认知无线多跳网中结合QoS查找的跨层多信道MAC协议

针对认知无线多跳网中频谱资源具有较大时变性及差异性的问题,设计了一种结合QoS查找的跨层多信道MAC协议。该协议将按需QoS查找与动态频谱分配跨层相结合,仅让参与传输的节点执行频谱分配并按QoS要求获取频谱资源。此外,协议使用频分双工收发机实现了对公共控制信道的不间断监听,并设计了一套支持不同数量收发机节点间混合通信的接入算法。大量仿真结果表明,该协议能有效保证对端到端传输的QoS要求的满足,并显著提高端到端吞吐量及时延。     

浅谈无线IP网络中的QoS规范

随着下一代网络的飞速发展,用户之间可以通过多种多样的无线设备相互联络,而这些无线设备则通过一个基于IP的核心网络所提供的无线链路相互连结的。虽然存在如IP协议之类的共同规范,但是要将许多不同的网络融合起来,而这些网络有着各自不同的QoS模型,这无疑将使端到端的QoS保证变得更加复杂。文中讨论了对端到端QoS协议进行标准化的必要性,重点研究了位于服务层的QoS规范,提出了一种通用服务规范(GSS),并对端到端提供QoS保证的服务等级进行了规范。     

一种异构网络多媒体业务QoS类弹性映射方法

 多媒体业务在异构网络传输过程中,由于现有的QoS(Quality of Service)类映射方法存在灵活性不足的问题,从而降低了系统端到端效能。针对这个问题,该文在深入分析当前的QoS类映射方法基础上,结合用户QoE (Quality of Experience)特点,借助于网络微积分理论,构建了QoS类映射的数学分析模型,并进行了理论分析。基于该数学分析模型,该文从用户QoE角度提出了具有弹性的QoS类映射方法(Elastic QoS Class Mapping Method, EQCMM),该方法根据当前网络资源的使用情况,通过灵活地调整QoS类映射,充分利用网络现有资源,提高了端到端带宽资源的利用率,改善了系统端到端的效能。最后,通过仿真验证了该方法的有效性。     

Design of the QoS framework for the IEEE 802.16 mesh networks

IEEE 802.16 (WiMax) technology is designed to support broadband speeds over wireless networks for the coming era of broadband wireless access (BWA). IEEE 802.16 is expected to provide transmission of high‐rate and high‐volume multimedia data streams for fixed and mobile applications. As an extension of point‐to‐multipoint (PMP) configuration, the IEEE 802.16 mesh mode provides a quicker and more flexible approach for network deployment. Multimedia networking requires quality‐of‐service (QoS) support, which demands elaborate mechanisms in addition to the four service types defined in the specification. By examining standard centralized and distributed scheduling/routing schemes in the mesh mode from QoS aspect, a BS‐controlled and delay‐sensitive scheduling/routing scheme is proposed in the paper. Associate mechanisms including admission control, flow setup and link state monitoring are also proposed. Integration of the proposed mechanisms is presented as a complete QoS framework. Simulation study has demonstrated that the average delay as well as the delay jitters per hop in the proposed scheme is smaller than that of the distributed scheme and much smaller than that of the centralized scheme. Furthermore, proposed mechanisms can also achieve higher throughput than the contrasts and generate much smaller signaling overhead, making the proposed framework a promising scheme for multimedia support in the IEEE 802.16 mesh network. Copyright © 2009 John Wiley & Sons, Ltd.     

一种异构网络中基于聚集流的水平QoS映射方法

保证无线异构网络端到端QoS需求,同时兼容现有网络业务和未来需求,是下一代网络的一个研究热点。QoS映射是保证异构网络端到端QoS的有效方法。该文提出一种基于聚集流的QoS映射方法(QoS Mapping Technology based on Flow Aggregate, QMT-FA),该方法在现有物理网络上建立虚拟的流处理层,在流处理层,原网络中的QoS参数被映射执行器透明封装,映射执行器根据网络情况决定是原样转发还是解聚集。通过建立基于高维的聚集流映射空间,屏蔽了多级网络间映射累积误差影响终端网络QoS指标,保证了异构网络端到端QoS;基于聚集流的QoS映射方法具有较好的可扩展性和伸缩性,能应用于现有的各种异构网络系统和应用业务。最后,通过数值和仿真分析验证了该方法的有效性。     

