University of Oulu

K. Tsujimura, K. Umebayashi, J. Kokkoniemi, J. Lehtomäki and Y. Suzuki, "A Causal Channel Model for the Terahertz Band," in IEEE Transactions on Terahertz Science and Technology, vol. 8, no. 1, pp. 52-62, Jan. 2018. doi: 10.1109/TTHZ.2017.2771476 URL:

A causal channel model for the terahertz band

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Author: Tsujimura, Kazuhiro1; Umebayashi, Kenta1; Kokkoniemi, Joonas2;
Organizations: 1Department of Electrical and Electronic Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan
2Centre for Wireless Communications, University of Oulu, Oulu 90014, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 3 MB)
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Language: English
Published: Institute of Electrical and Electronics Engineers, 2018
Publish Date: 2018-03-08


Impulse response is vital for wireless communication analysis and modeling. This paper considers the impulse response of the terahertz band (THz band: 0.1–10 THz) for short range (1–100 cm) wireless communication. Earlier works derived the impulse response from transmittance by assuming a linear phase, which corresponds to a line-of-sight (LoS) propagation delay to a receiver. However, the linear phase leads to a symmetric impulse response before and after the LoS propagation delay. Physically, it is impossible for a signal to arrive before the LoS propagation delay since this violates causality. To address this issue, this study derives a phase function leading to an impulse response that satisfies causality. The validity of the derived model is verified with experimental THz band measurements (up to 2 THz), which show excellent agreement with the results predicted by the theory. From the impulse response, coherence bandwidth is found for both the entire THz band and its subbands. The results show significant variations in the coherence bandwidth as a function of the center frequency. Knowledge of these variations supports selection of the proper center frequency for wireless communications in the THz band.

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Series: IEEE transactions on terahertz science and technology
ISSN: 2156-342X
ISSN-E: 2156-3446
ISSN-L: 2156-342X
Volume: 8
Issue: 1
Pages: 52 - 62
DOI: 10.1109/TTHZ.2017.2771476
Type of Publication: A1 Journal article – refereed
Field of Science: 213 Electronic, automation and communications engineering, electronics
Funding: The work of J. Kokkoniemi and J. Lehtomäki was supported in part by the Academy of Finland, in part by the Infotech Oulu Doctoral Program, and in part by the TERRANOVA project funded by Horizon 2020, European Union’s Framework Programme for Research and Innovation under Grant 761794.
EU Grant Number: (761794) TERRANOVA - Terabit/s Wireless Connectivity by TeraHertz innovative technologies to deliver Optical Network Quality of Experience in Systems beyond 5G
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