Quality-of-service management for broadband residential videoservices

This paper introduces an approach to managing quality-of-service (QoS) for a residential video-on-demand (VoD) service employing MPEG-2 transport streams using an experimental asynchronous transfer mode (ATM)/asymmetric digital subscriber line (ADSL) access network testbed. The paper examines the complex multilayer propagation of ATM layer parameters over an underlying physical layer and their relationship to video quality. The results obtained from the testbed provide an important insight into the factors relevant to the provisioning and management of new multiservice network infrastructures. Overall, these results contribute to an understanding of the multilayer QoS relationship and provide a basis for comparison with, and development of, similar systems. The paper proposes a method to aid the comparison of results based on a multilayer QoS approach     

Adaptive QoS Management for IEEE 802.11 Future Wireless ISPs

Wireless Internet Service Providers (WISPs) are expected to be the new generation of access providers using the emerging IEEE 802.11 technology. Face to the high competition of providing network services, the WISP have to offer the best service to the users. For this purpose, the WISP networks' managers need to provide Quality of Service (QoS) with a minimum cost in their wireless networks. The current link layer IEEE 802.11b provides fair sharing of the radio resource with no service differentiation mechanism; similarly to the Internet best effort service. However, the ongoing standard IEEE 802.11e should implement a priority mechanism at the link layer to differentiate the users' traffic. In order to overcome the lack of differentiated mechanism in the current link layer IEEE 802.11b, hence controlling the utilization of the scarce radio resource, we propose in this article to deploy Diffserv architecture coupled with an adaptive provisioning of QoS to provide better services to the users with minimum WISP cost and improve the utilization of the radio resource. Compliant with the current and future IEEE 802.11 link layer, the proposed adaptive QoS provisioning mechanism reacts to the radio resource fluctuation and improves the number of accepted clients in the IEEE 802.11 wireless cells based on the WISP business policies. The network layer differentiation provided by the Diffserv architecture intends to control the concurrent access of the traffic to the scarce radio resources at the IP layer of the mobile hosts for the uplink traffic on one hand, and at the IP layer of the base stations for the downlink traffic on the other hand.     

A Novel Analytical Framework for Integrated Cross-Layer Study of Call-Level and Packet-Level QoS in Wireless Mobile Multimedia Networks

We present a novel integrated analytical framework for analyzing the quality-of-service (QoS) performance measures in a wireless mobile multimedia network. The framework integrates physical, radio link, and network layer parameters and protocols to analyze the call-level and packet-level performances. In the network layer, call admission control (CAC) is responsible for deciding whether an incoming call can be accepted or not so that the performances of the ongoing calls do not deteriorate below the acceptable level. Also, an adaptive channel allocation (ACA) scheme is used to maximize the utilization of the radio resources. In the data link layer, queue management and error control are used for non-real-time loss-sensitive traffic. In the physical layer, a finite state Markov channel (FSMC) is used to model channel fading, and adaptive modulation is used for rate adaptation according to channel quality. Various call-level and packet-level QoS measures for real-time, non-real-time, and best-effort traffic are obtained. The analytical results are validated by extensive simulations. Examples of the applications of the presented analytical framework are also provided     

