A mobile virtual-distributed system architecture for supporting wireless mobile computing and communications

This paper describes a novel mobile virtual-distrubuted system architecture for supporting global mobile computing and communications. the principal contribution of this paper is to innovatively apply virtual memory concepts to mobile systems by deploying mobile-floating agents to de-couple services and resources from the underlying network and allow them to move around following their mobile users. The mobile-floating agents maintain data structures associated with a mobile user. By combining the mobile-floating agent functions with a predictive mobility management algorithm and location-aware caching and prefetching, services and user data structure are pre-connected and pre-assigned at the locations to which the user is moving. Thus, the users can maintain their data structures or immediately receive service with virtually the same efficiency as at the previous location.     

A C/I advantageous satellite system configuration for land mobile applications

A satellite system based on the frequency scanning concept has been recently assessed for L‐band land mobile communications. The study – promototed by ESA/ESTEC for an European application mission – has reached an advanced electrical design phase. The selected configuration is particularly advantageous in terms of Carrier‐to‐Intermodulation ratio (C/I) performance, which constitutes a requirement of key‐importance in the envisaged user applications. The advantage in C/I is due to the proper choice of the on‐board transmitter configuration, which adopts power module pairs where the overall power demand is evenly distributed. The consequent improved C/I is then achievable at both transmitter and radiated far field level. The present paper aims a contribution to the design methodology of frequency scanning satellite systems, by joining two key‐aspects: in fact an analytical approach is proposed to demonstrate the C/I advantage achievable through frequency scanning satellite systems and the methodology is applied to a concrete example, the ESA/ESTEC system, whose feasibility has been fully proved in previous studies. The analysis is performed both at transmitter level and in the far field. The main results achieved are hereinafter presented. This revised version was published online in June 2006 with corrections to the Cover Date.     

一种用于手持移动终端的九频段双天线系统

提出了一种应用于手持移动终端的九频段双天线系统.该双天线系统由两个对称的天线单元、一个解耦地枝和一个浮置结构组成.构成天线单元的驱动分枝和寄生地枝共同激励起多个谐振模式.通过采用解耦地枝,降低了低频带内的互耦,改善了高频带内的阻抗匹配.通过添加浮置结构,增加了低频带和高频带的工作带宽,降低了高频带下限频率附近的互耦.实测结果表明:天线样品在低频带和高频带内的-6 dB公共阻抗带宽分别为276 MHz (692～968 MHz)和1 110 MHz(1 636～2 746 MHz),覆盖了LTE700/2300/2500,GSM850/900,DCS/PCS/UMTS和2.4-GHz WLAN频段;低频带内的互耦低于-10 dB,高频带内的互耦低于-13.7 dB.根据实测三维辐射方向图计算了双天线系统的包络相关系数、平均有效增益和分集增益计算结果表明,双天线系统具有良好的分集性能.     

基于SIP的移动学习系统的研究与设计

通过对SIP协议消息和SIP移动性的分析,结合移动学习的具体情况,提出了一种基于SIP的移动学习系统,并对该系统的结构和各个组成部分进行了描述,介绍了每个模块的功能实现.     

Digital mobile telephone system using TD/FDMA scheme

Multiple access is an indispensable technique for efficient radio spectrum utilization in mobile radio systems, because a large number of subscribers can be connected only when they require radio channels. Frequency division multiple access (FDMA) scheme using single channel per carrier (SCPC) has been widely used. However, the SCPC-FDMA scheme has some problems, such as difficulty in setting up a large number of base station transceivers and in realizing a low-cost highly stabilized local oscillator. A time and frequency division multiple access (TD/FDMA) scheme, which is a combination scheme of TDMA and FDMA, is proposed as one of the possible solutions for these problems. After explaining the background of the proposal, some of the restrictions of the TD/FDMA scheme resulting from the land mobile radio channel characteristics are described. Basic concept of the digital mobile radio telephone system using TD/ FDMA scheme is then presented. An example of the possible system design is finally shown.     

