Proposal of Cooperative Communication to Enhance Accuracy of Wireless Control Systems

Control systems are being changed from wired to wireless communications because of flexibility, mobility and extensibility of wireless communication systems;however the reliability of wireless communications is suspected. In this paper, we propose cooperative communication scheme for wireless control systems which consist of a controller and multiple machines;these machines cooperatively work in a group and for the same duty. In the proposed method, the controller can communicate with machines directly or via other machines, whereas in the conventional method, the controller only communicates with machines directly. The simple 2-link arm plant is used to evaluate our proposed system, and the simulation results indicate that the proposed method is more accurate, and more stable than the conventional method.

A Wireless Solution for Train Switchgear Contact Temperature Monitoring and Alarming System Based on Wireless Communication Technology

We present a temperature monitoring and warning system, which is based on wireless communi- cation technology and applied in train switchgear in this paper. The system is consists of three parts, including wireless temperature detection module, inter-vehicle transmission networks module and?remote monitoring server. The switchgear contact temperature data are collected via the wireless temperature detection module and exchanged in inter-vehicle wireless networking by Zigbee modules. Then the temperature of train switchgear cabinets can be monitored remotely through the GPRS wireless communication.

MDL-based root-mean-squared delay spread estimation for MIMO OFDM systems

This paper studied the application of minimum description length (MDL) criterion for estimating root-mean-squared (RMS) delay spread (RDS) for MIMO OFDM systems. The analytic relationship between the powers and the correlation matrix of multipath components established the feasibility of the application of the MDL criterion to RDS estimation. The estimator presented both the estimate of instantaneous RDS and the estimates of noise variance, channel power and SNR of current channel with low computational complexity. Given the powers of the estimated multipath components, the MDL criterion was adopted to acquire the number of paths and the time delays of each path of current channel without making eigendecomposition of the correlation matrix normally required by MDL criterion, following which the noise variance and the power of each path can be estimated. The power delay profile (PDP) and RDS of the current channel were achieved. Simulation results showed that the proposed estimator was insensitive to variance of SNR and robust against frequency-selectivity.

Modeling research of train tracing based on UML sequence diagram and UPPAAL

The zone control subsystem is a real-time control system,which requests the correctness of the control process.Train tracing scene is an important function of the zone controller(ZC)in the communication based train control(CBTC)system.In the process of deep development and design,to ensure the safety of the system,the system needs to be modeled,simulated and verified to discover the system design flaws.Unified modeling language(UML)is combined with timed automata,and timed automata network models of train-filter and train tracing demarcation-point are established.At the same time,the verification tool of UPPAAL is applied to simulate the system,and verify the requirements of performance and function of system.The results show that the function of train tracing demaraction-point meets the requirements of system safety and limited activity.Therefore,the method is feasible and can be applied to the modeling and verification of other scenes of train control system.

Guest editorial: special issue on high mobility wireless communications

The high-speed railway and high-way networks are now expanding at a phenomenal speed in Chinaand in many other parts of the world. The related broadband wireless communication over high-speed trains and highway vehicles is a very challenging task due to hostile transmission channel conditions. The demand for such services is growing rapidly, following the proliferation of laptop/tablet computers and smart phones. This motivates the research on wireless communications in the high mobility environments.

Model-Free Adaptive Frequency Calibration for Voltage-Controlled Oscillators

The operating frequency accuracy of the local oscillators is critical for the overall system performance in the communication systems.However,the high-precision oscillators could be too expensive for civil applications.In this paper,we propose a model-free adaptive frequency calibration framework for a voltage-controlled crystal oscillator(VCO)equipped with a time to digital converter(TDC),which can significantly improve the frequency accuracy of the VCO thus calibrated.The idea is to utilize a high-precision TDC to directly measure the VCO period which is then passed to a model-free method for working frequency calibration.One advantage of this method is that the working frequency calibration employs the system history of input/output(I/O)data,instead of establishing an accurate VCO voltagecontrolled oscillator model.Another advantage is the lightweight calibration method with low complexity such that it can be implemented on an MCU with limited computation capabilities.Experimental results show that the proposed calibration method can improve the frequency accuracy of a VCO from±20 ppm to±10 ppb,which indicates the promise of the modelfree adaptive frequency calibrator for VCOs.

