欧洲UMTS移动通信系统Qos保证体系结构

根据ETSI关于通用移动通信系统（UMTS）服务质量保证方面的一些研究报告^[1]和3GPP的相关协议[2,3]，介绍了UMTS QoS控制机制定义的原则，以及按照QoS特征划分的四类UMTS接入系统业务，概要讨论了UMTS系统的QoS保证体系结构，着重分析了其结构分层和QoS控制的层间映射／分段保证机制。     

ENGINE:基于软交换下一代网络解决方案

本文介绍了爱立信基于软交换的下一代网络解决方案ENGINE,并从网络结构、业务创建、与移动网络的融合等方面论述了发展下一代网络的必要性。     

A Simple Analytical Framework for the Performance Evaluation of a Tree-Based Connection Rerouting Architecture in a UMTS Network

The enormous increase in wireless communications and the growing request for transmission bandwidth have led to the need to configure wireless access networks with cellular structures based on the use of micro- and pico-cells. Applying these structures means that handovers between neighboring cells are more frequent and therefore have to be carefully managed. A key issue in connection with this is the rerouting of the data flows directed to a user making a handover. In fact, the time interval needed to update all the routing tables in the crossover switches is critical because in this interval data have to be stored, and later forwarded once the route towards the new location has been determined. The paper considers a connectionless protocol, the Signaling Network Layer (SNL), which has been conceived for use in the Universal Mobile Telecommunication System (UMTS) context for connection rerouting purposes and is based on a tree-structured rerouting architecture. Through an analytical model based on a queueing network, its performance is analyzed in terms of the distribution of the rerouting delay. The proposed model is then applied to a case study to demonstrate its versatility and manageability and to get insight into the dimensioning of the rerouting architecture.     

Performance Evaluation of Distributed Database Architectures for UMTS Service Deployed in an Urban Area

The design of distributed databases (DDBs) destined to store user information is a key issue in third-generation mobile communication systems such as UMTS. In particular, the problem of determining the most appropriate DDB architectures for UMTS is critical due to the anticipated requirements of high distribution and adaptability of information. This paper presents a model which allows different DDB architectures to be evaluated, in terms of query loads and average search times. The model proposed puts no constraints on either the DDB structure arrangement or the user position characterization. The paper also discusses a real, significant case study, concerning a query operation arising from an access procedure performed on the DDB of a communication network covering an urban area.     

我国光伏产品出口遭遇的严峻挑战分析

近年来,我国光伏产业快速发展,规模不断扩大。我国已成为全球第一大太阳能电池出口国。但是,2012年我国太阳能光伏产品出口额同比下降35.0%,出口数量同比下降8.1%,表明我国光伏产品出口面临严峻挑战。主要原因是由于目前我国光伏企业缺乏核心技术、出口市场过于集中、国内市场尚未全面启动等问题造成的。为此,我国要采取有效措施加以应对：积极应对欧美的“双反”调查、加快实施光伏企业“走出去”战略、提高光伏企业自主创新能力、加速启动国内市场等。如此,才能促进国内光伏产品的出口。     

浅析中国联通部署UMTS900带来的挑战

UMTS900相对UMTS2100来说,具有一定的技术优势,本文结合中国联通的网络特点,分析中国联通部署UMTS900会给网络带来怎样的挑战以及规划上的难点。     

GSM核心网络向3G(UMTS)演进的策略及其全IP多媒体网络

在简单介绍UMTS的基础上讨论了GSM核心网络向3G(UMTS)演进的策略，并就演进过程中的相关技术进行了说明。     

UMTS体系结构研究

基于3GPP IMS的网络架构支持固定网络接入需求和未来网络的各种业务需求,有利于实现未来固定、移动网络在核心业务控制层的共享和融合,并提供对高层多种业务的支持,已经成为下一代网络的发展方向。文章研究了3GPP规范的演进情况,分析了3GPPR5的网络体系结构,给出了相关实体的功能与特点,并介绍了IP多媒体子系统的基本结构。     

基于移动端多天线系统的无线衰落信道模型

根据当前无线移动通信对多天线移动接收端性能仿真的要求，讨论并建立了适于空时信号处理的移动端矢量信道模型。通过分析无线移动信道特点。研究了影响接收信号幅度相位的诸多因素，建立了相应的数学模型。并对随机参数选取进行了探讨。其中考虑到移动端接收信号到达角扩散的特点，采用GBSB椭圆模型产生了适于移动端接收信号仿真的随机角度，改进了一种瑞利衰落生成算法。最后信道的数值仿真结果符合理论和经验。同时，通过TD-SCDMA系统链路级仿真，也证明了该信道模型的有效性。     

