The non-stationary behavior, caused by the train rmverrent, is the rmin factor for the variation of high speed railway channel. To measure the tirce-variant effect, the parameter of stationarity interval, in which the...The non-stationary behavior, caused by the train rmverrent, is the rmin factor for the variation of high speed railway channel. To measure the tirce-variant effect, the parameter of stationarity interval, in which the channel keeps constant or has no great change, is adopted based on Zhengzfiou- Xi＇an （Zhengxi） passenger dedicated line measurement with different train speeds. The stationarity interval is calculated through the definition of Local Region of Stationarity （LRS） under three train ve- locities. Furthermore, the time non-stationary characteristic of high speed pared with five standard railway channel is corn- Multiple-Input MultipleOutput （MIMO） channel models, i.e. Spatial Channel Model （SCM）, extended version of SCM （SCME）, Wireless World Initiative New Radio Phase II （WINNERII）, International Mobile Teleconmnications-Advanced （IMT-Advanced） and WiMAX models which contain the high speed moving scenario. The stationarity interval of real channel is 9 ms in 80% of the cases, which is shorter than those of the standard models. Hence the real channel of high speed railway changes more rapidly. The stationarity intervals of standard models are different due to different modeling methods and scenario def- initions. And the compared results are instructive for wireless system design in high speed railway.展开更多
In this paper,we introduce one full-duplex(FD) relaying transmission scheme for high speed railway and compare its ergodic capacity and outage performance with half-duplex(HD) relaying scheme. Both decode-and-forward(...In this paper,we introduce one full-duplex(FD) relaying transmission scheme for high speed railway and compare its ergodic capacity and outage performance with half-duplex(HD) relaying scheme. Both decode-and-forward(DF) amplify-and-forward(AF) relay modes are considered. Moreover,the carriage penetration loss(CPL) and the self-interference(SI) cancellation ratio are investigated. We derive the closed-form expressions for the outage probability and ergodic capacity of both HD and FD relay transmission schemes. It is shown that when CPL is larger than a certain level,the FD relay can achieve better performance in terms of capacity and keep the outage probability in a low level. It is also found that three factors: AF or DF modes,CPL and SI cancellation ratio,can have impact on capacity performance,and that CPL is one decisive factor. Our results can provide theoretical supports for development and deployment of future wireless communication systems on high speed railways.展开更多
Large-scale array aided beamforming improves the spectral efficiency(SE) as a benefit of high angular resolution.When dual-beam downlink beamforming is applied to the train moving towards cell edge,the inter-beam ambi...Large-scale array aided beamforming improves the spectral efficiency(SE) as a benefit of high angular resolution.When dual-beam downlink beamforming is applied to the train moving towards cell edge,the inter-beam ambiguity(IBA) increases as the directional difference between beams becomes smaller.An adaptive antenna activation based beamforming scheme was proposed to mitigate IBA.In the district near the base station(BS),all antenna elements(AEs) were activated to generate two beams.As the distance from the train to the BS increased,only the minimum number of AEs satisfying the resolution criterion would be activated.At the cell edge,one beam was switched off due to intolerable IBA.The proposed scheme can achieve SE gain to the non-adaptive scheme and show more robustness against the direction-of-arrival(DOA) estimation error.展开更多
With the rapid deployment of high speed railway(HSR) worldwide,both safety operation and comfort experience can be desired to evolve into a future era of intelligent transportation system.To eliminate boredom and prov...With the rapid deployment of high speed railway(HSR) worldwide,both safety operation and comfort experience can be desired to evolve into a future era of intelligent transportation system.To eliminate boredom and provide entertainment for passengers,an intranet for internal communications among passengers named as onboard social network system(SNS) is needed.In this paper,the latest progress in HSR network architectures and technology building blocks are discussed to enable the implementation of the SNS.Meanwhile,based on the device-to-device(D2 D) communication technology for proximal information interaction,SNS can be efficiently facilitated.A dynamic resource allocation algorithm is proposed to maximize the total utility of the onboard SNS,which is solved with the matching theory method.Simulation results verify the convergence and efficiency of the proposed algorithm.展开更多
In order to make further study on the mechanical property of CRTSIII type slab non-ballast track structures,which was self-designed in China,based on the method of the multiscale finite element model(FEM),the traditio...In order to make further study on the mechanical property of CRTSIII type slab non-ballast track structures,which was self-designed in China,based on the method of the multiscale finite element model(FEM),the traditional FEM of slab non-ballast track structures was improved.The multiscale FEM of CRTSII type slab nonballast track structures was established based on the general finite element program ABAQUs.Then the comparative calculation was made between various FEMs,showing that the high solution precision,fast modelling speed and high solution efficiency could be obtained.Therefore,the multiscale FEM was suitable for the parametric study on mechanical behaviour of CRTSII type slab non-ballast track structures,and then the key influence factor and constructions could be optimized.展开更多
