Search

HSR has been developed rapidly all over the world, which puts forward requirements for a reliable and efficient wireless communication system between the moving train and the ground. According to International Union of Railways (UIC) E-Train Project, the train-ground wireless communication services for HSR system mainly include the train control services, the train monitoring services, and the passenger services from/to Internet. The train control and monitoring services are special services for train needs and provided by train operators mainly using Global System for Mobile Communications-Railway (GSM-R), which is an international wireless communications standard for railway communication and applications. With the rapid growth of HSR services, GSM-R has been unable to support the broadband communication systems. Therefore, from GSM-R to long-term evolution for railway (LTE-R) is the essential trend to guarantee a reliable communication systems. By introducing and comparing the network architecture and key technologies of GSM-R and LTE-R system, this chapter discusses the development of the next-generation HSR broadband communication systems.

In this chapter covers security schemes of dedicated mobile communications for railway. Due to the control signal is transmitted via wireless channel, communication security is crucial to the whole rail transit system. Although currently the mobile communication infrastructure in railway is based on public cellular mobile communications, considering the rail transit has characteristics of ultra-high moving velocity and high reliability and safety demand, traditional security mechanism is unable to satisfy the basic requirements of the rail transit scenario. On the one hand, there are still some threats remained in GSM-R. On the other hand, the future dedicated mobile network for railway is heterogeneous and complicated, including 2G, 3G, 4G, WLAN networks, and mobile relays. How to achieve fast authentic handover scheme across domains is a problem that must be solved. In this chapter, we first introduce the security problems in mobile communications. Next, we describe in detail the key improvements of railway communication technology. Finally, we introduce some key technologies in heterogeneous network environment and give a brief prospect of the future research.

High-speed railway (HSR) communications will become a key feature supported by intelligent transportation communication systems. To the end of 2015, the operating mileage of China railway has reached 121,000 km, and the operating mileage of China HSR has reached 19,000 km, which accounting for more than 60% of the world’s HSR operation mileage, and ranking the first all over the world. Within the past few decades, HSR has been widely introduced to meet the increasing demand for passenger rail travel. HSR becomes more competitive in areas of higher population density due to its faster than normal speed of operation. Meanwhile, a reliable communication system with high capacity and security is a challenging task for HSR. This chapter briefly reviews the development of HSR communication system and explores the necessity and significance for future HSR communications.

In this chapter, we study radio propagation and wireless channels for railway communications. The first part of the chapter focuses on definitions of propagation scenarios. To begin with, high-speed railway propagation scenarios are partitioned, and the characteristics of each scenario are described in detail. Then, traditional concepts of railway communications and vehicular communications are summarized together to constitute a more general concept—wide-sense V2X (WSV2X). In this manner, the vehicles, trains, and infrastructures build up a wireless network enabling them to exchange controlling and traffic information, such as road obstacles, accidents, and so forth, via the wireless communication links. Correspondingly, all the propagation scenarios of WSV2X communications are defined in detail.

High-speed railway (HSR) communications will become a key feature supported by intelligent transportation communication systems. The increasing demand for HSR communications leads to significant attention on the study of radio resource management (RRM), which enables efficient resource utilization and improved system performance. RRM design is a challenging problem due to heterogenous quality of service (QoS) requirements and dynamic characteristics of HSR wireless communications. The objective of this chapter is to provide an overview on the key issues that arise in the RRM design for HSR wireless communications. We provide a literature survey on state-of-the-art RRM schemes for HSR wireless communications, with an in-depth discussion on various RRM aspects including admission control, power control, and resource allocation. The studies on joint power control and resource allocation problem, and dynamic resource management problem are presented. Finally, this chapter outlines the current challenges and open issues in the area of RRM design for HSR wireless communications.

The railway broadband mobile communication systems are required to be continuous, high capable, extremely reliable, and bidirectional [1–2]. Unlike wired channels, the radio channels between train and Infrastructure are random dynamic and unpredictable [3–4]. Thus, it is important to evaluate the performance for railway broadband mobile communication systems.

