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Free space optical (FSO) communication channels are typically used to transmit high-speed data between sites over the air. Here we repurpose an FSO digital communication system and use it directly for two-way time transfer. We demonstrate…

Instrumentation and Detectors · Physics 2018-08-22 Isaac Khader , Hugo Bergeron , Laura C. Sinclair , William C. Swann , Nathan R. Newbury , Jean-Daniel Deschênes

Cell-free Massive multiple-input multiple-output (MIMO) ensures ubiquitous communication at high spectral efficiency (SE) thanks to increased macro-diversity as compared cellular communications. However, system scalability and performance…

Information Theory · Computer Science 2019-09-09 Giovanni Interdonato , Marcus Karlsson , Emil Björnson , Erik G. Larsson

In this paper, we characterize the asymmetric total degrees of freedom (DoF) of a multiple-input multiple-output (MIMO) 3-way channel. Each node has a separate-antenna full-duplex MIMO transceiver with a different number of antennas, where…

Information Theory · Computer Science 2016-08-02 Adel M. Elmahdy , Amr El-Keyi , Yahya Mohasseb , Tamer ElBatt , Mohammed Nafie , Karim G. Seddik , Tamer Khattab

This paper proposes two approaches for overcoming access points' phase misalignment effects in the downlink of cell-free massive MIMO (CF-mMIMO) systems. The first approach is based on the differential space-time block coding technique,…

Information Theory · Computer Science 2025-03-10 Marx M. M. Freitas , Stefano Buzzi , Giovanni Interdonato

Wi-Fi tracking technology demonstrates promising potential for future smart home and intelligent family care. Currently, accurate Wi-Fi tracking methods rely primarily on fine-grained velocity features. However, such velocity-based…

Signal Processing · Electrical Eng. & Systems 2026-01-19 Mengning Li , Wenye Wang

A full-duplex (FD) multiple antenna access point (AP) communicating with single antenna half-duplex (HD) spatially random users to support simultaneous uplink (UL)/downlink (DL) transmissions is investigated. Since FD nodes are inherently…

Information Theory · Computer Science 2016-11-18 Mohammadali Mohammadi , Himal A. Suraweera , Yun Cao , Ioannis Krikidis , Chintha Tellambura

In this paper, we formulate two multi-objective optimization problems (MOOPs) in orthogonal frequency-division multiple access (OFDMA)-based in-band full-duplex (IBFD) wireless communications.~The aim of this study is to exploit the…

Information Theory · Computer Science 2020-07-29 Ata Khalili , Mohammad Robat Mili , Derrick Wing Kwan Ng

We present the generalised design of low-complexity, small aperture optical terminals intended for kilometre-scale, terrestrial, free-space laser links between fixed and dynamic targets. The design features single-mode fibre coupling of the…

Instrumentation and Detectors · Physics 2024-07-09 Alex M. Frost , Benjamin P. Dix-Matthews , Shane M. Walsh , David R. Gozzard , Sascha W. Schediwy

We show that an M X N user MIMO X network with A antennas at each node has AMN/(M+N-1) degrees of freedom (DoF), thus resolving in this case a discrepancy between the spatial scale invariance conjecture (scaling the number of antennas at…

Information Theory · Computer Science 2013-08-23 Hua Sun , Chunhua Geng , Tiangao Gou , Syed A. Jafar

In this paper, we present an experimental and simulation based study to evaluate the use of full-duplex as a mode in practical IEEE 802.11 networks. To enable the study, we designed a 20 MHz multi-antenna OFDM full-duplex physical layer and…

Networking and Internet Architecture · Computer Science 2014-07-15 Melissa Duarte , Ashutosh Sabharwal , Vaneet Aggarwal , Rittwik Jana , K. K. Ramakrishnan , Christopher Rice , N. K. Shankaranarayanan

This paper investigates reconfigurable intelligent surface (RIS)-aided frequency division duplexing (FDD) communication systems. Since the downlink and uplink signals are simultaneously transmitted in FDD, the phase shifts at the RIS should…

Information Theory · Computer Science 2024-01-23 Gyoseung Lee , Hyeongtaek Lee , Donghwan Kim , Jaehoon Chung , A. Lee. Swindlehurst , Junil Choi

We study the sum degrees of freedom (DoF) of the bursty MIMO X channel without feedback, where the four transmitter-receiver links are intermittently on-and-off, controlled by four Bernoulli random sequences which may be arbitrarily…

Information Theory · Computer Science 2018-01-03 Shih-Yi Yeh , I-Hsiang Wang

We demonstrated combined free-space optics (FSO) and D-band(110-170GHz) millimeter(mm-wave) transceiver enabled by precisely locked lasers with low phase noise. Combined capacity and tolerance to angle misalignment are studied using 100Gb/s…

Optics · Physics 2026-01-01 Zichuan Zhou , Amany Kassem , Zun Htay , Izzat Darwazeh , Zhixin Liu

We consider two-way amplify and forward relaying, where multiple full-duplex user pairs exchange information via a shared full-duplex massive multiple-input multiple-output (MIMO) relay. We derive closed-form lower bound for the spectral…

Information Theory · Computer Science 2017-10-04 Ekant Sharma , Rohit Budhiraja , K Vasudevan

Free space optical (FSO) communication refers to the information transmission technology based on the propagation of optical signals in space. FSO communication requires that the transmitter and receiver directly see each other.…

Networking and Internet Architecture · Computer Science 2023-01-20 Dieu Linh Truong , Xuan Vuong Dang , The Ngoc Dang

Designing beamforming techniques for the downlink (DL) of frequency division duplex (FDD) massive MIMO is known to be a challenging problem due to the difficulty of obtaining channel state information (CSI). Indeed, since the…

Signal Processing · Electrical Eng. & Systems 2020-04-02 François Rottenberg , Ming-Chun Lee , Thomas Choi , Jianzhong Zhang , Andreas F. Molisch

In this paper, we first propose interference alignment (IA) scheme for uplink transmission of multiple-input-mulitple-output (MIMO) cellular network with a help of relay which operates in halfduplex mode. The proposed scheme only requires…

Information Theory · Computer Science 2017-05-23 Hoyoun Kim , Jong-Seon No

This paper introduces a novel beam tracking scheme for full-duplex ground user terminals aiming to transmit uplink and receive downlink from two low Earth orbit (LEO) satellites at the same time and same frequency. Our proposed technique…

Signal Processing · Electrical Eng. & Systems 2024-11-15 Chaeyeon Kim , Joohyun Son , Daesik Hong , Ian P. Roberts

We investigate transmission protocols for relay-assisted free-space optical (FSO) systems, when multiple parallel relays are employed and there is no direct link between the source and the destination. As alternatives to all-active FSO…

In this paper, we analyze the performance of a two- way subcarrier intensity-modulated (SIM) amplify-and-forward (AF) relaying system over free-space optics (FSO) communication channels. The analysis takes into consideration attenuations…

Information Theory · Computer Science 2017-08-18 Jaedon Park , Chan-Byoung Chae , Giwan Yoon