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Joint Design of Coalition Formation and Semi-Blind Channel Estimation in fog Radio Access Networks

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China Communications 2019年第11期16卷 1-15页

作者： Zhifeng Wang Feifan Yang Shi Yan Saleemullah Memon Zhongyuan Zhao Chunjing Hu State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications

Coordinated signal processing can obtain a huge transmission gain for fog Radio Access Networks(F-RANs).However,integrating into large scale,it will lead to high computation complexity in channel estimation and spectral efficiency loss in transmission performance.Thus,a joint cluster formation and channel estimation scheme is proposed in this paper.Considering research remote radio heads(RRHs)centred serving scheme,a coalition game is formulated in order to maximize the spectral efficiency of cooperative RRHs under the conditions of balancing the data rate and the cost of channel estimation.As the cost influences to the necessary consumption of training length and estimation error.Particularly,an iterative semi-blind channel estimation and symbol detection approach is designed by expectation maximization algorithm,where the channel estimation process is initialized by subspace method with lower pilot length.Finally,the simulation results show that a stable cluster formation is established by our proposed coalition game method and it outperforms compared with full coordinated schemes.

关键词： channel estimation cluster formation game theory fog radio access networks(F-RANs)

fog Research in China:An Overview

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Advances in Atmospheric Sciences 2010年第3期27卷 639-662页

作者：牛生杰陆春松于华英赵丽娟吕晶晶 Key Laboratory of Meteorological Disaster of Ministry of Education School of Atmospheric PhysicsNanjing University of Information Science and Technology

fog can adversely affect human activity directly and indirectly, resulting in large losses both in terms of the local economy and lives. Much effort has been devoted to studies of fog across many areas of China, and in that context this paper aims to summarize climatic characteristics and review fog field experiments and their major results relating to fog mechanisms, physical properties and chemical characteristics. Progress in the application of remote sensing techniques and numerical simulation in fog research are also discussed. In particular, the effects of urbanization and industrialization on fog are highlighted. To end, perspectives on future fog research are outlined. The goal of this review paper is to introduce fog research in China to the global academic community and thus promote international collaboration on fog research. This is important because most papers on fog in China are published in Chinese, which are unreadable for the vast majority of non-Chinese researchers.

关键词： fog climatic characteristics fog observations fog mechanisms physicochemical characteristics,remote sensing fog modeling

An investigation of numerical aperture of air-core photonic bandgap fiber

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Science China(Technological Sciences) 2015年第2期58卷 352-356页

作者： XU Xiao Bin GAO Fu Yu ZHANG Zhi Hao JIN Jing SONG Ning Fang Institute of Opto-electronics Technology Beihang University

Air-core photonic bandgap fiber(PBF)is the perfect choice of the next-generation fiber optical gyroscope(fog),with excellent temperature,electromagnetism and radiation adaptability.Numerical aperture is an important optical parameter of PBF for application in fog.The PBF’s maximum theoretical numerical aperture(NAmax)is calculated and compared with the far-field numerical aperture(NAeff)through experiments.The result indicates that the relationship between NAmax and NAeff has much stronger dependence on wavelength than that of the conventional fiber,and they get close at wavelengths near the middle of the photonic bandgap with the error less than 5%.Furthermore,photonic bandgap fiber optical gyroscope(PBfog)with no fusion splicing points is proposed,and the optimization method and results of the PBF’s structure parameters for application in PBfog are given from the aspect of numerical aperture.

关键词：光子带隙光纤数值孔径空芯光纤陀螺仪 PBF 电磁辐射结构参数 fog

Energy-Efficient Computation Offloading and Resource Allocation in fog Computing for Internet of Everything

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China Communications 2019年第3期16卷 32-41页

作者： Qiuping Li Junhui Zhao Yi Gong Qingmiao Zhang School of Electronic and Information Engineering Beijing Jiaotong UniversityBeijing 100044China School of Information Engineering East China Jiaotong UniversityNanchang 330013China Shenzhen Engineering Laboratory of Intelligent Information Processing for IoT Southern University of Science and TechnologyShenzhen 518055China

