一种基于和差波束的机载 SAR 定位方法

机载 SAR 绝对定位技术可以直接对地面目标进行定位,无需地面参考点,对于军事及民事应用具有重要的实用价值.该文提出一种新的机载 SAR 对地定位方法,主要研究在无地面参考点的情况下,利用和差波束 SAR图像直接对地面目标定位,获取地面目标3维坐标信息.论文分析了载机速度、高度及测角误差对定位精度的影响,并与传统基于距离多普勒模型的定位方法进行了比较,最后通过仿真实验验证了该定位方法的有效性.     

Mobile WiMAX系统中一种改进的信道估计算法

在Mobile WiMAX OFDMA系统下,研究了线性插值、二阶多项式插值和三次样条插值等几种经典的内插拟合的信道估计方法,仿真发现它们不能很好地支持高速移动性,基于分段线性插值算法提出了一种改进方法。在ITUVA60和Va120信道环境下,对这几种内插算法的误比特率和均方误差性能进行了仿真。仿真结果证明,在高速移动环境下,提出的改进方法要比其他几种算法的性能要好。     

为预付费移动用户提供拨号上网业务

在后付费移动用户已能享受与手机统一缴费的拨号上网业务的情况下，提出一种利用移动智能网业务控制点(SCP)中的预付费账户为移动用户提供拨号上网业务的解决方案，讨论了网络结构，远程鉴权拨入用户业务(RADIUS)协议和智能网应用协议(INAP)的协议协作关系处理。并举例说明了成功接入Internet的信令流程。下一步的研究要解决用户使用拨号上网业务的同时禁止使用其他业务的问题。     

Integrated Full-Digital U-Interface Circuit for ISDN Subscriber Loops

Reasons for using the echo-cancellation (EC) technique for full-duplex two-wire transmission of ISDN signals are given. Analysis of the performances achievable with different codes, such as 3B/2T, MMS43, partial response class 4 (PR4), and diphase, justifies the final selection of MMS43. A full-digital integrated U-interface circuit with MMS43 code and with Barker codeword synchronization is described. First laboratory test results are presented.     

A Hybrid SS–ToA Wireless NLoS Geolocation Based on Path Attenuation: ToA Estimation and CRB for Mobile Position Estimation

We propose a new hybrid wireless geolocation scheme that requires only one observation quantity, namely, the received signal. The attenuation model is explored herein to capture the propagation features from the received signal. Thus, it provides a more accurate approach for wireless geolocation. To investigate geolocation accuracy, we consider the time-of-arrival (ToA) estimation in the presence of path attenuation. The maximum-correlation (MC) estimator is revisited, and the exact maximum-likelihood (ML) estimator is derived to estimate the ToA. The error performance of the ToA estimates is derived using a Taylor expansion. It is shown that the ML estimate is unbiased and has a smaller error variance than the MC estimate. Numerical results illustrate that, for a low effective bandwidth, the ML estimator well outperforms the MC estimator. Afterward, we derive the CramÉr–Rao bound (CRB) for the mobile position estimation. The obtained result, which is applicable to any value of path loss exponents, gives a generalized form of the CRB for the ordinary geolocation approach. In seven hexagonal cells, numerical examples show that the accuracy of the mobile position estimation exploring the path loss is improved compared with that obtained by the usual geolocation.      

Practical Approach of Modeling and Parameters Estimation for Omnidirectional Mobile Robots

This paper presents a nonlinear modeling approach for omnidirectional mobile robots. Three experimental methods of estimation of the parameters related to dynamic equations of the robot's model are developed. The estimation methods are based on least-squares methods to obtain the viscous friction coefficients, the coulomb friction coefficients, and the moment of inertia of the robot. Simulation results and real results of navigation are provided to demonstrate the performance of the proposed modeling approach.     

An Integrated Approach for Agricultural Ecosystem Management

Sustainable development and growth of agriculture sector calls for improving its competitiveness through a better understanding of lands, weather and climate, and planting, especially prediction of events with increased accuracy, and systematic integration of observations and prediction into decision-making in agriculture management. In this short paper, a systematic approach based on integrated information systems (IISs) for agricultural ecosystem management is proposed. The approach involves establishing an IIS called agricultural ecosystem enterprise information system (AEEIS) that extracts data on terrain, land use, planting, and others, and integrates them for the purpose of agricultural and ecosystem management. The integration helps in generating managerial/policy alternatives in consultation not only with agricultural and ecological specialists, but also with agriculture and ecosystems management. AEEIS, a platform of enterprise information systems, includes operational database, extract transform and load, data warehouse, data mining, simulation modeling, and knowledge management for generating managerial strategies on land use, planting species/variety, and optimal coverage of plants. AEEIS is part of efforts on integrated agricultural information services that is one of the main applications of China's sustainable agricultural development plan. The short paper concludes that, for effective management of agriculture and ecosystems, a systematic approach is essential in which IISs play a crucial role.     

浅谈数字移动电话用户管理

浅谈数字移动电话用户管理石涛勇（湖北省十堰市邮电局移动分局４４２０００）收稿日期：１９９７１０２０十堰市数字移动电话交换系统自１９９７年６月２５日投入运行以来，一直比较稳定，数字移动电话作为一种新鲜事物，进入中国市场时间不长，并且，随着用户服务意...     

