Human mobility prediction is important for many applications.However,training an accurate mobility prediction model requires a large scale of human trajectories,where privacy issues become an important problem.The ris...Human mobility prediction is important for many applications.However,training an accurate mobility prediction model requires a large scale of human trajectories,where privacy issues become an important problem.The rising federated learning provides us with a promising solution to this problem,which enables mobile devices to collaboratively learn a shared prediction model while keeping all the training data on the device,decoupling the ability to do machine learning from the need to store the data in the cloud.However,existing federated learningbased methods either do not provide privacy guarantees or have vulnerability in terms of privacy leakage.In this paper,we combine the techniques of data perturbation and model perturbation mechanisms and propose a privacy-preserving mobility prediction algorithm,where we add noise to the transmitted model and the raw data collaboratively to protect user privacy and keep the mobility prediction performance.Extensive experimental results show that our proposed method significantly outperforms the existing stateof-the-art mobility prediction method in terms of defensive performance against practical attacks while having comparable mobility prediction performance,demonstrating its effectiveness.展开更多
How can individual mobility in urban areas be maintained alongside scooters and cargo bikes if conventional vehicles are foreseeably no longer allowed to enter city centers?And how can urban living be combined with in...How can individual mobility in urban areas be maintained alongside scooters and cargo bikes if conventional vehicles are foreseeably no longer allowed to enter city centers?And how can urban living be combined with individual mobility in a sustainable and socially acceptable way?LiMo-2040 attempts to provide answers to these questions.It follows a holistic approach according to the criteria:As light,as compact and as simple(cost-effective)as possible.Modular e-vehicle concepts(consisting of vehicle cabin and chassis)are known,but have not yet been thought through to their logical conclusion.The LiMo cabin is not only a vehicle cabin,but also a component of a modern high-rise apartment.It therefore requires no parking space and combines urban living and individual mobility sustainably and cost-effectively.If a vehicle is needed,an app can be used to book a chassis that comes along autonomously and waits until the cabin,including its occupants,travels down a sophisticated rail system,docks and autonomously heads for the desired destination.展开更多
The fifth generation(5G) network is expected to support significantly large amount of mobile data traffic and huge number of wireless connections,to achieve better spectrum- and energy-efficiency,as well as quality of...The fifth generation(5G) network is expected to support significantly large amount of mobile data traffic and huge number of wireless connections,to achieve better spectrum- and energy-efficiency,as well as quality of service(QoS) in terms of delay,reliability and security.Furthermore,the 5G network shall also incorporate high mobility requirements as an integral part,providing satisfactory service to users travelling at a speed up to 500 km/h.This paper provides a survey of potential high mobility wireless communication(HMWC) techniques for 5G network.After discussing the typical requirements and challenges of HMWC,key techniques to cope with the challenges are reviewed,including transmission techniques under the fast timevarying channels,network architecture with mobility support,and mobility management.Finally,future research directions on 5G high mobility communications are given.展开更多
Two position-assisted fast handover schemes, scheme A and scheme B, for LTE-A system under very high mobility scenarios, are proposed, together with their performance evaluation. Scheme A is designed to reduce handove...Two position-assisted fast handover schemes, scheme A and scheme B, for LTE-A system under very high mobility scenarios, are proposed, together with their performance evaluation. Scheme A is designed to reduce handover delay by making handover preparation before handover starts. Scheme B aims at reducing unnecessary handovers and improving handover success rate, by calculating the geographically best target handover cell, which makes it easier for mobile terminals to access the target cell. A system level simulation is conducted to evaluate the performance of these two schemes. It is shown that, scheme A could reduce inter-site handover delay by about 50 ms, while scheme B could cut down nearly 50% of all handovers when time-to-trigger （TTT） is 0 ms. Besides, as TTT gets larger, Scheme B has much better success rate.展开更多
Increasing urbanization rates observed in the last decades have significantly contributed to a higher number of travelers to urban environments. The objective of this study was to identify measures and factors that en...Increasing urbanization rates observed in the last decades have significantly contributed to a higher number of travelers to urban environments. The objective of this study was to identify measures and factors that encourage the use of alternative transportation in the cities of Washington D.C., USA and Porto Alegre, Brazil. The methodology used to compare these two cities was an evaluation of their urban mobility plans, including strategic analyses and measures to promote the use of public transport. This approach was based on factors described in the following document： ＂Urban Sustainability： Impacts of Economic Development and Their Consequences on the Process of Urbanization in Emerging Countries＂, prepared by the United Nations. The results indicate different planning strategies, ranging from focusing on tax integration policies in order to become more financially attractive to the user, to using different modes of mass transportation integrated with active mobility. In Washington D.C., an innovative strategy was developed in preparation to forecast scenarios, as the measures comprised projection for the year 2040, which will respond to mobility demands in the coming decades.展开更多
ultra-Dense Network(UDN)has been envisioned as a promising technology to provide high-quality wireless connectivity in dense urban areas,in which the density of Access Points(APs)is increased up to the point where it ...ultra-Dense Network(UDN)has been envisioned as a promising technology to provide high-quality wireless connectivity in dense urban areas,in which the density of Access Points(APs)is increased up to the point where it is comparable with or surpasses the density of active mobile users.In order to mitigate inter-AP interference and improve spectrum efficiency,APs in UDNs are usually clustered into multiple groups to serve different mobile users,respectively.However,as the number of APs increases,the computational capability within an AP group has become the bottleneck of AP clustering.In this paper,we first propose a novel UDN architecture based on Mobile Edge Computing(MEC),in which each MEC server is associated with a user-centric AP cluster to act as a mobile agent.In addition,in the context of MEC-based UDN,we leverage mobility prediction techniques to achieve a dynamic AP clustering scheme,in which the cluster structure can automatically adapt to the dynamic distribution of user traffic in a specific area.Simulation results show that the proposed scheme can highly increase the average user throughput compared with the baseline algorithm using max-SINR user association and equal bandwidth allocation,while it guarantees at the same time low transmission delay.展开更多