Class of Service Support Layer for Wireless Mesh Networks

This paper presents an add-on Class of Service (CoS) layer for wireless mesh networks. The proposed protocol is applicable for contention-based MACs and is therefore compatible with most of the Wireless Local Area Network (WLAN) and Wireless Sensor Network (WSN) protocols. The protocol has a locally centralized control for managing data flows, which either reserve a fixed bandwidth or are weighted by fair scheduling. The protocol reduces transmission collisions, thus improving the overall throughput. IEEE 802.11 adhoc WLAN has been taken as a platform for simulations and prototyping for evaluating the protocol performance. Network Simulator Version 2 (NS2) simulations show that the CoS protocol efficiently differentiates bandwidth, supports bandwidth reservations, and reaches less than 10 ms transfer delay on IEEE 802.11b WLAN. Testing with a full prototype implementation verified the performance of the protocol.

Designing of New Data Synchronization System

As the rapid development of Wireless Communications and the popularity of the Intelligent Terminal, data synchronization has been a social focus, meanwhile, user terminal devices are increasingly diversified, traditional synchronization technology based C/S mode has such deficiencies as insufficient amount of transmitting data and bad Real-time efficiency. It has become increasingly unable to meet the needs of future development. In this paper, we proposed and designed a new method and system by separating control with transmission to synchronize data to ensure Real-time data and improve efficiency.

Energy efficiency optimization of relay-assisted D2D two-way communications with SWIPT

Aiming at the energy consumption of long-distance device-to-device(D2D) devices for two-way communications in a cellular network,this paper proposes a strategy that combines two-way relay technology(TWRT) and simultaneous wireless information and power transfer(SWIPT) technology to achieve high energy efficiency(EE) communication.The scheme first establishes a fractional programming problem to maximize EE of D2D,and transforms it into a non-fractional optimization problem that can be solved easily.Then the problem is divided into three sub-problems:power control,power splitting ratios optimization,and relay selection.In order to maximize EE of the D2D pair,the Dinkelbach iterative algorithm is used to optimize the transmitted power of two D2D devices simultaneously;the one-dimensional search algorithm is proposed to optimize power splitting ratios;an improved optimal relay selection scheme based on EE is proposed to select relay.Finally,experiments are carried out on the Matlab simulation platform.The simulation results show that the proposed algorithm has faster convergence.Compared with the one-way relay transmission and fixed relay algorithms,the proposed scheme has higher EE.

Overview of Key Technologies for Remote Wireless Operation Platform on Water Surface

The underwater environment is complicated and full of hazards,making it tough to complete with just one piece of underwater operation equipment.Building a high-speed,low-latency wireless connection between a remote wireless operation platform on water surface and other operation platforms in order to achieve long-distance transmission of high-definition image data and control commands,as well as collaborative operations among multiple platforms,has become a development trend and focus of exploring complex and dangerous waters.This paper summarizes and elaborates on underwater communication technology,long-distance data transmission technology,multi-submersible robot collaborative operation,and information interaction technology,as well as the development status of key technologies of remote wireless operation platform on water surface.And the research direction and focus of the remote wireless operation platform on water surface are prospected.

Dependability analysis of the data communication system in train control system

Communication based train control (CBTC) system is based on mobile communication and overcomes fixed blocks in order to increase track utilization and train safety. The data communication system (DCS) between trains and wayside equipment is a crucial factor for the safe and efficient operation of CBTC system. The dependability under various transmission conditions needs to be modeled and evaluated. In this paper,a stochastic reward net (SRN) model for DCS based IEEE 802.11 standard was developed,which captures all relevant failure and failure recovery behavior system aspects in a concise way. We compared the reliability,availability for DCS with and without access point (AP) and antenna redundant configuration. We also quantitatively evaluated and compared the frame loss probability for three DCS configurations with different train velocities and train numbers in one radio cell. Fixed-point iteration was adopted to simplify the analysis. Numerical results showed the significant improvement of the reliability,availability and the frame loss probability index for the full redundant configuration.

