Research on Neural Network Based QoS Routing

In this paper, the requirements of routing due to the multimedia applications are briefly discussed. In order to solve the QoS constrained routing effectively and efficiently, the scheme of routing based on Hopfield neural network is proposed after the analysis of related work. Then the QoS routing algorithm for unicast based on Hopfield NN is described and the result of emulation is given. At last, multicast QoS routing considerations based on Hopfield NN are proposed.

MANET中一种基于移动预测的unicast路由协议

MANET是由一系列可以自由移动的节点主机聚集而成的一个临时性动态网络。它没有固定基站,也没有作为控制管理中心的节点主机。由于其拓扑的动态性,其路由协议不同于其它网络。为更有效支持MANET的应用,文章提出了一种基于移动预测下的Unicast路由。该协议采用GPS定位机制,通过预测路径有效连接时间来实现。模拟结果表明这种方案能获得较好的网络性能和较低的控制开销。

IPv6中Anycast服务在应用层的分析与设计(英文)

IPv6以两种方式提供Anycast服务:一种是将Anycast组成员限制在共享一个地址前缀的特殊拓扑区内;另一个是将Anycast地址表示的共享某个特性的结点组分散在互联网的各个地方,这种方式使得路由表会随全球Anycast组数成比例增长,从而构成了Anycast的扩展性问题。提出了一种在应用层实现Anycast服务的解决方案,此方案不仅解决了Anycast服务的扩展性问题,同时也解决了IP层实现Anycast服务所存在的一些其他问题,如路由表膨胀、TCP通信失败等,同时分析和讨论了该方案的可行性及有效性。

具有规模性的Anycast算法实现

为了解决因在IPv6网络层中引入Anycast通信服务而引起的互联网中的路由器中路由表项的规模性问题,文中给出了利用Anycast单独路由和预先分配固定Anycast地址以及Anycast地址归并和拆分算法几项技术。通过理论分析这几种技术较好地解决了因为引入Anycast而引起的Unicast路由表的急剧扩大以及路由性能急剧下降的问题,较好地解决了Anycast实现中遇到的规模性问题并提供了灵活的选择标准。文中给出的相关技术能够解决当前IPv6网络中Anycast实现中遇到的规模性问题,为IPv6的应用建立了基础。

IPv6中Anycast的一种加权通信模型

本文提出了一种新的 Anycast 加权通信模型.此模型在某种程度上解决了应用层和 IP 层实现 Anycast 技术所存在的问题,如扩展性以及客户与服务器通信失败等等,本文对该 Anycast 的加权通信模型进行了深入分析和讨论,并验证了该模型的可行性及其有效性。

An Efficient and Reliable Multicasting for Smart Cities

The Internet of thing(IoT)is a growing concept for smart cities,and it is compulsory to communicate data between different networks and devices.In the IoT,communication should be rapid with less delay and overhead.For this purpose,flooding is used for reliable data communication in a smart cities concept but at the cost of higher overhead,energy consumption and packet drop etc.This paper aims to increase the efficiency in term of overhead and reliability in term of delay by using multicasting and unicasting instead of flooding during packet forwarding in a smart city using the IoT concept.In this paper,multicasting and unicasting is used for IoT in smart cities within a receiver-initiated mesh-based topology to disseminate the data to the cluster head.Smart cities networks are divided into cluster head,and each cluster head or core node will be responsible for transferring data to the desired receiver.This protocol is a novel approach according to the best of our knowledge,and it proves to be very useful due to its efficiency and reliability in smart cities concept because IoT is a collection of devices and having a similar interest for transmission of data.The results are implemented in Network simulator 2(NS-2).The result shows that the proposed protocol shows performance in overhead,throughput,packet drop,delay and energy consumption as compared to benchmark schemes.

Ant Colony Algorithm for Solving QoS Routing Problem

Based on the state transition rule, the local updating rule and the global updating rule of ant colony algorithm, we propose an improved ant colony algorithm of the least\|cost quality of service (QoS) unicast routing. The algorithm is used for solving the routing problem with delay, delay jitter, bandwidth, and packet loss\|constrained. In the simulation, about 52.33% ants find the successful QoS routing , and converge to the best. It is proved that the algorithm is efficient and effective.

A Password-Based Secure Communication Scheme in Battlefields for Internet of Things

Mobile Ad hoc NETwork （MANET） is a part of the Internet of Things （IoT）. In battlefield communication systems, ground soldiers, tanks, and unmanned aerial vehicles comprise a heterogeneous MANET. In 2006, Byun et al. proposed the first constant-round password-based group key ex- change with different passwords for such net- works. In 2008, Nam et al. discovered the short- comings of the scheme, and modified it. But the works only provide the group key. In this paper, we propose a password-based secure communication scheme for the loT, which could be applied in the battlefield communication systems and support dy- namic group, in which the nodes join or leave. By performing the scheme, the nodes in the heteroge- neous MANET can realize secure broadcast, secure unicast, and secure direct communication across realms. After the analyses, we demonstrate that the scheme is secure and efficient.

