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Tight capacity bounds for indoor visible light communications with signal-dependent noise

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arXiv 2020年

作者： Wang, Jin-Yuan Fu, Xian-Tao Lu, Rong-Rong Wang, Jun-Bo Lin, Min Cheng, Julian Key Laboratory of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Nanjing210003 China Shanghai Key Laboratory of Trustworthy Computing East China Normal University Shanghai200062 China Key Laboratory of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Nanjing210003 China National Mobile Communications Research Laboratory Southeast University Nanjing211111 China School of Engineering University of British Columbia KelownaBCV1V 1V7 Canada

Channel capacity bounds are derived for a point-to-point indoor visible light communications (VLC) system with signal-dependent Gaussian noise. Considering both illumination and communication, the non-negative input of VLC is constrained by peak and average optical intensity constraints. Two scenarios are taken into account: one scenario has both average and peak optical intensity constraints, and the other scenario has only average optical intensity constraint. For both two scenarios, we derive closed-from expressions of capacity lower and upper bounds. Specifically, the capacity lower bound is derived by using the variational method and the property that the output entropy is invariably larger than the input entropy. The capacity upper bound is obtained by utilizing the dual expression of capacity and the principle of "capacity-achieving source distributions that escape to infinity". Moreover, the asymptotic analysis shows that the asymptotic performance gap between the capacity lower and upper bounds approaches zero. Finally, all derived capacity bounds are confirmed using numerical results. Copyright © 2020, The Authors. All rights reserved.

关键词： Gaussian noise (electronic)

Scheme for realizing passive quantum key distribution with heralded single-photon sources

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Physical Review A 2016年第3期93卷 032312-032312页

作者： Qin Wang Chun-Hui Zhang Xiang-Bin Wang Institute of Signal Processing and Transmission Nanjing University of Posts and Telecommunications Nanjing 210003 China Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Ministry of Education Nanjing 210003 China Key Laboratory of Quantum Information University of Science and Technology of China Hefei 230026 China Department of Physics and State Key Laboratory of Low Dimensional Quantum Physics Tsinghua University Beijing 100084 China Jinan Institute of Quantum Technology Shandong Academy of Information Technology Jinan China

We present a scheme for realizing passive quantum key distribution with heralded single-photon sources. In this scheme, the idler light from the parametric down-conversion process is split into two parts and sent into two local detectors individually. Then all the clicking and nonclicking events are used to herald the arrival and nonarrival of the signal light. As a result, a precise estimation of the behavior of the single-photon pulses can be achieved without changing the light intensity. Furthermore, we compare our scheme with other existing methods with the Bennett-Brassard 1984 (BB84) protocol through numerical simulations. Our simulations demonstrate that the performance of our scheme can greatly overcome other existing practical methods and approach very close to the asymptotic case of using infinite-decoy-state methods.

关键词： Quantum cryptography

Measurement-device-independent quantum key distribution of multiple degrees of freedom of a single photon

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arXiv 2020年

作者： Yan, Yu-Fei Zhou, Lan Zhong, Wei Sheng, Yu-Bo Institute of Quantum Information and Technology Nanjing University of Posts and Telecommunications Nanjing210003 China Schoool of Science Nanjing University of Posts and Telecommunications Nanjing210003 China Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Ministry of Education Nanjing210003 China

Measurement-device-independent quantum key distribution (MDI-QKD) provides us a powerful approach to resist all attacks at detection side. Besides the unconditional security, people also seek for high key generation rate, but MDI-QKD has relatively low key generation rate. In this paper, we provide an efficient approach to increase the key generation rate of MDI-QKD by adopting multiple degrees of freedom (DOFs) of single photons to generate keys. Compared with other high-dimension MDI-QKD protocols encoding in one DOF, our protocol is more flexible, for our protocol generating keys in independent subsystems and the detection failure or error in a DOF not affecting the information encoding in other DOFs. Based on above features, our MDI-QKD protocol may have potential application in future quantum communication field. Copyright © 2020, The Authors. All rights reserved.

关键词： Quantum cryptography

First-order-reflection MIMO channel model for 60 GHz NLOS indoor WLAN systems

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First-order-reflection MIMO channel model for 60 GHz NLOS in...

International Conference on communication Systems

作者： Lei Wang Jianxin Chen Xin Wei Jingwu Cui Baoyu Zheng National Mobile Comm. Research Laboratory Southeast University Nanjing China Ministry of Education Key Lab of Broadband Wireless Comm. and Sensor Network Technology (Nanjing University of Posts & Telecomm.) Nanjing China

ISBN: (纸本)9781479958337

wireless communications employing 60 GHz millimeter wave are quite attractive recently due to the huge clean unlicensed bandwidth (up to 7 GHz) in this frequency band. In this paper, aiming at increasing channel capacity and improving the reliability of non-line-of-sight (NLOS) indoor wireless communications, we focus on a first-order-reflection multiple input multiple output (MIMO) model for 60 GHz wireless local area network (WLAN) systems based on the short-range indoor scenario provided by IEEE Std 802.11ad. Considering the special physical properties of 60 GHz millimeter wave in such scenario, we use large scale planar antenna arrays at both transmitter and receiver to eliminate link level interference. The antenna arrays are divided into several sub-arrays and each sub-array is considered as a high-gain steerable directional antenna unit. The essential characteristics of the physical layer of this model is to adjust these antenna units along different first-order-reflection clusters from walls or ceiling simultaneously at both transmitter and receiver to get several parallel channel links. System level simulation results demonstrate that the proposed model with multiple first-order-reflection links can increase the channel capacity for several times compared to the original model in this scenario.

