基于业务优先和用户优先的资源调度——UMTS中的QoS策略分析

本文首先分析了移动通讯网络中实施QoS的重要意义,随后以中兴通讯的设备为例,介绍了UMTS系统中QoS信息的签约、传递、协商和运用过程。     

基于GPRS／UMTS网络的无线Internet接人及MIP技术在其中的应用

随着GPRS/UMTS网络的即将投入商用和Internet网络及其业务的飞速发展 ,如何将这两种通信网络进行合理的融合以利用两者的不同优势实现更加快捷方便的网络服务越来越受到包括网络运营商 ,设备供应商乃至理论研究界的广泛关注。本文就这一课题详细介绍了目前通信业界的最新相关研究成果 ,并讨论了MIP技术在这一融合过程中的积极应用。     

Earliest Deadline First Scheduling with Active Buffer Management for Real-Time Traffic in the Internet

We studied the problem of QoS guarantee for differentiated services. A two-level hierarchical scheduling framework was deployed to separate QoS metrics. Due to its desirable property of minimizing the maximum packet lateness, the Earliest Deadline First (EDF) scheduling was adopted to provide the in-class scheduling for the time-sensitive traffic. We employed an EDF scheduler combined with an active buffer management scheme (CHOKe) to improve the fairness of resource allocation and to maintain a good delay performance for real-time applications. Simulation results showed that the proposed scheme can achieve a better delay performance and make a more fair bandwidth allocation between the real-time TCP and UDP connections than the First Come First Served (FCFS) scheduling with the drop-tail buffer management which is commonly deployed in traditional IP routers.     

因特网IP QoS机制及其在UMTS网络中的应用

目前广泛使用的因特网协议(IP)已经成为所有数据业务的传输标准。传统的因特网业务策略(BE策略)不能满足新兴的实时业务的需求,因此有必要引入IPQoS机制来更有效的分配资源。由于第三代通信系统网UMTS需要同时支持非实时和实时业务,而且无线网的资源和设备比固定网昂贵得多,所以IPQoS机制对于无线网络尤为重要。文中首先研究因特网IPQoS机制,然后讨论如何将其应用到UMTS网络中。     

Fair and efficient scheduling for UMTS forward link

This paper presents two scheduling algorithms, MWF²Q+ and MDRR, for multiple classes of service over the same spectrum in the forward link of the UMTS network. These scheduling algorithms can allocate bandwidth in proportion to weights of flows sharing the channel, and assign OVSF code to backlogged flows on a frame‐by‐frame basis. The MWF²Q+ algorithm has better fairness properties while the MDRR algorithm requires less computational complexity and space complexity. The fairness properties of these scheduling algorithms are analysed in this paper. Our simulation results show that these two algorithms support multiple traffic sources with heterogeneous rate guarantees while fully utilizing the system bandwidth. The impact of self‐similar traffic is also addressed in our simulations. Copyright © 2005 John Wiley & Sons, Ltd.     

移动互联网时代流量经营策略探析

移动互联网时代,国内电信运营商正面临被管道化的风险。如何在用户高普及背景下扭转收入、客户双份额缓增局面,是运营商亟待解决的问题之一。本文从消费者信息需求转变出发,以经营数据分析为基础,阐释流量经营的必要性。并结合国外运营商的先进经验,立足操作层面,提出了流量经营的策略建议。     

UMTS核心网中基于区分服务的QoS控制模型

3G新业务的发展，要求UMTS提供端到端QoS控制。文章构建了在UMTS核心网中为不同业务类提供QoS保证的区分服务模型，提出了从UMTS业务类到DiffServ域服务等级的映射方案，设计了一种新的队列调度算法，采用优先级和分离机制，在流量调整器配合下可满足不同业务类的QoS要求。最后，通过模拟实验证明了模型的有效性。     

