54 citations · 173 across the 14 of their papers we have counts for
14 papers
Learning Asymptotics with Convergence-Rate Guarantees using Linear Least Squares
Christos N. Efrem
We introduce a new research area that is called Asymptotics Learning Theory (ALT) and combines optimization with asymptotic analysis. In particular, ALT provides a unified approach…
Functional Equations for Generalized Collatz Dynamics Using Integral Representations and Residue Calculus
Christos N. Efrem
This paper focuses on a wide class of Collatz-type arithmetic dynamics, and presents a systematic derivation of recursive formulas and functional equations satisfied by the associa…
Joint Power Allocation and Reflecting-Element Activation for Energy Efficiency Maximization in IRS-Aided Communications Under CSI Uncertainty
Christos N. Efrem, Ioannis Krikidis
We study the joint power allocation and reflecting element (RE) activation to maximize the energy efficiency (EE) in communication systems assisted by an intelligent reflecting sur…
Transmit and Receive Antenna Port Selection for Channel Capacity Maximization in Fluid-MIMO Systems
Christos N. Efrem, Ioannis Krikidis
In this letter, we study a discrete optimization problem, namely, the maximization of channel capacity in fluid multiple-input multiple-output (fluid-MIMO) systems through the sele…
Recurrence relations for the joint distribution of the sum and maximum of independent random variables
Christos N. Efrem
In this paper, the joint distribution of the sum and maximum of independent, not necessarily identically distributed, nonnegative random variables is studied for two cases: i) cont…
Robust IRS-Element Activation for Energy Efficiency Optimization in IRS-Assisted Communication Systems With Imperfect CSI
Christos N. Efrem, Ioannis Krikidis
In this paper, we study an intelligent reflecting surface (IRS)-aided communication system with single-antenna transmitter and receiver, under imperfect channel state information (…