SNR Maximization in Beyond Diagonal RIS-Assisted Single and Multiple Antenna Links
Ignacio Santamarı́a, Mohammad Soleymani, Eduard A. Jorswieck, Jesús Gutiérrez
Abstract
Reconfigurable intelligent surface (RIS) architectures not limited to diagonal phase shift matrices have recently been considered to increase their flexibility in shaping the wireless channel. One of these beyond-diagonal RIS or BD-RIS architectures leads to a unitary and symmetric RIS matrix. In this letter, we consider the problem of maximizing the signal-to-noise ratio (SNR) in single and multiple antenna links assisted by a BD-RIS. The Max-SNR problem admits a closed-form solution based on the Takagi factorization of a certain complex and symmetric matrix. This allows us to solve the max-SNR problem for SISO, SIMO, and MISO channels.
Topics & Concepts
DiagonalMaximizationChannel (broadcasting)Matrix decompositionFactorizationSignal-to-noise ratio (imaging)WirelessAntenna (radio)QR decompositionUnitary matrixMatrix (chemical analysis)Computer scienceDiagonal matrixMathematicsAlgorithmMathematical optimizationTelecommunicationsUnitary statePhysicsMaterials scienceEigenvalues and eigenvectorsGeometryComposite materialPolitical scienceLawQuantum mechanicsAdvanced Wireless Communication TechnologiesAdvanced Antenna and Metasurface TechnologiesSatellite Communication Systems