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1.
TianHui LiYingyang 《电子科学学刊(英文版)》2003,20(2):116-120
This letter presents the design and performance of a multi-channel MAC protocol that supports multiple traffics for IEEE 802.11 mobile ad-hoc networks.The dynamic channel selection scheme by receiver decision is implemented and the number of the data channel is independent of the network topology.The priority for real-time traffic is assured by the proposed adaptive back off algorithm and different IFS.The protocol is evaluated by simulation and the results have shown that it can support multiple traffics and the performance is better than the performance that IEEE 802.11 standard provides. 相似文献
2.
Concurrent with the rapid expansion of wireless networks is an increasing interest in providing Quality-of-Service (QoS) support to them. As a consequence, a number of medium access control protocols has been proposed which aims at providing service differentiation at the distributed wireless medium access layer. However, most of them provide only average performance assurances. We argue that average performance guarantees will be inadequate for a wide range of emerging multimedia applications and “per-flow” service assurances must be provided instead. Based on m-ary tree algorithms, we propose an adaptive and distributed medium access algorithm for single-cell ad hoc networks to provide “per-flow” service assurances to flows whose QoS requirement can be expressed as a delay requirement. Both analytical and simulation experiments are conducted to assess the performance of the proposed scheme. 相似文献
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Wireless sensor networks (WSN) are formed by network-enabled sensors spatially randomly distributed over an area. Because the number of nodes in the WSNs is usually large, channel reuse must be applied, keeping co-channel nodes sufficiently separated geographically to achieve
satisfactory SIR level. The most efficient channel reuse configuration for WSN has been determined and the worst-interference scenario has been identified. For this channel reuse pattern and worst-case
scenario, the minimum co-channel separation distance consistent with an SIR level constraint is derived. Our results show that the two-hop co-channel separations often assumed for sensor and ad hoc
networks are not sufficient to guarantee communications. Minimum co-channel separation curves given various parameters are
also presented. The results in this paper provide theoretical basis for channel spatial reuse and medium access control for
WSN s and also serve as a guideline for how channel assignment algorithms should allocate channels. Furthermore, because the
derived co-channel separation is a function of the sensor transmission radius, it also provides a connection between network
data transport capacity planning and network topology control which is administered by varying transmission powers.
Xiaofei Wang is born on July 31st, 1974, in Jilin, People’s Republic of China. He received the M.S. degree in Electrical Engineering from
Delft University of Technology, Delft, The Netherlands in 1992, and the Ph.D. degree in Electrical and Computer Engineering
from Cornell University, Ithaca, New York in 2005.
From 1997 to 1998, he was selected as one of the twenty best master graduate candidates in all fields to participate in the
Japan Prizewinners Programme, an international leadership exchange program established by the Dutch Ministry of Culture, Science
and Education. From 1998 to 1999, he worked as a researcher at the Department of Electrical Engineering and Applied Mathematics
of Delft University of Technology in the areas of Secondary Surveillance Radar and Ground Penetrating Radar.
His research interests include wireless sensor networks, wireless mesh networks, wireless networking, error control coding,
communication theory and information theory. He is currently working at Qualcomm Incorporated in San Diego, CA.
Toby Berger was born in New York, NY on September 4, 1940. He received the B.E. degree in electrical engineering from Yale University,
New Haven, CT in 1962, and the M.S. and Ph.D. degrees in applied mathematics from Harvard University, Cambridge, MA in 1964
and 1966, respectively.
From 1962 to 1968 he was a Senior Scientist at Raytheon Company, Wayland, MA. From 1968 through 2005 he he held the position
of Irwin and Joan Jacobs Professor of Engineering at Cornell University, Ithaca, NY where in 2006 he became a professor in
the ECE Deportment of the University of Virginia, Charlottesville, VA.
Professor Berger’s research interests include information theory, random fields, communication networks, wireless communications,
video compression, voice and signature compression and verification, neuroinformation theory, quantum information theory,
and coherent signal processing.
