GPS和Galileo导航电文设计分析

导航电文设计的优劣直接影响卫星导航定位的可靠性,该文以GPS和Galileo导航系统的导航电文设计为例,汇总了GPS和Galileo系统导航电文设计的最新成果,比较分析GPS传统的导航电文格式NAV和新的民用导航电文格式CNAV以及Galileo系统的导航电文,并对导航电文数据结构、编排方式、差错控制以及播发方式等方面的性能进行评估,进行导航电文的优化设计,以期为我国北斗导航系统的电文设计提供借鉴。     

Policy implications of market segmentation as a determinant of fixed-mobile service substitution: What it means for carriers and policy makers

The determination whether mobile and fixed telecommunications services operate in the same market not only affects business decision of service providers, but also has wide implications on public policy decisions pertaining to the means by which they should be regulated in the United States. This study conducts a two-stage cluster analysis implementing the American Customer Satisfaction Model on two datasets of 3251 and 5060 data points pertaining to mobile and fixed-line phone services, respectively, collected by the National Quality Research Center at the University of Michigan in order to determine whether the way consumers perceive these services can indicate as to their levels of substitutability. It concludes that different types of customers with different needs consume these products and offers policy makers some insight on how to further the penetration of mobile services.     

供电营业厅服务渠道优化模型及算法研究

当前,随着新型技术的发展,网上营业厅、掌上营业厅、微信服务平台等服务渠道将传统营业厅的客户分流的比重逐渐上升,传统营业厅的服务资源出现了冗余、不合理等现象,对此,广东电网公司珠海供电局力求通过与客户进行深度访谈的形式,了解客户前往实体营业厅的主要目的及习惯,进而制定资源配置的有效方案。对此,应首先建立供电营业厅服务渠道优化模型,以实现对深度访谈结果的有效整合。     

基于业务中台的信息化系统架构演进研究

在信息化系统的发展过程中,传统的系统架构越发难以满足业务层面的需求。本文从业务发展面临的现实难点问题入手,介绍了业务中台的概念、作用、优势,并对信息化系统业务中台的功能框架组成、能力要素、应用场景等,进行了详细的研究并给出规划蓝图,为企业信息化系统的演进提供了明确的指导思路。     

基于GEF的业务模式图形编辑器的设计与实现

业务模式是根据客户需求而制定的一些规则和方法。改变传统手工编织代码来实现这些规则和方法,通过设计业务模式图形编辑器将这些规则和方法图形化使得项目开发效率更高。GEF提供了标准程序结构和组件框架,缩短了开发时间并提供了一致性的外观模型,GEF也提供了标准的开发框架,为图形编辑器的设计提供了基础组件,并进一步研究运用了框架中的命令设计模式,可以很容易地实现撤消/重做等功能。在此基于Eclipse平台和GEF架构设计和实现业务模式图形编辑器,提高开发效率和软件的可维护性。     

The optimal macro control strategies of service providers and micro service selection of users: quantification model based on synergetics

Multiple wireless technologies, possibly administered by same or different service providers (SPs), are expected to coexist in the rapidly-expanding heterogeneous networks. It is also economically beneficial for all SPs to cooperate with each other. In such model, one SP temporally shares a portion of its spectrum with other SPs at a certain price to allow better utilization of the available spectrum. To this end, users can make service selection decisions dynamically at micro level according to the performance satisfaction level and cost, depending on the pricing plans and spectrum sharing strategies of SPs at macro level. On the other hand, the users’ service selection population states in turn influence the control strategies of SPs. To model this dynamic interactive decision making problem, a novel approach based on synergetics is presented in this paper. The motion equations of population state decided by pricing and spectrum sharing are derived. Then, by taking into account the population state, an optimization problem is formulated to determine the optimal dynamic pricing and open access ratio for the SPs in order to maximize their respective benefits. A closed-loop feedback equilibrium is obtained as the solution of the formed optimization problem. Numerical results demonstrate the effectiveness and advantages of the proposed model in terms of dynamic control of the spectrum sharing and pricing as well as dynamic analysis of service selection.     