An Integrated Approach for Achieving Multirobot Task Formations

In this paper, a problem, called the initial formation problem, within the multirobot task allocation domain is addressed. This problem consists in deciding which robot should go to each of the positions of the formation in order to minimize an objective. Two different distributed algorithms that solve this problem are explained. The second algorithm presents a novel approach that uses cost means to model the cost distribution and improves the performance of the task allocation algorithm. Also, we present an approach that integrates distributed task allocation algorithms with a behavior-based architecture to control formations of robot teams. Finally, simulations and real experiments are used to analyze the formation behavior and provide performance metrics associated with implementation in realistic scenarios.     

综合业务接入网的用户线路测量技术

文章介绍了目前国内已使用的综合接入网用户线路测量技术和国外流行的测量手段,对综合接入网用户线路测量技术进行了分析。     

Wise-ShopFloor: An Integrated Approach for Web-Based Collaborative Manufacturing

This paper presents an integrated approach for Web-based collaborative manufacturing, including distributed process planning, dynamic scheduling, real-time monitoring, and remote control. It is enabled by a Web-based integrated sensor-driven e-ShopFloor (Wise-ShopFloor) framework targeting distributed yet collaborative manufacturing environments. Utilizing the latest Java technologies (Java 3D and Java Servlet) for system implementation, this approach allows users to plan and control distant shop floor operations based on runtime information from the shop floor. The objective of this research is to develop methodology and algorithms for Web-based collaborative planning and control, supported by real-time monitoring for dynamic scheduling. Details on the principle of the Wise-ShopFloor framework, system architecture, and a proof-of-concept prototype are reported in this paper. An example of distributed process planning for remote machining is chosen as a case study to demonstrate the effectiveness of this approach toward Web-based collaborative manufacturing.     

An Approach to Multi-Service Subscriber Loop System Using Packetized Voice/Data Terminals

A new subscriber communication system and its design philosophy are described. In addition to telephone communication, the system is simultaneously able to offer data communication, still picture communication, etc. The system is composed of a packetized voice/data terminal, a multi-service switching equipment and the digital subscriber loop connecting between them. The system utilizes the existing subscriber line efficiently and is entirely suitable for coming telephone and data public digital network. 64 kbit/s PCM coded voice conversation and 48 kbit/s data communication were achieved simultaneously over 96 kbit/s digital subscriber line which was spanned up to 2 km.     

移动通信中一种精确的多普勒频移估计方法

该文利用有效到达径上信道参数的估计值,统计其包络的电平通过率(Level Crossing Rate,LCR),据此估计出时变多径信道的多普勒频移。同时还在理论上分析了噪声环境下LCR方法的估计偏差,进而提出了精确的改进方法,使得通信系统在各种移动速度和信噪比下都具有较高的估计精度。     

移动通信用户信用度的预测评估

本文提出了一种以遗传算法和多维判别模型为核心的移动用户信用度预测评估方法并给出了试应用的结果。对以广东移动珠海分公司全球通用户为例进行的信用度预测评估，准确率接近90%，误判率和漏判率均低于15%。这种方法对于各级移动通信公司都是极有意义的。如推广应用，必将带来很大的社会和经济效益。     

一种利用多音激励估算非线性失真的方法

针对射频通讯电路中的非线性失真,将非线性电路简化为三阶无记忆模型.利用信号的互补累积分布函数,讨论不同音数的多音信号同窄带高斯白噪声的关系.通过时域随机相位平均的原理,得到了较少音数(K<100)情况下进行非线性参数精确仿真和测试的方法,减少了由于多音音数较少而引起的仿真误差和波动.     

追随型移动运营商客户规模裂谷跨越研究

当前通信市场环境下,新兴的全业务运营商再不能固守原来的封地,相互扩张和渗透成为市场常态.无论是移动领域向固网领域的渗透,还是固网领域向移动领域的扩张,都面临着客户规模增长难题:企业与客户之间存在一条不可见的裂谷,使得竞争对手的客户总是倾向围绕在原来的运营商周围,不肯走到自己这边.能否在这条裂谷上搭建起跨越的桥梁,成为决定新兴运营商生死的关键.本文从裂谷的形成和对策两个方面进行分析,并重点介绍助力新兴移动运营商跨越裂谷的新理论:基于产品生命周期的全程可用性测试体系.     

An Integrated Cluster-Based Multi-Channel MAC Protocol for Mobile Ad Hoc Networks

This paper proposes a novel joint clustering and multi-channel medium access control (MAC) protocol for mobile ad hoc networks, based on a scalable two-phase coding scheme. It employs the first-phase codes for differentiating the clusters and the second-phase codes for distinguishing the nodes in a specific cluster. The proposed protocol effectively integrates the procedure of code assignment with dynamic clustering and henceforth substantially reduces the control overhead of code assignment in a code division multiple access (CDMA) based multi-channel MAC protocol while simultaneously combating the hidden terminal problem. Furthermore, the confliction detection and resolution mechanism for the allocation of the first-phase codes as well as the collision avoidance mechanism for the allocation of the second-phase codes in the control channel are also introduced. Analytical framework and extensive simulation results, in terms of control overhead and delay, are provided and compared to the traditional distributed CDMA based multichannel MAC algorithms with or without clustering.     

面向移动LBS的智能手机室内定位技术探讨

移动互联网的发展给基于位置的服务(LBS)带来了广泛的应用前景,智能手机的普及使用户定位和获取LBS变得更加方便。目前,手机定位技术特别是室内定位,仍不够成熟,已经成为制约LBS业务发展的技术瓶颈。本文在研究定位技术现状和发展趋势的基础上,提出一种新的室内定位方法,依靠智能手机内置传感器进行图像特征识别和运动状态检测,即可完成室内环境的准确定位,具有成本低、简单方便、灵活易扩展的优点,能够满足移动LBS业务模式发展需求。