共查询到20条相似文献,搜索用时 15 毫秒
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基于已有的带宽管理机制,采用加权公平对竞争的流分配带宽,不仅可以对流实现准入控制,以保证每条流的最低信道时间需求,同时也能动态地调节流所分配的信道时间。另外,我们的方案,也适用于多跳的情况,通过例子说明,在考虑到用户需求的同时,也提高了网络的吞吐量。 相似文献
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Distributed weighted fair scheduling schemes for Quality of Service (QoS) support in wireless local area networks have not yet become standard. Therefore, we propose an Admission Control and Dynamic Bandwidth Management scheme that provides fairness and a soft rate guarantee in the absence of distributed MAC-layer weighted fair scheduling. This scheme is especially suitable for smart-rooms where peer-to-peer multimedia transmissions need to adapt their transmission rates co-operatively. We present a mapping scheme to translate the bandwidth requirements of an application into its channel time requirements. The center piece of our scheme is a Bandwidth Manager, which allots each flow a share of the channel, depending on the flow's requirements relative to the requirements of other flows in the network. Admitted flows control their transmission rates so they only occupy the channel for the fraction of time allotted to them. Thus co-operation between flows is achieved and the channel time is fair shared. As the available channel capacity changes and the traffic characteristics of various flows change, the Bandwidth Manager dynamically re-allocates the channel access time to the individual flows. Our simulation experiments show that, at a very low cost and with high probability, every admitted flow in the network will receive at least its minimum requested share of the network bandwidth. We also present extensive testbed experiments with our scheme using a real-time audio streaming application running between Linux laptops equipped with standard IEEE 802.11 network cards. 相似文献
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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. 相似文献
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Dynamic QoS Allocation for Multimedia Ad Hoc Wireless Networks 总被引:1,自引:0,他引:1
In this paper, we propose an approach to support QoS for multimedia applications in ad hoc wireless network. An ad hoc network is a collection of mobile stations forming a temporary network without the aid of any centralized coordinator and is different from cellular networks which require fixed base stations interconnected by a wired backbone. It is useful for some special situations, such as battlefield communications and disaster recovery. The approach we provide uses CSMA/CA medium access protocol and additional reservation and control mechanisms to guarantee quality of service in ad hoc network system. The reason we choose CSMA protocol instead of other MAC protocols is that it is used in most of currently wireless LAN productions. Via QoS routing information and reservation scheme, network resources are dynamically allocated to individual multimedia application connections. 相似文献
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无线特定网络--Ad Hoc网络 总被引:5,自引:0,他引:5
Ad Hoc网络是一种没有固定结构的无线移动网络。介绍了移动Ad Hoc网络(MANETs)的主特点和与传统有线分组交换网相比的特性,讨论了应用于Ad Hoc网络的路由机制和所需面临的问题。 相似文献
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Jipeng Zhou Liangwen Liu Yuhui Deng Shuqiang Huang 《Wireless Personal Communications》2014,75(1):273-291
Mobile multimedia applications have recently generated much interest in mobile ad hoc networks (MANETs) supporting quality-of-service (QoS) communications. Multiple non-interfering channels are available in 802.11 and 802.15 based wireless networks. Capacity of such channels can be combined to achieve higher QoS performance than for single channel networks. The capacity of MANETs can be substantially increased by equipping each network node with multiple interfaces that can operate on multiple non-overlapping channels. However, new scheduling, channel assignment, and routing protocols are required to utilize the increased bandwidth in multichannel MANETs. In this paper, we propose an on-demand routing protocol M-QoS-AODV in multichannel MANETs that incorporates a distributed channel assignment scheme and routing discovery process to support multimedia communication and to satisfy QoS bandwidth requirement. The proposed channel assignment scheme can efficiently express the channel usage and interference information within a certain range, which reduces interference and enhances channel reuse rate. This cross-layer design approach can significantly improve the performance of multichannel MANETs over existing routing algorithms. Simulation results show that the proposed M-QoS-AODV protocol can effectively increase throughput and reduce delay, as compared to AODV and M-AODV-R protocols. 相似文献
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Ad Hoc Probe是目前测量无线网络路径带宽的主要方法,由于发送探测分组数目固定,当负载较轻时,仅需要几组探测报文就能够获得正确的样本,所以限制了无线Ad Hoc网络的动态性。针对Ad Hoc Probe算法的不足,提出了AdHoc TP算法,一次发送三个报文,组成两个报文对,通过比较两个报文对的时间间隔和最小时延和提高样本的过滤速度,从而使测量速度更快。Qual Net仿真的结果表明,Ad Hoc TP算法能够正确地测量出有线/无线Ad Hoc混合网络的带宽,而且测量速度较快。 相似文献