In recent years, a new paradigm for communication called cooperative communications has been proposed for which initial information theoretic studies have shown the potential for improvements in capacity over traditional multi-hop wireless networks. Cooperative communication involves exploiting the broadcast nature of the wireless medium to form virtual antenna arrays out of independent single-antenna network nodes for transmission. The field of telecommunication networks involves exchange of information messages among a collection of terminals, links, and nodes that are connected together. The field has advanced tremendously and has generated many breakthroughs in research and technology innovations in the past century. The fundamental goals that have driven communications and networking research and technology developments mainly solve two problems: how to increase communication rates over a communication link connecting two nodes and how to increase the communication reliability to minimize the errors in information delivery. The first goal often refers to spectral efficiency, measured by bits per second per hertz. The second goal often refers to information multi-capacity or channel capacity, measured by the bits per second that can be achieved with arbitrarily small error probability. Emerging classes of wireless networks, such as ad hoc and sensor networks and cellular networks with multiple hops, often consist of a large number of nodes in different geometric locations. Compared with classical point-to-point systems, these new types of networks are extremely difficult to analyze and optimize. Therefore, new theoretical and practical techniques are needed to augment classical communication and networking theory and practice. The current spectrum allocation policy is highly inefficient, which is one of the main reasons that lead to significant underutilization of spectrum in the face of explosive growth in demand. The radio spectrum is the radio frequency (RF) portion of the electromagnetic spectrum, which is a natural resource used by the transmitter and receiver to transmit signals. In order to solve the shortage in spectrum resources and to improve the spectrum utilization, cognitive radio (CR) has been proposed, which allows a secondary user (unlicensed user) to exploit spectrum holes at a given time and location and transmit. The spectrum hole is the frequency band that is unoccupied by the primary user (licensed user), and can be exploited temporally, spectrally, and spatially. The concept of cognitive radio was first proposed by Mitola in 1999, whereby a radio can adapt and dynamically reconfigure itself based on its RF environment. After a decade of research, cognitive radio has attracted a lot of interest. Recently, cognitive radio has been considered as a promising candidate technique in the upcoming 5G wireless systems. In this chapter, we start from the introduction of fundamental cooperation and cognition, followed by a brief review of the application in railway communications.

We calculate the electronic structure and persistent current of graphene rings based on tight binding theory. The sixfold rotational symmetrical graphene rings exhibit diamagnetic response with carriers flowing anticlockwise along the rings. When symmetry is broken by defect, these rings remain diamagnetic response. While for asymmetrical graphene ring with the same size, the typical current is several orders of magnitude smaller than that of sixfold rotational symmetrical graphene ring. Especially, the asymmetrical graphene rings exhibit not only diamagnetic but also paramagnetic response.

An engineering failure with serious cracks and heaving in the roadway subbase because of the overuse of phosphogypsum was investigated, and an effective stabilization solution was implement...

With the rapid development of high-speed railway, subway, city railway, and intercity rail, how to ensure the reliability, safety, and comfort of such rail traffic transportation systems becomes the focus. Meanwhile, the social network service (SNS) is advancing so fast all over the world. How to combine the characteristics of rail traffic transportation systems with that of the social networks, which enable them to play an important role in the rail traffic operations, will become one of the core problems in the future development of intelligent rail traffic transportation systems. Based on the business requirements, the reliable transmission of information, and the characteristics of the rail traffic transportation systems, this article proposes a new concept of "dedicated social network" whose information are exchanged within the internal intranet. A novel social network architecture for rail traffic transportation system is proposed, including the SNS Management Center, a dedicated social network for internal information exchanges among the drivers, the dispatchers, and the train control center, the SNS for the information exchanges among the train marshals, crews, and passengers. The proposed framework attempts to exploit social networks in an active manner in the field of rail traffic transportation systems to make the system safer, more secure, reliable, comfortable, and humane.

Cuttings are widely used in high-speed railway (HSR) transportation to ensure the flatness of rails. The special structure of cuttings results in rich reflection and scattering, and creates dense multipath components. This paper presents a series of measurements of the propagation channel at 930 MHz conducted along the “Zhengzhou-Xi'an” HSR of China, to characterize the small-scale fading behavior of rail-cutting scenarios as a function of the geometry of cuttings, including crown width and bottom width. Raw data are collected in six cuttings (five cuttings are used for developing the model, while the other one is used for validation) in rural and suburban environments. We propose a set of effective methods to statistically model the spatial/temporal variations – including fade depth (FD), level crossing rate (LCR), average fade duration (AFD), and Ricean ${K}$ -factor – as a function of the structural parameters of cuttings. Akaike's Information Criterion (AIC)-based evaluation indicates that the Ricean distribution is the best to describe small-scale fading. In addition, the rich multipath and directionality of the transmitting antennas lead to a non-monotonous dependence of the ${K}$ -factor on the distance between transmitter and receiver. The autocovariance function of the deviation of the extracted ${K}$ -factors from the proposed model is presented and the coherence length is investigated. Our results show that even though a cutting is a scenario with severe fading, a “wide” cutting (i.e., with both wide crown and bottom widths) is conducive to the reduction of the severity of fading.

