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arXiv 2020年

作者： Einsiedler, Johanna Cheng, Yun Papst, Franz Saukh, Olga Vienna University of Business Economics CSH Vienna Austria Graz University of Technology CSH Vienna Austria Computer Engineering and Networks Lab. ETH Zurich Switzerland

The COVID-19 related lockdown measures offer a unique opportunity to understand how changes in economic activity and traffic affect ambient air quality and how much pollution reduction potential can the society offer through digitalization and mobility-limiting policies. In this work, we estimate pollution reduction over the lockdown period by using the measurements from ground air pollution monitoring stations, training a long-term prediction model and comparing its predictions to measured values over the lockdown month. We show that our models achieve state-of-the-art performance on the data from air pollution measurement stations in Switzerland, Austria and in China: evaluate up to -29.4% / +9.8% and -22.6% / +11.5%, change in NO2 / PM10 in Eastern Switzerland and Lower Austria respectively;-28.1%, / -10.8 % and -52.8 % / -50.0 % in NO2 / PM2.5 in Beijing and Wuhan respectively. Our reduction estimates are consistent with recent publications, yet in contrast to prior works, our method takes local weather into account. What can we learn from pollution emissions during lockdown? The lockdown period was too short to train meaningful models from scratch. To tackle this problem, we use transfer learning to newly fit only traffic-dependent variables. We show that the resulting models are accurate, suitable for an analysis of the post-lockdown period and capable of estimating the future air pollution reduction potential. © 2020, CC BY.

关键词： Air quality

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A delay guaranteed and services differentiated MAC protocol based on location and reservation in near-space

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Journal of Convergence Information Technology 2011年第2期6卷 120-130页

作者： Chen, Chen Gao, Xinbo Pei, Qingqi National Key Lab. of Integrated Service Networks Xidian Univ Xi'an 710071 China School of Electronic Engineering Xidian Univ Xi'an 710071 China Ministry of Edu. Key Lab. of Computer Network and Information Security Xidian Univ Xi'an 710071 China

With an ever-increasing interests and demands in Near-Space, more and more researchers have put their attentions on this field, leading to an emerging needs for modeling the 20-100km altitude space especially for broadband communications. Among the lots of works, Media Access Control (MAC) undoubtedly has chief importance and urgency with which communicating objects or nodes can effectively access to Near-Space. However, previous MAC designs mainly focus their attentions on service differentiation by application purposes without considering nodal mobility. In fact, access control for nodes with different mobility levels has significantly influences to MAC performance and is complex and difficult to be implemented together with present MAC protocols. In this paper, we first presented a location method for Near-Space vehicles such as airships and unmanned planes and then modeled the mobile networks infrastructure with mobility considered. For determining the vehicles joining/leaving events locally, we quantify the communication range with Received Signal Strength Indicator (RSSI) aid. Then, for better managing the nodes access to the Near-Space with aforementioned works, we designed a TDMA based reservation MAC protocol to guarantee the servicedelay and networks coverage with best efforts. Simulation results showed that our proposed model better fit for Near-Space mobile communication environments and presented a lower delay and higher coverage regarding to different mobility levels.

关键词： Medium access control

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Independence and coloring problems on intersection graphs of disks

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Lecture Notes in computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 2006年 3484 LNCS卷 135-155页

作者： Erlebach, Thomas Fiala, Jiří ETH Zürich Computer Engineering and Networks Lab. CH-8092 Zürich Switzerland Charles University Department of Applied Mathematics Institute for Theoretical Computer Science Malostranské nám. 2/25 118 00 Prague Czech Republic

This chapter surveys on-line and approximation algorithms for the maximum independent set and coloring problems on intersection graphs of disks. It includes a more detailed treatment of recent upper and lower bounds o... 详细信息

ISBN: (纸本)3540322124

关键词： Approximation algorithms

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Loss temporal dependency characteristic inference in wireless sensor network

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Journal of Computational Information Systems 2008年第5期4卷 2303-2308页

