Multi-User MIMO Beamforming via Subset Matrix Segmentation
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Solution Overview
Problem
Multi-user MIMO systems face challenges in achieving diversity gain while minimizing computational load, as existing methods either lose diversity gain due to simple inverse matrix calculations or require high computational resources for singular value decomposition.
Innovation Solution
A transmitting apparatus and method that sets a subset matrix for each antenna, calculates a beamforming matrix using inverse matrix calculations, and performs beamforming to generate transmission signals, effectively removing interference between user terminals with a relatively small computational load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple inverse matrix calculation is used for beamforming, then computational load is reduced, but diversity gain is lost
Solution Approach 1:
The channel matrix H is segmented into multiple subset matrices (H1, H2, ..., Hn), each corresponding to a different antenna. For each subset matrix, an inverse matrix is calculated separately to obtain beamforming weight vectors. This segmentation allows the system to achieve diversity gain through multiple independent calculations while keeping each individual computational task manageable.
Solution Approach 2:
Instead of calculating a single inverse matrix for the entire channel matrix, the patent performs inverse matrix calculations for multiple subset matrices (excessive action). This partial approach applied to each antenna subset provides diversity gain by capturing different spatial channels, while the overall computational load remains acceptable due to the structured segmentation of the problem.
2Reliability
If singular value decomposition is used for beamforming, then diversity gain is achieved, but computational load increases
Solution Approach 1:
The patent replaces the computationally expensive singular value decomposition with a simpler inverse matrix calculation method. The inverse matrix operation is computationally cheaper and can be performed efficiently for each antenna subset, achieving diversity gain without the high computational burden of SVD. This substitution uses a 'cheaper' mathematical operation that suffices for the application requirements.
3Device complexity
If beamforming is performed without subset matrices, then computational load is low, but interference between user terminals cannot be removed
Solution Approach 1:
The patent segments the beamforming process by creating separate subset matrices for different antennas. Each subset matrix is processed independently to generate specific beamforming weight vectors. This segmentation enables targeted interference cancellation for each antenna while maintaining overall system simplicity and manageable computational complexity.
Solution Approach 2:
Different beamforming weight vectors are generated for different antennas based on their specific channel characteristics captured in each subset matrix. This local optimization ensures that each antenna's transmission is tailored to minimize interference in its specific spatial direction, achieving effective interference removal without requiring a completely complex system-wide optimization.
Data Source
AI summary
A transmitting apparatus includes a subset matrix setting unit to set a subset matrix corresponding to a channel matrix with respect to each of a plurality of antennas of at least one of a plurality of user terminals, using channel matrices fed back from the plurality of user terminals; a beamforming matrix calculator to perform a predetermined operation using the set subset matrix so as to calculate a beamforming matrix composed of weight vectors respectively corresponding to the plurality of antennas of each of the plurality of user terminals; a beamforming processor to perform a beamforming process on data to be transmitted according to the calculated beamforming matrix so as to generate a transmission signal; and antennas to transmit the transmission signal to the plurality of user terminals. The transmitting apparatus obtains a diversity effect while removing interference between user terminals with a small quantity of computations.