This paper reports (i) a set of measurements of the wireless propagation channel at 930 MHz, conducted along the "Zhengzhou-Xian" high-speed railway of China in various railway viaduct scenarios, and (ii) an analysis and modeling of the small-scale and large-scale channel parameters based on those measurements. The environment can be categorized into four cases, covering viaducts with different heights and in different suburban environments. Small values of fade depth, level crossing rates, and average fade duration are observed. Akaike's Information Criterion (AIC)-based evaluation indicates that the Ricean distribution is the best to describe small-scale amplitude fading. An analysis of the envelope autocovariance function shows that the coherence distance is less than 10 cm. The Ricean K-factor is modeled as a piecewise-linear function of distance. Moreover, a breakpoint path loss model is developed and shadow fading is investigated using the same break point as for the distance-dependent K-factor model. The Suzuki distribution is found to offer a good fit for the composite multipath/shadowing channels. We find that the viaduct height H, together with the number of surrounding scatterers, significantly affects the small- and large-scale channel parameters. These results are applicable to both normal-speed and high-speed railways, and will be useful in the modeling of railway viaduct channels and the design of railway wireless communication systems.

To ensure the stability of radio signal transmission in high-speed railway station, a detailed channel modeling for this special environment is essential and valuable. In this work, an evaluation of the performance of radio propagation in a real high speed railway station scenario is conducted. The corresponding measurements in the actual environment are carried out with the assistance of hardware testbed at 950 MHz and 2150 MHz, respectively. The propagation in both Line of Sight (LOS) and None-Line of Sight (NLOS) conditions are considered and tested. The measurement scenarios and configurations are presented in detail. Furthermore, the key parameters, such as power delay profile, reverberation time are extracted from the broadband measurement results and compared at both frequencies to achieve a rational solution for broadband communication system applying in the development of next generation high-speed railway.

High-speed rail line consists of a variety of complex terrain structures. To ensure the stability of radio signal transmission, a detailed channel modeling for this special environment is essential and valuable. In this work, an evaluation of the performance of radio propagation in a high speed railway cutting scenario is conducted. The corresponding measurements in the actual environment are carried out with the assistance of hardware testbed at 950 MHz and 2150 MHz, respectively. The measurement scenarios and configurations are presented in detail. The key parameters, such as power delay profile, reverberation time are extracted from the broadband measurement results and compared at both frequencies to achieve a rational solution for broadband communication system applying in railway environment.

By using the multiple-scale method, we analytically study the dynamical properties of a temporal optical soliton under the consideration of the high order effects and cross-coupling relaxation of longitudinal optical phonons (CCRLOP) in an asymmetrical four-level semiconductor double quantum wells. The results reveal that when increasing strength of CCRLOP, the amplitude of the soliton shows a decrease-to-increase behavior. At fixed CCRLOP intensity, the amplitude and width of the soliton both exhibit a minimum or/and a maximum as a function of three-photon detuning. Moreover, these extremums will shift to the smaller side of the three-photon detuning with the increasing strength of CCRLOP. In addition, with the increasing strength of CCRLOP, the whole trend of group velocity of the soliton changes from an initial increase followed by a decrease to a direct decrease. These results may supply a reference value for experimentally adjusting and controlling the dynamical characteristics of the solitons.

Sedimentation model tests were carried out on four clays in China for investigating the sedimentation behavior of slurries. The sedimentary process can be divided into fluid state and consolidation state. The consolidation state of slurries can be divided into Non-Terzahi soil and Terzaghi soil. The void ratio responsible for the intersect point of fluid state and consolidation state is determined as 8.6 times the void ratio at liquid limit based on the difference of settling type which can be divide into Consolidation settling and Zone settling with the initial void ratio increase. According to the relationship between the stable void ratio (at the end of consolidation) and the initial void ratio, the suggested value of void ratio at the transition point from Non-Terzaghi soil to Terzaghi soil is 2.8 times its value at liquid limit.