作者： Li, Yongjun Ji, Wenli Dai, Yafei Computer Networks and Distributed Systems Laboratory Peking University Beijing 100871 China School of Computer Science Northwestern Polytechnical University Xi'an 710072 China School of Communication Engineering Xi'an University of Science and Technology Xi'an 710075 China State Key Lab. for Adv. Opt. Commun Syst and Networks Beijing 1000871 China

The internal link loss characteristic inference has become an increasingly important issue for operating and evaluating a wireless sensor network. Due to the inherent stringent bandwidth and energy constraints, it is usually impractical to directly collect link loss statistical data from each node in sensor network. Here we consider the problem of inferring the internal link loss characteristics from end-to-end measurement. We use the Gilbert error model to model the sensor link losses, formulate the problem of link loss characteristics estimation as a Bayesian inference problem, and propose a Markov Chain Monte Carlo (MCMC) algorithm to solve it. The simulation shows that the link loss performance parameters can be inferred accurately, and the proposed algorithm scales well according to the sensor network size. © 2008 Binary Information Press.

关键词： Inference engines

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Clipping Noise-based Tone Injection for PAPR Reduction in OFDM Systems

Clipping Noise-based Tone Injection for PAPR Reduction in OF...

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IEEE International Conference on Communications

作者： Jun Hou Chintha Tellambura Jianhua Ge The State Key Lab. of Integrated Service Networks Xidian University Xi'an P. R. China Department of Electrical and Computer Engineering University of Alberta Edmonton AB Canada

Tone injection (TI) mitigates the high peak-to-average power ratio problem without incurring data rate loss or extra side information. However, optimal TI requires an exhaustive search over all possible constellations, which is a hard optimization problem. In this paper, a novel TI scheme that uses the clipping noise to find the optimal equivalent constellations is proposed. By minimizing the mean error of the clipping noise and possible constellation points, the proposed scheme easily determines the size and position of the optimal equivalent constellations. The proposed scheme achieves significant PAPR reduction while maintaining low complexity.

关键词： Peak to average power ratio Noise Indexes Wireless communication Computational complexity

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Building the Knowledge Base through Bayesian Network for Cognitive Wireless networks

Building the Knowledge Base through Bayesian Network for Cog...

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International Conference on Parallel and Distributed Systems (ICPADS)

作者： Niandong Du Yuebin Bai Lianhe Luo Wei Wu Jianli Guo School of Computer Science and Engineering Beihang University Beijing China Sci. & Technol. on Inf. Transm. & Dissemination in Commun. Networks Lab. Shijiazhuang China

Tactical communication networking faces complexity, heterogeneity, and reliability requirements. The emerging research area of cognitive networks offers a potential for dealing with these problems. A key feature of cognitive networks is the knowledge base, which is produced during the process of learning and responsible for the decision making. We propose a cognitive network model integrated with the knowledge base, which is a primary part of cognitive networks. And then we focus on the construction of the knowledge base and the expression form of the knowledge in the model. In this paper, we use the Bayesian Network (BN) to construct the knowledge base, which is a unique tool for creating a representation of the dependence relationships among network protocol parameters. The data structure of the dependence relationships of the BN is translated into the knowledge which is expressed by the probability. In the simulation experiments, we create the BN through the sampling data to construct the knowledge base using the mathematical tool MATlab.and prove the efficiency of our cognitive network model for optimizing network performance in the OPENT simulation platform.

关键词： Knowledge based systems Bayesian methods Protocols Knowledge engineering Decision making Delay Mathematical model

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Optimal operating conditions and modulation format for 160 Gb/s signals in a fiber parametric amplifier used as a slow-light delay line element

Optimal operating conditions and modulation format for 160 G...