MCIP: A 3G/IP Interworking System Supporting Inter-Cluster Soft Handoff

In this paper, a novel 3-tier Mobile Cellular IP (MCIP) access network is proposed for interworking between a third generation (3G) wireless cellular system and a wireline Internet Protocol (IP) based network. An inter-cluster hard handoff scheme and an inter-cluster soft handoff scheme are proposed, based on the 3-tier MCIP system model, the core network protocol stacks, and the underlying MCIP routing algorithm. The core network protocol stack is presented to integrate the 3G radio interface and the IP-based core network, and to provide the access network with capability to support soft handoff macroscopic space diversity. The MCIP hard and soft handoff schemes are compared with the hard handoff schemes used in the Cellular IP and HAWAII access networks. The MCIP access network is more efficient in terms of signaling cost, but has the same scalability as Cellular IP and HAWAII. Both MCIP hard and soft handoff schemes enable IP packets to be delivered within the MCIP access network in-order without loss and duplication, a highly desired attribute for real-time multimedia applications. The advantages of supporting soft handoffs and quality-of-service (QoS) provisioning for real-time services are achieved at slightly increased system complexity.This work was supported by a research grant from the Natural Science and Engineering Research Council (NSERC) of Canada. The authors wish to thank the anonymous reviewers for their helpful comments and suggestions which improve the presentation of this paper. Xin Liu received his B.E. and M.E. degrees in radio engineering from Harbin Institute of Technology (China), in 1990 and 1993, respectively, and his M.A.Sc degree in electrical engineering from the University of Waterloo in 2002. He joined Research In Motion in 2002 as a firmware developer. His current work involves GSM/GPRS and WCDMA firmware development. Weihua Zhuang received the B.Sc. and M.Sc. degrees from Dalian Maritime University (China) and the Ph.D. degree from the University of New Brunswick (Canada), all in electrical engineering. Since October 1993, she has been with the Department of Electrical and Computer Engineering, University of Waterloo, Canada, where she is a full professor. She is a co-author of the textbook Wireless Communications and Networking (Prentice Hall, 2003). Her current research interests include multimedia wireless communications, wireless networks, and radio positioning. Dr. Zhuang received the Premier's Research Excellence Award (PREA) in 2001 from the Ontario Government for demonstrated excellence of scientific and academic contributions. She is an Editor of IEEE Transactions on Wireless Communications, an Associate Editor of IEEE Transactions on Vehicular Technology, and an Editor of EURASIP Journal on Wireless Communications and Networking.     

Optical burst switching: a viable solution for terabit IP backbone

Wavelength-division multiplexing has emerged as an important physical layer technology. Optical transmission provides a physical layer capable of carrying bits at the speed at the order of a gigabit per second. Optical burst switching is proposed to overcome the shortcomings of conventional WDM deployment, such as lack of fine bandwidth granularity in wavelength routing and electronic speed bottlenecks in SONET/SDH. We describe an architecture for IP network over the OBS WDM transmission core. The use of MPLS-type technique for forwarding data bursts and the inclusion of a medium access control layer between the optical (WDM) and IP layers are the key ingredients of the proposed architecture. In particular, the architecture is based on provisioning MPLS paths, also called label switched paths, of desired quality of service through the OBS WDM transmission core. The MAC layer performs various OBS-specific functions, such as burst assembly, burst scheduling, and offset setting/traffic shaping. While burst assembly and burst scheduling are relatively straightforward, we point out that the offset setting strategy has significant impact on the performance of IP network operating over OBS WDM core. We describe a shaping scheme to set the offset, an important system parameter for OBS, between the successive data bursts of a given data stream (label switched path) and their associated control packets. This scheme results in robust operation of the network and also facilitates traffic engineering. Guidelines are provided for implementing various IP QoS mechanisms in the optical backbone using OBS.     

IP micromobility and QoS virtual network testbed

This paper examines issues related to the interaction of QoS and IP micromobility management. More precisely, the inter‐working of a tunnel‐based IP micromobility management with the bandwidth broker QoS control plane is considered. Furthermore, the implementation of the system is detailed and it is tested using a virtual network testbed, based on ‘user‐mode‐Linux’. Finally, as a proof of concept the signalling between the different entities is examined with the protocol analyser ‘ethereal’. Copyright © 2007 John Wiley & Sons, Ltd.     

