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1.
To find the optimal routing is always an important topic in wireless sensor networks （WSNs）. Considering a WSN where the nodes have limited energy, we propose a novel Energy^＊Delay model based on ant algorithms （＂E＆D ANTS＂ for short） to minimize the time delay in transferring a fixed number of data packets in an energy-constrained manner in one round. Our goal is not only to maximize the lifetime of the network but also to provide real-time data transmission services. However, because of the tradeoff of energy and delay in wireless network systems, the reinforcement learning （RL） algorithm is introduced to train the model. In this survey, the paradigm of E＆D ANTS is explicated and compared to other ant-based routing algorithms like AntNet and AntChain about the issues of routing information, routing overhead and adaptation. Simulation results show that our method performs about seven times better than AntNet and also outperforms AntChain by more than 150% in terms of energy cost and delay per round. 相似文献
2.
This paper proposes a modification to distributed coordination function (DCF) to improve the channel utilization in IEEE 802.11 wireless local area networks (WLANs). In the modified DCF, when a station has contended for the channel, it may transmit multiple data frames continuously to the same destination, which is called transmission burst(TB). When the maximum number of data packets transmitted continuously in a TB is set to be 2, the performance is expected to be the best. The theoretical analysis and simulation results show that compared with the standard DCF, the modified DCF can increase the throughput and decrease the delay of the WLAN, and the modification does not introduce any additional control overhead. 相似文献
3.
ZUO Dong-hong DU Xu YANG Zong-kai 《浙江大学学报(A卷英文版)》2007,8(8):1191-1198
Media streaming delivery in wireless ad hoc networks is challenging due to the stringent resource restrictions,po-tential high loss rate and the decentralized architecture. To support long and high-quality streams,one viable approach is that a media stream is partitioned into segments,and then the segments are replicated in a network and served in a peer-to-peer(P2P) fashion. However,the searching strategy for segments is one key problem with the approach. This paper proposes a hybrid ants-like search algorithm(HASA) for P2P media streaming distribution in ad hoc networks. It takes the advantages of random walks and ants-like algorithms for searching in unstructured P2P networks,such as low transmitting latency,less jitter times,and low unnecessary traffic. We quantify the performance of our scheme in terms of response time,jitter times,and network messages for media streaming distribution. Simulation results showed that it can effectively improve the search efficiency for P2P media streaming distribution in ad hoc networks. 相似文献
4.
INTRODUCTION The convenience of wireless communications has led to increasing use of wireless networks for civilian and critical applications. With the advent of Internet technology and the increasing popularity of wireless data devices, the wireless industry is evolv- ing its core networks toward IP-based networks. It will be necessary to integrate the wireless networks and the existing wired networks into the Internet. TCP has been the predominant transport protocol used in the wired … 相似文献
5.
Wireless sensor networks consist of hundreds or thousands of sensor nodes that involve numerous restrictions including computation capability and battery capacity. Topology control is an important issue for achieving a balanced placement of sensor nodes. The clustering scheme is a widely known and efficient means of topology control for transmitting information to the base station in two hops. The automatic routing scheme of the self-organizing technique is another critical element of wireless sensor networks. In this paper we propose an optimal algorithm with cluster balance taken into consideration, and compare it with three well known and widely used approaches, i.e., LEACH, MEER, and VAP-E, in performance evaluation. Experimental results show that the proposed approach increases the overall network lifetime, indicating that the amount of energy required for communication to the base station will be reduced for locating an optimal cluster. 相似文献
6.
Recent research challenges in the wireless communication include the usage of diversity and efficient coding to improve data transmission quality and spectral efficiency. Space diversity uses multiple transmitting and/or receiving antennas to create independent fading channels without penalty in bandwidth efficiency. Space-time block coding is an encoding scheme for communication over Rayleigh fading channels using multiple transmitting antennas. Space-time block codes from complex orthogonal designs exist only for two transmitting antennas. This paper generalizes a new complex orthogonal space-time block code for four transmitting antennas, whose decoding complexity is very low. Simulations show that the generalized complex orthogonal space-time block code has low bit error rate, full rate and possibly large diversity. 相似文献
7.
Reputation-based linear cooperation for spectrum sensing in cognitive radio networks 总被引：1，自引：0，他引：1
We propose a reputation-based cooperative spectrum sensing scheme in cognitive radio （CR） networks to solve the uncertainty resulting from the multipath fading and shadowing effect. In the proposed scheme, each cooperative CR user has a reputation degree that is initialized and adjusted by the central controller, and used to weight the sensing result from the corre- sponding CR user in the linear fusion process at the central controller. A simple method for adjusting the reputation degree of CR users is also presented. We analyzed and evaluated the detection performance of the reputation-based cooperative spectrum sensing scheme. Simulation results showed that our proposed scheme alleviates the problem of corrupted detection resulting from destructive channel conditions between the primary transmitter and the CR user. The performance of our proposed scheme was improved compared to the average-based linear cooperation scheme, and was similar to that of the optimal linear cooperation scheme with feasible computational complexity. Moreover, our proposed scheme does not require knowledge of channel statistics. 相似文献
8.