Analysis of the different locomotive wireless multi-traction synchronous control systems for heavy-haul combined trains and their performance

This paper looks at the heavy-haul combined train composed of different types of locomotives and its distributed power control system with a combination of 800 MHz and TD-LTE wireless communication.It analyses some key characteristic parameters that affect the synchronism and communication of the differential wireless multi-traction synchronous control systems for heavy-haul combined trains.At the same time,in order to reduce the latency of instruction and information transfer between different types of locomotives,improve the time-limit certainty of wireless transmission and optimize the control quality of multi-traction control systems for heavy-haul combined trains,a synchronism optimization strategy based on the Markov decision process on the basis of Petri networkconstruction is proposed.Relevant experiments and tests are carried out to verify the effectiveness of the synchronism optimization of the control system,which provides a guarantee for improving the differential wireless multi-traction synchronous control system for combined trains and optimizing train control.

CTCS3-300H型列控车载设备状态在线监测与智能分析系统开发与应用

针对CTCS3-300H型列控车载设备(简称:列控车载设备)各单元运行日志数据分散存储、数据转储下载接口多、数据分析工作繁琐耗时的问题,根据列控车载设备结构特点,设计了列控车载设备状态在线监测及智能分析系统。该系统统一了列控车载设备各单元的日志数据采集与传输接口,借助既有的车地无线传输通道,设计了灵活、务实的车地数据传输方案,实现了用于列控车载设备状态在线监测的事件通告报文的实时传输,提供故障日志自动下载、手动按需下载两种日志数据无线下载方式,在满足列控车载设备状态在线监测和故障分析需要的前提下,最大限度地减少车地数据传输量。通过有效利用列控车载设备日志数据进行智能分析,能够快速、准确定位故障原因,实现故障自动报警并给出处置建议,提高了列控车载设备故障应急处置和维护效率,为动车组安全运行提供强有力的技术保障。

一种基于无线专网的CTC3.0多岗位联动技术方案

在调度集中系统3.0(Centralized Traffic Control System 3.0,CTC3.0)推广使用过程中,对于接发车作业中的流程管理功能,因覆盖岗位多,需要通过多岗位联动来实现接发车作业流程的流转,尤为获得车站的关注与重视。通过分析车站运输生产过程中的接发车作业流程业务,结合CTC3.0作业流程管理功能,探讨一种基于无线专网的CTC3.0多岗位联动技术方案,以期在未来的实践中,实现CTC3.0车站接发车作业流程管理数字化,减轻车站人员的作业负担。

基于5G-R的CTCS3-300H型列控车载设备车地无线通信冗余技术方案

随着铁路移动通信由GSM-R向5G-R演进,基于GSM-R的CTCS-3级列控系统车地无线通信技术面临更新替代的问题。根据近年来5G-R承载CTCS-3级列控系统车地无线通信业务研究取得的成果,为充分利用5G-R的优势,将5G-R下CTCS-3级列控系统车地无线通信由单链路改为双链路冗余技术。以CTCS3-300H型列控车载设备为研究对象,分析车地无线通信冗余技术的适应性,研究车地无线通信的系统架构,以及不同网络制式下的移交方案等,提出适合于CTCS3-300H型列控车载设备的车地无线通信冗余技术实现方案。研究成果为CTCS-3级列控系统在5G-R下实现车地无线通信冗余技术提供思路和借鉴。