基于传输块调度的WCDMA上行负荷控制算法

在WCDMA系统中,小区的无线资源管理通常是在无线网络控制器(RNC)节点内完成.然而,专用传输信道上传输格式可以逐帧改变,基于传输格式的快速变化实际上构成一种无线资源控制能力。这种控制能力是由UE和Node B的MAC实体以及物理层协同完成的,完全不需要三层信令参与。该文根据WCDMA专用传输信道传输格式的快速变化能力,结合基于类的QoS策略,针对上行信道提出一种负荷控制算法,用以支持全分组业务。研究结果表明,在多业务环境下,各个用户能公平共享无线资源、同时能够实现实时业务时延保证。     

IMS网络中基于策略的QoS视频会话研究

为了检验基于策略QoS机制在IP多媒体系统(IMS)中对媒体会话发起的应用情况,在构建的IMS平台上提出视频会话系统方案,并分析了基于策略QoS机制的视频会话发起中存在的问题以及改进建议.     

Network-based mobility management in the evolved 3GPP core network

A key aspect of the 3GPP system architecture evolution is the specification of an evolved packet core that supports multiple access networks. The EPC enables operators to deploy and operate one common packet core network for 3GPP radio accesses (E-UTRAN, UTRAN, and GERAN), as well as other wireless and wireline access networks (e.g., eHRPD, WLAN, WIMAX, and DSL/Cable), providing the operator with a common set of services and capabilities across the networks. A key requirement of the EPC is to provide seamless mobility at the IP layer as the user moves within and between accesses. This article provides an overview of the EPC specifications that use a network-based mobility mechanism based on Proxy Mobile IPv6 to enable mobility between access networks. An important facet of providing seamless mobility for a user?s sessions across technologies is to ensure that quality of service is maintained as the user moves between accesses. An overview of the ?off-path? QoS model to supplement PMIPv6 is also provided.     

A programmable optical network testbed in support of C-RAN: a reliability study

With both mobile network services and related data traffic volume on the rise, reliability of the radio access network is of the essence. A number of radio functional splits are defined by 3GPP to offer increased flexibility of implementation and feasibility of new mobile network services. For example, it is possible to implement certain radio functions in the Cloud, an architectural solution referred to as C-RAN. C-RAN solutions require highly reliable backhaul and fronthaul network designs. This paper describes PROnet, a programmable optical software-defined network testbed, which has been upgraded to offer backhaul and fronthaul transport capabilities in support of C-RAN functionalities with increased reliability. The testbed is upgraded with a specially designed 1 + 1 protection mechanism at the Ethernet layer in order to meet the stringent network round-trip requirements imposed by one of the C-RAN functional split options on the fronthaul.

     

IP网实时业务服务质量问题的研究

分析了ＩＰ电话／传真业务对于服务质量的要求,对解决 其服务质量问题做了较深入的分析和探讨。列出了应用 层可采取的提高服务质量的方法,并详细分析了国际上 解决网络服务质量的两大研究模型： ＲＳＶＰ和 ＤＩＦＦ－Ｓｅｒｖ 的技术内容和优缺点。提出Ｄｉｆｆ－Ｓｅｒｖ才是解决网络服务 质量问题的研究方向。     

广电网络多终端视频服务平台的设计与实现

本文主要阐述如何融合广电DVB网络和IP宽带城域网的优势,为用户提供一个高可靠、高稳定、高QoS的多终端视频服务平台和CDN分发网络,用户可以通过数字电视机顶盒、电脑、手机和智能终端无差别享受优质的广播电视节目内容服务,不断提升广电网络的核心竞争力。     

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。     

MPLS技术研究及其应用

多协议标记交换(MPLS)技术将网络层路由功能与数据链路层交换功能结合,充分利用第二层和第三层功能,使IP网具备高速交换、流量控制和QoS等性能。文章介绍了MPLS技术的基本原理、核心技术及其应用。     

Supporting QoS in Integrated Ad-Hoc Networks

Ad-hoc networking is becoming a promising solution to increase the radio coverage of wireless systems. Integrated mobile ad-hoc networks (MANETs), considered as multi-hop networks connected to fixed networks through one or more gateways, seem to be very profitable for both the provider and the user. This article describes an architecture for end-to-end QoS in such MANETs, developed within the IST project DAIDALOS II. In order to explain the framework’s functionality, the technology, service differentiation mechanisms, MAC layer measurements, and signalling protocols are discussed. The modules required by the network elements as well as their integration are also described. Additionally, the paper presents the results obtained during verification tests performed in exemplary testbed scenarios.     