To ensure authenticity of sesame oil,an authentication technology was proposed using ion mobility spectrometry(IMS)and chemometrics.One-class classification(OCC)methods including one-class partial least squares(OCPLS)...To ensure authenticity of sesame oil,an authentication technology was proposed using ion mobility spectrometry(IMS)and chemometrics.One-class classification(OCC)methods including one-class partial least squares(OCPLS)and one-class support vector machine(OCSVM)were employed to build authentication models for sesame oil.Subsequently,an independent test set was used to validate the constructed models.Validation set of 45 adulterated oils indicated that prediction correction rate of OCPLS model reached 95.6%(43 out of 45).Moreover,the complete set of sesame oils adulterated by sesame oil essence could be identified as counterfeit.Compared with previous studies,OCPLS model could work to identify untargeted adulteration.In conclusion,OCC method could effectively detect adulterated sesame oils containing as little as 10%other vegetable oils.This study provided a rapid screening method for adulterated sesame oil in market surveillance and a reference for developing authentication methods of other edible oils.展开更多
This research aims to evaluate walkability as a strategy of urban mobility in relation to physical characteristics of accessibility and attractiveness from public sidewalks characteristics in the city of Passo Fundo/R...This research aims to evaluate walkability as a strategy of urban mobility in relation to physical characteristics of accessibility and attractiveness from public sidewalks characteristics in the city of Passo Fundo/RS-Brazil using the IAAPE （indicators of attraction and pedestrian accessibility） method. The concept of walkability corresponds to the simple act of walking in a pleasant way along the footpaths. Therefore, the IAAPE method was used, which considers aspects of connectivity, comfort, conviviality, coexistence, convenience, clarity and commitment in relation to the space evaluated. In this study, 40 adults, elderly, pregnant and wheelchair subjects were interviewed for evaluating the importance criteria on public sidewalks for a given type of user. In general, reduced sidewalk dimensions and obstacle presence are the main displacement hurdles in most of the cases analyzed. Thus, improvements are needed to avoid stress situations that arise from daily routine, to encourage physical activities, accessibility, and the emergence of meeting and leisure points.展开更多
Current mobility management solutions based on ID/Locator separation are not easily deployed and cannot solve routing scalability and mobility problems. This paper proposes a novel network architecture based on ID/Loc...Current mobility management solutions based on ID/Locator separation are not easily deployed and cannot solve routing scalability and mobility problems. This paper proposes a novel network architecture based on ID/Locator separation and suggests a new mobility management solution. This solution solves the problem of scalability in the network and also provides better support for mobility. It can be easily deployed because no modification of the mobile host’s protocol stack is required. The identifier contains some routing information; so the solution provides intrinsic interworking with traditional mobile hosts. Because the mapping systems are distributed to the edge networks, robustness of the whole system is enhanced and handover delay is decreased.展开更多
The mobility of relay has great influence on the performance of a cooperative relay system.This paper proposes a dynamic selection scheme under the amplify-and-forward communication mode in high mobility environment,b...The mobility of relay has great influence on the performance of a cooperative relay system.This paper proposes a dynamic selection scheme under the amplify-and-forward communication mode in high mobility environment,based on the estimation of channels and the power allocation for each relay node by comparing it with the pre-set threshold.This scheme is used to choose the cooperative relay dynamically for a multiple relay scenario.Simulation results show that this proposed relay selection scheme decreases the outage probability effectively,maintains system capacity well,and improves the performance of the relay system.展开更多
Human effects and environment impacts associated with nanoparticles generated from road traffic have recently attracted wide attention.Knowledge of the influencing variables on both number and mass of nanoparticles,so...Human effects and environment impacts associated with nanoparticles generated from road traffic have recently attracted wide attention.Knowledge of the influencing variables on both number and mass of nanoparticles,sources,characteristics and limitations of advanced commercially accessible instruments for monitoring nanoparticles,are still scarce and not sufficient to make regulatory decision on solid particles smaller than 23 nm(SPN<23 nm).Given the harmful effects of nanoparticles on human health(i.e.visibility impairment,cardiac-rhythm disturbance,heart attacks,premature death,etc.),their control and assessment seem to be an absolute priority.In this overview,we classify and analyze the existing knowledge of nanoparticles in road traffic atmosphere,recent progress,and emerging priorities in research related to these topics.The major aspects of ongoing research in this field,and a brief discussion of the main sources of atmosphere nanoparticles are presented.The subsequent section focuses on the influencing parameters of nanoparticles including climate conditions,height above the road surface and distance between source(road traffic)and sampling site.The next section provides a comprehensive summary on sampling measurement methodologies and instrumental techniques.We also review the health and environment implications associated with particle exposure.Finally,an evaluation of the state of research related to nanoparticles together with highlights for future research activities are also presented.展开更多