Evaluation of the Algerian photovoltaic market potential

The Algerian energy sector will certainly face a crisis this century with the gradual diminution of oil and gas reserves estimated at 4.2 billion Toe (Tons of oil equivalent), which can last for only a few decades at today's production levels. In the meantime the population and its energy needs will have doubled. This situation is complicated by the fact that the energy sector is Algeria's major source of revenue, and finances the national economy at a level of 66%. Many decision‐makers now agree that time has come to implement a new energy policy, based on energy diversification, and to set up new mechanisms. The Algerian energy sector is still dominated by hydrocarbons, and has promoted a major effort to reach a mean national electrification rate of 96%. Nevertheless, the remaining zones are very isolated and widespread. The conventional electrification solutions or grid extensions are no longer economically viable. The recourse to renewable energies in general and PV solar energy in particular has become a reality. This source represents a good alternative for 85% of Algerian territory, which is composed of arid and semi‐arid zones, characterized by low population density and limited energy needs. These regions represent a strategic alternative in order to reverse the population migration and to encourage a new migration to the south, since northern Algeria is less and less welcoming (high population density, unemployment, shrinkage of agricultural land, inflation). In this paper we try to evaluate the potential of the Algerian PV market in order to inform decision‐makers and future investors. To this end, and after identifying the PV solar energy segments, we attempt to estimate them under different scenarios. Copyright © 2002 John Wiley & Sons, Ltd.     

雷达健康管理的性能评估方法

针对相控阵雷达,分析了阵面性能对雷达战术指标的影响,提出了利用相控阵多通道实时监测信息评估雷达战术指标的方法。仿真结果显示:利用该方法可有效评估相控阵雷达阵面的健康状态以及阵面性能恶化对雷达技术指标的影响,实现雷达健康管理与维修保障的有机结合,提升雷达全寿命周期保障的智能化程度。同时,对提高雷达作战效能和战 斗力快速生成具有重要意义。     

UMTS和GSM／EDGE异构环境下多维马尔科夫模型分析

研究了异构网环境下多维马尔科夫建模问题。以UMTS和GSM／EDGE异构网为例,建立了一个四维马尔科夫模型,并通过降维和迭代得到其数值解,进而得到各子网和异构网的拥塞率、交通量、负载量和吞吐量。为进一步研究异构网环境下的接入选择问题建立了基础。     

Power allocation in the context of dimensioning the air‐interface of third generation W‐CDMA‐based cellular systems

The adoption of W‐CDMA as an essential component of the air‐interface of third‐generation cellular systems brings to the foreground the need for new planning methodologies and software tools. In this perspective, this paper addresses planning problems that are important to the dimensioning of W‐CDMA‐based cellular networks. The problems aim at finding the optimal feasible allocation of transmission power to the sets of uplink and downlink connections that should be supported by the system, so as to cope with a corresponding traffic load scenario. The problems are concisely defined, mathematically formulated and solved by means of two computationally efficient, novel algorithms. The solutions of the problems may be seen as operating points at which the system performance should be driven. Finally, numerical results are presented and concluding remarks are drawn. Copyright © 2002 John Wiley & Sons, Ltd.     

Support of multiple content variants in the multimedia broadcast/multicast service

The Multimedia Broadcast/Multicast Service (MBMS) was designed to enable the mass distribution of multimedia content in 3rd Generation and beyond cellular networks. If such services are to become commercially viable, they must be able to efficiently support widely heterogeneous user requirements, for example, due to terminal limitations and cost constraints. This paper presents an MBMS extension that allows multiple variants of the same content to be economically distributed to heterogeneous receivers, explicitly taking into account the possibility of using either dedicated or common radio channels. We describe our extended multiple content variant MBMS model by explaining the modifications that it imposes on the standard MBMS model, as well as the manner in which it can be combined with layered coding. We also present an analytical evaluation of our approach against alternatives based on the standard MBMS in terms of control and user plane overhead, and compare the analytical predictions with detailed simulation results. Both the analysis and the simulations indicate that our proposal can indeed satisfy heterogeneous user requirements, while consuming considerably lower resources than the standard‐based alternatives. Copyright © 2010 John Wiley & Sons, Ltd.     

A New Criteria Decision Applied on the Primary Synchronization in the DS-WCDMA Interface of the UMTS System

In DS-WCDMA mobile systems such the UMTS, asynchronous cell site operation,assigning different long spreading code to each cell, yields the advantageof flexible system deployment. We can design an indoor system basedon an outdoor one. However, in general, much longer search time isrequired in asynchronous operation than in synchronous. This paperproposes three techniques to take decisions about synchronizationbased on observation of correlated signals. Classical decision criterialike maximum and threshold criterion are presented. A new decisioncriteria that we call Threshold&Max combined decision criteriais analyzed. The results of this new introduced technique is comparedwith the classical ones.     