In this paper, the security technology of ad hoc networks is studied.To improve the previous multi-receiver signcryption schemes, an ID-based multi-message and multi-receiver signcryption scheme for rekeying in ad hoc networks is proposed.In this scheme, a sender can simultaneously signcrypt n messeges for n receivers, and a receiver can unsigncrypt the ciphertext to get his message with his own private key.An analysis of this scheme indicates that it achieves authenticity and confidentiality in the random oracle model while being of lower computation and communication overhead.Finally, for the application of our scheme in ad hoc, a threshold key updating protocol for ad hoc networks is given. 相似文献
9.
We propose a medium access control （MAC） protocol for uplink transmissions in wireless local area networks （WLANs）, where both stations and access points （APs） are equipped with multiple antennas. The protocol solves some common problems in utilizing multiple input multiple output （MIMO） under the 802.11 protocol, e.g., how to deploy preamble （training sequence） used for channel estimation and how to enable simultaneous data transmissions, and facilitates two simultaneous uplink data transmissions via a cross-layer approach. Furthermore, we develop a 3D discrete-time Markov model to analyze the performance of the proposed WLAN scheme. The analytical results are verified by simulation, and numerical results show that the system throughput can be significantly improved by our proposed scheme as compared with conventional schemes. 相似文献
10.
In this paper, a new three-dimensional Markov model is proposed for the estimation of saturation throughput of RTS/CTS （request to send/clear to send） scheme in an error-prone wireless local area network （WLAN） channel. The model takes account of the effect of bit error on all the frames, and station short and long retry limits. Saturation throughput was re-analyzed using the new Markov model and numerical results closely matched those from simulation, confirming the accuracy of the new model. Evaluation of the influence of different parameters on throughput showed that the saturation throughput is sensitive to channel bit error rates and packet length, especially in high bit error conditions. 相似文献
11.
数据汇聚是降低传感器网络传输能耗的重要手段.分簇传感网数据汇聚通常包括簇内汇聚及传递汇聚结果到基站两个阶段,现有方案大多关注第二阶段数据汇聚结果传递到基站的效率.现提出一种基于位置信息的分簇传感网数据汇聚方案,通过利用位置信息选择代理点,仅与代理点有不同测量值的节点进行数据发送,有效减少了第一阶段中的数据传输.理论分析与模拟试验表明,方案簇内消息发送数优于相关方案,减少了通信开销,延长了网络生命期. 相似文献
12.
TCP Vegas是运输层的一种可靠算法,但是在无线网络中不能最高效率的占用网路带宽,使得数据传输受到限制,不适合在无线网络中传输。对TCP Vegas算法进行改进,提出了一种适用于异构网络的TCP New Vegas算法。该算法将diff控制在两个动态门限值a,b之间,根据a,b两个动态门限值的设定,可有效的提高算法的拥塞窗口及吞吐量。以无线传感器网络接入第三代移动通信网络为仿真背景,对该算法进行了仿真实验。仿真结果表明,改进后的TCP New Vegas算法具有较大的拥塞窗口和较高的吞吐量,更适合应用于异构网络中数据的传输。 相似文献
13.
INTRODUCTION With the emergence of wireless technology, various multimedia services, e.g., audio and/or video, are reaching us today through portable devices any- time, anywhere and even more increasingly accessi- ble in the near future. High quality video streaming over wireless IP is one of the most attractive applica- tions by ongoing deployment of wireless local area network (WLAN) hotspots and even powerful Wi- MAX mobile coverage. However, the present Internet is not providing a… 相似文献
14.
提出一种在车辆自组织网络(VANET)中应用的无线多跳视频传输实验系统的设计和实现方案及其对应的传输控制和路由选择协议.该系统将嵌入式Linux与IEEE 802.11n传输协议集成到ARM内核,由S3C6410主控模块、无线局域网网卡及LCD屏等构成.针对VANET的无线多跳视频传输场景,对视频编译码分别采用H.264和JPEG两种标准实现并对它们的压缩比、时延、传输丢包率等性能进行了理论分析和实验比较,进行了室内室外多种不同场景的实际测试.结果表明:所设计的多跳视频传输实验系统方案能够适应VANET等多种场景的应用,所提出的传输控制和路由选择协议能够保证视频传输的多跳和实时性要求. 相似文献
15.
Harsh Vardhan 《Resonance》2002,7(1):53-63
This article traces the history of radio broadcasting beginning with the experiments of Heinrich Hertz and the successful transatlantic transmission of wireless signals by Marconi to the current satellite based radio broadcasting. 相似文献
16.
[1]Engebretsen,L.,Sudan,M.,2002.Harmonic Broadcasting is Bandwidth-Optimal Assuming Constant Bit Rate.Proc.Annual ACM-SIAM Symposium on Discrete Algorithms.San Francisco,CA,USA.
