基于智能终端定位的智能交通疏导系统研发

在城市发展到比较成熟的阶段,缓解交通堵塞可借鉴智能交通系统(Intelligent Transportation System,ITS)的理念,文章在现有的无线通信设施和车辆系统上,通过融合信息与通信技术、移动互联网和智能终端设备构建一套道路交通流量计算和道路交通服务系统。该系统通过车载智能终端的GPS数据进行实时交通流量计算,并且将计算的交通流量信息实时地反馈给驾驶车辆的用户,方便用户出行道路选择,缓解交通阻塞。     

VANET网络中小尺度衰落信道仿真

车载网络（VANET）是智能交通系统的核心部分,能够提高道路交通的安全性与高效性。分析电波在VANET网络中的传播特点,着重分析该网络中双移动节点间的小尺度衰落信道,包括多普勒功率谱模型和用成型滤波器法仿真VANET网络中小尺度衰落信道特性,给出经历该信道后接收信号的包络。仿真结果表明,随着移动车辆速度比增大,接收信号衰落更深。该结果对于VANET网络下无线多媒体业务性能评估有着重要的作用。     

Field evaluation of UHF radio propagation for an ITS safety system in an urban environment

Roadside-to-vehicle and vehicle-to-vehicle communication systems have been proposed as part of ITS development to help achieve vehicle safety and realize more secure road traffic environments. In this article we first introduce several typical applications and their radio range requirements for vehicle safety communication systems to clarify the technical point of view. Then we show some field experiment results in an urban area in Tokyo to investigate and verify the radio propagation characteristics and the quality of communications by using a wireless radio prototype system. Finally, we conclude that the current prototype system has potential to fulfill the radio range requirements of vehicle safety communications, but there are still lots of issues that need to be addressed.     

Hardware Simulator Design for MIMO Propagation Channel on Shipboard at 2.2 GHz

A wireless communication system can be tested either in actual conditions or with a hardware simulator reproducing actual conditions. With a hardware simulator it is possible to freely simulate a desired radio channel, making it possible to test “on table” mobile radio equipments. This paper presents new architectures for the digital block of a hardware simulator of MIMO propagation channels. This simulator can be used for LTE and WLAN IEEE 802.11ac applications, in indoor and outdoor environments. However, in this paper, specific architectures of the digital block of the simulator for shipboard environment are presented. A hardware simulator must reproduce the behavior of the radio propagation channel. Thus, a measurements campaign has been conducted to obtain the impulse responses of the shipboard channel using a channel sounder designed and realized at IETR. After the presentation of the channel sounder, the channel impulse responses are described and implemented. Then, the new architectures of the digital block of the hardware simulator, implemented on a Xilinx Virtex-IV FPGA are presented. The accuracy, the occupation on the FPGA and the latency of the architectures are analyzed.     

A wireless multimedia framework for the management of emergency situations in automotive applications: The AIDER system

Automotive applications would greatly benefit of multimedia telematic services for many purposes, from tourism and entertainment, to most important issues such as security and traffic management. Within this context, the AIDER system (AIDER is the acronym of Accident Information and Driver Emergency Rescue) is one of the most advanced multimedia mobile services targeted at emergency situations such as road accidents. The AIDER allows the interactive exchange of multimedia data (and in particular, audio, video and biomedical information) between the vehicle and a remote rescue centre, by using several different narrowband radio channels including cellular networks and satellite. In this paper an overview of the AIDER architecture is provided, focusing on the advanced video communication system.     

Performance evaluation of a protocol for packet radio network in mobile computer communications

The need to provide computer network access to mobile terminals and computer communications in the mobile environment has stimulated and motivated the current developments in this area. Packet radio technology has developed over the past decade in response to the need for real-time, interactive communications among mobile users and shared computer resources. In computer communication systems we have a great need for sharing expensive resources among a collection of high peak-to-average (i.e., bursty) users. Packet radio networks provide an effective way to interconnect fixed and mobile resources. The results of an attempt to study the performance of the mobile packet radio network for computer communications over degraded channels are presented. We develop a model under fading conditions and derive a protocol for evaluating the performance of the mobile packet radio network (MPRNET) in terms of the packet error rate, packet delay, throughput and average number of retransmitted packets per cycle. The analytical results are presented and numerical examples are given to illustrate the behavior of these performance criteria as a function of packet transmission rate, packets transmitted per cycle, packet size, and vehicle speed with the help of appropriate plots.     

