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Robust and Low-Complexity Timing Synchronization for DCO-OFDM LiFi Systems

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Robust and Low-Complexity Timing Synchronization for DCO-OFDM LiFi Systems. / Jiang, Yufei; Wang, Yunlu; Cao, Pan; Safari, Majid; Thompson, John; Haas, Harald.

In: IEEE Journal of Selected Areas in Communications, Vol. 36, No. 1, 01.01.2018, p. 53-65.

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Jiang, Yufei ; Wang, Yunlu ; Cao, Pan ; Safari, Majid ; Thompson, John ; Haas, Harald. / Robust and Low-Complexity Timing Synchronization for DCO-OFDM LiFi Systems. In: IEEE Journal of Selected Areas in Communications. 2018 ; Vol. 36, No. 1. pp. 53-65.

Bibtex

@article{7db932e3847a4d9e8dfbca2ca9b0fcb7,
title = "Robust and Low-Complexity Timing Synchronization for DCO-OFDM LiFi Systems",
abstract = "Light fidelity (LiFi), using light emitting devices such as light emitting diodes (LEDs) which are operating in the visible light spectrum between 400 and 800 THz, provides a new layer of wireless connectivity within existing heterogeneous radio frequency wireless networks. Link data rates of 10 Gbps from a single transmitter have been demonstrated under ideal laboratory conditions. Synchronization is one of these issues usually assumed to be ideal. However, in a practical deployment, this is no longer a valid assumption. Therefore, we propose for the first time a low-complexity maximum likelihood-based timing synchronization process that includes frame detection and sampling clock synchronization for direct current-biased optical orthogonal frequency division multiplexing LiFi systems. The proposed timing synchronization structure can reduce the high-complexity two-dimensional search to two low-complexity one-dimensional searches for frame detection and sampling clock synchronization. By employing a single training block, frame detection can be realized, and then sampling clock offset (SCO) and channels can be estimated jointly. We propose three frame detection approaches, which are robust against the combined effects of both SCO and the low-pass characteristic of LEDs. Furthermore, we derive the Cram{\'e}r-Rao lower bounds (CRBs) of SCO and channel estimations, respectively. In order to minimize the CRBs and improve synchronization performance, a single training block is designed based on the optimization of training sequences, the selection of training length, and the selection of direct current (DC) bias. Therefore, the designed training block allows us to analyze the trade-offs between estimation accuracy, spectral efficiency, energy efficiency, and complexity. The proposed timing synchronization mechanism demonstrates low complexity and robustness benefits and provides performance significantly better than achieved with existing methods.",
keywords = "DCO-OFDM, Light fidelity (LiFi), frame detection, sampling clock offset (SCO), timing synchronization",
author = "Yufei Jiang and Yunlu Wang and Pan Cao and Majid Safari and John Thompson and Harald Haas",
note = "Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.",
year = "2018",
month = jan,
day = "1",
doi = "10.1109/JSAC.2017.2774419",
language = "English",
volume = "36",
pages = "53--65",
journal = "IEEE Journal of Selected Areas in Communications",
issn = "0733-8716",
publisher = "Institute of Electrical and Electronics Engineers Inc.",
number = "1",

}

RIS

TY - JOUR

T1 - Robust and Low-Complexity Timing Synchronization for DCO-OFDM LiFi Systems

AU - Jiang, Yufei

AU - Wang, Yunlu

AU - Cao, Pan

AU - Safari, Majid

AU - Thompson, John

AU - Haas, Harald

N1 - Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

PY - 2018/1/1

Y1 - 2018/1/1

N2 - Light fidelity (LiFi), using light emitting devices such as light emitting diodes (LEDs) which are operating in the visible light spectrum between 400 and 800 THz, provides a new layer of wireless connectivity within existing heterogeneous radio frequency wireless networks. Link data rates of 10 Gbps from a single transmitter have been demonstrated under ideal laboratory conditions. Synchronization is one of these issues usually assumed to be ideal. However, in a practical deployment, this is no longer a valid assumption. Therefore, we propose for the first time a low-complexity maximum likelihood-based timing synchronization process that includes frame detection and sampling clock synchronization for direct current-biased optical orthogonal frequency division multiplexing LiFi systems. The proposed timing synchronization structure can reduce the high-complexity two-dimensional search to two low-complexity one-dimensional searches for frame detection and sampling clock synchronization. By employing a single training block, frame detection can be realized, and then sampling clock offset (SCO) and channels can be estimated jointly. We propose three frame detection approaches, which are robust against the combined effects of both SCO and the low-pass characteristic of LEDs. Furthermore, we derive the Cramér-Rao lower bounds (CRBs) of SCO and channel estimations, respectively. In order to minimize the CRBs and improve synchronization performance, a single training block is designed based on the optimization of training sequences, the selection of training length, and the selection of direct current (DC) bias. Therefore, the designed training block allows us to analyze the trade-offs between estimation accuracy, spectral efficiency, energy efficiency, and complexity. The proposed timing synchronization mechanism demonstrates low complexity and robustness benefits and provides performance significantly better than achieved with existing methods.

AB - Light fidelity (LiFi), using light emitting devices such as light emitting diodes (LEDs) which are operating in the visible light spectrum between 400 and 800 THz, provides a new layer of wireless connectivity within existing heterogeneous radio frequency wireless networks. Link data rates of 10 Gbps from a single transmitter have been demonstrated under ideal laboratory conditions. Synchronization is one of these issues usually assumed to be ideal. However, in a practical deployment, this is no longer a valid assumption. Therefore, we propose for the first time a low-complexity maximum likelihood-based timing synchronization process that includes frame detection and sampling clock synchronization for direct current-biased optical orthogonal frequency division multiplexing LiFi systems. The proposed timing synchronization structure can reduce the high-complexity two-dimensional search to two low-complexity one-dimensional searches for frame detection and sampling clock synchronization. By employing a single training block, frame detection can be realized, and then sampling clock offset (SCO) and channels can be estimated jointly. We propose three frame detection approaches, which are robust against the combined effects of both SCO and the low-pass characteristic of LEDs. Furthermore, we derive the Cramér-Rao lower bounds (CRBs) of SCO and channel estimations, respectively. In order to minimize the CRBs and improve synchronization performance, a single training block is designed based on the optimization of training sequences, the selection of training length, and the selection of direct current (DC) bias. Therefore, the designed training block allows us to analyze the trade-offs between estimation accuracy, spectral efficiency, energy efficiency, and complexity. The proposed timing synchronization mechanism demonstrates low complexity and robustness benefits and provides performance significantly better than achieved with existing methods.

KW - DCO-OFDM

KW - Light fidelity (LiFi)

KW - frame detection

KW - sampling clock offset (SCO)

KW - timing synchronization

UR - http://www.scopus.com/inward/record.url?scp=85035094085&partnerID=8YFLogxK

U2 - 10.1109/JSAC.2017.2774419

DO - 10.1109/JSAC.2017.2774419

M3 - Article

VL - 36

SP - 53

EP - 65

JO - IEEE Journal of Selected Areas in Communications

JF - IEEE Journal of Selected Areas in Communications

SN - 0733-8716

IS - 1

ER -