An End-to-End Bandwidth Allocation Algorithm for Ad Hoc Networks

Bandwidth-guaranteed QoS service in ad hoc networks is a challenging task due to several factors such as the absence of the central control, the dynamic network topology, the hidden terminal problem and the multihop routing property. An end-to-end bandwidth allocation algorithm was proposed in [Lin and Liu, 15] to support the QoS service in ad hoc networks. However, without exploring the global resource information along the route, the performance of that algorithm is quite limited. In addition, it also incurs significant control overhead. We develop a new algorithm for end-to-end bandwidth calculation and assignment in ad hoc networks which utilizes the global resource information along the route to determine the available end-to-end bandwidth. Our method also employs the topology-transparent scheduling technology to reduce the control overhead. The proposed algorithm can be efficiently utilized in a distributed manner. Both theoretical analysis and simulation results show that our end-to-end bandwidth allocation scheme can significantly improve the network capacity compared with the existing method.     

A Quality of Service Support Module (QASM) for a Wireless Multi-Segment Integrated 3G Network

Deployment of IP multimedia services with guaranteed Quality of Service (QoS) is a primary requirement for Beyond 3G (B3G) systems. In this paper we propose a new architecture to support Internet QoS-sensitive services (e.g., video-conferencing, voice over IP, interactive gaming), thus providing users with end-to-end QoS guarantees. In particular, the paper discloses a new hybrid Intserv/Diffserv scheme for handling IP packets and an interworking procedure with the RSVP protocol which allows to support QoS over an integrated, multi-segment network. Such scheme is implemented by means of a suitable Quality of service Support Module (QASM). Advantages and drawbacks of QASM are discussed and the impact on both system architecture and Multi-Mode Mobile Terminal is investigated. Performance evaluations, carried out via computer simulations, confirm the effectiveness of the proposed solution.     

A novel approach for supporting deterministic quality-of-service in WDM EPON networks

Ethernet Passive Optical Network (EPON) is viewed by many as an attractive solution to the first mile problem. With the rapidly increasing number of user application, the capacity of current EPON has quickly become insufficient and upgrading its architecture with the wavelength division multiplexing (WDM) technology has become a natural choice. On the other hand, with more and more multimedia applications emerging in the network, providing good quality of service (QoS) to various classes of traffic is a challenge. In this paper, we propose a two-level WDM EPON upgrade solution which implements two main functions: efficient capacity scaling with bandwidth sharing at the first level, and deterministic QoS provisioning at the second level. At the first level, the scheme ensures that a minimum number of wavelengths are used for scaling. At the second level, an integrated scheme including the admission control policies and scheduling discipline is developed to guarantee deterministic QoS for multiple classes of traffic. Three different admission control policies, in particular fixed-proportional, non-preemptive and preemptive admission control, are proposed and a complete study of their unique features is presented. The simulation results show that they could all guarantee deterministic delay bounds for bursty traffic.     

A Bandwidth Control Method Providing Entrance QoS for Multimedia Communication

1 Motivation Nowadays , the QoS provided by the wideband IPnetwork starts at an edge-router and ends at anotheredge-router .Therefore ,the trunk QoSisfinished,suchas RSVP[1]and DiffServ[2].In order to complete theend-to-end QoS,the mechanism of entrance QoS (thebandwidth controller) is introduced. As Fig.1 shows ,if the bandwidth controller circledby the dashed frame is not used,the Ethernet is con-nected with the router directly through 100 Mbit/sbandwidth. Then this router is connect…     

Buffered fixed routing: a routing protocol for real-time transportin grid networks

We propose a new routing protocol called buffered fixed routing (BFR) for real-time applications on grid networks. While previous routing protocols for grid networks have been designed to improve network throughput, the BFR scheme is proposed to guarantee the end-to-end packet delay and sequencing without loss by using finite buffers at each node. Thus the proposed scheme can satisfy quality-of-service (QoS) requirements of real-time applications. The BFR scheme uses the token on the row ring to provide QoS guarantees. The performance of the BFR scheme is analyzed by using the Geom/Geom/1 queueing system under uniform traffic. In the simulation, the BFR scheme shows the zero-loss, high-throughput performance with the minimum delay variation compared to other routing protocols such as store and forward routing, deflection routing and vertical routing. In addition, it has shown the smallest average delay at intermediate and heavy loads     

