The non-stationary behavior, caused by the train movement, is the main factor for the variation of high speed railway channel. To measure the time-variant effect, the parameter of stationarity interval, in which the c...The non-stationary behavior, caused by the train movement, is the main factor for the variation of high speed railway channel. To measure the time-variant effect, the parameter of stationarity interval, in which the channel keeps constant or has no great change, is adopted based on Zhengzhou-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 velocities. Furthermore, the time non-stationary characteristic of high speed railway channel is compared with five standard Multiple-Input Multiple-Output (MIMO) channel models, i.e. Spatial Channel Model (SCM), extended version of SCM (SCME), Wireless World Initiative New Radio Phase II (WINNERII), International Mobile Telecommunications-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 definitions. And the compared results are instructive for wireless system design in high speed railway.展开更多
Wireless communication technologies play an essential role in supporting railway operation and control. The current Global System for Mobile Communications-Railway(GSM-R) system offers a rich set of voice services and...Wireless communication technologies play an essential role in supporting railway operation and control. The current Global System for Mobile Communications-Railway(GSM-R) system offers a rich set of voice services and data services related with train control, but it has very limited multimedia service bearer capability. With the development of commercial wireless industry, Long-Term Evolution(LTE) mobile broadband technology is becoming the prevalent technology in most of commercial mobile networks. LTE is also a promising technology of future railway mobile communication systems. The 3rd Generation Partner Project(3 GPP) and China Communications Standards Association(CCSA) have proposed two feasible LTE based broadband trunking communication solutions: the 3 GPP Mission Critical Push to Talk(MCPTT) solution and B-TrunC solution. In this paper, we first introduce the development of railway mobile communications and LTE technology. The user requirements of future railway mobile communication system(FRMCS) are then discussed. We also analyze the suitability of the two LTE-based solutions for LTE based Next-Generation Railway Mobile Communication System(LTE-R) from different aspects.展开更多
As a complement of terrestrial networks,non-terrestrial networks(NTN)have ad⁃vantages of wide-area coverage and service continuity.The NTN is potential to play an impor⁃tant role in the 5G new radio(NR)and beyond.To e...As a complement of terrestrial networks,non-terrestrial networks(NTN)have ad⁃vantages of wide-area coverage and service continuity.The NTN is potential to play an impor⁃tant role in the 5G new radio(NR)and beyond.To enable the massive machine type communi⁃cations(mMTC),the low earth orbit(LEO)satellite is preferred due to its lower transmission delay and path loss.However,the LEO satellite may generate notable Doppler shifts to de⁃grade the system performance.Recently,orthogonal time frequency space(OTFS)modulation has been proposed.It provides the opportunity to allocate delay Doppler(DD)domain resourc⁃es,which is promising for mitigating the effect of high mobility.Besides,as the LEO satellite constellation systems such as Starlink are thriving,the space spectrum resources have become increasingly scarce.Therefore,non-orthogonal multiple access(NOMA)is considered as a candidate technology to realize mMTC with limited spectrum resources.In this paper,the ap⁃plication of OTFS enabled NOMA for mMTC over the LEO satellite is investigated.The LEO satellite based mMTC system and the OTFS-NOMA schemes are described.Subsequently,the challenges of applying OTFS and NOMA into LEO satellite mMTC systems are discussed.Fi⁃nally,the potential technologies for the systems are investigated.展开更多
Cloud radio access network(C-RAN)is considered as a promising approach to solve the bandwidth crunch problem for future wireless network. Another important element for future network is sensors that can monitor physic...Cloud radio access network(C-RAN)is considered as a promising approach to solve the bandwidth crunch problem for future wireless network. Another important element for future network is sensors that can monitor physical or environmental conditions. Currently,most sensors need batteries for power,which is energy-consuming and maintenance-heavy. To further improve energy effi ciency(EE) of sensors in C-RAN,this paper proposes a new structure as well as practical circuit design for green sensors in C-RAN. The structure can enable sensors to harvest energy from radio signals transmitted by neighbor remote radio heads(RRHs) and user terminals(UTs). To demonstrate the validity of the new structure,a practical circuit design is suggested and the corresponding hardware platform is realized. Specifically,selection criteria for electrical component parameters and design of an impedance-matching network are discussed in details. In addition,two methods to stabilize the output voltage are proposed and analyzed. Finally,simulation results as well as experimental results are provided to corroborate our proposed studies.展开更多