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OFC/NFOEC 2007 - Optical Fiber Communication and the National Fiber Optic Engineers Conference 2007

作者： Liu, Fangfei Su, Yikai Voss, Paul L. State Key Lab. of Advanced Optical Communication Systems and Networks Department of Electronic Engineering Shanghai Jiao Tong University 800 DongChuan Rd Shanghai 200240 China School of Electrical and Computer Engineering Georgia Institute of Technology 777 Atlantic Drive Atlanta GA 30332-0250 United States Georgia Tech Lorraine GT-CNRS UMI 2958 2-3 rue Marconi Metz F-57070 France

We study optimal operating conditions for 160-Gb/s signals traversing a slow-light delay line based on parametric amplification. Six phase modulated formats are investigated, including CSRZ, PAP-CSRZ, GAP-CSRZ, RZ duo... 详细信息

ISBN: (纸本)1557528314

关键词： Fiber amplifiers

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Performance analysis of the affine projection CM algorithm

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Journal of Information and Computational Science 2011年第14期8卷 3275-3280页

作者： Ma, Lili Chen, Jinguang Wang, Huiran School of Computer Science Xi'an Polytechnic University Xi'an 710048 China School of Electronic Engineering Xidian University Xi'an 710071 China Science and Technology on Information Transmission and Dissemination in Communication Networks Lab. Shijiazhuang 050081 China

In this paper, we discuss the performance of the affine projection CM algorithm, which can deal with the cases that the input signals are correlated and decrease the filtering error. We describe the derivation of algorithm process and analysis the error performance and computational complexity. And an example of adaptive blind equalization is given to verify this algorithm. Some conclusions are obtained which are benefit to the researchers and engineers in the adaptive filtering field. 1548-7741/Copyright © 2011 Binary Information Press December 2011.

关键词： Adaptive filters

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Enhancing Next-Generation Urban Connectivity: Is the Integrated HAPS-Terrestrial Network a Solution?

arXiv

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arXiv 2023年

作者： Shamsabadi, Afsoon Alidadi Yadav, Animesh Yanikomeroglu, Halim Non-Terrestrial Networks Lab. Department of Systems and Computer Engineering Carleton University OttawaONK1S 5B6 Canada The School of Electrical Engineering and Computer Science Ohio University AthensOH45701 United States

Located in the stratospheric layer of Earth's atmosphere, high altitude platform station (HAPS) is a promising network infrastructure, which can bring significant advantages to sixth-generation (6G) and beyond wireless communications systems by forming vertical heterogeneous networks (vHetNets). However, if not dealt with properly, integrated networks suffer from several performance challenges compared to standalone networks. In harmonized spectrum integrated networks, where different tiers share the same frequency spectrum, interference is an important challenge to be addressed. This work focuses on an integrated HAPS-terrestrial network, serving users in an overlapped urban geographic area, and formulates a fairness optimization problem, aiming to maximize the minimum spectral efficiency (SE) of the network. Due to the highly nonconvex nature of the formulated problem, we develop a rapid converging iterative algorithm that designs the multiple-input multiple-output (MIMO) beamforming weights and the user association scheme such that the propagated inter- and intra-tier interference is managed. Simulation results demonstrate the proposed algorithm's superiority over standalone terrestrial networks and scenario where only the beamforming weights are optimized. © 2023, CC0.

关键词： Heterogeneous networks

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Loss cumulate generating function inference and application in wireless sensor network

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Journal of Computational Information Systems 2008年第4期4卷 1399-1407页

The internal link loss characteristic inference has become an increasingly important issue for operating and evaluating a wireless sensor network. Due to the inherent stringent bandwidth and energy constraints of sensors, it is usually impractical to directly monitor each node or link in wireless sensor network. We consider the problem of inferring the internal link loss characteristics from passive end-to-end measurement in this paper. Specifically, the link loss performance inference during the data aggregation is considered. Under the assumptions that the link losses are mutually independent, we elab.rate a bias corrected link loss Cumulant Generating Function (CGF) algorithm. The simulation results show that the internal link loss CGF can be inferred accurately comparable to the sampled internal link loss CGF. At the end of this paper, we apply the result of internal link loss CGF inference to identify the lossy link in sensor network.

关键词： Sensor nodes

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