基于BD技术的光突发竞争解决方案

将BD法结合波长资源预留算法提出一种新的突发竞争解决方案。该方案通过在突发竞争时牺牲低优先级突发的传输完整性,以保证高优先级的业务的丢失率,同时降低了传输时延。最后对基于BD法的突发竞争解决方案进行了网络仿真,并和传统的传统基于额外偏置时间(JET)的方案比较,结果表明在平均数据丢失率相当的前提下,改进的BD法能有效的降低突发包的端对端时延。     

Rate control for real-time video network transmission on end-to-end rate-distortion and application-oriented QoS

In the merged multimedia packet-switched networks, the limited or no end-to-end Quality of Service (QoS) guarantees induce that rate control has been evolved to joint source-channel adjustment architecture based on application-oriented QoS. Based on the statistical analysis under the spatial intra and temporal inter prediction subject to a universal spatial-temporal coding framework and a general error concealment by the decoder, an end-to-end distortion estimation model is proposed. On the basis of the analytic model, this paper fulfills a picture quality parameters selection solution with rate-distortion (R-D) Lagrange optimization for a general coding engine including H.264/AVC, exploiting either the source-driven iterative prediction or feedback recursion. Further, a corresponding joint source-channel rate control strategy is proposed. For the real-time variable bit-rate (VBR) video transmission under a given time-varying network condition, the strategy could estimate an instantaneous available transmission rate on traffic smoothing and codec's buffer control, adopt the proposed an end-to-end distortion regressive model and a global optimal error control parameters selection, and address the consistent bit allocation in group of picture (GOP) level, picture level, and MB level. The extensive network simulation experiments show a better and more consistent end-to-end picture quality, in contrast with the locally optimal control strategy at MB level.     

QoS routing based on mobile agent for LEO satellite IP networks

Current quality of service (QoS) routing schemes for low earth orbit (LEO) satellites IP networks either neglect the varying population density or fail to guarantee end-to-end delay. As a remedy, QoS routing protocol based on mobile agent (QoSRP-MA) is proposed. QoSRP-MA is a source-based routing protocol. Once connection requests arrive, QoS mobile agents are dispatched from ingress satellite to explore routes, which migrate using satellite routing tables. Upon arriving in egress satellite, QoS mobile agents migrate back towards ingress satellite to reserve bandwidth. To construct satellite routing tables, load balancing routing algorithm based on mobile agent (LBRA-MA) is presented. In LBRP-MA, at regular intervals mobile agents launched on all satellites migrate autonomously to evaluate path cost and update routing tables. Moreover, path cost between source and destination is evaluated considering satellite geographical position as well as inter-satellite link (ISL) cost. Furthermore, ISL congestion index is considered to update routing table. Through simulations on a Courier-like constellation, it shows that QoSRP-MA can achieve guaranteed end-to-end delay bound with higher throughput, lower connection failing ratio and signaling overhead compared to high performance satellite routing (HPSR) scheme.     

A distributed laxity-based priority scheduling scheme for time-sensitive traffic in mobile ad hoc networks

Characteristics of Mobile Ad hoc Networks such as shared broadcast channel, bandwidth and battery power limitations, highly dynamic topology, and location dependent errors, make provisioning of quality of service (QoS) in such networks very difficult. The Medium Access Control (MAC) layer plays a very important role as far as QoS is concerned. The MAC layer is responsible for selecting the next packet to be transmitted and the timing of its transmission. We have proposed a new MAC layer protocol that includes a laxity-based priority scheduling scheme and an associated back-off scheme, for supporting time-sensitive traffic. In the proposed scheduling scheme, we select the next packet to be transmitted, based on its priority value which takes into consideration the uniform laxity budget of the packet, the current packet delivery ratio of the flow to which the packet belongs, and the packet delivery ratio desired by the user. The back-off mechanism devised by us grants a node access to the channel, based on the rank of its highest priority packet in comparison to other such packets queued at nodes in the neighborhood of the current node. We have studied the performance of our protocol that combines a packet scheduling scheme and a channel access scheme through simulation experiments, and the simulation results show that our protocol exhibits a significant improvement in packet delivery ratio under bounded end-to-end delay requirements, compared to the existing 802.11 DCF and the Distributed Priority Scheduling scheme proposed recently in [ACM Wireless Networks Journal 8 (5) (2002) 455–466; Proceedings of ACM MOBICOM '01, July 2001, pp. 200–209].     