[2]ETSI,2005.IP Datacast over DVB-H:Content Delivery Protocols.ETSI Standard,Draft,V0.0.9.
[3]Horn,G.B.,Knudsgaard,P.,Lassen,S.B.,Luby,M.,Rasmussen,J.E.,2001.A scalable and reliable paradigm for media on demand.IEEE Computer,34(9):40-45.
[4]Hu,A.,2001.Video-on-Demand Broadcasting Protocols:A Comprehensive Study.Proc.IEEE Infocom.Anchorage,Alaska.
[5]Huang,C.,Janakiraman,R.,Xu,L.,2004.Loss-Resilient Media Streaming Using Priority Encoding.Proc.ACM International Conference on Multimedia (MM‘04).New York,USA.
[6]Jenka(c),H.,Stockhammer,T.,2005.Asynchronous Media Streaming over Wireless Broadcast Channels.Proc.of International Conference on Multimedia and Expo (ICME).Amsterdam,The Netherlands.
[7]Luby,M.,Gemmel,J.,Vicisano,L.,Rizzo,L.,Handley,M.,Crowcroft,J.,2002a.Asynchronous Layered Coding (ALC) Protocol Instantiation.RFC 3450,IETF.
[8]Luby,M.,Gemmel,J.,Vicisano,L.,Rizzo,L.,Handley,M.,Crowcroft,J.,2002b.Layered Coding Transport (LCT)Building Block.RFC 3451,IETF.
[9]Luby,M.,Vicisano,L.,Gemmel,J.,Handley,M.,Crowcroft,J.,2002c.Forward Error Correction (FEC) Building Block.RFC 3452,IETF.
[10]Luby,M.,Watson,M.,Gasiba,T.,Stockhammer,T.,Xu,W.,2006.Raptor Codes for Reliable Download Delivery in Wireless Broadcast Systems.Proc.Consumer and Communications Networking Conference (CCNC).Las Vegas,NV,USA.
[11]Paila,T.,Luby,M.,Lehtonen,R.,Roca,V.,Walsh,R.,2004.FLUTE-File Delivery over Unidirectional Transport.RFC 3926,IETF.
[12]Peltotalo,J.,Peltotalo,S.,Harju,J.,2005.Analysis of the FLUTE Data Carousel.Proc.10th EUNICE Open European Summer School.Colmenarejo,Spain.
[13]Shokrollahi,A.,2003.Raptor Codes.Tech.Rep.DR2003-06-001,Digital Fountain.
[14]TM-CBMS1361,2005.Proposal for Simulations for Evaluation of Application Layer FEC for File Delivery.
[15]Xu,L.,2001.Efficient and Scalable on-Demand Data Streaming Using UEP Codes.Proc.ACM International Conference on Multimedia (MM‘01).Ottawa,Ontario,Canada. 相似文献
17.
A novel MAC mechanism to resolve 802.11 performance anomaly 总被引：1，自引：0，他引：1
CHENG Yan-hong LI Zhi-shu XING Jian-chuan ZHU Li 《浙江大学学报(A卷英文版)》2007,8(10):1573-1583
In the 802.11b networks, the guarantee of an equal long-run channel access probability causes performance anomaly in a multi-rate wireless cell. Much interest has been involved in this issue and many effective mechanisms have been proposed. The usual MAC layer solutions include the initial contention window adaptation, the maximum transfer unit size adaptation and the packet bursting. In this paper, we propose a novel approach which introduces a new parameter called the transmission prob- ability pt to the legacy protocol. By adjusting pt according to the transmission rate, the proposed scheme can solve the performance anomaly problem cleanly. Throughput analysis and performance evaluation show that our scheme achieves significant im- provement in the aggregate throughput and the fairness. 相似文献
18.
分析了无线传感器网络的特点及各种路由协议的优缺点,将改进的遗传算法方案应用到无线传感器网络分簇路由优化问题中,在满足传感器网络约束条件的基础上智能地计算出最佳路由,使通信距离最小化。模拟实验的结果表明,本文提出的算法方案在解决无线传感器网络路由优化问题中具有良好的综合求解能力。 相似文献
19.
随着通信技术、嵌入式计算技术、信息处理技术和传感器技术的飞速发展和日益成熟,集数据采集、处理、传输、通信于一体的无线传感器网络引起了人们极大的重视。目前,各国研究者致力于无线传感器网络的路由协议、MAC层协议、QoS、网络拓扑控制、网络安全等各方面的研究,并取得了一定的研究成果。本文将着重研究无线传感器网络路由协议的设计原则及在设计中需要考虑的因素。 相似文献
20.
传感网络经常采用Flooding协议作为路由管理,但碰撞和重传会导致大量重复的数据包,造成有限资源的浪费.讨论了隐藏节点及邻居节点对碰撞的影响,并进行了仿真.结果表明当发射半径达到一定区域时,隐藏节点引起的碰撞数量达到一个峰值,从而可以通过合适的设计避免高碰撞概率的网络分布区域.另外,还可以通过增加传输延迟来减少节点碰撞. 相似文献