Multi-User Beamforming Vector Selection for Interference Mitigation
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Solution Overview
Problem
Current linear beamforming schemes for multi-user terminal MIMO systems suffer from significant power loss and residual interference due to the lack of consideration for interference mitigation during user terminal selection and the finite resolution of transmit beamforming codebooks, especially at high signal-to-noise ratios.
Innovation Solution
A method and apparatus for multi-user joint transmit-receive beamforming that involves receiving channel information from access terminals, selecting a set of access terminals based on this information, creating beamforming vectors, and transmitting signals using these vectors to maximize signal power while minimizing interference, employing a close-form Minimum Mean Squared Error solution and spatial nulling techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If Zero-Forcing beamforming schemes are used, then implementation complexity is reduced, but power loss increases significantly
Solution Approach 1:
The patent changes the beamforming parameter selection criterion from simple ZF (minimizing interference only) to MMSE (optimizing signal-to-noise-plus-interference ratio). This parameter change allows the system to achieve better power efficiency by considering both interference mitigation and signal strength, resolving the contradiction between low complexity and high power loss.
2Device complexity
If transmit beamforming codebooks with finite resolution are used, then device complexity is reduced, but residual interference increases
Solution Approach 1:
The patent implements a feedback mechanism where user terminals feed back channel state information (CSI) to the base station. This feedback enables the base station to select beamforming vectors that are optimized for current channel conditions, thereby reducing residual interference caused by finite codebook resolution while maintaining manageable device complexity.
3Power
If user terminals select beamforming vectors to maximize their own energy, then individual terminal performance is improved, but interference to other terminals increases
Solution Approach 1:
The base station acts as an intermediary that coordinates beamforming vector selection across multiple user terminals. Instead of terminals independently selecting beams, the base station receives channel information from all terminals, processes this information centrally, and selects a set of compatible terminals to serve simultaneously. This intermediary coordination reduces mutual interference while maintaining good signal power for each terminal.
4Object-generated harmful factors
If base station selects terminals with small spatial correlation, then interference is reduced, but system productivity decreases due to limited simultaneous users
Solution Approach 1:
The patent implements dynamic terminal selection based on current channel conditions rather than static spatial correlation constraints. The base station dynamically selects a set of user terminals to serve simultaneously by evaluating channel state information from all terminals and choosing combinations that optimize overall system performance. This dynamic approach allows more terminals to be served concurrently while maintaining acceptable interference levels, thereby increasing system productivity.
Data Source
AI summary
A method of wireless communication is disclosed that includes receiving detected channel information from a plurality of access terminals (402); selecting a set of access terminals from the plurality of access terminals based on the received channel information; creating a beamforming vector for each access terminal in the set of selected access terminals (406); and transmitting a signal using at least one of the created beamforming vectors (408). An apparatus for performing the method is also disclosed herein.