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Several auctions have been proposed and applied to perform contract negotiation and resource allocation in reservation-based networks. The methods proposed by these works perceive resources as single items with multiple units and place importance on a limited efficiency inside each node. However, as a user evaluates resources not individually, but rather as a whole set of required resources, the economical efficiency of the overall network cannot be achieved by these methods. To solve this problem, we propose a bandwidth allocation system using GVA (Generalised Vickrey Auction). Network resources, which are composed of many links at various bandwidths, are regarded by the proposed method as multiple items with multiple units. We describe how to apply GVA protocol to bandwidth allocations among multiple users. We investigate algorithmic and accounting problems inside multiple nodes using an end-to-end approach. We evaluate the proposed method's performance from various viewpoints: the utilisation of resources, profits of the telecommunications carriers, users' utility and users' satisfaction. We show that, by adopting GVA, the total utility of users can be maximised and the revenues of networks can also be improved. 相似文献
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Wireless Personal Communications - Mobile ad hoc networks are non-dependent on any wired infrastructure and provide exceptional benefits during typical situations like conference, fair/exhibition,... 相似文献
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Flooding for Reliable Multicast in Multi-Hop Ad Hoc Networks 总被引:1,自引:0,他引:1
Ad hoc networks are gaining popularity as a result of advances in smaller, more versatile and powerful mobile computing devices. The distinguishing feature of these networks is the universal mobility of all hosts. This requires re-engineering of basic network services including reliable multicast communication. This paper considers the special case of highly mobile fast-moving ad hoc networks and argues that, for such networks, traditional multicast approaches are not appropriate. Flooding is suggested as a possible alternative for reliable multicast and simulation results are used to illustrate its effects. The experimental results also demonstrate a rather interesting outcome that even flooding is insufficient for reliable multicast in ad hoc networks when mobility is very high. Some alternative, more persistent variations of flooding are sketched out. 相似文献
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Throughput Analysis of IEEE802.11 Multi-Hop Ad Hoc Networks 总被引:3,自引:0,他引:3
Ping Chung Ng Soung Chang Liew 《Networking, IEEE/ACM Transactions on》2007,15(2):309-322
In multi-hop ad hoc networks, stations may pump more traffic into the networks than can be supported, resulting in high packet-loss rate, re-routing instability and unfairness problems. This paper shows that controlling the offered load at the sources can eliminate these problems. To verify the simulation results, we set up a real 6-node multi-hop network. The experimental measurements confirm the existence of the optimal offered load. In addition, we provide an analysis to estimate the optimal offered load that maximizes the throughput of a multi-hop traffic flow. We believe this is a first paper in the literature to provide a quantitative analysis (as opposed to simulation) for the impact of hidden nodes and signal capture on sustainable throughput. The analysis is based on the observation that a large-scale 802.11 network with hidden nodes is a network in which the carrier-sensing capability breaks down partially. Its performance is therefore somewhere between that of a carrier-sensing network and that of an Aloha network. Indeed, our analytical closed-form solution has the appearance of the throughput equation of the Aloha network. Our approach allows one to identify whether the performance of an 802.11 network is hidden-node limited or spatial-reuse limited 相似文献
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There is considerable interest in modeling the performance of ad hoc networks analytically. This paper presents approximate
analytical models for the throughput performance of single-hop and multi-hop ad hoc networks. The inherent complexity of analysis
of a multi-hop ad hoc network together with the fact that the behavior of a node is dependent not only on its neighbors' behavior,
but also on the behavior of other unseen nodes makes multi-hop network analysis extremely difficult. However, our approach
in this paper to analyze multi-hop networks offers an accurate approximation with moderate complexity. Our approach is based
on characterizing the behavior of a node by its state and the state of the channel it sees. This approach is used to carry
out an analysis of single-hop and multi-hop ad hoc networks in which different nodes may have different traffic loads. In
order to validate the model, it is applied to IEEE 802.11-based networks, and it is shown through extensive simulations that
the model is very accurate.