With the rapid development of railway transportation,higher requirements for capacity are increasing and amount of communication,computer and control technologies are applied in train control systems which is the popu...With the rapid development of railway transportation,higher requirements for capacity are increasing and amount of communication,computer and control technologies are applied in train control systems which is the popular method for train control.The application of 3 C brings the enhancement of railway transportation performance.However,the number of internal and external cyber security threats is rising,which could lead to some railway accidents.On the other hand,safety is the core of the design process for railway but security is rarely considered due to the closure of traditional railway systems.As cyber security is threatening the normal operation of industrial control systems and the critical infrastructure,security ssues of train control systems should be paid more attention as railway transportation play an important role for society and economy.However,due to the safety-critical characteristics,safety assessment and analysis works have been performed for a long time,but cyber security related works are rarely considered.In the paper,we demonstrate the security situation of train control systems based on the inherent features and the experience of other industrial control systems,where the technical defects and potential threats are summarized.According to the practical engineering experience,the current security protection strategies are illustrated,which shows the popular security protection methods are limited and cannot realize the defense-in-depth.Finally,some research challenges of security issues of train control systems are identified.展开更多
To handle the handover challenge in Express Train Access Networks(ETAN).mobility fading effects in high speed railway environments should be addressed first.Based on the investigation of fading effects in this paper,w...To handle the handover challenge in Express Train Access Networks(ETAN).mobility fading effects in high speed railway environments should be addressed first.Based on the investigation of fading effects in this paper,we obtain two theoretical bounds:HOTiming upper bound and HO-Margin lower bound,which are helpful guidelines to study the handover challenge today and in the future.Then,we apply them to analyze performance of conventional handover technologies and our proposal in ETAN.This follow-up theory analyses and simulation experiment results demonstrate that the proposed handover solution can minimize handover time up to 4ms(which is the fastest one so far),and reduce HO-Margin to 0.16 dB at a train speed of 350km/h.展开更多
The varying trajectory of Doppler frequency under changing speed motion conditionsare investigated in Highspeed Railway(HSR) scenarios.Based on the geometrical physical parameters,instantaneous Doppler trajectories an...The varying trajectory of Doppler frequency under changing speed motion conditionsare investigated in Highspeed Railway(HSR) scenarios.Based on the geometrical physical parameters,instantaneous Doppler trajectories and expression forms of the change rate arededuced,including acceleration and deceleration cases.These modified models provide more accurate and realisticapproximations in modeling rapidly fading channels.展开更多
基金Acknowledgements This work was supported partially by the Beijing Natural Science Foundation under Crant No. 4112048 the Program for New Century Excellent Talents in University under Gant No. NCET-09-0206+4 种基金 the National Natural Science Foundation of China under Crant No. 60830001 the Key Project of State Key Laboratory of Rail Traffic Control and Safety under Crants No. RCS2008ZZ006, No. RCS2011ZZ008 the Program for Changjiang Scholars and Innovative Research Team in University under Crant No. IRT0949 the Project of State Key kab. of Rail Traffic Control and Safety under C~ants No. RCS2008ZT005, No. RCS2010ZT012 the Fundamental Research Funds for the Central Universities under Crants No. 2010JBZ（~8, No. 2011YJS010.
文摘The non-stationary behavior, caused by the train rmverrent, is the rmin factor for the variation of high speed railway channel. To measure the tirce-variant effect, the parameter of stationarity interval, in which the channel keeps constant or has no great change, is adopted based on Zhengzfiou- Xi＇an （Zhengxi） passenger dedicated line measurement with different train speeds. The stationarity interval is calculated through the definition of Local Region of Stationarity （LRS） under three train ve- locities. Furthermore, the time non-stationary characteristic of high speed pared with five standard railway channel is corn- Multiple-Input MultipleOutput （MIMO） channel models, i.e. Spatial Channel Model （SCM）, extended version of SCM （SCME）, Wireless World Initiative New Radio Phase II （WINNERII）, International Mobile Teleconmnications-Advanced （IMT-Advanced） and WiMAX models which contain the high speed moving scenario. The stationarity interval of real channel is 9 ms in 80% of the cases, which is shorter than those of the standard models. Hence the real channel of high speed railway changes more rapidly. The stationarity intervals of standard models are different due to different modeling methods and scenario def- initions. And the compared results are instructive for wireless system design in high speed railway.
基金supported by the National Natural Science Foundation of China(No.61571037)by the Fundamental Research Funds for the Central Universities(No.2016JBZ006)
文摘In this paper,we introduce one full-duplex(FD) relaying transmission scheme for high speed railway and compare its ergodic capacity and outage performance with half-duplex(HD) relaying scheme. Both decode-and-forward(DF) amplify-and-forward(AF) relay modes are considered. Moreover,the carriage penetration loss(CPL) and the self-interference(SI) cancellation ratio are investigated. We derive the closed-form expressions for the outage probability and ergodic capacity of both HD and FD relay transmission schemes. It is shown that when CPL is larger than a certain level,the FD relay can achieve better performance in terms of capacity and keep the outage probability in a low level. It is also found that three factors: AF or DF modes,CPL and SI cancellation ratio,can have impact on capacity performance,and that CPL is one decisive factor. Our results can provide theoretical supports for development and deployment of future wireless communication systems on high speed railways.
