Efficient delivery of multimedia streams over broadband networks using QOAS

Quality Oriented Adaptation Scheme (QOAS) is compared against other adaptive schemes such as TCP Friendly Rate Control Protocol (TFRCP), Loss-Delay-based Adaptation Algorithm (LDA+), and a nonadaptive (NoAd) solution when streaming multiple multimedia clips with various characteristics over broadband networks. Streaming efficiency is assessed in terms of loss rate, bandwidth utilization, number of concurrent clients and end-user perceived quality. Simulation results show that using QOAS a significantly higher number of simultaneous clients can be served than when using the other schemes given a target average end-user quality. This is while having higher bandwidth utilization. Testing results also indicate that higher performance is achieved when streaming to the same number of clients using QOAS than when other solutions are used.     

Wireless personal area networks architecture and protocols for multimedia applications

Wireless Personal Area Networks (WPANs) are an emerging technology for future short-range indoor and outdoor multimedia and data centric applications. Two types of WPANs have been standardized by the IEEE 802.15 working group; namely: High data Rate WPANs (HR-WPANs) and Low data Rate WPANs (LR-WPANs). These standards define the network architecture, the physical layer and the medium access control sublayer for these systems. A tremendous number of performance studies through mathematical analysis and simulation have been published. Also, many products have appeared in the market which indicate a clear sign of a quick acceptance to the published standards. An organized review of the network architecture, the physical layer specifications, the Medium Access Control (MAC) protocols and the general network operation concepts of the WPAN systems deserves time and effort to be presented in a collective manner. In this paper we describe the concept of WPANs and its applications. Then, the communication architecture and the allocated frequency spectrum for WPAN operation are explained. The developed MAC sublayer protocols in the literature are explored.     

QoS-based routing of multimedia streams in computer networks

Continuous media such as audio and video require a certain quality-of-service (QoS) when transferred through computer networks. The selection of a network route for a particular media stream should hence take into account which route is best-suited for providing this QoS. QoSFinder is a method for QoS-based routing of multimedia streams. It is based on a path vector protocol that takes into account throughput, delay, and loss rate of individual route segments. A simulation of QoSFinder shows that its heuristic is superior to metrics that are only based on one of these parameters. QoSFinder increases the probability of finding suitable paths through networks for distributed multimedia applications     

Efficient broadcasting protocols for regular wireless sensor networks

The wireless sensor network (WSN) has attracted lots of attention recently. Broadcast is a fundamental operation for all kinds of networks and it has not been addressed seriously in the WSN. Therefore, we propose two types of power and time efficient broadcasting protocols, namely one‐to‐all and all‐to‐all broadcasting protocols, for five different WSN topologies. Our one‐to‐all broadcasting protocols conserve power and time by choosing as few relay nodes as possible to scatter packets to the whole network. Besides, collisions are carefully handled such that our one‐to‐all broadcasting protocols can achieve 100% reachability. By assigning each node a proper channel, our all‐to‐all broadcasting protocols are collision free and efficient. Numerical evaluation results compare the performance of the five topologies and show that our broadcasting protocols are power and time efficient. Copyright © 2005 John Wiley & Sons, Ltd.     

Efficient channel assignment method for multimedia traffic in wireless mesh networks

In wireless mesh networks, the availability of spectrum should be utilized efficiently because the exchanging of traffic rate of multimedia applications is increasing day to day. The traffic of multimedia content may degrade the network performance in terms of high packet loss and throughput degradation because of asynchronous behavior between the sender and the receiver. The proposed Efficient Channel Reservation and Assignment (EchRA) results in successful originating and handing off of multimedia call transmissions using the four dimensional Markov chain process. The EChRA algorithm, proposed in this paper, achieves the maximum throughput performance considering the parameters of blocking probability, dropping probability, and synchronized dwell time between the source and destination. The quality of service is guaranteed by sharing the available slots and by using efficient queuing model to service the incoming and handoff calls, and henceforth, the successful completion of handoff calls rate is increased. Copyright © 2015 John Wiley & Sons, Ltd.     