基于铁路5G-R的自主化机车无线同步操控技术方案

为探讨基于5G-R的自主化机车无线同步操控技术方案,通过调研自主化机车无线同步操控业务需求,分析我国重载铁路既有通信系统的不足,充分考虑5G-R网络的高带宽、低延迟、IP化链路、分组域传输、QoS优先级保障等特性,提出总体技术方案,重点论述主从控机车数据传输、可控列尾数据传输、编组请求、多司机通话等功能的实现方案。该研究结果有利于提升自主化机车无线同步操控系统的先进性,确保其在复杂环境下的可靠运行,对提升重载铁路运输生产安全和效率具有指导意义,为重载铁路的现代化和智能化发展提供强有力的技术支持。

基于压缩感知的车地传输数据压缩算法研究

动车组车地无线传输受限于移动网络带宽限制,数据传输间隔较长,无法准确反映车载系统运行状态,提出了一种基于压缩感知的车地传输数据压缩算法,能够在地面高精度地还原车载原始数据的同时,大幅压缩车地传输数据量,提高了车地带宽利用率,为动车组运行监测和故障应急指挥提供了更详实的数据支撑。

基于通信网络的列车控制系统

自动组网(初运行)是列车控制与管理系统(TCMS)的重要特征,通过初运行,确定列车通信网络(TCN)内的节点组成、节点之间的顺序、总线主以及各个节点相对总线主的朝向,这是TCMS对列车进行控制与管理的基础。对于基于无线通信的TCMS,由于无线列车骨干网(WLTB)的网络节点之间没有通信线缆的物理连接,以传统的方式实现自动初运行十分困难,因此实际工程中采用人工设置参数的方式来组网。同样,在虚拟联挂(VC)系统中,多列列车通过WLTB组成列车编队,也存在动态自动组网的问题。在VC系统中,由于跟随列车处于自动驾驶模式,通过人工设置参数来组网的方式也不可行。文章分析了TCN、WLTB的初运行和VC列车编队/解编,探讨了基于无线通信的列车编组初运行或编队动态组网问题的实质与根源,提出通过引入一个更大的网络系统、融合TCMS和信号系统来解决自动组网问题的方法,基于列车控制的视角给出了面向列车全自动运行的基于通信网络的列车控制(NBTC)系统自动组网方法、分层次功能和系统架构,并提出了与NBTC相关的研究方向。

CBTC系统WLAN车地无线通信网络在线监测关键技术及应用

目前国内大部分城市轨道交通车地无线通信系统仍采用IEEE 802.11 b/g协议,工作在2.4 GHz ISM开放频段,车地通信故障易造成列车紧急停车等情况。针对目前车地无线通信监测完整性和实用性不足、全链条监测手段缺乏等问题,结合无线通信系统范围广、场景多、故障现象迷惑性强等特点,融合无线场强采集、数据流监听、无线图谱定位、贝叶斯网络故障等定位技术,利用软硬件结合的方式构建全链条车地无线智能分析监测系统。采用射频处理单元+运行处理单元软硬件分离的架构模式设计无线监测终端,采用C/S架构和人工智能技术设计车地无线智能分析监测系统,实现从车载到轨旁无线场强、漫游切换、多信道监测等智能分析功能。该系统已在北京地铁亦庄线、昌平线、10号线等多条线路上应用,运用效果良好,满足现场无线监测需求,大幅提升了车地无线通信监测能力及应急处置响应效率,对保障列车运营安全具有重要意义。

基于监测数据的ATP车载电台健康状态评估算法研究

在列车运行过程中,ATP车载电台运用不稳定会引起车地无线通信超时,导致CTCS-3级列控系统降级,影响列车运行效率。针对此类问题,通过研究电台多种常见故障及特征,设计一套用于ATP车载电台健康状态评估的算法。以接口监测数据、基站空口监测数据和车载空口监测数据为基础,通过学习与迭代,建立表征电台健康状态的模型作为评分基准;通过对比电台相关特征值与模型基准值,对各个电台进行健康状态评估。经验证,该算法可准确描述车载电台的健康状态,供运维人员对健康状态差的电台提前处理,从而实现电台故障的事前预防,对降低CTCS-3级列控系统无线通信超时概率、保障列车安全运行、提高铁路运维水平等具有重要意义。