GSM/UMTS的系统模型、网络结构及GPRS/IP分析

本文简述了GSM/UMTS的系统模型及主要接口 ,重点分析了一种可能的GSM/UMTS网络结构及其合理性 ,提出了一种支持多媒体业务的GPRS/IP结构及用户平面协议参考模型 ,最后指出了研究UMTS的重要性。     

Design and measurements of a RF front-end for Bi-band simultaneous reception

In this paper, we explore spectrum field band simultaneous receivers, with a special emphasis on only one aspect of these systems – the radio front-end. We propose, to validate in the lab, a receiver scheme for the simultaneous down-conversion of two signals in different bands. Obviously, the dedicated scheme is intended for practical use in an integrated circuit. In this work, the chosen receiver is implemented with discrete components. A test set is evaluated and compared to simulations; it contains mostly standard lab equipment, processing signals, according to the receiver scheme; this receiver presents merits and it is worth demonstrating in an integrated circuit.In order to give credit to the use of this type of receiver, the EDA model and results have to be validated by measurement. Therefore, based on the receiver architecture dedicated to an 802.11/UMTS simultaneous dual-channel processing, we design and fabricate a prototype. Firstly, we measure the intrinsic metrics of this prototype in terms of noise figure, gain, linearity, phase and gain mismatch between the two branches of the quadrature mounted mixers. In the present work, we demonstrate that, for instance, as NF and IIP3 change with the RF front-end gain with the improvement of the RF front-end performance, the linearity and the noise requirements are well handled. Afterwards, these metrics are injected in the EDA receiver model and simulations are done in order to evaluate the BER evolution.     

An Overview of MAI Effect on the Uplink Performance of the UMTS Air Interface

Universal Mobile Telecommunications System (UMTS) is the main standard of the third generation of mobile communications and its air interface is called WCDMA. This paper considers the effect of multiple access interference (MAI) on the uplink performance of a simple WCDMA system. The transmitted signal of a defined user is destroyed by interferences from other users and executable resolves are presented and applied. The performance measure is the probability of error, BER, for different number of users. The results indicate that an increase in the number of users would degrade system performance considerably. Furthermore, the channel effect on the signal quality is a problem in transmission that should be considered. The goal of this paper is the observation of uplink performance in presence of MAI. Finally, we represent all ways for resolving the MAI as an undesired effect. FDD mode has been chosen as the operation mode of transmission as well. We consider an identical user's power of received signals at the base station. Hassan Moradi received his B.S. degree in Electrical Engineering from Shiraz University, Shiraz, Iran in 1998 and the M.S. in communications systems from K.N. Toosi University of Technology, Tehran, Iran in 2001. He joined the Iran Telecommunications Research Center (ITRC) as an assistant researcher of wireless communications in 2001. Also, he is currently a member of technical staff of ITRC. His current research interests are in Mobile Communications Network, Radio Transmission and Signaling Protocols. He has authored several papers in the wireless communications field especially about access network of CDMA-based systems. Moreover, after finishing Mobile Switching Center (MSC) project in ITRC, he now works and manages the Implementation Switch Lab project at ITRC. Mahdi Samie received his B.S. in Computer Engineering from Isfahan University of Technology (IUT), Isfahan, Iran, in 1996, and M.S. in Computer System Architecture from Iran University of Science and Technology (IUST), Tehran, Iran in 2001. Since 1999 he is teaching at the department of Computer Engineering in IUST. He joined the Iran Telecommunications Research Center (ITRC) in September of 2001, where he is currently pursuing research on communication protocols for mobile networks as a Research Assistant. His research interest includes Signaling Protocols, Mobile Network Protocols, mobile IP, Digital Transmission and Database in Telecommunication Networks. Maryam Fallah-Pour received the B.S. degree in Electrical Engineering from K.N. Toosi University of Technology (KNTU), Tehran, Iran in 2003. Her primary current research interests are Industrial Control, Instrumentation, Control of Communication Systems, Software and Hardware design of PLC systems, analysis and modeling of control systems. In addition, she is interested in simulation and implementation of communications protocols. Now, addition to working at Patsa Industry group in Tehran, she is continuing his studies as a M.Sc. student at KNTU.     

On the support of voice call continuity across UMTS and wireless LANs

In this paper, we address the architecture and the procedures that can enable voice call handover from UMTS to WLAN and we also study how efficiently the WLAN can support the voice calls transferred from UMTS. Our study is based on a practical simulation model that lets us quantify the maximum number of voice calls that can be handed over from UMTS to WLAN, subject to maintaining the same level of UMTS QoS and respecting some WLAN policies. In addition, several other voice call performance metrics are derived. Our results indicate that an IEEE 802.11e access point can support a limited number of voice calls handed over from UMTS, which depends primarily on the applied WLAN bandwidth sharing policy (i.e., how the bandwidth is shared between WLAN voice and data users) and the QoS requirements. The performance of the WLAN scheduling algorithm is also of paramount importance and in our study we consider the so‐called ARROW scheduler. Although the simulation results are derived for a specific bandwidth sharing policy, they can readily be scaled and provide practical upper bounds for the number of UMTS voice calls that can be seamlessly admitted to a WLAN access point. Copyright © 2007 John Wiley & Sons, Ltd.