A rate based congestion control algorithm in networks with coexisting unicast and multicast sessions

The optimal rate control problem in networks with unicast and multiratemulticast sessions is investigated. A penalty function approach is used to solve a convex programformulation of this problem, and then a heuristic rate control algorithm is derived. The algorithmis distributed, and suitable both for source-driven unicast sessions and receiver-driven multicastsessions. To obtain practical viability, the computational burden on core routers as well asend-hosts is kept very low, also is the overhead of network congestion feedback. Simulation resultsshow that the algorithm guarantees TCP (Transmission Control Protocol)-based unicast sessionscoexisting with multirate multicast sessions in a fair and friendly manner. It is also shown thatvarious fairness criteria of resource allocation could be achieved by choosing appropriate utilityfunctions, and resource-utilizing efficiencies would be likewise different.

MINIMIZING INTERMEDIATE MULTICAST ROUTING FOR DYNAMIC MULTI-HOP AD HOC NETWORKS

A Minimizing Intermediate Multicast Routing protocol (MIMR) is proposed for dynamic multi-hop ad hoc networks. In MIMR,multicast sessions are created and released only by source nodes. In each multicast session process,the source node keeps a list of intermediate nodes and destinations,which is encapsulated into the packet header when the source node sends a multicast packet. Nodes receiving multicast packets decide to accept or forward the packet according to the list. Depending on topology matrix maintained by unicast routing,the shortest virtual hierarchy routing tree is con-structed by improved Dijkstra algorithm. MIMR can achieve the minimum number of intermediate nodes,which are computed through the tree. No control packet is transmitted in the process of mul-ticast session. Load of the network is largely decreased. Experimental result shows that MIMR is flexible and robust for dynamic ad hoc networks.

Analysis of a Cyclic Multicast Proxy Server Architecture

The exponential growths of the World Wide Web (WWW) users have made the deployment of proxy servers popular on a network with limited resources. WWW clients perceive better response time, improved performance and speed when response to requested pages are served from the cache of a proxy server, resulting in faster response times after the first document fetch. This work proposes cyclic multicast as a scalable technique for improving proxy server performance for next generation networks. The proposed system uses a cyclic multicast engine for the delivery of popular web pages from the proxy server cache to increasingly large users under limited server capacity and network resources. The cyclic multicast technique would be more efficient for the delivery of highly requested web pages from the cache to large number of receivers. We describe the operation of the cyclic multicast proxy server and characterized the gains in performance.

WindowsMediaServices集成开发技术

使用Windows Media Services可以通过各类网络传送流式化多媒体内容,从低带宽、拨号Internet连接到高带宽、局域网等,通过集成Windows Media Services,可轻松地给应用程序添加多媒体信息网上传送功能。

Unified casting(UniCast)aluminum alloy—a sustainable and low-carbon materials solution for vehicle lightweighting

Casting aluminum(Al)alloys have been widely used in the automotive industry to improve fuel economy as well as to reduce greenhouse gas(GHG)emissions in the vehicle use phase.However,the casting Al alloys used for load-bearing body and chassis components today are mostly made from primary Al with a low impurity Fe content typically less than 0.2 wt.%,owing to the requirements for high ductility and adequate fatigue strength.Primary Al is made directly from alumina which was refined from aluminum ore(bauxite),using an electrolytic process which consumes a lot of energy and produces GHG emissions that are much higher than those from steel making.The objective of this paper is to present a Unified Casting(UniCast)Al alloy concept as a sustainable materials solution for vehicle lightweighting.The UniCast alloy chemistry is intentionally designed to be more tolerant of Fe impurity.This chemistry can not only satisfy the requirements on castability,but also deliver mechanical properties needed for a variety of thin-walled and thick-walled automotive structural components that are produced by various casting processes.The UniCast alloy concept will contribute to the establishment of a closed-loop recycling system in the future as the shredded scrap obtained from the disposed end-of-life vehicles can be directly recycled back into UniCast alloy ingot with a more efficient sorting process.In addition,by setting the upper limit of Fe content in the UniCast alloy to a higher level,it will become possible to use a high fraction of post-consumer scraps to produce this alloy.To demonstrate the feasibility of this concept,an exemplary UniCast alloy chemistry has been elaborated in this article.Furthermore,challenges and future research opportunities related to the realization of UniCast alloy concept in the automotive industry are discussed.It is hoped that this article will be of great implication to industrial researchers and academicians for making concerted efforts to establish closed-loop recycling of Al castings for the automotive and other transportation industry segments.