Alternative Schemes for Dynamic Secure VPN Deployment in UMTS

Three alternative schemes for secure Virtual Private Network (VPN) deployment over the Universal Mobile Telecommunication System (UMTS) are proposed and analyzed. The proposed schemes enable a mobile node to voluntarily establish an IPsec-based secure channel to a private network. The alternative schemes differ in the location where the IPsec functionality is placed within the UMTS network architecture (mobile node, access network, and UMTS network border), depending on the employed security model, and whether data in transit are ever in clear-text, or available to be tapped by outsiders. The provided levels of privacy in the deployed VPN schemes, as well as the employed authentication models are examined. An analysis in terms of cost, complexity, and performance overhead that each method imposes to the underlying network architecture, as well as to the mobile devices is presented. The level of system reliability and scalability in granting security services is presented. The VPN management, usability, and trusted relations, as well as their behavior when a mobile user moves are analyzed. The use of special applications that require access to encapsulated data traffic is explored. Finally, an overall comparison of the proposed schemes from the security and operation point of view summarizes their relative performance. Christos Xenakis received his B.Sc. degree in computer science in 1993 and his M.Sc. degree in telecommunication and computer networks in 1996, both from the Department of Informatics and Telecommunications, University of Athens, Greece. In 2004 he received his Ph.D. from the University of Athens (Department of Informatics and Telecommunications). From 1998–2000 was with the Greek telecoms system development firm Teletel S.A., where was involved in the design and development of advanced telecommunications subsystems for ISDN, ATM, GSM, and GPRS. Since 1996 he has been a member of the Communication Networks Laboratory of the University of Athens. He has participated in numerous projects realized in the context of EU Programs (ACTS, ESPRIT, IST). His research interests are in the field of mobile/wireless networks, security and distributed network management. He is the author of over 15 papers in the above areas. Lazaros Merakos received the Diploma in electrical and mechanical engineering from the National Technical University of Athens, Greece, in 1978, and the M.S. and Ph.D. degrees in electrical engineering from the State University of New York, Buffalo, in 1981 and 1984, respectively. From 1983 to 1986, he was on the faculty of Electrical Engineering and Computer Science at the University of Connecticut, Storrs. From 1986 to 1994 he was on the faculty of the Electrical and Computer Engineering Department at Northeastern University, Boston, MA. During the period 1993–1994 he served as Director of the Communications and Digital Processing Research Center at Northeastern University. During the summers of 1990 and 1991, he was a Visiting Scientist at the IBM T. J. Watson Research Center, Yorktown Heights, NY. In 1994, he joined the faculty of the University of Athens, Athens, Greece, where he is presently a Professor in the Department of Informatics and Telecommunications, and Director of the Communication Networks Laboratory (UoA-CNL) and the Networks Operations and Management Center. His research interests are in the design and performance analysis of broadband networks, and wireless/mobile communication systems and services. He has authored more than 150 papers in the above areas. Since 1995, he is leading the research activities of UoA-CNL in the area of mobile communications, in the framework of the Advanced Communication Technologies & Services (ACTS) and Information Society Technologies (IST) programmes funded by the European Union (projects RAINBOW, Magic WAND, WINE, MOBIVAS, POLOS, ANWIRE). He is chairman of the board of the Greek Universities Network, the Greek Schools Network, and member of the board of the Greek Research Network. In 1994, he received the Guanella Award for the Best Paper presented at the International Zurich Seminar on Mobile Communications.     

User Needs for Services in UMTS

Wireless Personal Communications - The business cases for the emerging Universal Mobile Terrestrial System (UMTS) networks can only be fulfilled if the present voice revenues are expanded by...     

MPLS在Internet流量工程中的应用

首先回顾了IP网络流量工程的概念和所面临的挑战,然后讨论了MPLS(多协议标记交换)的基本概念和发展,指出了MPLS巨大的流量工程能力和主要功能,最后着重分析了MPLS在IP网络流量工程中的应用.     

Multicast in UMTS: evaluation and recommendations

It is known that multicasting is an efficient method of supporting group communication as it allows the transmission of packets to multiple destinations using fewer network resources. Along with the widespread deployment of the third generation cellular networks, the fast‐improving capabilities of the mobile devices, content and service providers are increasingly interested in supporting multicast communications over wireless networks and in particular over Universal Mobile Telecommunications System (UMTS). Multicasting is a more efficient method of supporting group communication than unicasting or broadcasting, as it allows transmission and routing of packets to multiple destinations using fewer network resources. In this paper, the three above mentioned methods of supporting group communication are analyzed in terms of their performance. The critical parameters of primary interest for the evaluation of any method are the packet delivery cost and the scalability of the method. Copyright © 2006 John Wiley & Sons, Ltd.     

Adaptive and reliable video transmission over UMTS for enhanced performance

This paper proposes a mechanism for the congestion control for video transmission over universal mobile telecommunications system (UMTS). Our scheme is applied when the mobile user experiences real‐time multimedia content and adopts the theory of a widely accepted rate control method in wired networks, namely equation‐based rate control. In this approach, the transmission rate of the multimedia data is determined as a function of the packet loss rate, the round trip time and the packet size and the server explicitly adjusts its sending rate as a function of these parameters. Furthermore, we examine the performance of the UMTS for real‐time video transmission using real‐time protocols. Through a number of experiments, we measure performance parameters such as end‐to‐end delay, delay in radio access network, delay jitter and throughput in the wireless link. Copyright © 2006 John Wiley & Sons, Ltd.     