Based on a recursive Green's function method, we investigate the conductance of mesoscopic graphene rings in the presence of disorder, in the limit of phase coherent transport. Two models of disorder are considered: edge disorder and surface disorder. Our simulations show that the conductance decreases exponentially with the edge disorder and the surface disorder. In the presence of flux, a clear Aharonov–Bohm conductance oscillation with the period Φ0 (Φ0=h/e) is observed. The edge disorder and the surface disorder have no effect on the period of AB oscillation. The amplitudes of AB oscillations vary with gate voltage and flux, which is consistent with the previous results. Additionally, ballistic rectification and negative differential resistance are observed in I–V curves, with on/off characteristic.

In this letter, the underlying factor that leads to the change of path loss exponent n is investigated, using a reasonable and reliable indirect demonstration that is based on the simple two-ray model and a developed multiray model. It is found that the first Fresnel zone is the underlying factor that affects n. n will change only if the situation of the obstacles in the first Fresnel zone changes. The conclusion helps to understand the essences of the propagation.

The upconversion luminescences of YAlO3:Er3+ phosphor co-doping with different Gd3+ concentrations are investigated under the excitation of 980- and 532-nm diode lasers. A near ultraviolet upconversion emission at 410 nm is observed in YAlO3 under 532-nm excitation. Moreover, the inactive Gd3+ ions can improve the upconversion intensity efficiently in a certain range of concentration. Under 980-nm excitation, the visible upconversion emissions at 546 and 646 nm are enhanced by about 10 and 8 times at the Gd3+ concentration of 40%, respectively. The upconversion emission at 410 nm under 532-nm excitation is also enhanced by 7 times. The substitution of Gd3+ ions for Y3+ sites changes the local symmetry of Er3+, leading to the improvement of upconversion efficiency.

Based on the narrowband 930-MHz measurements taken along the “Zhengzhou-Xi'an” high-speed railway in China, an empirical path loss model is proposed. It is applicable to high-speed railway viaduct scenarios, considering the influences of viaduct height H and base station antenna relative height h, which are not well-covered by existing large-scale models. The path loss exponents are investigated, based on which the influence of viaduct on propagation is discussed. The fading depth up to 15.96 dB and the Ricean K -factor with mean value of 3.79 dB are obtained.

The formation energies of single vacancies and vacancy pairs in the tetragonal BaTiO3 were studied using first principles computational method. The results show that under reduction conductions, oxygen vacancies have the lowest formation energy among single vacancies. For vacancy pairs, the formation energies of the Ba-O pair are lower than that of Ti-O under most thermodynamical conditions. Calculation of the polarization for system containing Ba-O vacancy pairs shows that depending on the direction of the electric dipole of the pair, the polarization is either enhanced or decreased, which may be related to the imprint behavior of ferroelectric materials.

Dredged materials (DMs) with high initial water content are often generated during construction projects of ports and waterways, as well as during the dredging of rivers and lakes in China. The cement mixing method is commonly introduced to render these waste materials sustainable earthwork resources. In this study, phosphogypsum is used as a water reducing agent together with cement to stabilize the DMs at high water content. An unconfined compressive strength test, a scanning electron microscopy test (SEM), and a mercury intrusion porosimetry (MIP) test were used in combination to investigate the strength properties and microstructural characteristics of the stabilized dredged material (SDM). It is found that there exists an optimal phosphogypsum content when it is used to stabilize the DMs together with cement. SEM results showed that the strength of the SDM originates from the cementitious bonding and pore-filling of hydration products. MIP results further clarified that total pore volume, average entrance pore diameter, and Dp50 were suppressed with an increase in cementing material content and curing period. The strength properties and microstructural characteristics show a high consistency.

Based on density functional theory, the geometric and electronic structures of the Ti doped α-Al2O3 system (Ti:α-Al2O3) are calculated by using a first-principles method. Due to the Ti-doping, both the lengths and angles of bonds in the local geometries are distorted, from which a trigonal–triclinic structural transition may be expected. With increasing Ti-doping, an insulator–semimetal transition is observed in the Ti:α-Al2O3 system, mainly due to a complete spin polarization of electrons at the Fermi level. The dielectric function and absorption edge are further calculated. It is found that the absorption edge is decreased, and is much lower than that of pure Al2O3 crystals, which is in good agreement with the experiment. The results indicate the potential applications of the Ti:α-Al2O3 optical system.

