PDF HTML阅读 XML下载 导出引用 引用提醒 无线网状网的QoS研究 DOI: 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: Supported by the National Natural Science Foundation of China under Grant No.60672080 (国家自然科学基金); the National Basic Research Program of China under Grant Nos.2006CB303004, 2009CB3020402 (国家重点基础研究发展计划(973)); the National High-Tech Research and Development Plan of China under Grant No.2008AA01Z216 (国家高技术研究发展计划(863)) Research of QoS on Wireless Mesh Networks Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:作为下一代无线通信网络的关键技术,无线网状网能够融合异构网络,满足多类型的业务需求,因此必须提供一定的服务质量(QoS)保证.对目前各种QoS体系结构进行了分析,讨论了无线网状网的QoS体系结构.针对无线网状网网络层以下各层的QoS问题,对近年来国内外在功率控制、无线环境感知、支持QoS的MAC协议、QoS路由以及跨层QoS设计等方向所取得的研究成果进行了全面的概括总结和比较分析.最后对未来的研究发展趋势提出了自己的观点. Abstract:As a key technology for next-generation wireless networking, wireless mesh networks (WMNs) should support the quality of service (QoS) because of its capability of integrating with other networks and providing various services. In this paper, the state-of-the-art QoS research on WMNs is presented. By analyzing the current QoS architectures, the QoS architecture on WMNs is discussed. To address the QoS issues below network layer, the research of recent years on the power control, wireless environment awareness, MAC(medium access control) protocol based on QoS, QoS routing, cross-layer design for QoS and other aspects is comprehensively summarized and deeply analyzed. At the end of this paper, future work of QoS on WMNs is proposed. 参考文献 相似文献 引证文献
As energy supply on Unmanned Aerial Vehicle (UAV) is limited, energy efficient data transmission in UAV networks would be of great concern to the researchers. Nevertheless, UAV networks exhibit strong dynamic nature compared to ordinary Mobile Ad hoc Network (MANET), it is not rare that some nodes will be disjoint from other nodes from time to time. Under such circumstance, ordinary hop-by-hop routing schemes can not be used anymore, for there is no route existed from source to destination. Some solutions use store-carry-forward (SCF) routing to facilitate end to end data transmission. However, when should we use SCF routing, when we should use hop-by-hop routing if we taking energy into consideration? Is hop-by-hop routing always better than SCF? If it is good or not when the hop-by-hop routing is combined with the SCF routing? All these questions need to be answered. In this paper, we answered above questions by proposing three types of minimum energy consumption models of hop-by-hop routing, and two SCF routing models. We compared all these models and considered four tactics of combination modes for the transmissions in a rotary-wing UAV network. The researches show that two tactics have better performance than other modes in energy saving capabilities by reducing 70% at most with the hop-by-hop routing, and the transmission time of combination modes are in same scale compared with hop-by-hop routing. The two tactics are appropriate for different UAV networks respectively, in which the source UAV can or cannot get the GPS information of relay UAVs in the route. The research conclusion can also be used for the transmissions in a fixed-wing UAV network by modifying the energy consumption models of fixed wing UAV, which is different from rotary wing UAVs.
Network coding has been proven to be an effective technique to increase the throughput and enhance robustness of various wireless networks including tactical heterogeneous wireless networks. Usually, the tactical heterogeneous wireless networks consist of different wireless links including high bandwidth links like IEEE 802.11 and low bandwidth links like UHF and VHF. Load balancing is an effective way to mitigate the network loading and improve overall performance of heterogeneous network. Traditional flow-based load balancing scheme performs poor and has a negative effect when applying network coding in tactical heterogeneous wireless networks. How to enhance the performance of network coding over tactical heterogeneous network is worthy of research. In this paper, with full consideration of different channel propagation characteristics and distinct transmission demands of different packets in a single stream, we propose a packet-based load balancing scheme, making appropriate use of highly unbalanced links by transmitting different types of packets on different channels. By making full use of the propagation characteristics of low bandwidth channels, our scheme can significantly shorten the end to end delay of feedback packets and improve the transmission reliability of feedback packets. Compared with flow-based load balancing, our scheme can reduce 63.47% of the redundant transmissions on average and achieve 15.53% improvement of throughput.
Rapid nitridation processing of Ti evaporated on Si wafer using a large-area electron beam is described. RBS, SIMS and sheet resistance analyses indicated that TiN and TiSi2 film were formed simultaneously in 20 s, and may be applied as a diffusion barrier for IC fabrications.
Unmanned aerial vehicle (UAV) swarm needs to broadcast routing messages to each other, accept unified control commands, and return the discovered targets' information to the ground control station in time. Most of these messages are broadcast in the UAV swarm. Therefore, in the UAV swarm network, the efficiency of broadcasting and rebroadcasting will determine the network efficiency of the entire network. Aiming at the broadcasting problem of UAV network, in order to adapt to the dynamic nature of the network and improve the broadcasting ability and efficiency, this paper focuses on the rebroadcasting mechanism based on dynamic probability. A prediction method of collision probability of rebroadcasting behavior, and a multi-agent cooperative rebroadcasting method based on virtual action and reinforcement learning are proposed. Simulation results show that the dynamic probability mechanism of rebroadcasting has obvious performance advantages over fixed probability flooding and simple flooding in dynamic scenarios after pre-learning.