The upcoming 6G wireless networks have to provide reliable communications in high-mobility scenarios at high carrier frequencies.However,high-mobility or high carrier frequencies will bring severe inter-carrier interf...The upcoming 6G wireless networks have to provide reliable communications in high-mobility scenarios at high carrier frequencies.However,high-mobility or high carrier frequencies will bring severe inter-carrier interference(ICI)to conventional orthogonal fre⁃quency-division multiplexing(OFDM)modulation.Orthogonal time frequency space(OTFS)modulation is a recently developing multi-carrier transmission scheme for wireless commu⁃nications in high-mobility environments.This paper evaluates the performance of coded OT⁃FS systems.In particular,we consider 5G low density parity check(LDPC)codes for OTFS systems based on 5G OFDM frame structures over high mobility channels.We show the per⁃formance of the OTFS systems with 5G LDPC codes when sum-product detection algorithm and iterative detection and decoding are employed.We also illustrate the effect of channel estimation error on the performance of the LDPC coded OTFS systems.展开更多
Addressing urban mobility is a priority for government agencies due to increasing problems of travel and lack of accessibility, generated by increasing rates of population growth and motorization. The general objectiv...Addressing urban mobility is a priority for government agencies due to increasing problems of travel and lack of accessibility, generated by increasing rates of population growth and motorization. The general objective of this study is to propose a method of analysis of the adequacy of policies, aimed at sustainable mobility and its impacts on urbanism. Methodologically, the analysis is based on the parameters proposed by the UN （United Nations）, namely, sectorial planning, mobility funding, management efficiency of urban mobility systems; and mobility system and support for green technology. The object of study is the public policies expressed in urban mobility plans, master plans and regional development plans. Through the applicability of this method, the results show the possibility of verifying the adequacy of public policies as a mechanism that induces improvements in urban mobility with greater levels of sustainability and the possibility of universalized access to users.展开更多
This study explores urban air mobility(UAM)as a strategy for mitigating escalating traffic congestion in major urban areas as a consequence of a static transportation supply versus dynamic demand growth.It offers an i...This study explores urban air mobility(UAM)as a strategy for mitigating escalating traffic congestion in major urban areas as a consequence of a static transportation supply versus dynamic demand growth.It offers an indepth overview of UAM development,highlighting its present state and the challenges of integration with established urban transport systems.Key areas of focus include the technological advancements and obstacles in electric vertical take-off and landing(eVTOL)aircrafts,which are essential for UAM operation in urban environments.Furthermore,it explores the infrastructure requirements for UAM,including vertiport deployment and the creation of adept air traffic control(ATC)systems.These developments must be integrated into the urban landscape without exacerbating land-use challenges.This paper also examines the regulatory framework for UAM,including existing aviation regulations and the necessity for novel policies specifically designed for urban aerial transport.This study presents a comprehensive perspective for various stakeholders,from policymakers to urban planners,highlighting the need for a thorough understanding of UAM’s potential and effective assimilation into urban mobility frameworks.展开更多
Federated learning(FL)is an intricate and privacy-preserving technique that enables distributed mobile devices to collaboratively train a machine learning model.However,in real-world FL scenarios,the training performa...Federated learning(FL)is an intricate and privacy-preserving technique that enables distributed mobile devices to collaboratively train a machine learning model.However,in real-world FL scenarios,the training performance is affected by a combination of factors such as the mobility of user devices,limited communication and computational resources,thus making the user scheduling problem crucial.To tackle this problem,we jointly consider the user mobility,communication and computational capacities,and develop a stochastic optimization problem to minimize the convergence time.Specifically,we first establish a convergence bound on the training performance based on the heterogeneity of users’data,and then leverage this bound to derive the participation rate for each user.After deriving the user-specific participation rate,we aim to minimize the training latency by optimizing user scheduling under the constraints of the energy consumption and participation rate.Afterward,we transform this optimization problem to the contextual multi-armed bandit framework based on the Lyapunov method and solve it with the submodular reward enhanced linear upper confidence bound(SR-linUCB)algorithm.Experimental results demonstrate the superiority of our proposed algorithm on the training performance and time consumption compared with stateof-the-art algorithms for both independent and identically distributed(IID)and non-IID settings.展开更多
This paper presents a comprehensive agent-based model for the spread of an infection in a network of cities.Directional mobility is defined between each two cities and can take different values.The work examines the r...This paper presents a comprehensive agent-based model for the spread of an infection in a network of cities.Directional mobility is defined between each two cities and can take different values.The work examines the role that such mobility levels play in containing the infection with various vaccination coverage and age distributions.The results indicate that mobility reduction is sufficient to control the disease under all circumstances and full lockdowns are not a necessity.It has to be reduced to different ratios depending on the vaccination level and age distribution.A key finding is that increasing vaccination coverage above a certain level does not affect the mobility suppression level required to control the infection anymore for the cases of young population and heterogeneous age distributions.By investigating several migration and commuting patterns,it is found that shutting mobility in a few local places is favored against reducing mobility over the entire country network.In addition,commuting-and not migration-influences the spread level of the infection.The work offers an exclusive combined network-based and agent-based model that makes use of randomly generated mobility matrices.展开更多
