Antenna Array Precoder Transformation for Mutual Coupling
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Solution Overview
Problem
Existing antenna array systems with mutual coupling face challenges in maintaining equal radiated power across different precoders, leading to errors in channel quality evaluation and data rate optimization due to variations in transmit power.
Innovation Solution
Transforming precoders using a transformation matrix with eigenvectors and a diagonal matrix of inverse eigenvalues to ensure equal radiated power across antenna patterns, allowing existing precoders to map to equal energy patterns without requiring additional signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If precoders with equal L2 norm are used in antenna arrays with mutual coupling, then compatibility with existing standards is maintained, but radiated power varies across different precoders leading to channel quality evaluation errors
Solution Approach 1:
The patent transforms the precoder parameters by applying a transformation matrix that accounts for mutual coupling effects. This changes the parameter space from equal L2-norm precoders to equal radiated power precoders, resolving the contradiction by adapting the parameter definition to the physical reality of coupled antennas while maintaining standard compatibility through the transformation relationship
2Measurement precision
If precoders are transformed to achieve equal radiated power, then channel quality evaluation accuracy improves, but additional signaling and processing complexity are required
Solution Approach 1:
The transformation matrix is pre-computed based on the known antenna impedance matrix and mutual coupling characteristics. This preliminary action eliminates the need for real-time computation during operation, reducing processing complexity while maintaining the accuracy benefits of equal radiated power precoding
Solution Approach 2:
The transformation matrix acts as an intermediary that bridges the gap between standard-compliant equal L2-norm precoders and the physically accurate equal radiated power precoders. It translates between the two representations without requiring fundamental changes to the system architecture or signaling protocols
3Device complexity
If mutual coupling is ignored in precoder design, then system simplicity is maintained, but transmit power varies across antenna patterns reducing system efficiency
Solution Approach 1:
The patent modifies the precoder parameter definition to incorporate mutual coupling effects through the transformation matrix. This changes the design from ignoring coupling to explicitly accounting for it, resolving the contradiction by making the system slightly more complex but significantly more energy efficient through equal radiated power normalization
Data Source
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AI summary
A method (700) and apparatus (800) provide equal energy codebooks for antenna arrays with mutual coupling. A plurality of precoders can be received (720) from a codebook in a transmitter having an antenna array. Each precoder of the plurality of precoders can be transformed (730) using a transformation that maps each precoder to equal radiated power to generate transformed precoders. A transformation matrix for the transformation can be a matrix with column vectors equal to the eigenvectors of a Hermitian and non-negative definite matrix multiplied by a diagonal matrix with the value of each diagonal element equal to the inverse of the positive square root of the eigenvalue of the corresponding eigenvector. A signal can be received (740) for transmission. A transformed precoder of the plurality of transformed precoders can be applied (750) to the signal to generate a precoded signal for transmission over a physical channel. The precoded signal can be transmitted (770).