Enabling End-to-End QoS over Hybrid Wired-Wireless Networks

Providing end-to-end parameterized QoS is desirable for many network applications and has received a lot of attention in recent years. However, it remains a challenge, especially over hybrid networks involving both wired networks and wireless access segments (such as IEEE 802.11 Wireless Local Area Networks (WLANs)). The difficulty in achieving such QoS arises mainly because wireless segments often constitute “gaps" in terms of resource guarantee, due to the lack of efficient resource scheduling and management ability over shared wireless media, as well as the lack of an appropriate QoS signaling interface to seamlessly embed these wireless segments into an end-to-end QoS signaling system. In this paper, we consider the scenario where an IEEE 802.11 wireless node wishes to make an end-to-end resource reservation to a remote wired Internet node and vice versa. We propose Wireless Subnet Bandwidth Manager (Wireless SBM), an extension of SBM protocol to WLANs, to provide seamless end-to-end resource reservations. Wireless SBM utilizes the enhanced resource management ability provided by Hybrid Coordination Function (introduced in the upcoming IEEE 802.11e standard) to provide parameterized resource reservation and admission control.     

Network-Adaptive Rate Control and Unequal Loss Protection with TCP-Friendly Protocol for Scalable Video Over Internet

Video communication with Quality of Service (QoS) is an important and challenging task. To have QoS provision at application level in the current best-effort Internet, rate control, congestion control and error control are several effective approaches. In this paper, we propose a new network-adaptive rate control and Unequal Loss Protection (ULP) scheme in conjunction with TCP-friendly congestion control for scalable video streaming. Our proposed approach is capable of simultaneously controlling congestion and packet loss occurred across the Internet. More specifically, we first dynamically estimate the available network bandwidth on the fly. Then, TCP-friendly congestion control is performed to smoothly adjust the sending rate for transmission of continuous media. Considering the characteristic of scalable video, unequal loss protection at packet level is adopted for different video layers while performing congestion control. Consequently, a fixed-length and priority-based packetization scheme is introduced to enhance the capability of loss protection and improve the efficiency of network-bandwidth utilization. Moreover, Rate-Distortion (R-D) based bit allocation is proposed to minimize the expected end-to-end distortion. Simulation results demonstrate the effectiveness of our proposed scheme.     

A framework for dynamic SLA-based QoS control for UMTS

With the evolution of QoS-capable 3G wireless networks, the wireless community has been increasingly looking for a framework that can provide effective network-independent end-to-end QoS control. In this article we first construct such a framework and then describe how dynamic SLA-based control can be used to achieve end-to-end QoS in a wired and wireless (UMTS) environment. The proposed framework, which is an extension to the IST CADENUS project, offers effective wired-wireless QoS translation, efficient QoS control and management, and dynamic SLA policy-based QoS provisioning.     

Adaptive per hop differentiation for end-to-end delay assurance in multihop wireless networks

As the rapid growth of smart hand-held devices, multihop wireless access networks have a lot of potential applications in a variety of fields in civilian and military environments. Many of these applications, such as realtime audio/video streaming, will require some form of end-to-end QoS assurance. In this paper, we present an adaptive per hop differentiation (APHD) scheme towards achieving end-to-end delay assurance in multihop wireless networks. Our scheme is based on EDCA technique which is proposed in 802.11e draft. In EDCA, data packets of different priorities will use different MAC contention parameter set, which translate into different delays. Our APHD scheme extends the capability of EDCA into multihop environment by taking end-to-end delay requirement into consideration at each intermediate hop. Following a cross-layer design approach, APHD is aimed to be a distributed and localized technique. Individual nodes keep track of the channel state independently without any intercommunication overhead. Data packets carry end-to-end delay requirement along with other important information in the packet header. At an intermediate node, based on data packet’s end-to-end requirement, its accumulative delay so far, and the current node’s channel status, APHD smartly adjusts data packet’s priority level in order to satisfy its end-to-end delay requirement. Simulation results show that APHD scheme can provide excellent end-to-end delay assurance while achieving much higher network utilization, compared to a pure EDCA scheme.     

