance performance and complexity based on actual user correlation characteristics.
2Device complexity
If linear pre-coding is used, then computational complexity is reduced, but performance deteriorates with increasing user correlation
Solution Approach 1:
The patent segments users based on correlation thresholds, creating a first group for high-correlation users and a second group for low-correlation users. This segmentation allows the system to apply appropriate pre-coding methods to each segment, ensuring that linear pre-coding is only used where it is effective (low correlation) while non-linear pre-coding is applied where needed (high correlation).
Solution Approach 2:
The patent changes the pre-coding method parameter based on user correlation characteristics. By monitoring correlation values and dynamically selecting between linear and non-linear pre-coding methods, the system adapts to different correlation scenarios, optimizing performance while managing computational complexity.
3Quantity of substance
If user plurality is maintained without reduction, then system capacity is preserved, but complexity of handling high correlation increases
Solution Approach 1:
The patent extracts high-correlation users from the general user pool and places them in a separate first group. This extraction allows the system to handle high-correlation users with simplified linear pre-coding, removing the complexity burden from the main processing path while still maintaining support for all users.
Solution Approach 2:
The patent segments the user plurality into distinct groups based on correlation characteristics. This segmentation reduces the complexity of handling correlation by isolating high-correlation users into a separate category that can be processed with simpler methods, while the majority of low-correlation users continue to benefit from efficient linear pre-coding.
Data Source
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AI summary
A pre-coding method is disclosed of a multi-user, multi-antenna transmitter configured for transmission of respective signals to a plurality of users. The method comprises determining (for each pair of users of the plurality) a spatial correlation value for the pair of users, sorting the plurality of users into a first group and a second group based on the spatial correlation values, generating the respective signals for transmission to the users of the first group by application of linear pre-coding, and generating the respective signals for transmission to the users of the second group by application of non-linear precoding. For example, a particular user may be sorted into the first group when all pairs comprising the particular user have a spatial correlation value that falls below a first correlation threshold value, and the particular user may be sorted into the second group when at least one pair comprising the particular user has a spatial correlation value that falls on or above the first correlation threshold value. Corresponding apparatus, transmitter, base station and computer program product are also disclosed.