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无线Ad Hoc网络QoS路由协议研究的进展与展望 总被引:6,自引:0,他引:6
无线ad hoc网络是一种无固定通信设备支持、节点可自由移动的多跳全分布式无线网络。无线ad hoc网络的应用环境以及与Internet的互连要求它必须提供一定的服务质量(QoS)保证,而QoS路由协议是无线ad hoc网络支持QoS的一个关键理论和技术,也是目前的一个研究热点。本文回顾了近年来国内外在无线ad hoc网络QoS路由协议研究方面取得的研究成果,对已有的无线ad hoc网络的QoS路由协议进行了分类.并对它们作了较全面的概括。总结和深入的比较分析,系统阐述了在无线ad hoc网络中实现QoS路由协议时需要考虑的因素,指出了亟待解决的问题和今后的研究方向。 相似文献
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随着无线局域网的快速发展,人们对服务质量提出了迫切的要求,IEEE 802.11e协议应运而生,为QoS的实施提供了参考标准。EDCA是802.11e中实现QoS的分布式机制,本文基于EDCA,提出了一整套接纳控制方案和EDCA参数调节机制。本方案QoS参数考虑全面,实现简单,而且能够运用在全分布的ad hoc网络中。 相似文献
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Above Cable公司最近宣布推出了基于802.11标准的终端PVA(Personal Video/Voice Assistant)设备,工作在2.4GHz-2.497GHz频段,支持802.11b和802.11g无线标准,这就是手机家族的新成员——WLAN手机。它与现有的PDA、Smart Phone、GSM、CDMA手机家族的所有成员以及小灵通不同,这种第一代PVA是借助无线局域网和Internet实现语音传输的智能通信终端设备。 相似文献
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无线Ad Hoc网络支持QoS的研究进展与展望 总被引:29,自引:0,他引:29
无线ad hoc网络的应用环境以及与Internet的互连要求它必须提供一定的服务质量(QoS)保证,然而,无线信道固有的特点及节点移动造成网络拓扑的频繁变化,使得在无线ad hoc网络中支持QoS面临许多新的挑战.从无线ad hoc网络的QoS体系结构、QoS路由、QoS信令、支持业务区分和资源预留的介质访问控制协议这4个方面出发,对近年来国内外在该方向取得的研究成果作了全面的概括总结和比较分析,系统阐述了在无线ad hoc网络中支持QoS的问题,指出了亟待解决的问题和今后的研究方向. 相似文献
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夏铭 《网络安全技术与应用》2008,(6):46-47
无线ad hoc网络是一种新型的无线移动网络。介绍了ad hoc网络的体系结构和主要特点,归纳了ad hoc网络的安全目标,提出了解决其安全问题的安全策略。最后,展望了无线ad hoc网络的研究方向。 相似文献
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蓝牙SIG定义了蓝牙网络封装协议BNEP,该协议对上层口协议提供了类似于以太网的接口。对于IEEE802.3/Ethemet封装支持的网络协议,蓝牙网络封装均支持。BNEP协议把这些网络协议包封装起来,直接通过蓝牙I2CAP协议进行无线传输。蓝牙网络封装主要应用在蓝牙个人无线局域网(PAN)中,PAN应用是指由两个或者更多的设备形成一个特定网络,而且这些设备能通过一个网络接入点来访问远程网络。由于蓝牙SIG只是用自然语言定义了协议规范,不同的实现者由于理解的差异可能会导致不同的结果,这可能会影响到产品的互通性,因此对协议的测试是至关重要的。BNEP协议的测试是蓝牙一致性测试,这种测试是完全自动化的。 相似文献
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该文首先分析了无线ad hoc网络的QoS体系结构、QoS信令,接着对常见的QoS路由作了简单的概括。最后对ad hoc网络的AODV协议和基于AODV的、支持Qos的Q_AODV协议做了分析和比较,仿真实验表明Q_AODV在某些性能上优于AODV。 相似文献
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Communication demands have grown from separate data and voice to integrated multimedia, paving the way to converging fixed,
mobile and IP networks. Supporting Multimedia is a challenging task for wireless ad hoc network designers. Multimedia forms
high data rate traffic with stringent Quality of Service (QoS) requirements. Wireless ad hoc networks are characterized by
frequent topology changes, unreliable wireless channel, network congestion and resource contention. Providing scalable QoS
is the most important challenge for multimedia delivery over ad hoc networks. We introduce here a provisioning and routing
architecture for ad hoc networks which scales well while provisioning QoS. The proposed architecture is analysed using a mix
of HTTP, voice and video streaming applications over 54 Mbps 802.11 g-based ad hoc networks. The architecture is simulated
and compared to well-known routing protocols using the OPNET Modeller. The results show that our architecture scales well
with increase in the network size, and outperforms well-known routing protocols. 相似文献
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Meng-Yen Hsieh Yueh-Min Huang Tzu-Chinag Chiang 《Multimedia Tools and Applications》2007,34(2):155-177
Mobile ad hoc networks without centralized infrastructure change their topology rapidly because of node mobility, making multimedia
applications difficult to run across wireless networks. Moreover, video transmission over ad hoc networks causes frequent
transmission loss of video packets owing to end-to-end transmission with a number of wireless links, and requires essential
bandwidth and restricted delay to provide quality-guaranteed display. This paper presents an architecture supporting transmission