机会网络中用户属性隐私安全的高效协作者资料匹配协议

在机会网络中,用户通过移动造成的相遇性机会,借助协作者实现消息的传输与内容的共享。为了克服现有协作者匹配协议加解密效率不高的问题,针对机会网络中用户的不同隐私要求,设计了3个不依赖同态加密的高效隐私内积计算协议,可以证明所提出的协议是隐私安全并且正确的。在此基础上,对所提出的3个协议的计算开销与通信开销,与现有工作进行了理论上的比较。仿真结果表明,所提协议能够高效地完成隐私安全匹配,其加解密时间要比基于Paillier加密体系的协议要少至少一个数量级。     

Proxy-assisted techniques for delivering continuous multimedia streams

We present a proxy-assisted video delivery architecture that can simultaneously reduce the resources requirements at the central server and the service latency experienced by clients (i.e., end users). Under the proposed video delivery architecture, we develop and analyze two novel proxy-assisted video streaming techniques for on-demand delivery of video objects to a large number of clients. By taking advantage of the resources available at the proxy servers, these techniques not only significantly reduce the central server and network resource requirements, but are also capable of providing near-instantaneous service to a large number of clients. We optimize the performance of our video streaming architecture by carefully selecting video delivery techniques for videos of various popularity and intelligently allocating resources between proxy servers and the central server. Through empirical studies, we demonstrate the efficacy of the proposed proxy-assisted video streaming techniques.     

Multicasting multimedia streams in IEEE 802.11 networks: a focus on reliability and rate adaptation

Multicasting multimedia streams in IEEE 802.11 wireless LANs has two issues: reliability and rate adaptation. We address these issues by proposing two mechanisms that augment the current multicasting standards in a backward-compatible fashion. Semi-reliable multicasting (SRM) selects a leader who sends feedback information to lessen the reliability problem of multicast frames. Probing-based auto-rate fallback (PARF) allows the multicast source to adjust the bit rate depending on the link conditions of multicast recipients. Comprehensive simulation experiments reveal that SRM + PARF achieves reliability and link efficiency close to those of an omniscient multicasting framework.     

A four-channel monolithic optical/electronic selector for fastpacket-switched WDMA networks

We report the characteristics of a four-channel monolithic GaAs optical/electronic selector for applications in fast packet-switched wavelength division multiaccess networks. The selector chip consists of four metal-semiconductor-metal photodetectors sharing a single differential transimpedance amplifier selected by four enhancement-mode MESFET switches. The channel switching time is about 2 ns and no appreciable crosstalk is observed from neighboring channels     

A survey and analysis of multipath routing protocols in wireless multimedia sensor networks

The main objective of this research is to conduct a performance analysis of various multipath routing protocols in wireless multimedia sensor networks for the efficient transmission of the image, audio and video data. To provide efficient routing for the large sized multimedia content, various multipath routing protocols such as energy-aware routing, QoS based routing and geographical routing methods are analyzed. In this analysis, the efficient routing techniques including geographical routing techniques such as GPSR, DGR, PW-DGR presented for wireless multimedia sensor networks are studied and the performance of each technique is evaluated to determine the efficient multipath routing technique. Comparisons are made for evaluated protocols and it is proved that the PW-DGR provides better routing performance for the multimedia data. The findings of the research also show that the PW-DGR method efficiently overcomes the routing problems such as energy bottleneck problem, energy-hole, reduced network lifetime and high delay in packet transmission.     

Temporal validation of multimedia protocols

With the emergence of distributed multimedia systems, temporal constraints are becoming a fundamental feature in specifying and validating distributed systems. We have already developed an approach for specifying and validating end-to-end protocols with temporal constraints. The method based on reachability analysis, consists in constructing a temporal reachability graph describing the communication between two temporal machines through two temporal FIFO channels. The structure and states of this graph are then studied according to given communication properties to validate the related protocol. In this paper, we show how to genera lize this model for describing and validating multimedia protocols that are generally made up of more than two temporal machines communicating either through temporal FIFO channels or by rendezvous. Two examples of such protocols are considered as case studies.     

Internet protocols for multimedia communications. I. IPng-thefoundation of Internet protocols

Surveys recent and current standardization work by the Internet Engineering Task Force (IETF) on Internet communication protocols. The author describes the IPng project and the IPv6 protocol that will form the basis for upper-layer protocols such as resource reservation, transport and application level protocols. The IETF decided in 1992 to develop a new version of the Internet Protocol (IP) because the available address space of IP version 4 (IPv4) will probably run out early in the 21st Century. The need for a new IP version provided the opportunity to redesign the protocol and add new functions     

Cooperative diversity in wireless networks: Efficient protocols and outage behavior