Berger has served as editor-in-chief of the IEEE Transactions on Information Theory and as president of the IEEE Information
Theory Group. He has been a Fellow of the Guggenheim Foundation, the Japan Society for Promotion of Science, the Ministry
of Education of the People’s Republic of China and the Fulbright Foundation. In 1982 he received the Frederick E. Terman Award
of the American Society for Engineering Education, he received the 2002 Shannon Award from the IEEE Information Theory Society
and has been designated the recipient of the IEEE 2006 Leon K. Kirchmayer Graduate Teaching Award. Berger is a Fellow and
Life Member of the IEEE, a life member of Tau Beta Pi, and an avid blues harmonica player. 相似文献
5.
为了解决无线Mesh网络中的信道分配问题,提出了一种基于博弈论的信道分配算法.该算法将网络中每一个节点模型化为一个博弈者,每个博弈者的策略为信道的分配方案,并将整个网络的吞吐量作为效用函数的目标,效用函数的物理意义则是在给定流量需求矩阵下传输的成功率.博弈者通过相互博弈来优化收益函数以最大化网络吞吐量.通过NS2.34仿真分析得出,GBCA算法在收敛性、丢包率和吞吐量上都要优于当前的算法. 相似文献
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由于存在"隐藏终端"和"暴露终端"的问题,无线Ad hoc网络的应用受到极大的限制.进一步,由于水声信道的特点,例如有用的频率带宽很窄,强时变、多途和长传播时延,使得设计水声Ad hoc网络具有自身特点和难度.本文中,我们为此提出了一种新的多址接入控制(MAC)协议,即并行传输多址接入(PTMA)协议.该协议基于如下思想:为消除冲突而进行多信道预约,这样能在多个信道上并行地传输数据;为缩短等待clear-to-send(CTS)的时间,当request-to-send(RTS)刚发送完就立即发送分组数据,而不必收到CTS后再发.通过使用OPNET Modeler/Radio仿真器得到的仿真结果显示:PTMA协议能取得较之于适合无线Ad hoc网络的多址接入协议更高的吞吐性能和较低的端到端传播时延. 相似文献
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This paper considers a wireless network consisting of large number of clusters, wherein each cluster represents a decode-and-forward (DF) relay network. Two main scenarios according to the distances among the nodes in the network are investigated. In the case of deterministic distances, the outage probability is obtained in a closed-form expression. Whereas for the case when these distances are independent random variables, the framework of Stochastic Geometry (SG) is exploited for deriving the closed-form of the outage probability in case of Rayleigh fading channel. Furthermore, a lower and upper bound for the outage probability in case of general fading channel have been also provided. Numerical simulations are carried out to validate the derived analytical expressions, and to illustrate how the obtained results can be utilized in interference management of such networks. 相似文献
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Mobility affects routing protocol performance in a Mobile Ad Hoc NETwork (MANET). This paper introduces a novel concept of “macro-mobility” information obtained from the sociological movement pattern of MANET users, and proposes a routing protocol that can take advantage of the macro-mobility information. This macro-mobility information is extracted from our observation that the movement of a mobile user exhibits a partially repetitive “orbital” pattern involving a set of “hubs”. This partially deterministic movement pattern is not only practical, but also useful for locating nodes without the need for constant tracking and for routing packets to them without flooding.More specifically, this paper makes the following two contributions. First, it proposes an ORBIT mobility framework to achieve this macro-level abstraction of orbital movement. Second, to take advantage of this hub-based orbital pattern, it proposes a Sociological Orbit aware Location Approximation and Routing (SOLAR) protocol. Extensive performance analysis shows that SOLAR significantly outperforms conventional routing protocols like Dynamic Source Routing (DSR) and Location Aided Routing (LAR) in terms of higher data throughput, lower control overhead, and lower end-to-end delay. 相似文献
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Network topology construction and its channel assignment for each node in the constructed network topology are two main problems in the initialization of topology building. Topology control is an effective way to solve the problem of topology building. To investigate the joint effect of topology control and channel assignment, we propose a joint processing scheme composed of a k‐Neighbor topology control algorithm and a greedy channel assignment (GCA) algorithm in this paper. Based on this joint processing scheme, the relationships between the energy consumption, the total required channel number and the network connectivity are discussed. We also discuss the impact of some parameters on the performance of networks in terms of the path loss factor, node density, maximum node degree, etc. Our main contributions in this paper is that we find that topology control has a good effect on improving the performance of channel assignment, and the proposed joint processing scheme can reduce the required channel number effectively, compared with its theoretical upper bound. In particular, if the node degree in a network is not more than k, various simulations indicate that the required channel number is not more than 2k + 1. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
11.