End-to-end QoS framework for heterogeneous wired-cum-wireless networks

With information access becoming more and more ubiquitous, there is a need for providing QoS support for communication that spans wired and wireless networks. For the wired side, RSVP/SBM has been widely accepted as a flow reservation scheme in IEEE 802 style LANs. Thus, it would be desirable to investigate the integration of RSVP and a flow reservation scheme in wireless LANs, as an end-to-end solution for QoS guarantee in wired-cum-wireless networks. For this purpose, we propose WRESV, a lightweight RSVP-like flow reservation and admission control scheme for IEEE 802.11 wireless LANs. Using WRESV, wired/wireless integration can be easily implemented by cross-layer interaction at the Access Point. Main components of the integration are RSVP-WRESV parameter mapping and the initiation of new reservation messages, depending on where senders/receivers are located. In addition, to support smooth roaming of mobile users among different basic service sets (BSS), we devise an efficient handoff scheme that considers both the flow rate demand and network resource availability for continuous QoS support. Furthermore, various optimizations for supporting multicast session and QoS re-negotiation are proposed for better performance improvement. Extensive simulation results show that the proposed scheme is promising in enriching the QoS support of multimedia applications in heterogeneous wired-cum-wireless networks. Ming Li received his B.S. and M.S. in Engineering from Shanghai Jiao Tong University, China, in 1995 and 1998, respectively. He is currently a Ph.D. candidate in department of Computer Science, University of Texas at Dallas, where he received M.S. degree in Computer Science in Dec. 2001. His research interest includes QoSschemes for mobile ad-hoc networks and multimedia over wireless networks. Hua Zhu received the Ph.D. degree in Electrical Engineering from the University of Texas at Dallas, Texas. Since 2005, he has been working for San Diego Research Center, Inc., San Diego, CA, as a Research Engineer. His research interests include all layers of wireless communication systems. His particular interest is in L2/3 air interface design, performance analysis, and optimization for ad hoc and sensor networks. Imrich Chlamtac is the President of CREATE-NET and the Bruno Kessler Professor at the University of Trento, Italy. He has held various honorary and chaired professorships in USA and Europe including the Distinguished Chair in Telecommunications Professorship at the University of Texas at Dallas, Sackler Professroship at Tel Aviv University and has been on faculty at Technion, and UMass. Dr. Imrich Chlamtac has made significant contribution to various networking technologies as scientist, educator and entrepreneur. Dr. Chlamtac is the recipient of multiple awards and recognitions including Fellow of the IEEE, Fellow of the ACM, Fulbright Scholar, the ACM Award for Outstanding Contributions to Research on Mobility and the IEEE Award for Outstanding Technical Contributions to Wireless Personal Communications. Dr. Chlamtac published over three hundred and fifty refereed journal, book, and conference articles and is the co-author of four books. Dr. Chlamtac has widely contributed to the scientific community as founder and Chair of ACM Sigmobile, founder and steering committee chair of some of the lead conferences in networking including Mobicom, OptiComm, Mobiquitous, Broadnets, Securecomm. Dr. Chlamtac also serves as the founding Editor in Chief of the ACM/URSI/Springer Wireless Networks (WINET), the ACM/Springer Journal on Special Topics in Mobile Networks and Applications (MONET). B. Prahbakaran is with the faculty of Computer Science Department, University of Texas at Dallas. He has been working in the area of multimedia systems: animation & multimedia databases, authoring & presentation, resource management, and scalable web-based multimedia presentation servers. Dr. Prabhakaran received the prestigious National Science Foundation (NSF) CAREER Award in 2003 for his proposal on Animation Databases. He has published several research papers in various refereed conferences and journals in this area. He has served as guest-editor (special issue on Multimedia Authoring and Presentation) for ACM Multimedia Systems journal. He is also serving on the editorial board of Multimedia Tools and Applications journal, Kluwer Academic Publishers. He has also served as program committee member on several multimedia conferences and workshops. B. Prabhakaran has served as a visiting research faculty with the Department of Computer Science, University of Maryland, College Park. He also served as a faculty in the Department of Computer Science, National University of Singapore as well as in the Indian Institute of Technology, Madras, India.