Scheduling Real-Time Traffic With Deadlines over a Wireless Channel

Recently, there has been widespread interest in the extension of data networks to the wireless domain. However, scheduling results from the wireline domain do not carry over to wireless systems because wireless channels have unique characteristics not found in wireline channels, namely, limited bandwidth, bursty channel errors and location-dependent channel errors.In this paper, we study the problem of scheduling multiple real-time streams with deadlines, over a shared channel. We show that, in general, unlike the wireline case, the earliest due date (EDD) or shortest time to extinction (STE) policy is not always the optimal policy, even if the channel state is perfectly known and EDD is implemented only over channels in a Good state. Here, optimality is measured with respect to the number of packets lost due to deadline expiry. However, for most values of the channel parameters that are of practical interest, we show through analytical and numerical results that the EDD policy over Good channels is nearly optimal. Finally, through simulations, we also show that by combining this policy with fair scheduling mechanisms would result in scheduling algorithms that provide some degree of isolation between the sources as well as provide a natural way of compensating channels that see prolonged error bursts.     

基于OPNET Modeler的UMTS性能分析仿真平台

随着计算机性能和仿真技术的提高,计算机仿真技术得到越来越广泛的运用.OPNET是一种具有高可靠度的网络建模、设计、仿真和分析工具.文中主要介绍了基于OPNET建立的UMTS仿真平台,并基于该平台研究了UMTS网络典型业务端到端的关键性能参数,以及根据业务服务质量的需求提供不同等级服务的可行性.仿真结果表明,该系统级仿真平台对UMTS系统的性能分析是有效的,为网络的规划设计提供客观、可靠的定量依据.     

Adaptive Resource Sharing Strategies for UMTS Multiservice Mobiles

In this paper, a multiservice transmission scheme which joints voice, video, interactive game and signaling is evaluated for the dedicated channel of the Universal Mobile Telecommunications System. The transmission rate for each service is determined by means of an adaptive transport format selection. In the UMTS standard, this selection is based on power allocation provided by radio resource controller, trying to match the Eb/No requirements of the individual services. An appropriate selection of the individual rates of each multiplexed service, taking into account its particular QoS requirements, will provide a more efficient resource management than the transmission only restricted to power allocation. For this purpose, we propose and evaluate a new selection strategy based on buffer occupation, delay requirements and target bit rate keeping power constraints that intends to improve the basic operation trying to minimize the impact of the whole network. Video and game services are multiplexed in upper layers (logical channels) sharing a common transmission rate (transport channel). In this paper, it is proposed a new strategy to share the transmission rate set for this transport channel between both services taking into account their particular requirements. Results show that considering delay constraints provides a more balanced performance of the multiplexed services.     

TWDM-PON中带有业务区分的混合资源调度算法

针对时分波分复用无源光网络长距离和广覆盖特性带来往返时延增大,造成高优先级业务时延性能严重恶化的问题,提出带有业务区分的混合资源调度算法.根据网络负载实时调整光网络单元组的波长数以实现资源共享,并动态划分子周期以对不同优先级业务进行区分服务;设计混合资源调度算法,以在线方式填充波长空隙,以离线方式保障资源高效调度.仿真结果表明,所提算法能够满足不同优先级业务的时延要求,保证服务质量,并提高信道利用率.     

一种基于OFDMA的组播单播联合自适应调度算法

 面向未来的大型多媒体组播应用环境,在IEEE 802.16业务分类的基础上,提出了名为VARTUL的业务分类及制约关系,在此基础上,研制了基于OFDMA的VARTUL节能调度算法,力求终端休眠时间最长,切换次数最少.算法中组播和单播共存,在制约前提下支持大量级用户的自由订阅,从而支持广播电视业务与数据业务的融合与运营.实验仿真表明,VARTUL算法能自适应上下行流量变化和各业务流量分布,支持各种业务组合,确保用户体验,并节约终端能量.     

下一代光互联网域间流量疏导解决方案

目前的互联网中,端到端(P2P)应用模式的出现及其广泛应用可能将改变网络的流量模式,对于传统的传送网络结构带来了新的挑战,需要从业务、网络控制和传送层面共同规划.采用协议与算法相结合的方式进行流量疏导,扩展传统多粒度概念,给出综合的域间网络规划解决思路.     

Cost analysis and efficient radio bearer selection for multicasting over UMTS

Along with the widespread deployment of the Third Generation (3G) cellular networks, the fast‐improving capabilities of the mobile devices, content, and service providers are increasingly interested in supporting multicast communications over wireless networks and in particular over Universal Mobile Telecommunications System (UMTS). To this direction, the Third Generation Partnership Project (3GPP) is currently standardizing the Multimedia Broadcast/Multicast Service (MBMS) framework of UMTS. In this paper, we present an overview of the MBMS multicast mode of UMTS. We analytically present the multicast mode of the MBMS and analyze its performance in terms of packet delivery cost under various network topologies, cell types, and multicast users' distributions. Furthermore, for the evaluation of the scheme, we consider different transport channels for the transmission of the multicast data over the UMTS Terrestrial Radio‐Access Network (UTRAN) interfaces. Finally, we propose a scheme for the efficient radio bearer selection that minimizes total packet delivery cost. Copyright © 2008 John Wiley & Sons, Ltd.