One of the main issues in hybrid wireless networks is vertical handoff. Dropping probability is one of the important parameters that must be considered in planning the wireless communication systems. However, there has not been much effort in dropping rate reduction in loosely coupled hybrid wireless networks. In loosely coupled WLAN/cellular systems the system administrator of the WLAN is different from the cellular one. Therefore, in these situations, reducing the dropping probability based on classical methods such as using reserved guard channels is difficult. A handoff from a WLAN to a cellular system occurs when a multi-mode device moves out of the WLANs coverage area. This is an upward vertical handoff in a hybrid network. In this paper, we propose to employ ad hoc relaying during the upward vertical handoff in a hybrid WLAN/cellular system. Two-hop and multi-hop relaying approaches, which we propose in this paper, improve the dropping probability regardless of the number of reserved channels. Simulation results support the effectiveness of the proposed methods. Also, practical routing protocols are proposed in order to implement the suggested relaying methods. 相似文献
12.
In wireless access, transmitter nodes need to make individual decisions for distributed operation and do not necessarily cooperate
with each other. We consider a single-receiver random access system of non-cooperative transmitters with the individual objectives
of optimizing their throughput rewards, transmission energy costs and delay costs. The non-cooperative transmitter behavior
may be purely selfish or may also reflect malicious objectives of generating interference to prevent the successful transmissions
of the other nodes as a form of denial of service attack. Our goal is to evaluate the interactions between selfish and malicious
nodes that have the dual objectives of optimizing their individual performance measures and blocking the packet transmissions
of the other selfish nodes. We assume saturated packet queues of infinite buffer capacities and consider a general multi-packet
reception channel that allows packet captures in the presence of simultaneous transmissions. In this context, we formulate
a non-cooperative random access game of selecting the individual probabilities of transmitting packets to a common receiver.
We derive the non-cooperative transmission strategies in Nash equilibrium. The analysis provides insights for the optimal
strategies to block random access of selfish nodes as well as the optimal defense mechanisms against the possible denial of
service attacks of malicious nodes in wireless networks. The results are also compared with the cooperative equilibrium strategies
that optimize the total system utility (separately under random access and scheduled access). A pricing scheme is presented
to improve the non-cooperative operation. For distributed implementation, we formulate a repeated game of the best-response
strategy updates and introduce adaptive heuristics (based on the channel feedback only) provided that the system parameters
are not explicitly known at the individual transmitters.