Traffic offloading and Long Term Evaluation Unlicensed (LTE-U) are two significant techniques proposed to cope with the ongoing heavy burden of cellular wireless networks. Though many works has focused on developing coexistence mechanisms for WiFi and LTE-U on the unlicensed bands, much less have paid the attention to offload traffic from LTE-U to WiFi. In this paper, we consider the maximization of per-user throughput of LTE-U and minimum throughput of WiFi networks simultaneously when offloading users from LTU-U to multiple WiFi networks under WiFi delay constraint. Since the optimization objectives are conflicting, we propose to solve the multi-objective optimization problem based on the ε-constraint method in two steps, and we give some analysis on the maximum and minimum throughput of LTE-U users and WiFi users under the multi-objective optimization framework. Simulations demonstrate that the proposed algorithm can achieve the Pareto optimal solution and help achieve the fairness when offloading traffic from LTE-U to multiple WiFi networks.
ABSTRACT A significant interest for Web process design is to discover the discrepancies between the users' transaction process sequences and the desired process sequence for the Web transaction process. Sequence data analysis has been an important approach to analyzing Web log data in the e-commerce field. There have been many methods for sequence data analysis; however, few existing methods can be applied to analyzing designed Web transaction process sequence data for improving Web process design. This paper proposes an adaptable sequence matching algorithm for analyzing designed Web process sequence data for discovering knowledge about the Web process design. An application of this algorithm to a case of online shopping cart abandonment analysis is presented. Keywords: Web design, Web process sequence data analysis, designed Web process sequences, shopping cart abandonment. (ProQuest: ... denotes formulae omitted.) 1. Introduction A Web process is a business process carried out on the World Wide Web. Traditionally, Web process design has been studied in the field of workflow analysis [Cardoso & Sheth 2003; Cardoso 2006]. Recent research has suggested that Web page design has significant impact on online consumers' attitude and behavior towards Web processes [Chatterjee 2008]. A right Web page design must meet specific needs of right consumers for right Web processes [Zhou et al. 2004; Shergill & Chen 2005; Singh et al. 2008]. Web log sequences (i.e., user click-stream sequences) represent users' Web access behaviors in carrying out Web processes. Massive Web log sequences can be used to discover the general patterns of these process sequences [Wen et al. 2007; Greco & Guzzo 2007]. These patterns are useful for us to understand the online consumers' behaviors as well as problems in Web process design. For instance, by analyzing online shopping Web log sequences of an online store, one might be able to understand more about why online shoppers abandon shopping carts so often, and how the design of the Web site and transaction processes can be improved to reduce shopping cart abandonment. This paper presents a Web log sequence analysis method for improving Web process design. In the literature, various data analysis methods have been proposed to analyze Web log data [Cadez et al. 2000; Ester et al. 2002; Jiang & Tuzhilin 2006; Mobasher et al.2002; Manavoglu et al. 2003; Yang & Padmanabhan 2005]. In general, these methods aim at discovering interesting patterns of sets of sequences [Fayyad et al. 1996; Pei et al. 2004]. Common approaches to analyzing sequence data include time series analysis (e.g., [LeBaron & Weigend 1998]), association rules induction (e.g., [Lee et al. 2003]), and sequences pattern discovery (e.g., [Dutta et al. 2007]). While many research reports have been emphasizing on the performance of algorithms, exploring applications of process sequence data analysis results directly to e-commerce is imperative [Wu et al. 2000]. In this paper, we present a new method of analyzing Web log sequence data for the diagnosis of Web process design. This algorithm can be used to reveal useful information and develop knowledge for improving Web process design. The remainder of this paper is organized as follows. First, we provide a brief overview and discussion of major methods used for analyzing sequence data. Next, we develop an adaptable process sequence matching algorithm of analysis of Web process sequence data. Then, we present an application of the proposed algorithm to a case of shopping cart abandonment. Finally, we conclude with a summary of the study. 2. Related Work: Methods of Process Sequence Data Analysis Web process design is a topic in the field of business process design, and has been extensively studied through workflow analysis and management [Ould 1995; Cardoso & Sheth 2003; Cardoso 2006; Rozinat & van der Aalst 2008; van der Aalst et al. …
WANETs (Wide-Area wireless NETworks) is a recent network architecture where the nodes are spread out all over the world but behave exactly as if they are part of a single-hop or multi-hop wireless network at the PHY and MAC layers. At the same time, IEEE 802.11 devices are popular all over the world. When IEEE 802.11 meets with WANETs, the transparent Software Defined Access Points (SoDA) in WANETs will prevent IEEE 802.11 devices from utilizing the spatial reuse opportunities effectively and thus may underutilize the wireless medium. In this paper, we propose a scheme to utilize the delay experienced by the packets to address the throughput issue when IEEE 802.11 meets with WANETs. We build a wireless network testbed to evaluate the proposed scheme. Our implementation experiences show that the proposed scheme can make the IEEE 802.11 devices which locate in geographically separate locations utilize the parallel transmission opportunities effectively.
In the past few decades, wireless networks based on different standards have been developed quickly, and the coexistence of multiple communication systems has turned into reality. Due to the need for mobile computing or pervasive computing, quick and accurate protocol identification and analysis technology is required. Rather than employing the traditional demodulation-based method that requires to implement all known protocol modules in one single device, in this paper, we fully analyze the features in both time domain and frequency domain of physical (PHY) layer signals that can be used to describe a protocol, and present a new method of identifying and analyzing protocols without demodulation, which uses PHY layer signals only. This method can be used in battlefield and other situations where demodulation is impractical. To validate the feasibility of our method, we implement a system using GNU Radio and Universal Software Radio Peripheral (USRP). The results show that the system can successfully identify three different signals (including Wi-Fi, Bluetooth and Zigbee signals) with frequency domain features, and detect the period of beacons in Wi-Fi networks with the help of time domain features.
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