对流层气溶胶和水汽的车载激光雷达系统的探测

利用研制的一套具备昼夜测量能力的新型车载大气探测激光雷达系统为试验工程和环境监测提供应用研究。该激光雷达系统由水平测量模块和垂直测量模块构成,可通过接收激光与大气中气溶胶粒子、水汽分子、氮气分子作用的米散射和拉曼散射信号,反演大气水平能见度、垂直的气溶胶消光系数和水汽混合比。并可实现昼夜连续观测,实际测量结果与对比实验表明,大气水平能见度的测量误差小于10%, 6 km以下垂直大气气溶胶的测量误差小于10%,水汽的测量误差最大不超过20%,能够满足大气参数测量的实际需求。     

A switched diversity receiving system for mobile radio

A low cost switched diversity receiving system has been developed for use in UHF-FM mobile radio. The input of a single receiver is switched back and forth between two antennas upon command from a signal level sensing logic circuit. The system has been measured on simulated Rayleigh fading channels and has been found to give a significant improvement to both voice and data signals.     

A dynamic space division multiplex mobile radio system

The dispersed array mobile radio system represents a radical new approach to the problem of spectrum congestion in the land-mobile radio service. This new approach provides a very substantial improvement in spectrum utilization over the present mode of operation and at a cost to the user of about 20 percent less. Spectrum efficiency is achieved by a dynamic combination of space, time, and frequency diversity. Cost reduction is achieved because the mobile radio unit is a compact low-power short-range all solid-state transceiver.     

A mobile care system with alert mechanism.

Hypertension and arrhythmia are chronic diseases, which can be effectively prevented and controlled only if the physiological parameters of the patient are constantly monitored, along with the full support of the health education and professional medical care. In this paper, a role-based intelligent mobile care system with alert mechanism in chronic care environment is proposed and implemented. The roles in our system include patients, physicians, nurses, and healthcare providers. Each of the roles represents a person that uses a mobile device such as a mobile phone to communicate with the server setup in the care center such that he or she can go around without restrictions. For commercial mobile phones with Bluetooth communication capability attached to chronic patients, we have developed physiological signal recognition algorithms that were implemented and built-in in the mobile phone without affecting its original communication functions. It is thus possible to integrate several front-end mobile care devices with Bluetooth communication capability to extract patients' various physiological parameters [such as blood pressure, pulse, saturation of haemoglobin (SpO2), and electrocardiogram (ECG)], to monitor multiple physiological signals without space limit, and to upload important or abnormal physiological information to healthcare center for storage and analysis or transmit the information to physicians and healthcare providers for further processing. Thus, the physiological signal extraction devices only have to deal with signal extraction and wireless transmission. Since they do not have to do signal processing, their form factor can be further reduced to reach the goal of microminiaturization and power saving. An alert management mechanism has been included in back-end healthcare center to initiate various strategies for automatic emergency alerts after receiving emergency messages or after automatically recognizing emergency messages. Within the time intervals in system setting, according to the medical history of a specific patient, our prototype system can inform various healthcare providers in sequence to provide healthcare service with their reply to ensure the accuracy of alert information and the completeness of early warning notification to further improve the healthcare quality. In the end, with the testing results and performance evaluation of our implemented system prototype, we conclude that it is possible to set up a complete intelligent healt care chain with mobile monitoring and healthcare service via the assistance of our system.     

A mobile 12 GHz DBS television receiving system

A practical, mobile, 12-GHz direct broadcast satellite (DBS) television receiving system for receivers on vehicles is described. The system is housed in a cylindrical radome of 350 mm height and 862 mm diameter, and it weighs 50 kg. Two pairs of high performance flat-panel antenna units (640×180 mm each) are used to reduce the system. For rapid recatch of DBS, antenna control is based on a gyroscope that is corrected using a phase-comparison monopulse. To simplify the system, the antenna units and receivers are used for antenna tracking as well as signal reception. The antenna units are in-phase combined to allow electronic tracking, which reduces the influence of pointing error caused by vibration of vehicles. The system maintains a reception rate of more than 90% on expressways     

一种基于WSAN的移动学习系统

为了解决目前移动学习在实时互动、各取所需等方面存在的问题,提出了一种使用新兴无线传感器执行器网络(Wireless Sensor and Actor Network,WSAN)技术来实现移动学习的方法。采用排名指标和搜索指导机制理清学习对象间的关系,基于轻量级存储系统实现WSAN节点间的移动学习对象共享,借助贝叶斯定理获取全局可分享学习对象信息,进而实现基于WSAN的移动学习系统。研究工作基于WSAN技术和容错感知技术进一步丰富了移动学习的信息形式,提升了以学员为中心的培训与教育水平,使个性化学习和随时随地访问学习成为可能,在移动学习领域具有较高的应用和参考价值。     

