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Zak-transform based orthogonal time frequency space (Zak-OTFS) is a delay-Doppler (DD) domain modulation scheme in which the signal processing is carried out in the DD domain. The channel when viewed in the DD domain is predictable.…

Signal Processing · Electrical Eng. & Systems 2025-07-21 Sandesh Rao Mattu , Nishant Mehrotra , Robert Calderbank

In recent years, orthogonal chirp-division multiplexing (OCDM) has been increasingly considered as an alternative multicarrier scheme, e.g., to orthogonal frequency-division multiplexing, in digital communication applications. Among reasons…

Orthogonal Time Frequency Space ({OTFS}) modulation offers significant advantages over Orthogonal Frequency Division Multiplexing ({OFDM}), particularly in high speed environments. Hence, we consider {OTFS} transmission over high-Doppler…

Signal Processing · Electrical Eng. & Systems 2026-05-12 Xinyu Feng , Chao Zhang , Mohammed EL-Hajjar , Chao Xu , Lajos Hanzo

Wireless channels generally exhibit dispersion in both time and frequency domain, known as doubly selective or doubly dispersive channels. To combat the delay spread effect, multicarrier modulation (MCM) such as orthogonal frequency…

Information Theory · Computer Science 2019-09-19 Xiaojie Wang , Stephan ten Brink

This study examines the coexistence of orthogonal time-frequency space (OTFS) modulation with current fourth- and fifth-generation (4G/5G) wireless communication systems that primarily use orthogonal frequency-division multiplexing (OFDM)…

Signal Processing · Electrical Eng. & Systems 2024-10-28 Akram Shafie , Jinhong Yuan , Yuting Fang , Paul Fitzpatrick , Taka Sakurai

We study channel parameter estimation for multiuser orthogonal time frequency space (OTFS) systems in the delay-Doppler (DD) domain. To enable structured parametric estimation, we adopt a multi-user pilot cyclic prefix (MU-PCP) design,…

Signal Processing · Electrical Eng. & Systems 2026-05-07 Hanning Wang , Rong-Rong Chen , Arman Farhang

Millimeter-wave (mmWave) communication offers vast bandwidth for next-generation wireless systems but faces severe path loss, Doppler effects, and hardware impairments. Orthogonal Time Frequency Space (OTFS) modulation has emerged as a…

Signal Processing · Electrical Eng. & Systems 2025-11-12 Sabarinath Ramachandran , Venkatesh Khammammetti , Prasanthi Maddala , Narayan Mandayam , Ivan Seskar , Robert Calderbank

Orthogonal frequency division multiplexing (OFDM) is a modulation technique susceptible to source, channel and amplifier nonlinearities because of its high peak-to-average ratio (PAPR). The distortion gets worse by increasing the average…

Information Theory · Computer Science 2014-04-07 Mohammad Noshad , Maite Brandt-Pearce

We study multipath parameter estimation from orthogonal frequency division multiplex signals transmitted over doubly dispersive mobile radio channels. We are interested in cases where the transmission is long enough to suffer time…

Information Theory · Computer Science 2016-11-18 Nick Letzepis , Alex Grant , Paul Alexander , David Haley

In this paper, we present a unique word (UW)-based channel estimation approach for multiple-input multiple-output (MIMO) systems under doubly dispersive channels, which is applied to orthogonal time frequency space (OTFS) with space time…

Signal Processing · Electrical Eng. & Systems 2021-04-05 Roberto Bomfin , Marwa Chafii , Ahmad Nimr , Gerhard Fettweis

In this work, we derive a equivalent delay-Doppler channel matrix of the Orthogonal Time Frequency Space (OTFS) modulation that has not been studied in previous literature. It has the similar structure as the banded channel matrix of OFDM…

Information Theory · Computer Science 2017-09-11 Li Li , Hua Wei , Yao Huang , Yao Yao , Weiwei Ling , Gong Chen , Peng Li , Yunlong Cai

Visible light communications (VLC) have recently attracted a growing interest and can be a potential solution to realize indoor wireless communication with high bandwidth capacity for RF-restricted environments such as airplanes and…

Information Theory · Computer Science 2016-11-18 Bilal A. Ranjha , Mohammadreza A. Kashani , Mohsen Kavehrad , Peng Deng

We propose and model an optical communication scheme for short distance datacom links based on the distribution of information across a wide comb spectrum. This modulation format, orthogonal delay division multiplexing, allows the…

Optics · Physics 2023-10-27 Andrea Zazzi , Jeremy Witzens

Orthogonal time frequency space modulation (OTFS) has been recently proposed to achieve time and frequency diversity, especially in linear time-variant (LTV) channels with large Doppler frequencies. The idea is based on the precoding of the…

Signal Processing · Electrical Eng. & Systems 2019-07-11 Ahmad Nimr , Marwa Chafii , Maximilian Matthe , Gerhard Fettweis

In dynamically varying optical wireless communication (OWC) links, conventional quadrature amplitude modulation (QAM) in optical orthogonal frequency-division multiplexing (OFDM) requires frequent channel estimation and equalization,…

Optics · Physics 2026-03-19 Tian Cao , Ping Wang , Tianfeng Wu , Kaile Wang , Jian Song

We provide a performance evaluation of orthogonal time frequency space (OTFS) modulation in cell-free massive MIMO (multiple-input multiple-output) systems. By leveraging the inherent sparsity of the delay-Doppler (DD) representation of…

Information Theory · Computer Science 2022-04-13 Mohammadali Mohammadi , Hien Quoc Ngo , Michail Matthaiou

This tutorial derives the mathematical foundations of what it means for a carrier waveform to be predictable and non-selective. We focus on Zak-OTFS, where each carrier waveform is a pulse in the delay-Doppler (DD) domain, formally a…

Information Theory · Computer Science 2026-04-21 Sandesh Rao Mattu , Nishant Mehrotra , Venkatesh Khammammetti , Robert Calderbank

Orthogonal delay-Doppler division multiplexing (ODDM) is a promising modulation technique for reliable communications in high-mobility scenarios. However, the existing channel estimation frameworks for ODDM systems cannot achieve both high…

Econometrics · Economics 2026-02-10 Jiasong Han , Xuehan Wang , Jingbo Tan , Jintao Wang , Yu Zhang , Hai Lin , Jinhong Yuan

Wavelength division multiplex (WDM) system with on / off keying (OOK) modulation and direct detection (DD) is generally simple to implement, less expensive and energy efficient. The determination of the possible design capacity limit, in…

Signal Processing · Electrical Eng. & Systems 2018-10-16 Akinwumi Amusan , Elizabeth Amusan

In this paper, we propose a novel joint coding-modulation technique based on serial concatenation of orthogonal linear transform, such as discrete Fourier transform (DFT) or Walsh-Hadamard transform (WHT), with memoryless nonlinearity. We…

Information Theory · Computer Science 2018-01-22 Sergey V. Zhidkov