As different requirements on mobility support will be introduced by diversified communication scenarios in the fifth generation （5G）, on demand mobility management is put forward to simplify signaling process, reduc...As different requirements on mobility support will be introduced by diversified communication scenarios in the fifth generation （5G）, on demand mobility management is put forward to simplify signaling process, reduce terminal power consumption, improve network efficiency and so on. In order to enable on demand mobility management in 5G networks, a mobility driven network slicing （MDNS） was proposed, which takes individual mobility support requirements into account while customizing networks for different mobile services. Within the MDNS framework, the actual levels of required mobility support are determined by a mobility description system, and network slice templates with the corresponding mobility management schemes are defined by a network slice description function. By instantiating the network slices, each mobile terminal could be directed to the network slice with the most appropriate mobility management scheme. Based on this, a prototype was implemented to validate the feasibility of MDNS framework, i.e. creating multiple network slices with different mobility management schemes. In addition, the performance evaluation on average cost of processing a mobility event is conducted for the proposed MDNS framework and the long term evolution （LTE） system, and operating benefits are analyzed including efficiency and scalability.展开更多
Accurate channel state information(CSI)is crucial for 6G wireless communication systems to accommodate the growing demands of mobile broadband services.In massive multiple-input multiple-output(MIMO)systems,traditiona...Accurate channel state information(CSI)is crucial for 6G wireless communication systems to accommodate the growing demands of mobile broadband services.In massive multiple-input multiple-output(MIMO)systems,traditional CSI feedback approaches face challenges such as performance degradation due to feedback delay and channel aging caused by user mobility.To address these issues,we propose a novel spatio-temporal predictive network(STPNet)that jointly integrates CSI feedback and prediction modules.STPNet employs stacked Inception modules to learn the spatial correlation and temporal evolution of CSI,which captures both the local and the global spatiotemporal features.In addition,the signal-to-noise ratio(SNR)adaptive module is designed to adapt flexibly to diverse feedback channel conditions.Simulation results demonstrate that STPNet outperforms existing channel prediction methods under various channel conditions.展开更多
The environment of low-altitude urban airspace is complex and variable due to numerous obstacles,non-cooperative aircraft,and birds.Unmanned Aerial Vehicles(UAVs)leveraging environmental information to achieve three-d...The environment of low-altitude urban airspace is complex and variable due to numerous obstacles,non-cooperative aircraft,and birds.Unmanned Aerial Vehicles(UAVs)leveraging environmental information to achieve three-dimension collision-free trajectory planning is the prerequisite to ensure airspace security.However,the timely information of surrounding situation is difficult to acquire by UAVs,which further brings security risks.As a mature technology leveraged in traditional civil aviation,the Automatic Dependent Surveillance-Broadcast(ADS-B)realizes continuous surveillance of the information of aircraft.Consequently,we leverage ADS-B for surveillance and information broadcasting,and divide the aerial airspace into multiple sub-airspaces to improve flight safety in UAV trajectory planning.In detail,we propose the secure Sub-airSpaces Planning(SSP)algorithm and Particle Swarm Optimization Rapidly-exploring Random Trees(PSO-RRT)algorithm for the UAV trajectory planning in law-altitude airspace.The performance of the proposed algorithm is verified by simulations and the results show that SSP reduces both the maximum number of UAVs in the sub-airspace and the length of the trajectory,and PSO-RRT reduces the cost of UAV trajectory in the sub-airspace.展开更多
The global adoption of Electric Vehicles(EVs)is on the rise due to their advanced features,with projections indicating they will soon dominate the private vehicle market.However,improper management of EV charging can ...The global adoption of Electric Vehicles(EVs)is on the rise due to their advanced features,with projections indicating they will soon dominate the private vehicle market.However,improper management of EV charging can lead to significant issues.This paper reviews the development of high-power,reliable charging solutions by examining the converter topologies used in rectifiers and converters that transfer electricity from the grid to EV batteries.It covers technical details,ongoing developments,and challenges related to these topologies and control strategies.The integration of rapid charging stations has introduced various Power Quality(PQ)issues,such as voltage fluctuations,harmonic distortion,and supra-harmonics,which are discussed in detail.The paper also highlights the benefits of controlled EV charging and discharging,including voltage and frequency regulation,reactive power compensation,and improved power quality.Efficient energy management and control strategies are crucial for optimizing EV battery charging within microgrids to meet increasing demand.Charging stations must adhere to specific converter topologies,control strategies,and industry standards to function correctly.The paper explores microgrid architectures and control strategies that integrate EVs,energy storage units(ESUs),and Renewable Energy Sources(RES)to enhance performance at charging points.It emphasizes the importance of various RES-connected architectures and the latest power converter topologies.Additionally,the paper provides a comparative analysis of microgrid-based charging station architectures,focusing on energy management,control strategies,and charging converter controls.The goal is to offer insights into future research directions in EV charging systems,including architectural considerations,control factors,and their respective advantages and disadvantages.展开更多
基金supported in part by the National Key Research and Development Program of China under 2020AAA0106000the National Natural Science Foundation of China under U20B2060 and U21B2036supported by a grant from the Guoqiang Institute, Tsinghua University under 2021GQG1005
文摘Human mobility prediction is important for many applications.However,training an accurate mobility prediction model requires a large scale of human trajectories,where privacy issues become an important problem.The rising federated learning provides us with a promising solution to this problem,which enables mobile devices to collaboratively learn a shared prediction model while keeping all the training data on the device,decoupling the ability to do machine learning from the need to store the data in the cloud.However,existing federated learningbased methods either do not provide privacy guarantees or have vulnerability in terms of privacy leakage.In this paper,we combine the techniques of data perturbation and model perturbation mechanisms and propose a privacy-preserving mobility prediction algorithm,where we add noise to the transmitted model and the raw data collaboratively to protect user privacy and keep the mobility prediction performance.Extensive experimental results show that our proposed method significantly outperforms the existing stateof-the-art mobility prediction method in terms of defensive performance against practical attacks while having comparable mobility prediction performance,demonstrating its effectiveness.