Based on the analysis of the impact of Doppler shift to the railway dedicated mobile communication quality under the condition of high-speed mobility,this paper presents a Doppler shift measurement approach based on t...Based on the analysis of the impact of Doppler shift to the railway dedicated mobile communication quality under the condition of high-speed mobility,this paper presents a Doppler shift measurement approach based on the phase estimation of frequency correction channel(FCCH) which correctly reflects the time-varying characteristic of the channel with a testing system developed.The Doppler shift data under the high-speed condition is collected,processed,analyzed,and compared with the simulation results.The scientific laws of the Doppler shift distribution of radio channel under high-speed condition are obtained.These data and analysis are essential for the establishment of high-speed railway Doppler power spectrum model and the development of the key technology of antiDoppler shift.展开更多
Communication based train control systems(CBTC) must work even in the worst situation—train crossing.This paper models the propagation characteristics in one of the most common and pivotal scenarios—train crossing i...Communication based train control systems(CBTC) must work even in the worst situation—train crossing.This paper models the propagation characteristics in one of the most common and pivotal scenarios—train crossing in subway tunnels which is rarely mentioned in previous publications.Firsdy,measurements for train crossing scenario at 2.4 GHz in a real subway line in Madrid have been made.The field measurement is the most reliable way to reveal the propagation characteristics involving shadowing effect and fast fading.Moreover,to precisely describe the fast fading distribution and eliminate the inevitable weak points of traditional fitting way,a best numerical approximation method using Legendre orthogonal polynomials has been proposed.Comparisons show that this method works better and is of greater physical significance.Finally,a complete statistical model is given and all the coefficients can be applied by system designers for the link and system level simulations.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 movement, is the main factor for the variation of high speed railway channel. To measure the time-variant effect, the parameter of stationarity interval, in which the channel keeps constant or has no great change, is adopted based on Zhengzhou-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 velocities. Furthermore, the time non-stationary characteristic of high speed railway channel is compared with five standard Multiple-Input Multiple-Output (MIMO) channel models, i.e. Spatial Channel Model (SCM), extended version of SCM (SCME), Wireless World Initiative New Radio Phase II (WINNERII), International Mobile Telecommunications-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 definitions. And the compared results are instructive for wireless system design in high speed railway.
基金partly supported by ZTE Industry-Academia-Research Cooperation FundsFundamental Research Funds for the Central Universities(No.2016JBM076)+1 种基金the National Natural Science Foundation of China(No.61501023,No.U1334202,and No.U1534201)the Project of China Railway Corporation(No.2016X009-E)
文摘Wireless communication technologies play an essential role in supporting railway operation and control. The current Global System for Mobile Communications-Railway(GSM-R) system offers a rich set of voice services and data services related with train control, but it has very limited multimedia service bearer capability. With the development of commercial wireless industry, Long-Term Evolution(LTE) mobile broadband technology is becoming the prevalent technology in most of commercial mobile networks. LTE is also a promising technology of future railway mobile communication systems. The 3rd Generation Partner Project(3 GPP) and China Communications Standards Association(CCSA) have proposed two feasible LTE based broadband trunking communication solutions: the 3 GPP Mission Critical Push to Talk(MCPTT) solution and B-TrunC solution. In this paper, we first introduce the development of railway mobile communications and LTE technology. The user requirements of future railway mobile communication system(FRMCS) are then discussed. We also analyze the suitability of the two LTE-based solutions for LTE based Next-Generation Railway Mobile Communication System(LTE-R) from different aspects.
基金supported by the Fundamental Research Funds for the Cen⁃tral Universities under Grant Nos.2021YJS202,2020JBZD005 and 2021RC205the National Key Research and Development Program under Grant Nos.2016YFE0200900 and 2016YFB1200102-04,NSFC under Grant Nos 61725101 and U1834210+6 种基金the Royal Society Newton Advanced Fellow⁃ship under Grant Nos.61961130391 and NA191006Beijing Natural Haidian Joint Fund under Grant No.L172020Major Projects of Beijing Municipal Science and Technology Commission under Grant No.Z181100003218010State Key Lab of Rail Traffic Control and Safety under Grant Nos.RCS2021ZQ002,RCS2018ZZ007 and RCS2020ZT010Teaching Reform Project under Grant No.134496522the Open Research Fund from Shen⁃zhen Research Institute of Big Data under Grant No.2019ORF01006the PCL Future Greater-Bay Area Network Facilities for Large-scale Exper⁃iments and Applications Project under Grant No.LZ0019.