Yalin Evren Sagduyu received his B.S. degree from Bogazici University, Turkey, in 2000 in Electrical and Electronics Engineering, and M.S. and Ph.D. degrees from the University of Maryland at College Park in 2002 and 2007, respectively, in Electrical and Computer Engineering. He has been a graduate research assistant with the Institute for Systems Research at the University of Maryland. He is currently a postdoctoral fellow in the Department of Electrical Engineering and Computer Science at Northwestern University. His research interests are in the areas of design and optimization of wireless ad hoc and sensor networks, game theory applications in communication systems, multi-user information theory and network coding. Anthony Ephremides received his B.S. degree from the National Technical University of Athens (1967), and M.S. (1969) and Ph.D. (1971) degrees from Princeton University, all in Electrical Engineering. He has been at the University of Maryland since 1971, and currently holds a joint appointment as professor in the Electrical Engineering Department and the Institute of Systems Research (ISR). He is co-founder of the NASA Center for Commercial Development of Space on Hybrid and Satellite Communications Networks established in 1991 at Maryland as an offshoot of the ISR. He was a visiting professor in 1978 at the National Technical University of Athens, Greece, and in 1979 at the Electrical Engineering and Computer Science Department of the University of California at Berkeley and INRIA, France. During 1985–1986 he was on leave at Massachusetts Institute of Technology and the Swiss Federal Institute of Technology, Zurich. He has been President of the Information Theory Society of the IEEE (1987), and served on the Board of the IEEE (1989 and 1990). His interests are in the areas of communication theory, communication systems and networks, queuing systems, signal processing, and satellite communications. 相似文献
Anthony EphremidesEmail: |
Yalin Evren Sagduyu received his B.S. degree from Bogazici University, Turkey, in 2000 in Electrical and Electronics Engineering, and M.S. and Ph.D. degrees from the University of Maryland at College Park in 2002 and 2007, respectively, in Electrical and Computer Engineering. He has been a graduate research assistant with the Institute for Systems Research at the University of Maryland. He is currently a postdoctoral fellow in the Department of Electrical Engineering and Computer Science at Northwestern University. His research interests are in the areas of design and optimization of wireless ad hoc and sensor networks, game theory applications in communication systems, multi-user information theory and network coding. Anthony Ephremides received his B.S. degree from the National Technical University of Athens (1967), and M.S. (1969) and Ph.D. (1971) degrees from Princeton University, all in Electrical Engineering. He has been at the University of Maryland since 1971, and currently holds a joint appointment as professor in the Electrical Engineering Department and the Institute of Systems Research (ISR). He is co-founder of the NASA Center for Commercial Development of Space on Hybrid and Satellite Communications Networks established in 1991 at Maryland as an offshoot of the ISR. He was a visiting professor in 1978 at the National Technical University of Athens, Greece, and in 1979 at the Electrical Engineering and Computer Science Department of the University of California at Berkeley and INRIA, France. During 1985–1986 he was on leave at Massachusetts Institute of Technology and the Swiss Federal Institute of Technology, Zurich. He has been President of the Information Theory Society of the IEEE (1987), and served on the Board of the IEEE (1989 and 1990). His interests are in the areas of communication theory, communication systems and networks, queuing systems, signal processing, and satellite communications. 相似文献
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To improve the capacity of wireless ad hoc networks by exploiting multiple available channels, we propose a distributed channel
assignment protocol that is based on a cross-layer approach. By combining channel assignment with routing protocols, the proposed
channel assignment protocol is shown to require fewer channels and exhibit lower communication, computation, and storage complexity
than existing channel assignment schemes. A multi-channel MAC (MC-MAC) protocol that works with the proposed channel assignment
protocol is also presented. We prove the correctness of the proposed channel assignment protocol. In addition, through a performance
study, we show that the proposed protocol can substantially increase throughput and reduce delay in wireless ad hoc networks,
compared to the IEEE 802.11 MAC protocol and an existing multi-channel scheme.
相似文献
Shiwen MaoEmail: |
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支持资源预留的介质访问控制(MAC)机制是无线ad hoc网络提供服务质量保证的关键.本文在分析分组预留多址接入(PRMA)的基础上,给出了一种新的支持资源预留的无线ad hoc网络MAC机制:分布式PRMA(D-PRMA).D-PRMA的主要特点是分布式的,这适合无线ad hoc网络无中心的特点,同时,D-PRMA具有很短的碰撞持续时间,支持不同速率的实时业务,避免了对分组的分片和重组.通过仿真,本文进一步分析了D-PRMA的性能,仿真结果表明D-PRMA能保证实时业务的带宽和时延. 相似文献
16.