Integrated Services on High Altitude Platform: Receiver Driven Smart Selection of HAP-Geo Satellite Wireless Access Segment and Performance Evaluation

A renewed interest in the development of high-altitude platforms (HAPs), which are stratospheric aircraft or airship carrying payloads tailored for a wide range of applications in telecommunications and remote sensing, is becoming progressively widespread. HAPs offer a reduced propagation delay and they are especially suitable for interactive multimedia services. In this paper, the inter-working between HAP and satellite segments in an integrated QoS architecture has been addressed. A new way to manage integrated services over a new hybrid wireless platform has been proposed. A smart terminal device has been considered in order to perform an intelligent switching on the wireless access segment. The switching criteria applied in the HAP/satellite architecture is based on the available bandwidth and on the admissible data packet end-to-end delay. Performance evaluations of the integrated HAP–satellite platform have been evaluated in terms of bandwidth utilization and number of admitted calls. The simulations show an improvement of admitted calls, reduced data packet end-to-end delay and increased bandwidth utilization.     

电离层闪烁对跟踪测量的影响分析及规避策略

针对某南方卫星测控站测控信号频繁被干扰的情况展开研究。首先介绍国内外对电离层闪烁原理及监视预警方面的研究成果,然后分析电离层闪烁的时空效应原理,通过计算对比电离层强闪烁监测预报数据和卫星测控站的实时观测数据,发现电离层闪烁与卫星测控站跟踪测量信号的幅度、相位抖动以及接收机失锁之间的相关性,最后提出相应的规避策略,期望为后续测控设备的电离层闪烁防护预警研究提供一定的借鉴和参考。     

Petri net model of protocol conversion for CTF service: its universal coupling criteria and property analysis

Protocol conversion is a critical issue requiring much research attention. In this paper, the protocol conversion methodology proposed originally by Green is extended with the Petri nets theory to study application layer protocol conversion among more than two interfaces. The click‐to‐fax (CTF) service based on the Internet intelligent network (IIN) model is taken as an example to illustrate the extended part. A two‐step Petri net modelling method is proposed, which is easier compared to constructing the overall model directly in just one step. Universal coupling criteria of Petri net model of protocol conversion (PNPC) are abstracted. The PNPC of CTF service is analysed using analytical techniques of Petri nets, which are proved to be effective in finding and eliminating potential bugs. The necessity of the concept of service layer is also emphasized. Copyright © 2006 John Wiley & Sons, Ltd.     

Impact of TH‐UWB interference on MB‐OFDM UWB systems: interference modeling and performance analysis

In this paper, the coexistence issue between multiband‐orthogonal frequency‐division multiplexing (MB‐OFDM) and time‐hopping ultra‐wideband (TH‐UWB) networks is widely analyzed. For this purpose, to study and model the TH‐UWB interference, an analytical framework which describes key features of the interference distribution is provided. The interference distribution is studied in the context of TH‐UWB's signaling parameters. Our results reveal that the interference distribution highly depends on its time‐hopping parameters. Therefore, choosing proper time‐hopping parameters leads to less destructive interferences. The Generalized Gaussian and the Symmetric‐α‐Stable (SαS) distributions are used to model the interference‐plus‐noise signal. The maximum likelihood and a characteristic function‐based regression‐type methods are adopted to estimate parameters of Generalized Gaussian and SαS distributions, respectively. Moreover, the interference channel effects on the impulsive behavior of the TH‐UWB signal is studied. It is shown that impulsive behavior of the faded interference signals highly depends on the channel time‐dispersiveness. Furthermore, an exact performance of a multiband‐orthogonal frequency‐division multiplexing system impaired by a TH‐UWB system is derived. The comparison of the analytical performance, the empirical simulation, and the approximation results show that both approximation methods are valid for low interference‐to‐noise‐ratio, while SαS provides a more accurate approximation for high interference‐to‐noise‐ratio. Copyright © 2015 John Wiley & Sons, Ltd.