文摘How can individual mobility in urban areas be maintained alongside scooters and cargo bikes if conventional vehicles are foreseeably no longer allowed to enter city centers?And how can urban living be combined with individual mobility in a sustainable and socially acceptable way?LiMo-2040 attempts to provide answers to these questions.It follows a holistic approach according to the criteria:As light,as compact and as simple(cost-effective)as possible.Modular e-vehicle concepts(consisting of vehicle cabin and chassis)are known,but have not yet been thought through to their logical conclusion.The LiMo cabin is not only a vehicle cabin,but also a component of a modern high-rise apartment.It therefore requires no parking space and combines urban living and individual mobility sustainably and cost-effectively.If a vehicle is needed,an app can be used to book a chassis that comes along autonomously and waits until the cabin,including its occupants,travels down a sophisticated rail system,docks and autonomously heads for the desired destination.
基金supported by the National Basic Research Program of China (973 Program No.2012CB316100)
文摘The fifth generation(5G) network is expected to support significantly large amount of mobile data traffic and huge number of wireless connections,to achieve better spectrum- and energy-efficiency,as well as quality of service(QoS) in terms of delay,reliability and security.Furthermore,the 5G network shall also incorporate high mobility requirements as an integral part,providing satisfactory service to users travelling at a speed up to 500 km/h.This paper provides a survey of potential high mobility wireless communication(HMWC) techniques for 5G network.After discussing the typical requirements and challenges of HMWC,key techniques to cope with the challenges are reviewed,including transmission techniques under the fast timevarying channels,network architecture with mobility support,and mobility management.Finally,future research directions on 5G high mobility communications are given.
基金supported by the National Natural Science Foundation of China(No.61032002)the National Basic Research Program of China(973 Program No.2012CB316100)the 111 project(No.111-2-14)
文摘Two position-assisted fast handover schemes, scheme A and scheme B, for LTE-A system under very high mobility scenarios, are proposed, together with their performance evaluation. Scheme A is designed to reduce handover delay by making handover preparation before handover starts. Scheme B aims at reducing unnecessary handovers and improving handover success rate, by calculating the geographically best target handover cell, which makes it easier for mobile terminals to access the target cell. A system level simulation is conducted to evaluate the performance of these two schemes. It is shown that, scheme A could reduce inter-site handover delay by about 50 ms, while scheme B could cut down nearly 50% of all handovers when time-to-trigger （TTT） is 0 ms. Besides, as TTT gets larger, Scheme B has much better success rate.
文摘Increasing urbanization rates observed in the last decades have significantly contributed to a higher number of travelers to urban environments. The objective of this study was to identify measures and factors that encourage the use of alternative transportation in the cities of Washington D.C., USA and Porto Alegre, Brazil. The methodology used to compare these two cities was an evaluation of their urban mobility plans, including strategic analyses and measures to promote the use of public transport. This approach was based on factors described in the following document： ＂Urban Sustainability： Impacts of Economic Development and Their Consequences on the Process of Urbanization in Emerging Countries＂, prepared by the United Nations. The results indicate different planning strategies, ranging from focusing on tax integration policies in order to become more financially attractive to the user, to using different modes of mass transportation integrated with active mobility. In Washington D.C., an innovative strategy was developed in preparation to forecast scenarios, as the measures comprised projection for the year 2040, which will respond to mobility demands in the coming decades.
基金This work was partially supported by the National Natural Science Foundation of China(61801208,61671233,61931023)the Jiangsu Science Foundation(BK20170650)+2 种基金the Postdoctoral Science Foundation of China(BX201700118,2017M621712)the Jiangsu Postdoctoral Science Foundation(1701118B)the open research fund of National Mobile Communications Research Laboratory(2019D02).