在商用AdHoc网络中,对中继而言,为其他用户转发数据会带来额外的能量损耗,同时也会使用户自身的数据传输产生延迟,因此,网络中便会出现一些“自私节点”,不愿意为其它用户转发数据。在一定程度上影响了网络的正常运行。根据微观经济学中的博弈理论,给出了一种基于价格的协作转发方案,综合考虑网络收益和用户效用,由源节点决定补偿价格,并对中继进行价格补偿,来激励其转发数据。仿真结果表明,价格机制不仅可以激励转发,增加网络收益,而且改善了用户效用。特别是中继的效用。 相似文献
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无线网络的信道分配博弈分析,可分为单冲突域和多冲突域建模。在ad hoc网络中,采用多冲突域建模更符合实际。将ad hoc网络建模为多冲突域模型,提出一种基于完美信息的非合作信道分配算法,验证了算法的收敛性,仿真结果表明该算法相比其他算法在多冲突域中更能最大化信道使用率。 相似文献
18.
The use of codes to schedule transmissions is an attractive technique able to guarantee a non-zero throughput medium access performance for the nodes of a wireless ad hoc or sensor network regardless of network topology variations. Some authors refer to this technique as topology-transparent scheduling. In this paper, we use the term MAC coding in order to emphasize the exclusive use of codes to achieve topology-transparency within the MAC sub-layer. We present a new upper bound expression on the guaranteed throughput achievable by any linear code used in a MAC coding context. This bound proves to be tighter than the one obtained when the minimum distance of the code is equal to its length. Additionally, we derive new and simple closed analytical expressions for the parameters of maximum distance separable codes that maximize the minimum, average, or joint minimum-average throughput of MAC coding. The optimization methods presented here are also applicable to other codes with available analytical expressions for their minimum distance and distance distribution. Finally, we present system-level simulation results of MAC coding on static and dynamic topologies with mobility and including wireless channel errors. Throughput simulation results are compared with their corresponding analytical expressions and to a random scheduling approach. The results show agreement with analysis and confirm the robustness of MAC coding in maintaining minimum levels of performance with good average performance and graceful degradation. 相似文献
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This paper describes an ad hoc networking scheme and routing protocol for emergency communications. The objective of the network is to collect damage assessment information quickly and stably in a disaster. The network is configured with a hybrid wireless network, combining ad hoc networks and a cellular network to maintain connectivity between a base station (BS) and nodes even in a disaster. In the event that a direct link between the BS and a node is disconnected due to damage or obstacles, the node switches to the ad hoc mode, and accesses the BS via neighboring nodes by multihopping. The routing protocol proposed in this paper discovers and builds a route by way of monitoring neighbors’ communications instead of broadcasting a route request packet. The network employs a dedicated medium access control protocol based on TDM (Time Division Multiplexing) for multihopping in ad hoc networks to maintain accessibility and to perform a short delay. Experiments showed that approximately 90% of nodes are capable of reaching the BS within a few hops, even in conditions where only 20% of nodes maintain direct connections to the BS. In addition, the results showed that it is feasible for the network to operate in a short delay for delivering a packet to the BS. However, throughput is not retrieved sufficiently due to the restriction of the access protocol, whereas reachability does improve sufficiently. Therefore, the network is suitable for collecting damage assessment information and transmitting urgent traffic quickly and stably, while the data is restricted to a small amount. 相似文献
20.
无线自组网节点的能量有限导致网内节点往往拒绝承担新节点入网所带来的认证负荷.为激励无线自组网节点参与新节点的入网认证,引入博弈论的公共物品供给博弈理论和维克里-克拉克-格罗夫斯(VCG)机制理论,构建了无线自组网的动态接入激励机制.提出了认证节点选举办法,给出了新节点认证付酬和认证节点收益函数,分析了认证能量消耗.理论证明了激励机制具有策略防伪、个体理性和预算平衡3个特性.实例分析了不同参数设置情况下网内节点就新节点接入认证、个体与集体的合作博弈过程,结果表明该机制能有效地激励节点,为了自身的最大利益积极选择参与新节点的入网认证. 相似文献