Multicast Protocol for Uni-Directional Networks

A very inexpensive receive-only satellite receiver can receive high bandwidth traffic from a feeder. Therefore the connection between the feeder and the receiver is uni-directional. The existing routing protocols, such as Link-State and Distance-Vector, are designed on the premise that any links are bidirectional and they cannot handle the uni-directional links. In this paper,a dynamic multicast routing protocol is proposed, which can handle uni-directional networks. This protocol can also adapt to the dynamic change of the topology of the network and has good scalability. A formal description of the protocol by Petri net is given. Liveness, deadlock free and other properties of the protocol are proved.

Reducing feedback load for OFDM-based wireless system

In this paper, the feedback load reduction problem in wireless systems based on orthogonal frequency division multiplexing （OFDM） is investigated and an opportunistic feedback scheme （OFS） is proposed. The key idea behind OFS is that only the key channel gains which can significantly affect the system throughput are fed back to the BS. Firstly, the key channel gains are proved to belong to a channel gain interval. Secondly, a statistical method is proposed to estimate the channel gain interval. Thirdly, the opportunistic feedback scheme is formulated and the feedback load of OFS is analyzed. The advantage of OFS is threefold： the first is OFS can work in both OFDM-based multicast system and OFDM-based unicast system. The second is the channel fading type of the BS-user link is not required, which is more realistic. The third is OFS can get better feedback load performance compared with other schemes, while achieving almost the same throughput performance compared with that of full feedback scheme.

Interference coordination schemes for cellular network assisted device-to-device multicast

In this paper, a multicast concept for device-to-device （D2D） communication underlaying a cellular infrastruc^tre is investigated. To increase the overall capacity and improve resource utilization, a novel interference coordination scheme is proposed. The proposed scheme includes two steps. First, in order to mitigate the interference from D2D multicast transmission to cellular networks （CNs）, a dynamic power control scheme is proposed that can determine the upper bound of D2D transmitter power based on the location of base station （BS） and areas of adjacent cells from the coverage area of D2D multicast group. Next, an interference limited area control scheme that reduces the interference from CNs to each D2D multicast receiver is proposed. The proposed scheme does not allow the coexistence of cellular user equipments （CUEs） located in the interference limited area to reuse the same resources as the D2D multicast group. From the simulation results, it is confirmed that the proposed schemes improve the performance of the hybrid system compared to the conventional ways.

Unicast routing protocols for urban vehicular networks:review, taxonomy, and open research issues

Over the past few years, numerous traffic safety applications have been developed using vehicular ad hoc networks(VANETs). These applications represent public interest and require network-wide dissemination techniques. On the other hand, certain non-safety applications do not require network-wide dissemination techniques.Such applications can be characterized by their individual interest between two vehicles that are geographically apart. In the existing literature, several proposals of unicast protocols exist that can be used for these non-safety applications. Among the proposals, unicast protocols for city scenarios are considered to be most challenging.This implies that in city scenarios unicast protocols show minimal persistence towards highly dynamic vehicular characteristics, including mobility, road structure, and physical environment. Unlike other studies, this review is motivated by the diversity of vehicular characteristics and difficulty of unicast protocol adaption in city scenarios.The review starts with the categorization of unicast protocols for city scenarios according to their requirement for a predefined unicast path. Then, properties of typical city roads are discussed, which helps to explore limitations in efficient unicast communication. Through an exhaustive literature review, we propose a thematic taxonomy based on different aspects of unicast protocol operation. It is followed by a review of selected unicast protocols for city scenarios that reveal their fundamental characteristics. Several significant parameters from the taxonomy are used to qualitatively compare the reviewed protocols. Qualitative comparison also includes critical investigation of distinct approaches taken by researchers in experimental protocol evaluation. As an outcome of this review, we point out open research issues in unicast routing.

Seamless handover between unicast and multicast multimedia streams

With the deployment of heterogeneous networks, mobile users are expecting ubiquitous connectivity when using applications. For bandwidth-intensive applications such as Internet Protocol Television(IPTV), multimedia contents are typically transmitted using a multicast delivery method due to its bandwidth efficiency. However, not all networks support multicasting. Multicasting alone could lead to service disruption when the users move from a multicast-capable network to a non-multicast network. In this paper, we propose a handover scheme called application layer seamless switching(ALSS) to provide smooth real-time multimedia delivery across unicast and multicast networks. ALSS adopts a soft handover to achieve seamless playback during the handover period. A real-time streaming testbed is implemented to investigate the overall handover performance, especially the overlapping period where both network interfaces are receiving audio and video packets. Both the quality of service(QoS) and objective-mapped quality of experience(QoE) metrics are measured. Experimental results show that the overlapping period takes a minimum of 56 and 4 ms for multicast-to-unicast(M2U) and unicast-to-multicast(U2M) handover, respectively. The measured peak signal-to-noise ratio(PSNR) confirms that the frame-by-frame quality of the streamed video during the handover is at least 33 dB, which is categorized as good based on ITU-T recommendations. The estimated mean opinion score(MOS) in terms of video playback smoothness is also at a satisfactory level.