Time-dependent analysis of mobile communication traffic in aring-shaped service area with nonuniform vehicle distribution

A method of analysis for modeling cellular telephone systems which incorporates vehicular traffic theory into the model is introduced. By obtaining position- and time-dependent vehicle density data, it is possible to investigate the behavior of communication traffic for any type of road traffic. The method allows car movement in both directions on the highway to be considered. However, situations in which one direction carries such an intense load that the other may be ignored are treated, and a simplified model with enough information to examine worst-case scenarios is developed. Simulation and analysis results are presented     

A Hybrid Multichannel Hardware Simulator for Frequency-Selective Mobile Radio Paths

We present the analysis and design of an efficient hybrid digital/analog multichannel hardware simulator for frequencyselective Rayleigh-fading mobile radio paths. The simulator has eight RF outputs and is linear and reciprocal. All outputs exhibit mutually independent Rayleigh fading over a 45 dB range and have identical time delay spreads. Analog RF techniques are combined with a digital signal processor (DSP) to generate random path modulation. Frequency selectivity from time delay spread is created using several RF path delay elements. Simulated vehicle velocity is continuously variable from 6 to 60 mph. The simulator is thus a flexible tool for the study of mobile radio transmission techniques.     

Multihop R-ALOHA for intervehicle communications at millimeterwaves

With reference to road transport information (RTI) applications, such as cooperative driving, short-range intervehicle communications in a highway environment are investigated in this paper. The research in this field indicates the suitability of the 60-64-GHz band. Due to the distributed nature of the intervehicle communication system, an R-ALOHA protocol is considered; multihop (MH) and single-hop (SH) strategies are compared. Network performance is assessed by considering the joint impact of random access, interference, thermal noise, propagation, and packet capture effect. Several figures of merit are analyzed and discussed: packet success probability (PSP), system stabilization time (SST), first success time (FST), and deadline failure probability (DFP). Network performance is evaluated either by an analytical approach or by a software tool able to simulate a one-lane highway scenario. Both steady-state and transition situations are considered. System performance in terms of PSP (in the presence of two-way Rice fading, noise, and interference with antenna diversity and selection combining) is analytically evaluated to validate the simulation tool and to prove the suitability of an MH network strategy. The simulation approach allows the evaluation of the impact of protocol parameters on network performance, with reference to nonsteady-state situations     

Design and performance analysis of an advanced, narrowbandintegrated voice/data mobile radio system

Private land mobile communications have experienced significant demand for increased capacity and for new services, but congestion within the currently allocated 450 and 800 MHz bands has severely limited the capability of present generation systems to meet this demand. This paper proposes a narrowband integrated voice/data mobile radio system which triples current voice traffic capacity and simultaneously provides capacity for mobile data communications such as mobile data terminals, automatic vehicle location, and mobile facsimile by utilizing the silence gaps inherent in speech. The system is designed to fit within the narrowband 25 kHz channels in the 450 and 800 MHz frequency bands, and thus the system can replace existing private land mobile radio systems with minimum impact. The centerpiece of the system design is an evolutionary multiplexing and access control technique known as Packetized Data, Voice Dedicated (PDVD) Burst Switching which allows transmission of data within the silence gaps inherent in speech. Simulation results for various voice and data traffic loads show the flexibility and efficiency of the proposed narrowband integrated voice/data mobile radio system     

Talking with cars-traffic messaging

Fleet management, traffic control and vehicle navigation are being revolutionised by developments in road transport informatics. One of the unsung heroes supporting the new technologies is traffic messaging, which is the exchange of traffic-related digital coded information between traffic control centres, traffic information publishers and broadcasters, and the vehicles and drivers. The author discusses the application areas of traffic messaging and then describes the mobile radio and satellite communications technology which makes traffic messaging possible. The author then describes the European Community, DRIVE programme before addressing some of the obstacles to be overcome if traffic messaging is to become more widespread     

Estimation of Gilbert's and Fritchman's models parameters using thegradient method for digital mobile radio channels

A series of error sequence measurements in a typical mobile radio channel has been conducted to study the time distribution of transmission errors. E.N. Gilbert's (1960) and B.D. Fritchman's (1967) digital communication channel models are shown to describe adequately the observed error bursts occurring in the mobile radio channel. An estimation method based on the gradient algorithm is proposed for computing the parameters values of both models from the experimentally derived error distributions. A digital mobile radio channel simulator based on Gilbert's and Fritchman's models with the parameter values as estimated using the gradient technique is presented     

Design and analysis of cellular mobile communications system basedon DQRAP/CDMA MAC protocol

Future third-generation mobile communication systems will need multi-access control (MAC) protocols suitable for multimedia code division multiple access (CDMA) radio communications. Distributed queueing random access protocol (DQRAP)/CDMA is a general purpose MAC protocol oriented to the CDMA environment. Analytical model expressions and computer simulations have shown its capacity to achieve near-optimum performance under heterogeneous traffic scenarios in a unicellular environment. A cellular environment has been designed to verify that DQPAP/CDMA maintains its near-optimum performance in a packet switched mobile communication system. A new handover technique based on the protocol is proposed to further improve the system performance     