Farshid Alizadeh-Shabdiz received his B.Sc. in 1989 at University of Science and Technology, M.Sc. in 1991 at Tehran University, Iran, and D.Sc. in
2004 at the George Washington University. He is a senior research engineer in Advanced Solution Group, part of Cross Country
Automotive Services, and he is also a part time faculty member at Boston University.
Dr. Alizadeh-Shabdiz was part of the design and implementation team of the three first satellite-based mobile networks: ICO
global medium orbit satellite network voice and data services, Thuraya GEO satellite network, and the first phase of Inmarsat
high speed data network. His research interests include MAC layer, physical layer and network layer of wireless and satellite
networks.
Suresh Subramaniam received the Ph.D. degree in electrical engineering from the University of Washington, Seattle, in 1997. He is an Associate
Professor in the Department of Electrical and Computer Engineering at the George Washington University, Washington, DC. His
research interests are in the architectural, algorithmic, and performance aspects of communication networks, with particular
emphasis on optical and wireless ad hoc networks.
Dr. Subramaniam is a co-editor of the books “Optical WDM Networks – Principles and Practice” and “Emerging Optical Network
Technologies: Architectures, Protocols, and Performance”. He has been on the program committees of several conferences including
Infocom, ICC, Globecom, and Broadnets, and served as TPC Co-Chair for the 2004 Broadband Optical Networking Symposium. He
currently serves on the editorial boards of Journal of Communications and Networks and IEEE Communications Surveys and Tutorials.
He is a co-recipient of the Best Paper Award at the 1997 SPIE Conference on All-Optical Communication Systems. 相似文献
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Particle swarm optimization (PSO) is one of the most important biological swarm intelligence paradigms. However, the standard PSO algorithm can easily get trapped in the local optima when solving complex multimodal problems. In this paper, an improved adaptive particle swarm optimization (IAPSO) is presented. Based on IAPSO, a joint opportunistic power and rate allocation (JOPRA) algorithm is proposed to maximize the sum of source utilities while minimize power allocation for all links in wireless ad hoc networks. It is shown that the proposed JOPRA algorithm can converge fast to the optimum and reach larger total data rate and utility while less total power is consumed by comparison with the original APSO. This thanks to the dynamic change of the maximum movement velocity of the particles, the use of the modified replacement procedure in constraint handling, and the consideration of the state of the optimization run and the population diversity in stopping criteria. Numerical simulations further verify that our algorithm with the IAPSO outperforms that with the original APSO. 相似文献
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Ad hoc networks formed without the aid of any established infrastructure are typically multi-hop networks. Location dependent
contention and hidden terminal problem make priority scheduling in multi-hop networks significantly different from that in
wireless LANs. Most of the prior work related to priority scheduling addresses issues in wireless LANs. In this paper, priority
scheduling in multi-hop networks is discussed. We propose a scheme using two narrow-band busy tone signals to ensure medium
access for high priority source stations. The simulation results demonstrate the effectiveness of the proposed scheme.
Xue Yang received the B.E. degree and the M.S. degree from University of Electronic Science and Technology of China. She is currently
a Ph.D. candidate at University of Illinois at Urbana-Champaign (UIUC). She is awarded Vodafone-U.S. Foundation Graduate Fellowship
from 2003 to 2005. Her current research is in the areas of wireless networking and mobile computing, with the focus on medium
access control, quality of service and topology control. Her research advisor is Prof. Nitin Vaidya at UIUC. For more information,
please visit
Nitin H. Vaidya received the PhD degree from the University of Massachusetts at Amherst. He is presently an Associate Professor of Electrical
and Computer Engineering at the University of Illinois at Urbana-Champaign (UIUC). He has held visiting positions at Microsoft
Research, Sun Microsystems and the Indian Institute of Technology-Bombay. His current research is in the areas of wireless
networking and mobile computing. His research has been funded by various agencies, including the National Science Foundation,
DARPA, BBN Technologies, Microsoft Research, and Sun Microsystems. Nitin Vaidya is a recipient of a CAREER award from the
National Science Foundation. Nitin has served on the program committees of several conferences and workshops, and served as
program co-chair for the 2003 ACM MobiCom. He has served as editor for several journals, and presently serves as Editor-in-Chief
for IEEE Transactions on Mobile Computing, and as editor-in-chief of ACM SIGMOBILE periodical MC2R. He is a senior member
of IEEE and a member of the ACM. For more information, please visit 相似文献