文摘ultra-Dense Network(UDN)has been envisioned as a promising technology to provide high-quality wireless connectivity in dense urban areas,in which the density of Access Points(APs)is increased up to the point where it is comparable with or surpasses the density of active mobile users.In order to mitigate inter-AP interference and improve spectrum efficiency,APs in UDNs are usually clustered into multiple groups to serve different mobile users,respectively.However,as the number of APs increases,the computational capability within an AP group has become the bottleneck of AP clustering.In this paper,we first propose a novel UDN architecture based on Mobile Edge Computing(MEC),in which each MEC server is associated with a user-centric AP cluster to act as a mobile agent.In addition,in the context of MEC-based UDN,we leverage mobility prediction techniques to achieve a dynamic AP clustering scheme,in which the cluster structure can automatically adapt to the dynamic distribution of user traffic in a specific area.Simulation results show that the proposed scheme can highly increase the average user throughput compared with the baseline algorithm using max-SINR user association and equal bandwidth allocation,while it guarantees at the same time low transmission delay.
基金This work was supported by the National Science and Technology Major Project of China(2017YFC1601700)the National Nature Foundation Committee of P.R.China(31871886)+2 种基金the National Major Project for Agro-product Quality&Safety Risk Assessment(GJFP2019003)the earmarked fund for China Agricultural Research System(CARS-12)the Fundamental Research Funds for Central Non-profit Scientific Institution(1610172018002 and 1610172018012).
文摘To ensure authenticity of sesame oil,an authentication technology was proposed using ion mobility spectrometry(IMS)and chemometrics.One-class classification(OCC)methods including one-class partial least squares(OCPLS)and one-class support vector machine(OCSVM)were employed to build authentication models for sesame oil.Subsequently,an independent test set was used to validate the constructed models.Validation set of 45 adulterated oils indicated that prediction correction rate of OCPLS model reached 95.6%(43 out of 45).Moreover,the complete set of sesame oils adulterated by sesame oil essence could be identified as counterfeit.Compared with previous studies,OCPLS model could work to identify untargeted adulteration.In conclusion,OCC method could effectively detect adulterated sesame oils containing as little as 10%other vegetable oils.This study provided a rapid screening method for adulterated sesame oil in market surveillance and a reference for developing authentication methods of other edible oils.
文摘This research aims to evaluate walkability as a strategy of urban mobility in relation to physical characteristics of accessibility and attractiveness from public sidewalks characteristics in the city of Passo Fundo/RS-Brazil using the IAAPE （indicators of attraction and pedestrian accessibility） method. The concept of walkability corresponds to the simple act of walking in a pleasant way along the footpaths. Therefore, the IAAPE method was used, which considers aspects of connectivity, comfort, conviviality, coexistence, convenience, clarity and commitment in relation to the space evaluated. In this study, 40 adults, elderly, pregnant and wheelchair subjects were interviewed for evaluating the importance criteria on public sidewalks for a given type of user. In general, reduced sidewalk dimensions and obstacle presence are the main displacement hurdles in most of the cases analyzed. Thus, improvements are needed to avoid stress situations that arise from daily routine, to encourage physical activities, accessibility, and the emergence of meeting and leisure points.
基金funded by the European Commission funded ICT-FP7 IP Project EFIPSANS under Grant No. INFSO-ICT-215549the National Basic Research Program of China ("973"Program) under Grant No. 2009CB320504
文摘Current mobility management solutions based on ID/Locator separation are not easily deployed and cannot solve routing scalability and mobility problems. This paper proposes a novel network architecture based on ID/Locator separation and suggests a new mobility management solution. This solution solves the problem of scalability in the network and also provides better support for mobility. It can be easily deployed because no modification of the mobile host’s protocol stack is required. The identifier contains some routing information; so the solution provides intrinsic interworking with traditional mobile hosts. Because the mapping systems are distributed to the edge networks, robustness of the whole system is enhanced and handover delay is decreased.
基金Supported by the National Natural Science Foundation of China(No.61172073)the State Key Laboratory of Rail Traffic Control and Safety,Beijing Jiaotong University(No.RCS2011ZT003)+2 种基金the Open Research Fund of National Mobile Communications Research Laboratory,Southeast University(No.2012D19)the Fundamental Research Funds for the Central Universities of Ministry of Education of China(No.2013JBZ001)the Program for New Century Excellent Talents in University of Ministry of Education of China(No.NCET-12-0766)
文摘The mobility of relay has great influence on the performance of a cooperative relay system.This paper proposes a dynamic selection scheme under the amplify-and-forward communication mode in high mobility environment,based on the estimation of channels and the power allocation for each relay node by comparing it with the pre-set threshold.This scheme is used to choose the cooperative relay dynamically for a multiple relay scenario.Simulation results show that this proposed relay selection scheme decreases the outage probability effectively,maintains system capacity well,and improves the performance of the relay system.