关键词： MIMO Antenna arrays Signal to noise ratio wireless communication Interference IEEE standards Receivers

When Digital Twin Meets 6G: Concepts, Obstacles, and Research Prospects

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arXiv 2024年

作者： Liu, Wenshuai Fu, Yaru Shi, Zheng Wang, Hong The School of Science and Technology Hong Kong Metropolitan University 999077 Hong Kong The School of Intelligent Systems Science and Engineering Jinan University Zhuhai519070 China The Key Lab of Broadband Wireless Communication and Sensor Network Technology of Ministry of Education Nanjing University of Posts and Telecommunications Nanjing210003 China

The convergence of digital twin technology and the emerging 6G network presents both challenges and numerous research opportunities. This article explores the potential synergies between digital twin and 6G, highlighting the key challenges and proposing fundamental principles for their integration. We discuss the unique requirements and capabilities of digital twin in the context of 6G networks, such as sustainable deployment, real-time synchronization, seamless migration, predictive analytic, and closed-loop control. Furthermore, we identify research opportunities for leveraging digital twin and artificial intelligence to enhance various aspects of 6G, including network optimization, resource allocation, security, and intelligent service provisioning. This article aims to stimulate further research and innovation at the intersection of digital twin and 6G, paving the way for transformative applications and services in the future. Copyright © 2024, The Authors. All rights reserved.

关键词： Resource allocation

Biased decoy-state reference-frame-independent quantum key distribution

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arXiv 2017年

作者： Zhu, Jian-Rong Zhang, Chun-Mei Guo, Guang-Can Wang, Qin Institute of Signal Processing Transmission Nanjing University of Posts and Telecommunications Nanjing210003 China Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Ministry of Education Nanjing210003 China Key Laboratory of Quantum Information CAS University of Science and Technology of China Hefei230026 China

Without actively aligning the reference frames, the reference-frame-independent quantum key distribution (RFI-QKD) can generate secure keys even when the reference frames drift slowly. Here, we propose a new scheme on the decoy-state RFI-QKD, where the basis assignments of two legitimate parties are biased, reducing the fraction of mismatched-basis data. When accounting for statistical fluctuations under different misalignments of reference frames, we investigate the performance of biased decoy-state RFI-QKD with full parameter optimization. We also make a clear comparison between the new scheme with other practical schemes, e.g., unbiased decoy-state RFI-QKD and biased decoy-state BB84-QKD. Simulation results demonstrate that the new proposed biased decoy-state RFI-QKD can significantly improve the performance (secret key rate and secure transmission distance) of practical QKD systems. Copyright © 2017, The Authors. All rights reserved.

关键词： Quantum cryptography

Quantum key distribution with the single-photon-added coherent source

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Physical Review A 2014年第6期90卷 062315-062315页

作者： Dong Wang Mo Li Feng Zhu Zhen-Qiang Yin Wei Chen Zheng-Fu Han Guang-Can Guo Qin Wang Key Laboratory of Quantum Information University of Science and Technology of China CAS Hefei Anhui 230026 China Synergetic Innovation Center of Quantum Information & Quantum Physics University of Science and Technology of China Hefei Anhui 230026 China Institute of Signal Processing Transmission Nanjing University of Posts and Telecommunications Nanjing 210003 China Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Ministry of Education Nanjing 210003 China

In this paper, we present schemes on implementing the single-photon-added coherent source in quantum key distributions. We apply this source in either the standard BB84 protocol or the recently proposed measurement-device-independent quantum key distribution, comparing their performance with the cases of using other existing sources, e.g., the weak coherent source or the heralded single-photon source, and giving out corresponding numerical simulations. Our simulation results show that in both protocols the single-photon-added coherent source can greatly exceed all other existing sources. Moreover, even when taking statistical fluctuation into account, a high key generation rate can still be achieved at long distance by applying this source.

关键词： SINGLE photon generation QUANTUM measurement COHERENT scattering QUANTUM communication (Optics) QUANTUM states

A distributed compressed sensing approach for speech signal denoising

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Journal of Electronics 2011年第4期28卷 509-517页

作者： Ji, Yunyun Yang, Zhen College of Communication and Information Engineering Nanjing University of Posts and Telecommunications Nanjing 210003 China Key Lab of Broadband Wireless Communication and Sensor Network Technology Ministry of Education Nanjing University of Posts and Telecommunications Nanjing 210003 China Nanjing University of Posts and Telecommunications Nanjing 210006 No. 66 Xinmofan Road P. O. Box 214 China

Compressed sensing, a new area of signal processing rising in recent years, seeks to minimize the number of samples that is necessary to be taken from a signal for precise reconstruction. The precondition of compressed sensing theory is the sparsity of signals. In this paper, two methods to estimate the sparsity level of the signal are formulated. And then an approach to estimate the sparsity level directly from the noisy signal is presented. Moreover, a scheme based on distributed compressed sensing for speech signal denoising is described in this work which exploits multiple measurements of the noisy speech signal to construct the block-sparse data and then reconstruct the original speech signal using block-sparse model-based Compressive Sampling Matching Pursuit (CoSaMP) algorithm. Several simulation results demonstrate the accuracy of the estimated sparsity level and that this denoising system for noisy speech signals can achieve favorable performance especially when speech signals suffer severe noise. © 2011 Science Press, Institute of Electronics, CAS and Springer-Verlag Berlin Heidelberg.

关键词： Denoising Distributed compressed sensing Sparsity estimation Speech signal

Certifying quantum teleportation experimentally

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Quantum Engineering

Quantum Engineering 2019年第3期1卷

作者： Sheng, Yu-Bo Institute of Quantum Information and Technology Nanjing University of Posts and Telecommunications Nanjing China School of Science Nanjing University of Posts and Telecommunications Nanjing China Key Laboratory of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Ministry of Education Nanjing China