Exact bright self-similar solitary waves are analytically derived in a cigar-shaped condensate with time-dependent atomic scattering length as(t) in an expulsive parabolic potential. The straightforward relation between the Gross–Pitaevskii equation and the standard nonlinear Schrödinger equation is presented for as(t)=a0 exp (γt) at the growing or decaying coefficient γ=±|ωz|/ωt with ωz(ω⊥) the axial (transverse) frequency. In the expulsive parabolic potential, in particular, it is found that the bright self-similar solitary wave is accelerated and set into motion due to the expulsive force. The results tally with the experimental observations by Khaykovich et al. [Science296 (2002) 1290].

We present a family of soliton solutions of the quasi-one-dimensional Bose–Einstein condensates with time-dependent scattering length, by developing multiple-scale method combined with truncated Painleve expansion. Then, by numerical calculating the solutions, it is shown that there exhibit two types of dark solitons—black soliton (the zero minimum amplitude at its center) and gray soliton (the minimum density does not drop to zero) in a repulsive condensate. Furthermore, we propose experimental protocols to realize the exchange between black and gray solitons by varying the scattering length via the Feshbach resonance in currently experimental conditions.

The fast development of high speed railway (HSR) promotes the evolution process of wireless communication system. An accurate time delay line (TDL) channel model in HSR environments is thus necessary. In this paper, the correlation property of multi-path components based on empirical measurements at 950 MHz with 33 MHz bandwidth are characterized in real HSR propagation scenario. The results can be used for the design of TDL model in bridge and tunnel scenarios, which can be employed in the evaluation and comparison of different radio transmission techniques for the future broadband wireless communication system of HSR.

Railway communications have recently attracted much interest. In the last few years, most of the literature focus on the propagation issues for link budget. However, the railway coverage is different from the cellular radio systems. It is well-known that due to effect of shadow fading, some locations within a coverage area will have a received signal below a particular threshold. Computing how the boundary coverage relates to the overall percentage of coverage area is very useful for the link budget. While this problem has been well solved for the circular coverage of cellular systems, there is a lack of the determination of percentage of coverage area in the narrow-strip-shaped railway cells, i.e., the linear coverage. It is of interest to determine the percent of locations within a linear rail track in which the received signal strength from a radiating base station antenna exceeds a particular threshold.

In the past few years, there has been an increasing interest of wideband wireless communications of High-Speed Railways (HSRs), which have plenty of specific propagation scenarios. Wideband channel modeling of HSR is important for system design of the next generation of HSR communications. However, there is a lack of deep understanding regarding the characteristics of wideband channels in the complex environments such as railway cuttings and stations.

With the rapid development of high-speed railway HSR system, the resource allocation problem in HSR wireless network becomes one of the key issues to improve the efficiency of resource utilisation. In this paper, we investigate the downlink resource allocation problem for multimedia services delivery in HSR multiple-input multiple-output MIMO-orthogonal frequency division multiplexing OFDM system with a cellular/infostation integrated network architecture. Taking the train trajectory and network stability into account, we formulate the problem as a stochastic network optimisation programming, which aims at maximising the overall system utility while keeping the system stable under the total transmission power constraint. To address the NP-hard mixed integer programming, the original problem is firstly transformed into a queue stability problem, and then decomposed into two separate subproblems by the drift-plus-penalty DPP approach. Finally, based on the stochastic optimisation technique, a dynamic resource allocation algorithm is proposed and its efficiency is illustrated by theoretical analysis and numerical simulations.

High-speed railway (HSR) has been widely introduced to meet the increasing demand for passenger rail travel. While it provides more and more conveniences to the people, the huge cost of the HSR has laid big burden on the government finance. Reducing the cost of HSR has been necessary and urgent. Optimizing the arrangement of the base stations (BS) by improving the prediction of the communication link is one of the most effective methods, which could reduce the number of the BSs to a reasonable number. However, it requires a carefully developed propagation model, which has been largely neglected before in the research on the HSR. In this paper, we propose a standardized path loss model for HSR channels based on an extensive measurement campaign in 4594 HSR cells of the "Zhengzhou-Xian" HSR line. The measurements are conducted using a practically deployed and operative GSM-Railway (GSM-R) system to reflect the real conditions of the HSR channels. The proposed model is validated by the measurements conducted in another operative railway - "Beijing-Shanghai" HSR line. The results are helpful for the HSR communications system designers to gain a better tool in the system planning, and propagation researchers to assess where the most pressing needs in the modeling of HSR channels lie.