of multiple video streams in ad hoc networks by establishing multiple routing paths to provide extra video coding and transport
schemes. This study also proposes an on-demand multicast routing protocol to transport layered video streams. The multicast
routing protocol transmits layered video streaming based on a weight criterion, which is derived according to the number of
receivers, delay and expiration time of a route. A simulation is performed herein to indicate the viability and performance
of the proposed approach. The simulation results demonstrate that the proposed transport scheme is more effective than other
video transport schemes with single or multiple paths.
相似文献
Tzu-Chinag ChiangEmail: |
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为改善H. 264编码的视频流在802. 11e中的传输性能, 提出了一种结合H. 264/AVC中不同类型的数据分割对视频重建质量的重要性因子和队列状态的视频包映射方法。首先定量分析H. 264/AVC中A、B、C三种分割的丢失对视频重建质量的影响, 得到其重要因子; 然后依据重要因子和队列长度将视频数据包映射到802. 11e的不同EDCA队列中。算法改进了EDCA机制中数据包的静态映射机制, 根据视频分割数据的不等重要性, 提供差异性服务。仿真结果表明, 与目前的视频包静态映射机制相比, 该算法提高了视频重建质量, 最好可提高1 dB以上。 相似文献
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This paper is concerned with transmission of Moving Picture Expert Group (MPEG) video over a Bluetooth wireless network using a fuzzy approach. MPEG Variable Bit Rate (VBR) video sources suffer from long delay and excessive loss due to the sudden bursts in bit rate. Constant Bit Rate (CBR) encoding scheme may work well for a network with a guaranteed bandwidth. However, a Bluetooth channel is subject to wireless interference and can never guarantee a constant bandwidth. Subsequently, it is impossible to transmit a CBR video over Bluetooth wireless without data loss or image quality degradation. To resolve this problem, a fuzzy control system is introduced at the Host Controller Interface (HCI). The system consists of a traffic-shaping buffer whose role is to prevent excessive back-to-back cells being generated during the peak transmissions of MPEG video sources. The output bit rate of the traffic-shaping buffer is controlled by a fuzzy controller to ensure that the video stream from the host conforms to the traffic condition of the Bluetooth channel. Another fuzzy controller regulates the average arrival bit rate to the traffic-shaper to guarantee that the buffer is neither full nor empty. Computer simulation results demonstrate that the use of the fuzzy controllers reduces excessive data loss at the HCI as compared with an open loop VBR/CBR video transmission in Bluetooth. 相似文献
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Despite the popularity of watching videos online, challenges still remain in video streaming in many scenarios. Limited home broadband and mobile phone 3G bandwidths mean many users stream videos at compromised quality. To provide additional bandwidth for streaming, we propose CStream, a system that aggregates bandwidth from multiple cooperating users in a neighborhood environment for better video streaming. CStream exploits the fact that wireless devices have multiple network interfaces and connects cooperating users with a wireless ad-hoc network to aggregate their unused downlink Internet bandwidth. CStream dynamically generates a streaming plan to stream a single video using multiple connections, continuously adapting to changes in the neighborhood and variations in the available bandwidth. CStream is developed and evaluated on a test bed of computers, allowing for a detailed, controlled evaluation of performance. Analysis of the results shows a linear increase in throughput over single-connection streaming and improved video quality as the number of cooperating users in a neighborhood increase. 相似文献