基金supported partially by the 973 Program under the Grant 2012CB316100
文摘Large-scale array aided beamforming improves the spectral efficiency(SE) as a benefit of high angular resolution.When dual-beam downlink beamforming is applied to the train moving towards cell edge,the inter-beam ambiguity(IBA) increases as the directional difference between beams becomes smaller.An adaptive antenna activation based beamforming scheme was proposed to mitigate IBA.In the district near the base station(BS),all antenna elements(AEs) were activated to generate two beams.As the distance from the train to the BS increased,only the minimum number of AEs satisfying the resolution criterion would be activated.At the cell edge,one beam was switched off due to intolerable IBA.The proposed scheme can achieve SE gain to the non-adaptive scheme and show more robustness against the direction-of-arrival(DOA) estimation error.
基金supported by the National Key Research and Development Program Under Grant 2016YFB 1200102-04Natural Science Foundation of China under Grant U1334202+3 种基金supported in part by the National S&T Major Project 2016ZX03001021-003the Fundamental Research Funds for the Central Universities under Grant 2016RC056in part by the State Key Laboratory of Rail Traffic Control and Safety,Beijing Jiaotong University,under Contract RCS2017ZT009in part by the China Postdoctoral Science Foundation under Grant 2017M610040
文摘With the rapid deployment of high speed railway(HSR) worldwide,both safety operation and comfort experience can be desired to evolve into a future era of intelligent transportation system.To eliminate boredom and provide entertainment for passengers,an intranet for internal communications among passengers named as onboard social network system(SNS) is needed.In this paper,the latest progress in HSR network architectures and technology building blocks are discussed to enable the implementation of the SNS.Meanwhile,based on the device-to-device(D2 D) communication technology for proximal information interaction,SNS can be efficiently facilitated.A dynamic resource allocation algorithm is proposed to maximize the total utility of the onboard SNS,which is solved with the matching theory method.Simulation results verify the convergence and efficiency of the proposed algorithm.
基金supported by“111”Project(B18062)Fundamental Research Funds for the Central Universities(2019CDQYTM028).
文摘In order to make further study on the mechanical property of CRTSIII type slab non-ballast track structures,which was self-designed in China,based on the method of the multiscale finite element model(FEM),the traditional FEM of slab non-ballast track structures was improved.The multiscale FEM of CRTSII type slab nonballast track structures was established based on the general finite element program ABAQUs.Then the comparative calculation was made between various FEMs,showing that the high solution precision,fast modelling speed and high solution efficiency could be obtained.Therefore,the multiscale FEM was suitable for the parametric study on mechanical behaviour of CRTSII type slab non-ballast track structures,and then the key influence factor and constructions could be optimized.
文摘With the rapid development of railway transportation,higher requirements for capacity are increasing and amount of communication,computer and control technologies are applied in train control systems which is the popular method for train control.The application of 3 C brings the enhancement of railway transportation performance.However,the number of internal and external cyber security threats is rising,which could lead to some railway accidents.On the other hand,safety is the core of the design process for railway but security is rarely considered due to the closure of traditional railway systems.As cyber security is threatening the normal operation of industrial control systems and the critical infrastructure,security ssues of train control systems should be paid more attention as railway transportation play an important role for society and economy.However,due to the safety-critical characteristics,safety assessment and analysis works have been performed for a long time,but cyber security related works are rarely considered.In the paper,we demonstrate the security situation of train control systems based on the inherent features and the experience of other industrial control systems,where the technical defects and potential threats are summarized.According to the practical engineering experience,the current security protection strategies are illustrated,which shows the popular security protection methods are limited and cannot realize the defense-in-depth.Finally,some research challenges of security issues of train control systems are identified.
基金supported by the National Basic Research Program of China (973 Program)(No.2012CB315606 and 2010CB328201)
文摘To handle the handover challenge in Express Train Access Networks(ETAN).mobility fading effects in high speed railway environments should be addressed first.Based on the investigation of fading effects in this paper,we obtain two theoretical bounds:HOTiming upper bound and HO-Margin lower bound,which are helpful guidelines to study the handover challenge today and in the future.Then,we apply them to analyze performance of conventional handover technologies and our proposal in ETAN.This follow-up theory analyses and simulation experiment results demonstrate that the proposed handover solution can minimize handover time up to 4ms(which is the fastest one so far),and reduce HO-Margin to 0.16 dB at a train speed of 350km/h.
基金supported in part by the NSFC Project under Grants No.61371070Fundamental Research Funds for the Central Universities under grant2015JBM011+2 种基金the Beijing Nova Programme(No.xx2016023)the Open Research Fund of National Mobile Communications Research Laboratory,Southeast University,under Grant No.2012D07Beijing Natural Science Foundation project under grant No.4142041
文摘The varying trajectory of Doppler frequency under changing speed motion conditionsare investigated in Highspeed Railway(HSR) scenarios.Based on the geometrical physical parameters,instantaneous Doppler trajectories and expression forms of the change rate arededuced,including acceleration and deceleration cases.These modified models provide more accurate and realisticapproximations in modeling rapidly fading channels.