The high-speed railway propagation channel has significant effect on the design and performance analysis of wireless railway control systems. An important feature of the high-speed railway communications is the usage of directional transmitting antennas, due to which the receiver may experience strong attenuation of the line-of-sight (LOS) path under the base station (BS). This leads to a drop, and strong variations, of the signal strength under the BS. While the physical origin of the signal variations is different from conventional shadowing, it can be described by similar statistical methods. However, the effect has been largely neglected in the literature. In this paper we first define the region of the bottom of the BS, and then present a simple shadow fading model based on the measurements performed in high-speed railways at 930 MHz. It is found that the bottom area of the BS has a range of 400 m – 800 m; the standard deviation of the shadowing also follows a Gaussian distribution; the double exponential model fits the autocovariance of the shadow fading very well. We find that the directivity of the transmitting antenna leads to a higher standard deviation of shadowing and a smaller decorrelation distance under the BS compared to the region away from the BS.

This paper focus on the problem of the classification of the propagation scenario of the High-speed Railway GSM-R System. Common scenarios and particular scenarios are classified and discussed. For the conventional classified method cannot work well in the study on the propagation characteristics of the High-speed Railway GSM-R System, this paper proposes a scenario classification method based on GIS. And the definition method of the particular scenarios, which are model tuning and deterministic analysis, are discussed in detail. The methods proposed in this paper provide a feasible way to classify and define the propagation scenario of the High-speed Railway GSM-R System more preciously.

In the high-speed railway communication networks, interference is quite complicated and serious interference can even ruin the security of trains. So how to evaluate the effect is becoming more and more important. Both grey clustering evaluations and analytic hierarchy process are an effective comprehensive evaluation theory. In this paper, we apply the theory of grey clustering evaluations and analytic hierarchy process to assess the interference of the circuit domain in GSM-R networks and make a comprehensive evaluation on interference. Based on the theory of grey clustering evaluations, the interference is sorted into rough groups. Then further classification of the interference can be obtained. The results show that grey clustering evaluations combined with analytic hierarchy process can provide the reliable interference evaluation in the railway services.

This paper presents analysis and spatial channel modeling based on a series of 930 MHz measurements conducted along the “Zhengzhou-Xi'an” high speed rail (HSR) of China. Raw data are collected in five cuttings in rural and suburban environments subject to the consideration of the geometry of cuttings, including crown width and bottom width. A comparison among different distributions of the small-scale-fading is made by using a root mean squared errors (RMSE) goodness-of-fit test, which shows that the Ricean distribution offers the best fit. Moreover, it is found that the rich reflection and scattering components in the cutting scenario reduce the effect of the dominant component of the received signal, which results in a Rayleigh distribution, validating a good fit in this line-of-sight (LOS) scenario. Due to the rich multipath components and the directional transmitting antennas in HSR, the Ricean K-factor is modeled as a piecewise function of distance associated with the median K-factor and a standard deviation. Our analysis shows that a “wide” cutting scenario, such as with shallower slopes and wide crown and bottom widths, can reduce the impact of channel fading.

This paper proposes a distance-dependent Ricean K-factor model for a line-of-sight (LOS) viaduct scenario in the high-speed rail (HSR) of China. Extensive narrowband measurements conducted at 930 MHz are utilized. The propagation environment can be categorized into two cases: moderate suburban and dense suburban. The estimated K-factors are modeled as a piecewise-linear function of distance. The statistical fluctuations of K-factors are well considered by introducing the standard deviation to the expression. A detailed comparison between the piecewise-linear K-factor model and that of other literature validates the proposed model. Our results will be useful in the modeling of HSR viaduct channels and the performance analysis such as channel capacity and throughput for HSR wireless communication systems.

This paper indicates the presence of a big area with poor wireless coverage at the bottom of the directional antenna in high speed rail suburban environment, based on a set of 930 MHz narrowband measurements taken in three different high speed rail cells of China. The critical location of the directional antenna bottom area is calculated, using the height difference of the antennas, and the angle between transmitter antenna and the base station tower. An empirical path loss model is proposed for this directional antenna bottom area. The results help to ensure the safety of high speed rail wireless communications.

