10 citations · 12 across the 24 of their papers we have counts for
29 papers
Delay-Doppler Duality: Simplifying Exact Equalization of Zak-OTFS in Time or in Frequency
Mudasir Ahmad Sheikh, Robert Calderbank
The Zak-OTFS carrier waveform is a pulse in the delay-Doppler (DD) domain, and given the input-output (I/O) relation at one DD point in a frame, we can predict the I/O relation at…
Low-complexity Equalization of Zak-OTFS Via Neumann Series
Vineetha Yogesh, Saif Khan Mohammed, Sandesh Rao Mattu +2
We describe a general method for selecting an orthonormal basis of carrier waveforms that aligns the basis with delay / Doppler characteristics of a wireless channel. We show that…
Modulation Augmentation and Constellation Shaping for LDPC-Coded QPSK
Heping Wan, Joonyoung Cho, Sandesh Rao Mattu +4
While constellation shaping improves spectral efficiency, its application to quadrature phase-shift keying (QPSK) remains limited. We address this limitation by incorporating a sho…
Improving Doppler Resilience of OFDM through Delay-Doppler Sensing
Danish Nisar, Saif Khan Mohammed, Muhammad Ubadah +2
The performance of traditional CP-OFDM degrades severely in doubly-spread wireless channels due to inter-carrier interference (ICI). In this paper, we propose DD domain sensing bas…
Real-Time and Scalable Zak-OTFS Receiver Processing on GPUs
Junyao Zheng, Chung-Hsuan Tung, Yuncheng Yao +6
Orthogonal time frequency space (OTFS) modulation offers superior robustness to high-mobility channels compared to conventional orthogonal frequency-division multiplexing (OFDM) wa…
Zak-OTFS: A Predictable Physical Layer for Communications and Sensing
Sandesh Rao Mattu, Nishant Mehrotra, Venkatesh Khammammetti +1
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…
Delay-Doppler Channel Estimation using Arbitrarily Modulated Data Transmissions
Nishant Mehrotra, Sandesh Rao Mattu, Robert Calderbank
Conventional delay-Doppler (DD) communication and sensing systems require transmitting pilot frames at every channel coherence time interval in order to keep track of channel varia…
A Universal Neural Receiver that Learns at the Speed of Wireless
Lingjia Liu, Lizhong Zheng, Yang Yi +1
Today we design wireless networks using mathematical models that govern communication in different propagation environments. We rely on measurement campaigns to deliver parametrize…
Does 6G Need a New Waveform: Comparing Zak-OTFS with CP-OFDM
Imran Ali Khan, Saif Khan Mohammed, Ronny Hadani +6
Across the world, there is growing interest in new waveforms, Zak-OTFS in particular, and over-the-air implementations are starting to appear. The choice between OFDM and Zak-OTFS…
Increasing Data Rate through Shaping on Wireless Channels Subject to Mobility and Delay Spread
Sandesh Rao Mattu, Nishant Mehrotra, Robert Calderbank
This letter describes how to improve performance of cellular systems by combining non-equiprobable signaling (shaping) with low-density parity check (LDPC) coding for an orthogonal…
Over-the-Air Transmission of Zak-OTFS on mmWave Communications Testbed
Sabarinath Ramachandran, Venkatesh Khammammetti, Prasanthi Maddala +3
Millimeter-wave (mmWave) communication offers vast bandwidth for next-generation wireless systems but faces severe path loss, Doppler effects, and hardware impairments. Orthogonal…
A Design Framework that Unifies 6G Modulation Schemes for Double Selectivity
Nishant Mehrotra, Sandesh Rao Mattu, Robert Calderbank
There is significant recent interest in designing new modulation schemes for doubly-selective channels with large delay and Doppler spreads, where legacy modulation schemes based o…
Communication in a Fractional World: MIMO MC-OTFS Precoder Prediction
Evan Allen, Karim Said, Robert Calderbank +1
As 6G technologies advance, international bodies and regulatory agencies are intensifying efforts to extend seamless connectivity especially for high-mobility scenarios such as Mob…
Pulse Shaping Filter Design for Integrated Sensing & Communication with Zak-OTFS
Nishant Mehrotra, Sandesh Rao Mattu, Robert Calderbank
Zak-OTFS provides a framework for integrated sensing & communication (ISAC) in high delay and Doppler spread environments. Pulse shaping filter design enables joint optimization of…
Discrete Radar based on Modulo Arithmetic
Nishant Mehrotra, Sandesh Rao Mattu, Saif Khan Mohammed +2
Zak-OTFS is modulation scheme where signals are formed in the delay-Doppler (DD) domain, converted to the time domain (DD) for transmission and reception, then returned to the DD d…
Low-Complexity Equalization of Zak-OTFS in the Frequency Domain
Sandesh Rao Mattu, Nishant Mehrotra, Saif Khan Mohammed +2
4G/5G wireless standards use orthogonal frequency division multiplexing (OFDM) which is robust to frequency selectivity. Equalization is possible with a single tap filter, and low-…
Improving the Spectral Efficiency of Zak-OTFS via Mutually Unbiased Bases
Sandesh Rao Mattu, Nishant Mehrotra, Robert Calderbank
Orthogonal signaling or Nyquist signaling limits the number of information symbols transmitted in bandwidth and time to be , the time-bandwidth product. Transmitting mo…
Zak-OTFS over CP-OFDM
Saif Khan Mohammed, Saurabh Prakash, Muhammad Ubadah +7
Zak-Orthogonal Time Frequency Space (Zak-OTFS) modulation has been shown to achieve significantly better performance compared to the standardized Cyclic-Prefix Orthogonal Frequency…
Instantaneous Polarimetry with Zak-OTFS
Nishant Mehrotra, Sandesh Rao Mattu, Robert Calderbank
Polarimetry, which is the ability to measure the scattering response of the environment across orthogonal polarizations, is fundamental to enhancing wireless communication and rada…
Zak-OTFS Based Coded Random Access for Uplink mMTC
Alessandro Mirri, Venkatesh Khammammetti, Beyza Dabak +3
This paper proposes a grant-free coded random access (CRA) scheme for uplink massive machine-type communications (mMTC), based on Zak-orthogonal time frequency space (Zak-OTFS) mod…
Zak-OTFS based Multiuser Uplink in Doubly-Spread Channels
Imran Ali Khan, Saif Khan Mohammed, Ronny Hadani +2
Wireless users with different characteristics will be expected to share spectrum in next generation communication networks. One of the great strengths of wireless networks based on…
Differential Communication in Channels with Mobility and Delay Spread using Zak-OTFS
Sandesh Rao Mattu, Nishant Mehrotra, Robert Calderbank
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…
Precoded Zak-OTFS for Per-Carrier Equalization
Saif Khan Mohammed, Amit Kumar Pathak, Muhammad Ubadah +3
In Zak-OTFS (orthogonal time frequency space) modulation the carrier waveform is a pulse in the delay-Doppler (DD) domain, formally a quasi-periodic localized function with specifi…
Low-Complexity Frequency Domain Equalization of Zak-OTFS in Doubly-Spread Channels
Saif Khan Mohammed, Sandesh Rao Mattu, Nishant Mehrotra +2
We communicate over wireless channels by first estimating and then equalizing the effective channel. In Zak-OTFS (orthogonal time frequency space) modulation the carrier waveform i…