We develop and analyze low-complexity cooperative diversity protocols that combat fading induced by multipath propagation in wireless networks. The underlying techniques exploit space diversity available through cooperating terminals' relaying signals for one another. We outline several strategies employed by the cooperating radios, including fixed relaying schemes such as amplify-and-forward and decode-and-forward, selection relaying schemes that adapt based upon channel measurements between the cooperating terminals, and incremental relaying schemes that adapt based upon limited feedback from the destination terminal. We develop performance characterizations in terms of outage events and associated outage probabilities, which measure robustness of the transmissions to fading, focusing on the high signal-to-noise ratio (SNR) regime. Except for fixed decode-and-forward, all of our cooperative diversity protocols are efficient in the sense that they achieve full diversity (i.e., second-order diversity in the case of two terminals), and, moreover, are close to optimum (within 1.5 dB) in certain regimes. Thus, using distributed antennas, we can provide the powerful benefits of space diversity without need for physical arrays, though at a loss of spectral efficiency due to half-duplex operation and possibly at the cost of additional receive hardware. Applicable to any wireless setting, including cellular or ad hoc networks-wherever space constraints preclude the use of physical arrays-the performance characterizations reveal that large power or energy savings result from the use of these protocols.     

Efficient cooperative ARQ protocols based on relay selection in underwater acoustic communication sensor networks

Wireless Networks - The characteristics of the underwater acoustic communication such as large propagation delay, high bit error rate and half-duplex, bring challenges to traditional automatic...     

WDMA/subcarrier-FDMA lightwave networks: limitations due to opticalbeat interference

The authors present a general model of optical beat interference, and its contribution of channel outage in a WD-SFDMA (wavelength division-subcarrier frequency division multiple access) network. The probability of channel outage due to optical beat interference is determined from analysis and computer simulation for externally and directly modulated single-mode lasers. These results are used to calculate the ultimate limitation on the throughput and capacity of the network due to beat note interference, for a simple retransmission protocol. It is shown that, as more subcarrier channels are added, network capacity increases sublinearly and eventually saturates     

Efficient MPEG-4/H/263 video transcoder for interoperability of heterogeneous multimedia networks

As well as some similarities, there are a number of differences between MPEG-4 and the H.263 bitstream syntax. The inclusion of a video transcoder is proposed to achieve interoperability between the two video standards. This novel transcoding algorithm is proved to give highly improved service quality while reducing the complexity and the time delay of conventional cascaded decoding/re-encoding processes.     

Performance analysis of modified accelerative preallocation MAC protocol for passive star-coupled WDMA networks

For the passive star-coupled wavelength-division multiple-access (WDMA) network, a modified accelerative preallocation WDMA (MAP-WDMA) media access control (MAC) protocol is proposed, which is based on AP-WDMA. To show the advantages of MAP-WDMA as an adequate MAC protocol for the network over AP-WDMA, the channel utilization, the channel-access delay, and the latency of MAP-WDMA are investigated and compared with those of AP-WDMA under various data traffic patterns, including uniform, quasi-uniform type, disconnected type, mesh type, and ring type data traffics, as well as the assumption that a given number of network stations is equal to that of channels, in other words, without channel sharing. As a result, the channel utilization of MAP-WDMA can be competitive with respect to that of AP-WDMA at the expense of insignificantly higher latency. Namely, if the number of network stations is small, MAP-WDMA provides better channel utilization for uniform, quasi-uniform-type, and disconnected-type data traffics at all data traffic loads, as well as for mesh and ring-type data traffics at low data traffic loads. Otherwise, MAP-WDMA only outperforms AP-WDMA for the first three data traffics at higher data traffic loads. In the aspect of channel-access delay, MAP-WDMA gives better performance than AP-WDMA, regardless of data traffic patterns and the number of network stations.     

Medium access control protocols for multimedia traffic in wirelessnetworks

This article presents a survey on medium access control protocols for multimedia traffic in wireless networks. A basic overview of MAC protocol concepts is presented, and a framework is developed on which to base qualitative comparisons. The MAC protocols covered include third-generation TDMA and CDMA schemes intended for use in a single-hop wireless system. The operation of each protocol is explained, and its advantages and disadvantages ore presented. Finally, a qualitative comparative outline of the discussed protocols is provided, based on multimedia traffic requirements     

QoS provisioning for multimedia wireless networks

As we move towards IP-based multimedia wireless networks with voice, video and data convergence, quality of service (QoS) provisioning will become an increasingly challenging task. One implication is that greater emphasis on managing the call admission and overall network resources will be needed. This paper presents a conservative and adaptive quality of service (CAQoS) framework for provisioning the QoS for both real-time and non-real-time traffic in a multimedia wireless network. Unlike most conventional schemes, which gradually scale down the bandwidth of ongoing connections to accommodate new connection/hand-off requests, CAQoS introduces an early scaling-down of bandwidth for new connections based on a designated provisioning model. The performance of a CAQoS system is evaluated through simulations of a realistic wireless environment. Simulation results show that CAQoS meets our design goals and outperforms conventional schemes.