文摘Human effects and environment impacts associated with nanoparticles generated from road traffic have recently attracted wide attention.Knowledge of the influencing variables on both number and mass of nanoparticles,sources,characteristics and limitations of advanced commercially accessible instruments for monitoring nanoparticles,are still scarce and not sufficient to make regulatory decision on solid particles smaller than 23 nm(SPN<23 nm).Given the harmful effects of nanoparticles on human health(i.e.visibility impairment,cardiac-rhythm disturbance,heart attacks,premature death,etc.),their control and assessment seem to be an absolute priority.In this overview,we classify and analyze the existing knowledge of nanoparticles in road traffic atmosphere,recent progress,and emerging priorities in research related to these topics.The major aspects of ongoing research in this field,and a brief discussion of the main sources of atmosphere nanoparticles are presented.The subsequent section focuses on the influencing parameters of nanoparticles including climate conditions,height above the road surface and distance between source(road traffic)and sampling site.The next section provides a comprehensive summary on sampling measurement methodologies and instrumental techniques.We also review the health and environment implications associated with particle exposure.Finally,an evaluation of the state of research related to nanoparticles together with highlights for future research activities are also presented.
基金supported by National Key R&D Program of Chi⁃na(No.2020YFB1807802)the National Science Fund for Distinguished Young Scholars(No.61901453)Jiangsu Provincial Key Research and Development Program(No.BE2021013-2)。
文摘The upcoming 6G wireless networks have to provide reliable communications in high-mobility scenarios at high carrier frequencies.However,high-mobility or high carrier frequencies will bring severe inter-carrier interference(ICI)to conventional orthogonal fre⁃quency-division multiplexing(OFDM)modulation.Orthogonal time frequency space(OTFS)modulation is a recently developing multi-carrier transmission scheme for wireless commu⁃nications in high-mobility environments.This paper evaluates the performance of coded OT⁃FS systems.In particular,we consider 5G low density parity check(LDPC)codes for OTFS systems based on 5G OFDM frame structures over high mobility channels.We show the per⁃formance of the OTFS systems with 5G LDPC codes when sum-product detection algorithm and iterative detection and decoding are employed.We also illustrate the effect of channel estimation error on the performance of the LDPC coded OTFS systems.
文摘Addressing urban mobility is a priority for government agencies due to increasing problems of travel and lack of accessibility, generated by increasing rates of population growth and motorization. The general objective of this study is to propose a method of analysis of the adequacy of policies, aimed at sustainable mobility and its impacts on urbanism. Methodologically, the analysis is based on the parameters proposed by the UN （United Nations）, namely, sectorial planning, mobility funding, management efficiency of urban mobility systems; and mobility system and support for green technology. The object of study is the public policies expressed in urban mobility plans, master plans and regional development plans. Through the applicability of this method, the results show the possibility of verifying the adequacy of public policies as a mechanism that induces improvements in urban mobility with greater levels of sustainability and the possibility of universalized access to users.
基金supported by the National Natural Science Foundation of China(Grant Nos.52220105001,52221005,72322002,72361137001,and 72331001).
文摘This study explores urban air mobility(UAM)as a strategy for mitigating escalating traffic congestion in major urban areas as a consequence of a static transportation supply versus dynamic demand growth.It offers an indepth overview of UAM development,highlighting its present state and the challenges of integration with established urban transport systems.Key areas of focus include the technological advancements and obstacles in electric vertical take-off and landing(eVTOL)aircrafts,which are essential for UAM operation in urban environments.Furthermore,it explores the infrastructure requirements for UAM,including vertiport deployment and the creation of adept air traffic control(ATC)systems.These developments must be integrated into the urban landscape without exacerbating land-use challenges.This paper also examines the regulatory framework for UAM,including existing aviation regulations and the necessity for novel policies specifically designed for urban aerial transport.This study presents a comprehensive perspective for various stakeholders,from policymakers to urban planners,highlighting the need for a thorough understanding of UAM’s potential and effective assimilation into urban mobility frameworks.
文摘Federated learning(FL)is an intricate and privacy-preserving technique that enables distributed mobile devices to collaboratively train a machine learning model.However,in real-world FL scenarios,the training performance is affected by a combination of factors such as the mobility of user devices,limited communication and computational resources,thus making the user scheduling problem crucial.To tackle this problem,we jointly consider the user mobility,communication and computational capacities,and develop a stochastic optimization problem to minimize the convergence time.Specifically,we first establish a convergence bound on the training performance based on the heterogeneity of users’data,and then leverage this bound to derive the participation rate for each user.After deriving the user-specific participation rate,we aim to minimize the training latency by optimizing user scheduling under the constraints of the energy consumption and participation rate.Afterward,we transform this optimization problem to the contextual multi-armed bandit framework based on the Lyapunov method and solve it with the submodular reward enhanced linear upper confidence bound(SR-linUCB)algorithm.Experimental results demonstrate the superiority of our proposed algorithm on the training performance and time consumption compared with stateof-the-art algorithms for both independent and identically distributed(IID)and non-IID settings.
基金A.Tridane was supported by the UAEU UPAR,grant number 12S125.
文摘This paper presents a comprehensive agent-based model for the spread of an infection in a network of cities.Directional mobility is defined between each two cities and can take different values.The work examines the role that such mobility levels play in containing the infection with various vaccination coverage and age distributions.The results indicate that mobility reduction is sufficient to control the disease under all circumstances and full lockdowns are not a necessity.It has to be reduced to different ratios depending on the vaccination level and age distribution.A key finding is that increasing vaccination coverage above a certain level does not affect the mobility suppression level required to control the infection anymore for the cases of young population and heterogeneous age distributions.By investigating several migration and commuting patterns,it is found that shutting mobility in a few local places is favored against reducing mobility over the entire country network.In addition,commuting-and not migration-influences the spread level of the infection.The work offers an exclusive combined network-based and agent-based model that makes use of randomly generated mobility matrices.