Modeling a Mobile Cellular Network Using a Discrete-Event Simulator

In this paper we introduce a discrete-event-based simulation technology suitable to model cellular mobile radio systems with respect to their dynamic behavior. The latter results in the need for simulation tools which support mutable system configurations. The problems encountered when modeling mutable system configurations using conventional discrete-event simulators are discussed. In order to show a possible solution to this problem we introduce configuration events and configuration objects into the theory of discrete-event simulations. We demonstrate how configuration objects can be implemented in a discrete-event simulator using a dynamic map-function, hereby extending a definition of higher order functions. We apply the configuration objects in a Multiple Layer Model for modeling an entire mobile cellular radio network in a discrete-event simulator as an application for the extended theory. In this model we use the configuration objects to change the network's configuration during runtime. We show that this solution—combined with an object-oriented software design and, possibly, a visual programming language—is a powerful tool for the simulation of the dynamic aspects of mobile cellular radio networks. The software technology presented will be applied by the German cellular network operator Mannesmann Mobilfunk to model dynamic features applicable to the radio resource management of mobile radio networks and to access their performance by simulation.     

基于D-LinkNet与形态学计算的高分遥感图像车流量监测

针对城市交通路面车流量监测实时性和准确性高的需求,设计了一种利用高分遥感图像进行道路网自动提取和车辆自动监测的处理方法。综合利用D-LinkNet和形态学计算实现道路区域的二值化语义分割及连贯性、边缘扩展以及平滑性优化,同时将道路信息作为掩码并外溢后进行车辆目标检测,有效避免非道路区域车辆目标干扰。提出采用热力图的形式改进车流量监测方法,可以更直观显示道路拥挤程度。综合利用现有数据集对所提方法进行评价,车辆检测的平均精度达91.7%,道路提取平均交并比达85.3%,可以实现道路车流量的有效监测。     

Application of the “Contact Convoy” Concept to Hybrid Electric Vehicles

This paper applies an intelligent intervehicle device (termed a ldquobridging damperrdquo) to a convoy of in-contact vehicles. The field of application is backup for future automated highways and operation of novel guided systems using vehicle-following control. The vehicle represented in computer simulations is a parallel hybrid electric automobile. Using the advanced vehicle simulator (ADVISOR) model, the vehicle representation is tuned to achieve matching of the overall force and power characteristics and the same performance over an urban driving cycle. The model for which a dedicated Matlab Toolbox was constructed is described. Simulation results compare the vehicle-following control on its own with a passive damper and a ldquoquasi-activerdquo damper that is controlled in collaboration with the vehicle's drivetrain. Using transient disturbances in the form of wind gusts and short gradients, power peaks and longitudinal ride quality (vibration dose value) are used to evaluate the performance.     

Integrated Train Ground Radio Communication System Based TD-LTE

In existing metro systems, the train ground radio communication system for different applications are deployed independently. Investing and constructing the communication infrastructures repeatedly wastes substan-tial social resources, and it brings di?culties to maintain all these infrastructures. We present the communication Quality of service (QoS) requirement for different train ground radio applications. An integrated TD-LTE based train ground radio communication system for the metro system (LTE-M) is designed next. In order to test the LTE-M system performance, an indoor testing environment is set up. The channel simulator and programmable attenua-tors are used to simulate the real metro environment. Ex-tensive test results show that the designed LTE-M system performance satisfies metro communication requirements.     

基于三维GIS的城市高架环线噪声地图研究

随着中国城市道路交通的迅速发展,城市环线交通以高架环线为主。现有的各类道路噪声预测模型都缺乏处理城市高架环线这类复杂的空间三维实体的能力。以美国联邦公路局的FHWA噪声预测模型为基础,通过车辆等效计算、高架环线多层多车道修正、高架桥声屏障修正等措施,对FHWA噪声预测模型进行修正。并将修正后的噪声预测模型与三维GIS模型相结合,绘制出了城市高架环线噪声地图。最终通过与实测数据的对比,验证了所修正噪声模型的正确性。     

A voice scrambler for mobile communication

A new voice scrambling method for mobile communication is proposed. The principle is to invert the voice sample polarity selectively according to the scrambling code, smooth it with a low-pass filter, and feed it to the radio transmitter. To utilize the principle, the necessary techniques such as filtering, synchronizing and scrambling code design, are described. The whitened spectrum of the scrambled voice and a large number of key codes provide a high security communication. The scrambler presented here is designed for an adaptor to press-to-talk mobile radio. Voice spectrum variation by scrambling is demonstrated and articulation is measured under nonfading and fading conditions with signal to noise (S/N) variation. Those results show that the scrambling method is suitable for mobile communication with rapid synchronization for press-to-talk radio, noise, and fading immunity.     

A computer simulation model for the evaluation of mobile radio systems in the military tactical environment

A computer simulation model, designed specifically for the analysis and evaluation of military mobile radio communication systems in the tactical environment is discussed. The algorithms and performance models used in the simulation model are briefly described, while statistical characteristics are derived analytically for a simplified scenario. Typical computer-generated histograms and distribution functions are presented for the more complex scenarios. The computer simulation model is shown to be an effective design tool for many different applications.