With the dawning of the Internet of Everything(IoE) era, more and more novel applications are being deployed. However, resource constrained devices cannot fulfill the resource-requirements of these applications. This paper investigates the computation offloading problem of the coexistence and synergy between fog computing and cloud computing in IoE by jointly optimizing the offloading decisions, the allocation of computation resource and transmit power. Specifically, we propose an energy-efficient computation offloading and resource allocation(ECORA) scheme to minimize the system cost. The simulation results verify the proposed scheme can effectively decrease the system cost by up to 50% compared with the existing schemes, especially for the scenario that the computation resource of fog computing is relatively small or the number of devices increases.

关键词： fog computing cloud computing resource allocation computation offloading IoE

ANALYSES OF A MICROPHYSICAL RESPONSE TO THE SEEDING IN TWO CASES OF ARTIFICIAL fog DISSIPATION

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Journal of Tropical Meteorology 2013年第4期19卷 357-366页

作者：金华何晖张蔷黄梦宇马新成张磊嵇磊 Beijing Weather Modification Office Beijing Key Laboratory of Cloud Precipitation and Water Resources

Two field experiments were performed in order to dissipate the fog at Wuqing District of Tianjin in November and December of 2009.Hygroscopic particles were seeded to dissipate fog droplets on 6-7November,2009.Liquid nitrogen(LN)was seeded into the natural supercooled fog in the experiments of 30November–1 December,2009.Significant response was found after seeding.Significant changes were observed in the microstructure of fog in the field experiments.The of fog droplet changed dramatically;it increased first and then decreased after seeding.Remarkable variation also was found in the Liquid Water Content(LWC)and in the size of fog droplet.The Droplet Size Distribution(DSD)of fog broadened during the seeding experiments.The DSD became narrow after the seeding ended.After seeding,the droplets were found to be at different stages of growth,resulting in a transform of DSD between unimodal distribution and bimodal distribution.The DSD was unimodal before seeding and then bimodal during the seeding experiment.Finally,the DSD became unimodally distributed once again.

关键词： artificial dissipation of fog microphysical changes response

Churn-Resilient Task Scheduling in a Tiered IoT Infrastructure

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China Communications 2019年第8期16卷 162-175页

作者： Jianhua Fan Xianglin Wei Tongxiang Wang Tian Lan Suresh Subramaniam Nanjing Telecommunication Technology Research Institute Nanjing210007China George Washington University Washington DC20052US

Cloud-as-the-center computing paradigms face multiple challenges in the 5G and Internet of Things scenarios, where the service requests are usually initiated by the end-user devices located at network edge and have rigid time constraints. Therefore, fog computing, or mobile edge computing, is introduced as a promising solution to the service provision in the tiered IoT infrastructure to compensate the shortage of traditional cloud-only architecture. In this cloud-to-things continuum, several cloudlet or mobile edge server entities are placed at the access network to handle the task offloading and processing problems at the network edge. This raises the resource scheduling problem in this tiered system, which is vital for the promotion of the system efficiency. Therefore, in this paper, a scheduling mechanism for the cloudlets or fog nodes are presented, which takes the mobile tasks’ deadline and resources requirements at the same time while promoting the overall profit of the system. First, the problem at the cloudlet, to which IoT devices offload their tasks, is formulated as a multi-dimensional 0-1 knapsack problem. Second, based on ant colony optimization, a scheduling algorithm is presented which treat this problem as a subset selection problem. Third, to promote the performance of the system in the dynamic environments,a churn-refined algorithm is further put forward. A series of simulation experiments have shown that out proposal outperforms many state-of-the-art algorithms in both profit and guarantee ratio.