文摘As a complement of terrestrial networks,non-terrestrial networks(NTN)have ad⁃vantages of wide-area coverage and service continuity.The NTN is potential to play an impor⁃tant role in the 5G new radio(NR)and beyond.To enable the massive machine type communi⁃cations(mMTC),the low earth orbit(LEO)satellite is preferred due to its lower transmission delay and path loss.However,the LEO satellite may generate notable Doppler shifts to de⁃grade the system performance.Recently,orthogonal time frequency space(OTFS)modulation has been proposed.It provides the opportunity to allocate delay Doppler(DD)domain resourc⁃es,which is promising for mitigating the effect of high mobility.Besides,as the LEO satellite constellation systems such as Starlink are thriving,the space spectrum resources have become increasingly scarce.Therefore,non-orthogonal multiple access(NOMA)is considered as a candidate technology to realize mMTC with limited spectrum resources.In this paper,the ap⁃plication of OTFS enabled NOMA for mMTC over the LEO satellite is investigated.The LEO satellite based mMTC system and the OTFS-NOMA schemes are described.Subsequently,the challenges of applying OTFS and NOMA into LEO satellite mMTC systems are discussed.Fi⁃nally,the potential technologies for the systems are investigated.
基金supported by the National Natural Science Foundation of China(No.61571037, U1334202)by the Fundamental Research Funds for the Central Universities(No. 2014JBZ003)
文摘Cloud radio access network(C-RAN)is considered as a promising approach to solve the bandwidth crunch problem for future wireless network. Another important element for future network is sensors that can monitor physical or environmental conditions. Currently,most sensors need batteries for power,which is energy-consuming and maintenance-heavy. To further improve energy effi ciency(EE) of sensors in C-RAN,this paper proposes a new structure as well as practical circuit design for green sensors in C-RAN. The structure can enable sensors to harvest energy from radio signals transmitted by neighbor remote radio heads(RRHs) and user terminals(UTs). To demonstrate the validity of the new structure,a practical circuit design is suggested and the corresponding hardware platform is realized. Specifically,selection criteria for electrical component parameters and design of an impedance-matching network are discussed in details. In addition,two methods to stabilize the output voltage are proposed and analyzed. Finally,simulation results as well as experimental results are provided to corroborate our proposed studies.
基金Supported by the National Natural Science Foundation of China(No.U133420261222105)+1 种基金the Key Grant Project of Chinese Ministry of Education(No.313006)the Project of State Key Lab of Rail Traffic Control and Safety(No.RCS 2014ZT11)
文摘Based on the analysis of the impact of Doppler shift to the railway dedicated mobile communication quality under the condition of high-speed mobility,this paper presents a Doppler shift measurement approach based on the phase estimation of frequency correction channel(FCCH) which correctly reflects the time-varying characteristic of the channel with a testing system developed.The Doppler shift data under the high-speed condition is collected,processed,analyzed,and compared with the simulation results.The scientific laws of the Doppler shift distribution of radio channel under high-speed condition are obtained.These data and analysis are essential for the establishment of high-speed railway Doppler power spectrum model and the development of the key technology of antiDoppler shift.
基金Supported by the National Natural Science Foundation of China(No.60830001)Program for New Century Excellent Talents in University(No.NCET-09-0206)+2 种基金the Key Project of State Key Lab.of Rail Traffic Control and Safety(No.RCS2008ZZ006)Program for Changjiang Scholars and Innovative Research Team in University(No.IRT0949)the Project of State Key Lab.of Rail Traffic Control and Safety(No.RCS2008ZT005)
文摘Communication based train control systems(CBTC) must work even in the worst situation—train crossing.This paper models the propagation characteristics in one of the most common and pivotal scenarios—train crossing in subway tunnels which is rarely mentioned in previous publications.Firsdy,measurements for train crossing scenario at 2.4 GHz in a real subway line in Madrid have been made.The field measurement is the most reliable way to reveal the propagation characteristics involving shadowing effect and fast fading.Moreover,to precisely describe the fast fading distribution and eliminate the inevitable weak points of traditional fitting way,a best numerical approximation method using Legendre orthogonal polynomials has been proposed.Comparisons show that this method works better and is of greater physical significance.Finally,a complete statistical model is given and all the coefficients can be applied by system designers for the link and system level simulations.