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In this paper, we propose a novel lightweight approximate authentication algorithm that provides efficient protection for
wireless video streaming where attacks on the stream are possible, but classical integrity protection algorithms are impractical
because bit errors occur naturally. The benefits of the proposed algorithm over other algorithms are fast execution and small
message authentication code size. Moreover, the approximate authentication supports error resilient video decoding by dropping
seriously damaged packets, thus improving the perceived quality of the video stream. The performance of the algorithm is demonstrated
via numerical analysis, simulations and measurements over modeled and real wireless channels. 相似文献
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An adaptive control for video transmission over bluetooth 总被引:1,自引:0,他引:1
This paper is concerned with transmission of a moving picture expert group (MPEG) video stream over a Bluetooth channel, using an adaptive neuro-fuzzy technique. MPEG variable bit rate (VBR) video sources over a network generally experience long delay and unacceptable data loss, due to high variations in bit rate. Furthermore, transmission rate could be unpredictable in a Bluetooth network due to interferences by other wireless devices or general Bluetooth channel noises. Subsequently, it is almost impossible to transmit VBR data sources over Bluetooth without excessive delay or data loss. In this work, an adaptive scheme is introduced so that the controller may adjust itself to the current state of the system under control. This paper utilizes a traffic-shaping buffer to prevent excessive back-to-back transmissions of MPEG VBR data sources. A novel adaptive neuro-fuzzy scheme regulates the output rate of the buffer to ensure that the video stream from the host conforms to the traffic conditions of the Bluetooth channel during the transmission period. The computer simulation results show that the use of the neuro-fuzzy controller reduces excessive delay and data loss at the host-controller-interface, as compared with a conventional VBR video transmission and a rule-based fuzzy controller (RBF1) in Bluetooth. 相似文献
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Byung Joon Oh Chang Wen Chen 《Multimedia, IEEE Transactions on》2009,11(6):1052-1061
This paper presents a cross-layer design for a reliable video transmission over wireless ad hoc networks based on multichannel MAC protocol with TDMA. First, we conduct a study of the multichannel MAC protocol through Markov chain model. Based on this study, two novel cross-layer modules are adopted for the design of multichannel MAC protocol. First, we adopt maximum latency rate (MLR) as the channel quality metric. Unlike the traditional MAC design based on network allocation vector (NAV), MLR is implemented to provide differentiated traffic so that the channel with smaller MLR time is initiated for higher priority traffic. Second, we adopt two congestion-aware metrics, namely MAC utilization and queue length of MAC layer, to improve the congestion-aware routing protocols with AODV and DSR. These two novel modules allow the proposed MAC protocol design to achieve high performance video transmission over wireless ad hoc networks. Experimental results show that the proposed scheme outperforms the state-of-the-art schemes under multichannel environments in wireless ad hoc networks for as much as 3.6 dB in PSNR. Such significant performance enhancement confirms that the cross-layer approach is very effective for multichannel MAC protocol design. 相似文献