On the Coexistence of OTFS Modulation with OFDM-based Communication Systems

Fuente: arXiv
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Main Authors: Shafie, Akram, Yuan, Jinhong, Fitzpatrick, Paul, Sakurai, Taka, Fang, Yuting
Format: Preprint
Published: 2024
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author Shafie, Akram
Yuan, Jinhong
Fitzpatrick, Paul
Sakurai, Taka
Fang, Yuting
author_facet Shafie, Akram
Yuan, Jinhong
Fitzpatrick, Paul
Sakurai, Taka
Fang, Yuting
contents We investigate the coexistence of orthogonal time-frequency space (OTFS) modulation with current fourth- and fifth-generation (4G/5G) communication systems that primarily use orthogonal frequency-division multiplexing (OFDM) waveforms. We first derive the input-output-relation of OTFS in the considered coexisting system. In this derivation, we consider (i) the inclusion of multiple cyclic prefixes (CPs) with unequal lengths to the OTFS signal and (ii) edge carrier unloading (ECU), to account for the impacts of CP length, frame structure, and subcarrier arrangement described in 3GPP standards for 4G/5G systems. Our analysis reveals that the inclusion of multiple CPs to the OTFS signal and ECU lead to the channel response exhibiting spreading effects/leakage along the Doppler and delay dimensions, respectively. Consequently, the effective sampled delay-Doppler (DD) domain channel model for OTFS in coexisting systems may exhibit reduced sparsity. We also show that the effective DD domain channel coefficients for OTFS in coexisting systems are influenced by the unequal lengths of CPs. Subsequently, we propose an interference cancellation-based channel estimation (CE) technique for OTFS in coexisting systems. Through numerical results, we validate our analysis, highlight the importance of not ignoring the unequal lengths of CPs during signal detection, and show the significance of the proposed CE technique.
format Preprint
id arxiv_https___arxiv_org_abs_2406_18592
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On the Coexistence of OTFS Modulation with OFDM-based Communication Systems
Shafie, Akram
Yuan, Jinhong
Fitzpatrick, Paul
Sakurai, Taka
Fang, Yuting
Signal Processing
We investigate the coexistence of orthogonal time-frequency space (OTFS) modulation with current fourth- and fifth-generation (4G/5G) communication systems that primarily use orthogonal frequency-division multiplexing (OFDM) waveforms. We first derive the input-output-relation of OTFS in the considered coexisting system. In this derivation, we consider (i) the inclusion of multiple cyclic prefixes (CPs) with unequal lengths to the OTFS signal and (ii) edge carrier unloading (ECU), to account for the impacts of CP length, frame structure, and subcarrier arrangement described in 3GPP standards for 4G/5G systems. Our analysis reveals that the inclusion of multiple CPs to the OTFS signal and ECU lead to the channel response exhibiting spreading effects/leakage along the Doppler and delay dimensions, respectively. Consequently, the effective sampled delay-Doppler (DD) domain channel model for OTFS in coexisting systems may exhibit reduced sparsity. We also show that the effective DD domain channel coefficients for OTFS in coexisting systems are influenced by the unequal lengths of CPs. Subsequently, we propose an interference cancellation-based channel estimation (CE) technique for OTFS in coexisting systems. Through numerical results, we validate our analysis, highlight the importance of not ignoring the unequal lengths of CPs during signal detection, and show the significance of the proposed CE technique.
title On the Coexistence of OTFS Modulation with OFDM-based Communication Systems
topic Signal Processing
url https://arxiv.org/abs/2406.18592