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We investigate key aspects of coherent optical communications on inter-satellite links (ISLs) for the next-generation ultra-dense low-Earth orbit (LEO) constellations. Initially, the suitability of QPSK, 8-QAM, and 16-QAM modulation formats…

Signal Processing · Electrical Eng. & Systems 2023-07-06 I. P. Vieira , T. C. Pita , D. A. A. Mello

We investigate a new method to augment recurrent neural networks with extra memory without increasing the number of network parameters. The system has an associative memory based on complex-valued vectors and is closely related to…

Neural and Evolutionary Computing · Computer Science 2016-05-20 Ivo Danihelka , Greg Wayne , Benigno Uria , Nal Kalchbrenner , Alex Graves

An important topic of interest in imaging is the construction of protocols that are not diffraction limited. This can be achieved in a variety of ways, including classical superresolution techniques or quantum entanglement-based protocols.…

Quantum Physics · Physics 2015-10-28 Mark E. Pearce , Thomas Mehringer , J. von Zanthier , Pieter Kok

We present two hybrid linear-optical architectures that simultaneously exploit spatial and temporal degrees of freedom of light to effect arbitrary discrete unitary transformations. Our architectures combine the benefits of spatial…

Quantum Physics · Physics 2019-06-12 Daiqin Su , Ish Dhand , Lukas G. Helt , Zachary Vernon , Kamil Bradler

Next-generation networks explore the opportunistic assistance of airliner/high-altitude platforms (HAPs) in delivering high data rates for terrestrial networks to ensure consistent and reliable communication. When an airliner/HAP moves at…

Information Theory · Computer Science 2026-01-22 Ashok S Kumar , Shashank Shekhar , Gokularam Muthukrishnan , Muralikrishnan Srinivasan , Sheetal Kalyani

Spectroscopic experiments have identified long-lived coherences in several light-harvesting systems, suggesting that coherent effects may be relevant to their performance. However, there is limited experimental evidence of coherence…

Chemical Physics · Physics 2019-10-30 Stefano Tomasi , Sima Baghbanzadeh , Saleh Rahimi-Keshari , Ivan Kassal

Recent research on temporal networks has highlighted the limitations of a static network perspective for our understanding of complex systems with dynamic topologies. In particular, recent works have shown that i) the specific order in…

Physics and Society · Physics 2017-11-20 Ingo Scholtes , Nicolas Wider , Antonios Garas

This work addresses the design of multi-agent coordination through high-order consensus protocols. While first-order consensus strategies are well-studied -- with known robustness to uncertainties such as time delays, time-varying weights,…

Systems and Control · Electrical Eng. & Systems 2025-04-11 Jonas Hansson , Emma Tegling

In this paper, we propose time and frequency synchronization techniques for uplink multiuser OTFS (MU-OTFS) systems in high-mobility scenarios. This work focuses on accurately estimating and correcting timing offsets (TOs) and carrier…

Signal Processing · Electrical Eng. & Systems 2025-07-25 Mohsen Bayat , Sanoopkumar P. S. , Arman Farhang

The introduction of silicon chipsets with the capability of processing incoming optical packet traffic, creates a new generation of packet-optical nodes, the whiteboxes. Their inherent functionality of carrying pluggable coherent…

Networking and Internet Architecture · Computer Science 2025-02-05 Constantine A. Kyriakopoulos

Nonlinear optics is a rapidly growing field that has found a wide range of applications. A major limitation, however, is the demand of high power, especially for high-order nonlinearities. Here, by reconfiguring a multiple-scattering…

Optics · Physics 2022-08-19 Yaniv Eliezer , Ulrich Ruhrmair , Nils Wisiol , Stefan Bittner , Hui Cao

Holography has always held special appeal, for it is able to record and display spatial information in three dimensions. Here, we show how to augment the capabilities of digital holography by using a large number of narrow laser lines at…

Multivariate Time-Series (MTS) clustering is crucial for signal processing and data analysis. Although deep learning approaches, particularly those leveraging Contrastive Learning (CL), are prominent for MTS representation, existing…

Machine Learning · Computer Science 2026-01-13 Zexi Tan , Tao Xie , Haoyi Xiao , Baoyao Yang , Yuzhu Ji , An Zeng , Xiang Zhang , Yiqun Zhang

A new paradigm for large-scale spectrum occupancy learning based on long short-term memory (LSTM) recurrent neural networks is proposed. Studies have shown that spectrum usage is a highly correlated time series. Moreover, there is a…

Signal Processing · Electrical Eng. & Systems 2019-05-14 Mohsen Joneidi , Ismail Alkhouri , Nazanin Rahnavard

This paper introduces a new two-dimensional modulation technique called Orthogonal Time Frequency Space (OTFS) modulation. OTFS has the novel and important feature of being designed in the delay-Doppler domain. When coupled with a suitable…

We propose a decomposition method for the spectral peaks in an observed frequency spectrum, which is efficiently acquired by utilizing the Fast Fourier Transform. In contrast to the traditional methods of waveform fitting on the spectrum,…

Signal Processing · Electrical Eng. & Systems 2022-04-19 Kaan Gokcesu , Hakan Gokcesu

In the recent papers [1-4] including above paper time modulated frequency diverse arrays (FDAs) have been presented to obtain time invariant spatial patterns. The presented FDAs in [1-3] have the feature of time-invariant spatial focusing…

Signal Processing · Electrical Eng. & Systems 2019-12-03 Mahdi Fartookzadeh

Optical two-way time and frequency transfer is an enabling technology that has applications ranging from fundamental investigations of relativity to the operation of global navigation satellite systems. While fiber frequency combs have…

This paper studies the performance of hybrid radio-frequency (RF) and free-space optical (FSO) links assuming perfect channel state information (CSI) at the receiver. Considering the cases with and without hybrid automatic repeat request…

Information Theory · Computer Science 2016-11-15 Behrooz Makki , Tommy Svensson , Thomas Eriksson , Mohamed-Slim Alouini

Quantum communication and clock synchronization protocols can be significantly enhanced by the careful preparation of the wavepackets of the produced photons. Following the theoretical proposal published in [Optica, 4, 84 (2017)], we…

Quantum Physics · Physics 2019-03-13 K. Sedziak , M. Lasota , P. Kolenderski