关键词： fog computing task scheduling deadline constrained internet of things ant colony optimization

A Diagnostic Method for fog Forecasting Using Numerical Weather Prediction(NWP)Model Outputs

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Journal of Atmospheric Science Research 2022年第4期5卷 10-19页

作者： Aditi Singh R.S.Maheskumar Gopal R.Iyengar Ministry of Earth Sciences Lodi RoadNew Delhi110003India

An attempt has been made in the present study to forecast fog with a diagnostic method using the outputs of global NWP model.The diagnostic method is based on the combination of thresholds of meteorological variables involved in fog formation.The thresholds are computed using the observations during fog.These thresholds are applied to the output of a global NWP model for forecasting fog.The occurrence of fog is a common phenomenon during winter season over the northern plains of India.The diagnostic method is used to predict fog occurrences over three stations in north India.The proposed method is able to predict both occurrences and non-occurrences of fog at all the three stations.It is found that 94%of the fog events forecasted by the model using the diagnostic method have been actually observed at the selected stations.The performance of method in predicting fog is found best over Delhi with the highest accuracy(0.61)and probability of detection(0.60).The study signifies that diagnostic approach based on the output of a global model is a useful tool for predicting fog over a single location.

关键词： fog Diagnostic method Northern plains Winter Threshold

Grey Markov chain and its application in drift prediction model of fogs

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Journal of Systems Engineering and Electronics 2005年第2期16卷 388-393页

作者： Fan Chunling 1,2 , Jin Zhihua1, Tian Weifeng1 & Qian Feng11. Department of Information Measurement Technology and Instrument, Shanghai Jiaotong University,Shanghai 200030, P. R. China 2. College of Automation and Electric Engineering, Qingdao University of Science and Technology,Qingdao 266042, P. R. China Department of Information Measurement Technology and Instrument Shanghai Jiaotong University Shanghai 200030 P. R. China College of Automation and Electric Engineering Qingdao University of Science and Technology Qingdao 266042 P. R. China

A novel grey Markov chain predictive model is discussed to reduce drift influence on the output of fiber optical gyroscopes (fogs) and to improve fogs' measurement precision. The proposed method possesses advantages of grey model and Markov chain. It makes good use of dynamic modeling idea of the grey model to predict general trend of original data. Then according to the trend, states are divided so that it can overcome the disadvantage of high computational cost of state transition probability matrix in Markov chain. Moreover, the presented approach expands the applied scope of the grey model and makes it be fit for prediction of random data with bigger fluctuation. The numerical results of real drift data from a certain type fog verify the effectiveness of the proposed grey Markov chain model powerfully. The Markov chain is also investigated to provide a comparison with the grey Markov chain model. It is shown that the hybrid grey Markov chain prediction model has higher modeling precision than Markov chain itself, which prove this proposed method is very applicable and effective.

关键词： grey model Markov chain fog drift.

Mesoscale Characteristics Analysis of a fog Case with Complete Weather Information Derived from FengYun-4A Data

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Meteorological and Environmental Research 2022年第2期13卷 10-27页

作者： Wei WANG Ping QU Zhijie LIU Tianjin Key Laboratory for Oceanic Meteorology Tianjin 30074China Tianjin Institute of Meteorological Sciences Tianjin 300074China Meteorology Administration of Xiqing District Tianjin 300380China

Currently,there is a lack of sufficient ocean meteorological data required for mesoscale weather predictions and fog characteristics analysis in the North China Sea.This study presents a methodology to supplement deficiencies in wind information in retrieval data from the Geostationary Interferometric Infrared Sounder(GIIRS)onboard the FengYun-4A(FY4A)satellite and analyze mesoscale weather characteristics.Atmospheric semi-geostrophic wind data were derived from semi-geostrophic theory to complete the weather elements in FY4AGIIRS retrieval data.First,the retrieval data accuracy was analyzed between L-band radiosonde data from seven stations and retrieval data from FY4AGIIRS.The errors in the temperature,humidity,and geopotential height from 850 to 400 hPa were smaller than those of other atmospheric layers.Subsequently,the mesoscale weather characteristics of a fog event were analyzed by creating a mesoscale weather map with derived weather information between 875 and 500 hPa.The analyses showed that the derived weather information might provide a new means for fog mesoscale characteristics analysis,which can help forecasters understand the spatial inhomogeneity in the visibility of fog events.

关键词： Satellite fog Mesoscale Semi-geostrophic wind Weather map