12 papers
The manifold of unitary and symmetric matrices: characterization, Riemannian optimization and application to BD-RIS design
Ignacio Santamaria, Carlos Beltrán, Eduard Jorswieck +2
This paper proposes and analyzes Riemannian optimization algorithms on the manifold of unitary and symmetric matrices, denoted , which naturally models the scattering…
Optimal symmetric low-rank BD-RIS configuration maximizing the determinant of a MIMO link
Ignacio Santamaria, Mohammad Soleymani, Jesus Gutierrez +1
Beyond-diagonal reconfigurable intelligent surfaces (BD-RISs) significantly improve wireless performance by allowing tunable interconnections among elements, but their design in mu…
Riemannian optimization on the manifold of unitary and symmetric matrices with application to BD-RIS-assisted systems
Ignacio Santamaria, Mohammad Soleymani, Eduard Jorswieck +2
In this paper, we rigorously characterize for the first time the manifold of unitary and symmetric matrices, deriving its tangent space and its geodesics. The resulting parameteriz…
Spectral-Energy Efficiency Tradeoff of Nearly-Passive RIS in MIMO URLLC Downlink: Diagonal vs. Beyond Diagonal
Mohammad Soleymani, Alessio Zappone, Eduard Jorswieck +2
This paper investigates the spectral and energy efficiency (EE) tradeoff of nearly-passive (NP), both locally and globally NP (GNP), reconfigurable intelligent surface (RIS), consi…
STAR-RIS-aided RSMA for the URLLC multi-user MIMO Downlink
Mohammad Soleymani, Ignacio Santamaria, Eduard Jorswieck +2
Rate splitting multiple access (RSMA) is intrinsically amalgamated with simultaneously transmitting and reflecting (STAR) reconfigurable intelligent surfaces (RIS) to enhance energ…
Rate Splitting Multiple Access for RIS-aided URLLC MIMO Broadcast Channels
Mohammad Soleymani, Ignacio Santamaria, Eduard Jorswieck +3
The performance of modern wireless communication systems is typically limited by interference. The impact of interference can be even more severe in ultra-reliable and low-latency…