CogNS: A Simulation Framework for Cognitive Radio Networks

Cognitive radio technology has been used to efficiently utilize the spectrum in wireless networks. Although many research studies have been done recently in the area of cognitive radio networks (CRNs), little effort has been made to propose a simulation framework for CRNs. In this paper, a simulation framework based on NS2 (CogNS) for cognitive radio networks is proposed. This framework can be used to investigate and evaluate the impact of lower layers, i.e., MAC and physical layer, on the transport and network layers protocols. Due to the importance of packet drop probability, end-to-end delay and throughput as QoS requirements in real-time reliable applications, these metrics are evaluated over CRNs through CogNS framework. Our simulations demonstrate that the design of new network and transport layer protocols over CRNs should be considered based on CR-related parameters such as activity model of primary users, sensing time and frequency.     

A software radio testbed for two-transmitter two-receiver space-time coding OFDM wireless LAN

A real-time testbed based on the technology of software radio is adopted to efficiently evaluate cutting-edge technologies in wireless communications, and thus becomes a valuable tool for both academic research and system prototyping. In this article we describe a software radio testbed, established in the software radio laboratory at Georgia Institute of Technology, used to implement a physical layer similar to IEEE 802.11a space-time coded orthogonal frequency-division multiplexing. The testbed consists of a 2 x 2 multiple-input multiple-output configuration with powerful digital signal processor chains, high-speed data exchange interfaces, and many advanced subsystem modules, such as high-speed high-resolution analog-to-digital and digital-to-analog converters, digital up/downconverters, and wideband RF transmit and receive front-ends with synchronous channels and programmable settings. The design methodology and implementation for key algorithms, such as time, sampling, and frequency synchronization, and channel estimation and compensation are discussed. The experimental data obtained from a typical indoor environment demonstrates that the prototype is capable of providing 30 Mb/s peak data rate, operating at the central frequency of 2.435 GHz with a spectral occupancy of 6.25 MHz. Spatial-temporal diversity gain associated with space-time coding is verified by the experimental results.     

Next Generation Wireless Mobile System Efficient, Fair, Class Based Packet Scheduling Algorithm

Efficient utilization of network resources is a key goal for emerging broadband wireless access systems (BWAS). This is a complex goal to achieve due to the heterogeneous service nature and diverse quality of service (QoS) requirements of various applications that BWAS support. Packet scheduling is an important activity that affects BWAS QoS outcomes. This paper proposes a novel packet scheduling mechanism that improves QoS in mobile wireless networks which exploit IP as a transport technology for data transfer between BWAS base stations and mobile users at the radio transmission layer. In order to improve BWAS QoS the new packet algorithm makes changes at both the IP and the radio layers. The new packet scheduling algorithm exploits handoff priority scheduling principles and takes into account buffer occupancy and channel conditions. The packet scheduling mechanism also incorporates the concept of fairness. Performance results were obtained by computer simulation and compared to the well known algorithms. Results show that by exploiting the new packet scheduling algorithm, the transport system is able to provide a low handoff packet drop rate, low packet forwarding rate, low packet delay and ensure fairness amongst the users of different services.     

Providing sustainable QoS in next-generation networks

In this article we discuss QoS from a somewhat unconventional point of view. First of all, we argue that high availability is a key ingredient in the QoS perceived by the user. High availability with extremely short interruptions in case of failure is needed for acceptable QoS in real-time dialog services such as telephony or video conferencing. Second, an even distribution of the traffic load over the network is essential to ensure efficient network utilization given that some kind of admission control for QoS traffic has to be in place for overload avoidance. Unfortunately, both these features are not adequately provided in current IP networks. We therefore introduce a new routing scheme offering a massive improvement in availability as well as efficient traffic distribution, while causing only minor computational effort. Our proposals are then evaluated for a high-speed core network. We claim that our proposed approach would be a useful basis for QoS services in an NGN.