Uniform Power Coefficient Assignment in Cell-Free Massive MIMO
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Solution Overview
Problem
In massive MIMO wireless systems, existing technologies face challenges in optimizing transmit power to reduce interference between pilot sequences, which affects the accuracy of channel coefficient estimation and overall throughput for all access terminals.
Innovation Solution
A central node computes and assigns a uniform power coefficient to each access terminal, using an approximation vector to determine the power coefficients based on channel estimates, which are then used to create a precoding matrix that minimizes interference and optimizes signal transmission across the network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optimal power coefficients are computed using max-min criterion to reduce interference between pilot sequences, then the quality of channel coefficient estimation is improved, but the computational complexity increases
Solution Approach 1:
The patent employs a simplified approximation method for computing power coefficients that sacrifices some optimality for dramatically reduced computational complexity. Instead of using the computationally intensive max-min criterion, the system uses an approximation formula (Equation 36) that provides sufficiently accurate results with much lower computational burden, enabling practical deployment in cell-free massive MIMO systems.
Solution Approach 2:
The patent changes the computational approach from exact optimization to approximation by modifying how power coefficients are calculated. The system transitions from solving complex optimization problems to using closed-form approximations based on channel statistics, thereby reducing computational complexity while maintaining acceptable estimation quality.
2Productivity
If uniform power coefficients are assigned to all access terminals, then the system achieves uniformly high throughput for all ATs, but the ability to optimize individual terminal performance is reduced
Solution Approach 1:
The patent applies the equipotentiality principle by assigning uniform power coefficients to all access terminals, creating an equalized system where all terminals experience similar service quality. This approach ensures that no terminal is significantly disadvantaged, achieving uniformly high throughput across the network by eliminating power-based inequalities between terminals.
3Object-generated harmful factors
If precise power coefficient optimization is performed, then interference between pilot sequences is reduced, but the transmit power consumption increases
Solution Approach 1:
The patent applies partial action by using an approximation method that provides sufficient interference reduction without achieving complete optimal cancellation. This partial optimization approach reduces interference between pilot sequences to an acceptable level while avoiding the excessive transmit power consumption that would result from full optimization, thereby achieving a practical balance between interference suppression and energy efficiency.
Data Source
AI summary
A central node may include a processor configured to empirically compute an approximation of power coefficients based on estimates of the channel coefficients such that a same one of the approximation of the power coefficient is assigned to each of a plurality of access terminals (ATs), and transmit components of a signal vector to associated access points (APs), the signal vector being based on at least the approximation of the power coefficient.