This paper presents a set of 930 MHz measurements conducted along the “Zhengzhou-Xi'an” high-speed rail of China, to characterize short-term fading behavior of the rail viaduct scenario. Three measurement cases covering viaducts with different heights are reported. The analysis results include fade depth (FD), Ricean distribution fit and K-factor modeling, level crossing rates (LCR), and average fade duration (AFD). A small value of fade depth, around 15 dB, is observed. The Ricean distribution offers good fit in this line-of-sight (LOS) propagation scenario, and the K-factor estimated using moment-based method is modeled as a piecewise function, whose break point equals to the reference distance. It is found that the viaduct height H greatly affects the severity of fading and the feature parameters. The results are applicable to the design of high-speed rail communication systems and the modeling of the rail viaduct fading channels.

In this paper, the hard-in-the-loop(HIL) simulation system which consists of radio channel emulator and GSM for Railway (GSM-R) system is established. According to the network planning measurement specification of GSM-R, the simulation measurement parameters are chosen. The communication quality is measured under different channel conditions (different coverage level, co-channel interference and mobile speed). Based on the HIL simulation measurement, the impact of coverage level, co-channel interference and mobile speed on the communication quality of GSM-R is studied. The measurement results show that coverage level has only a little effect on the communication quality, while the rise of mobile speed and co-channel interference can worsen the communication quality of GSM-R system.

This paper presents the narrowband measurements taken along “Zhengzhou-Xi'an” high-speed railway of China at 930 MHz. The detailed measurements and data processing methods are given using the present GSM-Railways (GSM-R) network, which can be used as the guide method to conduct the narrowband measurements in high-speed railway viaduct scenarios. Based on the log-normal shadowing path loss model, the investigation is made on the effect of reference distance on path loss exponent and standard deviation, which are not well-covered by existing models. The values of path loss exponents and standard deviations calculated with different reference distances are compared. A novel model is proposed to describe the relation of them. It applies to high-speed railway viaduct scenarios, with base antenna heights higher or lower than 25 meters. It raises path loss prediction accuracy and gives the suggestion on large scale modeling considering the effect of reference distance.

Based on the dynamic consolidtion model test, the variation of dry density and improvement depth of loess have been studied. The test results revealed that dynamic consolidation method can improve the density and engineering properties of loess in a short time when high embankment is filled. The dynamic consolidation depth has been influenced by many factors such as tamping times,moisture content,initial dry density,pounder diameter and tamping energy. A mathematical equation is proposed to obtain the improvement depth,and its reliability is demonstrated.

A kind of municipal waste as a new solidfing aid and portland cement were used to solid sewage sludge. For optimal and effective utilization of the new binder, an experimental study on unconfined compressive strength was conducted to obtain the strength developmen with curing time in the matrices. Based on the results, a mathematical model relating the gain in strength to curing time is proposed in the paper. According to the mathematical model, the strength of the matrices at any curing time in 60 days of age can be predicted when the strength at 28 days of age is acquired. Illustrative examples show that the result of predition seems to be acceptable.

As the High-Speed Railways and Lines for Passenger Transportation are developing rapidly around the world as well as in China, the co-use of EGSM and GSM-R network is crucial, and the interference between China Mobile Communications Corporation (CMCC) GSM system and GSM-R (GSM for Railway) system is intensified. Thus the security and reliability problem of GSM-R system becomes more and more serious. This article illustrates five main steps to solve the interferences between GSM and GSM-R network with cooperation of the CMCC and the State Radio Regulatory Commission (SRRC). These five steps are: interferences location, data analysis, fixed-point interference test, interference clearance and electro-magnetic environment retest. The discussion followed aims at providing a standardized reference to the future GSM-R network optimization.

Presented is the statistical analysis of radio wave propagation in a high-speed railway cutting scenario, derived from 930 MHz measurements taken along the ‘Zhengzhou-Xi'an’ high-speed railway of China. The crown width and bottom width of the cutting are well-covered by the proposed models. The Ricean distribution offers a good fit and the K-factor is found to be lognormal, with a mean value of 1.88 dB and standard deviation of 3.29 dB.