A mobile teletrauma system using 3G networks

This paper introduces a cost-effective portable teletrauma system that assists health-care centers in providing prehospital trauma care. Simultaneous transmission of a patient's video, medical images, and electrocardiogram signals, which is required throughout the prehospital procedure, is demonstrated over commercially available 3G wireless cellular data service. Moreover, the physician can remotely control the information sent from the patient side. Such a technology will allow a trauma specialist to be virtually present at the remote location and participate in prehospital care, which improves the quality of trauma care and can potentially reduce mortality and morbidity. To alleviate the limited and fluctuant bandwidth barriers of the wireless cellular link, the system adapts to network conditions through media transformations, data prioritization, and application-level congestion control methods. Experimental evaluation of the system prototype over real network conditions, transmitting different media types between the trauma patient and hospital unit, is encouraging. The teletrauma system reported in this paper is the first of its kind and it provides a basis for future enhancements.     

手机上网业务质量端到端分析方法和系统S 钮远,卢海杨,缪骅,胥健

4G普及推动了移动数据业务的快速发展,手机上网感知成为影响客户体验的主要因素。为保障客户的上网体验,需要建立一套贴近客户感知的业务质量评估体系;需要贯通手机上网“端管云”各个环节,分析定位质差问题、开展优化提升。本文介绍了一种手机上网业务质量端到端分析方法和系统,基于4G信令构建业务感知评估体系,通过业务端到端分析模型定界到业务质差环节。     

手机上网业务质量端到端分析方法和系统

为保障客户的上网体验,需要建立一套贴近客户感知的业务质量评估体系;需要贯通手机上网“端管云”各个环节,分析定位质差问题、开展优化提升。本文介绍了一种手机上网业务质量端到端分析方法和系统,基于4G信令构建业务感知评估体系,通过业务端到端分析模型定界到业务质差环节。     

基于GPS/GIS技术的车载移动视频指挥系统

介绍了基于GPS与GIS技术的车载移动视频监控指挥系统在处置突发事件中的应用,分别对该系统的工作原理、主要功能以及在该领域发挥的作用进行论述,最后对该系统的应用前景进行了展望.     

A flat energy density antenna system for mobile telephone

The notch array designed as a crossed slot antenna for receiving the magnetic field components is replaced by the disk of a ring patch antenna. Since the electric field components are received by the ring patch antenna, this combination provides an energy density reception antenna. A prototype of the flat energy density antenna has been built and tested: and the measured results of the input impedance characteristics and the radiation patterns are presented. Indoor field measurements with this antenna also verified the energy density reception     

A shared service algorithm for a trunked mobile system

A model has been developed and solved which captures the essence of the concept of mobile dispatch service. There are two types of users, dispatch and interconnect (calls routed from the public switched telephone network, of much longer holding times). Also, only some of the available repeaters can be used for interconnect traffic, and blocked interconnect calls are cleared. Dispatch calls, however, can access all repeaters, and then are queued if all repeaters are busy. One design decision involves a trade between blocking of interconnect calls and queueing of dispatch calls. A formula has been derived for both interconnect blocking probability and the mean dispatch queueing time to permit this trade. The results indicate that a good operating point is to have (N - ad)(rounded down) interconnected repeaters, where there are N total repeaters and adErlangs of dispatch traffic.     

A mobile wide-band measurement system for urban man-made noise

This paper describes in detail the criteria for the design of a mobile laboratory for the characterization and measurement of man-made electromagnetic noise in the urban, suburban, and rural environment. A significant difference from previous similar measurements is the bandwidth of the receiving system, which is here of the order of 1 MHz. A simple model is proposed to describe the impulsive noise together with a series of experiments to validate the model and determine the significant necessary parameters. The detailed requirements for each of the subsystems of the mobile laboratory are discussed and some typical results obtained in trial runs are presented.     

A frequency scanning satellite system for land mobile communications

A frequency scanning system for mobile applications has been assessed for a European mission at L-band. Feasibility evaluations, electrical design and analysis have been performed for both the antenna and the entire repeater. Efforts have also been made to solve accommodation, thermal and mechanical problems, so as to demonstrate the actual feasibility of the frequency scanning concept in user-oriented applications. The very promising results obtained are presented in this paper.