基金supported by the National Science and Technology Major Project of China (2017ZX03001014)the National Natural Science Foundation of China for Distinguished Young Scholar (61425012)
文摘As different requirements on mobility support will be introduced by diversified communication scenarios in the fifth generation （5G）, on demand mobility management is put forward to simplify signaling process, reduce terminal power consumption, improve network efficiency and so on. In order to enable on demand mobility management in 5G networks, a mobility driven network slicing （MDNS） was proposed, which takes individual mobility support requirements into account while customizing networks for different mobile services. Within the MDNS framework, the actual levels of required mobility support are determined by a mobility description system, and network slice templates with the corresponding mobility management schemes are defined by a network slice description function. By instantiating the network slices, each mobile terminal could be directed to the network slice with the most appropriate mobility management scheme. Based on this, a prototype was implemented to validate the feasibility of MDNS framework, i.e. creating multiple network slices with different mobility management schemes. In addition, the performance evaluation on average cost of processing a mobility event is conducted for the proposed MDNS framework and the long term evolution （LTE） system, and operating benefits are analyzed including efficiency and scalability.
基金supported in part by the Natural Science Foundation of China under Grant Nos.U2468201 and 62221001ZTE Industry-University-Institute Cooperation Funds under Grant No.IA20240420002。
文摘Accurate channel state information(CSI)is crucial for 6G wireless communication systems to accommodate the growing demands of mobile broadband services.In massive multiple-input multiple-output(MIMO)systems,traditional CSI feedback approaches face challenges such as performance degradation due to feedback delay and channel aging caused by user mobility.To address these issues,we propose a novel spatio-temporal predictive network(STPNet)that jointly integrates CSI feedback and prediction modules.STPNet employs stacked Inception modules to learn the spatial correlation and temporal evolution of CSI,which captures both the local and the global spatiotemporal features.In addition,the signal-to-noise ratio(SNR)adaptive module is designed to adapt flexibly to diverse feedback channel conditions.Simulation results demonstrate that STPNet outperforms existing channel prediction methods under various channel conditions.
基金supported by the National Key R&D Program of China(No.2022YFB3104502)the National Natural Science Foundation of China(No.62301251)+2 种基金the Natural Science Foundation of Jiangsu Province of China under Project(No.BK20220883)the open research fund of National Mobile Communications Research Laboratory,Southeast University,China(No.2024D04)the Young Elite Scientists Sponsorship Program by CAST(No.2023QNRC001).
文摘The environment of low-altitude urban airspace is complex and variable due to numerous obstacles,non-cooperative aircraft,and birds.Unmanned Aerial Vehicles(UAVs)leveraging environmental information to achieve three-dimension collision-free trajectory planning is the prerequisite to ensure airspace security.However,the timely information of surrounding situation is difficult to acquire by UAVs,which further brings security risks.As a mature technology leveraged in traditional civil aviation,the Automatic Dependent Surveillance-Broadcast(ADS-B)realizes continuous surveillance of the information of aircraft.Consequently,we leverage ADS-B for surveillance and information broadcasting,and divide the aerial airspace into multiple sub-airspaces to improve flight safety in UAV trajectory planning.In detail,we propose the secure Sub-airSpaces Planning(SSP)algorithm and Particle Swarm Optimization Rapidly-exploring Random Trees(PSO-RRT)algorithm for the UAV trajectory planning in law-altitude airspace.The performance of the proposed algorithm is verified by simulations and the results show that SSP reduces both the maximum number of UAVs in the sub-airspace and the length of the trajectory,and PSO-RRT reduces the cost of UAV trajectory in the sub-airspace.
文摘The global adoption of Electric Vehicles(EVs)is on the rise due to their advanced features,with projections indicating they will soon dominate the private vehicle market.However,improper management of EV charging can lead to significant issues.This paper reviews the development of high-power,reliable charging solutions by examining the converter topologies used in rectifiers and converters that transfer electricity from the grid to EV batteries.It covers technical details,ongoing developments,and challenges related to these topologies and control strategies.The integration of rapid charging stations has introduced various Power Quality(PQ)issues,such as voltage fluctuations,harmonic distortion,and supra-harmonics,which are discussed in detail.The paper also highlights the benefits of controlled EV charging and discharging,including voltage and frequency regulation,reactive power compensation,and improved power quality.Efficient energy management and control strategies are crucial for optimizing EV battery charging within microgrids to meet increasing demand.Charging stations must adhere to specific converter topologies,control strategies,and industry standards to function correctly.The paper explores microgrid architectures and control strategies that integrate EVs,energy storage units(ESUs),and Renewable Energy Sources(RES)to enhance performance at charging points.It emphasizes the importance of various RES-connected architectures and the latest power converter topologies.Additionally,the paper provides a comparative analysis of microgrid-based charging station architectures,focusing on energy management,control strategies,and charging converter controls.The goal is to offer insights into future research directions in EV charging systems,including architectural considerations,control factors,and their respective advantages and disadvantages.
