Range patching: A novel scheme for video stream scheduling based on overlay multicast

A scheme for enhancing sensor network lifetime is proposed using multiple mobile CHs. The CHs controllably move toward the energy-rich sensors maintaining remaining energy more evenly, eliminating multihop transmission. Collaboration among CHs is considered to maintain their continuous connectivity to the base station (BS) to reduce the delay in communication. Network lifetime is increased by 75% by making CHs always move towards a stable equilibrium point whereas connectivity algorithm provides 40% improvement in transmission delays over existing schemes.

Multicast solutions have been evolving from "bottom" to "top", i.e., from IP layer (called IP multicast) to application layer (referred to as application layer multicast). Recently, there are some new proposals (named as overlay multicast) using certain "infrastructure" (composed of proxies) in the middle. Although it is well accepted that application layer multicast and overlay multicast are easier to deploy while sacrificing bandwidth efficiency compared with IP multicast, little research has been done to systematically evaluate and compare their performance. In this paper, we conduct a comparative study of different types of multicast routing protocols. We first present a qualitative comparison of three types of protocols, and then we provide a quantitative study of four representative protocols, namely, PIM-SSM, NARADA, NICE, and POM by extensive simulations. Our studies will help to answer some of the most important questions, such as which way to go: top, bottom, or in the middle?.

IP multicast is a technique that can transmit one copy of data traffic to multiple receivers at one time. Because it can greatly save the network bandwidth consumption and many applications are inherently multicast-based, it has been a research focus since the idea was proposed. However, because of many reasons, such as management, security, inter-domain routing, etc, it has not been widely deployed. Recently, many researchers have put their research focus on overlay multicast. In overlay multicast, the data replication, multicast routing, group management and other functions are all achieved at application layer. Because it does not require any change to the current Internet infrastructure, it can be easily deployed. Since the idea was proposed, many overlay multicast ideas have been proposed. In this paper, we propose a method for reliable data transfer on overlay multicast. It applies TCP at transfer-layer and local data buffering at application-layer. This paper explains the advantages and disadvantage of using TCP for reliable data transfer on overlay multicast, then, describes the operation of our method and induces an optimal buffer size in dynamic nodes based overlay multicast. Finally, we check the effect of data buffering with experiments on several models.

Multicast services can be provided either as a basic network service by IP multicast or as an application layer service called overlay multicast. How to build an efficient data delivery structure is the most critical problem for overlay multicast, which depends on a good routing algorithm. Many routing algorithms have been presented recent years. Some algorithms modeled overlay multicast's routing problem as a degree constrained spanning tree problem based on undirected completed graph, and some others were built on some special peer to peer routing protocols. However, detecting and obtaining a completed graph's all network state information needs consume expensive cost and restricts its scalability and sometime be impossible. On the contrary these routing algorithms built on p2p scheme are of good scalability but maybe fail in practical applications. This paper redefines the overlay multicast routing problem as to find a degree constrained sub-tree with minimum delay optimization for a general undirected connected graph not a completed graph. It is a NP-hard problem. A heuristic genetic algorithm for this problem is given and the simulation results verify its effectiveness.

A scheme transmitting superposition coding (SC), which superimposes unicast data to multicast data, using opportunistic multicast scheduling (OMS) scheme, is proposed and its performance is evaluated and simulated in this paper. Although the scheme is a little weaker than traditional scheme using QPSK modulation method in bit error rate (BER) performance, its throughput and system time delay promote considerably. Numerical results show that when user channel condition is weak and signal to noise ratio (SNR) is not high, the new scheme can outperform the conventional scheme in terms of system performances.

In this letter, a predictive unicast and multicast scheduling (PUMS) scheme is proposed for onboard buffered crossbar switches to cope with time-variant traffic composition. The multicast service ratios required with respect to traffic composition ratio are deduced in theory to guarantee stability and fairness. In the proposed scheme, the multicast service ratios are obtained by a real-time traffic prediction in advance. Accordingly, the bandwidth and crosspoint buffers are adaptively assigned. Simulation results indicate that the proposed PUMS exhibits a promising performance under various traffic scenarios with both fixed and time-variant traffic composition ratios.

IP multicast has not been deployed because of hardware problems. So a new scheme called end system multicast or overlay multicast for group communication has been emerged. It supports IP multicast functions, which is located on application level. For developing it, we have been focused on efficient overlay tree construction among group members with low stretch and stress. However, we should consider a variety of transmission or receipt condition since a real Internet environment has users with various transmission/receipt rates. Thus, we make on-demand one-time source specific tree depending on required bandwidth information of group members when a member requests data transmission. Our mechanism provides satisfied data quality limited maximum transmission rate of the source to each group members. Furthermore, we manage a large group enough as distributing control information to cores that are designated members for maintaining host member information. Lastly, we prove that our tree guarantees data quality to each group members, and show low tree construction time is required. In addition, for evaluating group scalability, we analyze control information increasing rate via group size, and validate its scalability.

As more applications of video and audio to be used more researches QoS measurement of multicast are being done nowadays. Even more experiments which are done at the international research network are more important than before. In this paper we use overlay multicast technology to construct a test-bed with overlay multicast relay (OMR) over international research network. We do multicast QoS experiments in the test-bed with international research network and make analysis and comparison. Through these research works, we get different kind of performance evaluation of multicast in international research network. We propose QoS measurement method of multicast video service in the international research network.

The network load is increasing due to the spread of content distribution services. Caching is recognized as a technique to reduce a peak network load by prefetching popular contents into memories of users. Coded caching is a new caching approach based on a carefully designed content placement in order to create coded multicasting opportunities. Coded caching schemes in single-rate networks are evaluated by the trade-off between the size of memory and the size of delivered data. Considering the network with multiple transmission rates, it is important how to operate multicast. The multicast needs to use the smallest rate among the available rates for target users. In multi-rate wireless networks, multicast scheduling schemes are evaluated by a throughput and a delay. In this paper, we discuss coded caching in the multi- rate wireless networks. We newly define a throughput and a delay for evaluating the coded caching scheme and propose a new coded caching scheme suitable for these metrics. We compare the proposed coded caching scheme with conventional coded caching schemes.

This paper surveys with the emerging research on various methods to identify the legitimate/illegitimate traffic on the network. Here, the focus is on the effective early detection scheme for distinguishing Distributed Denial of Service (DDoS) attack traffic from normal flash crowd traffic. The basic characteristics used to distinguish Distributed Denial of Service (DDoS) attacks from flash crowds are access intents, client request rates, cluster overlap, distribution of source IP address, distribution of clients and speed of traffic. Various techniques related to these metrics are clearly illustrated and corresponding limitations are listed out with their justification. A new method is proposed in this paper which builds a reliable identification model for flash crowd and DDoS attacks. The proposed Probabilistic Neural Network based traffic pattern classification method is used for effective classification of attack traffic from legitimate traffic. The proposed technique uses the normal traffic profile for their classification process which consists of single and joint distribution of various packet attributes. The normal profile contains uniqueness in traffic distribution and also hard for the attackers to mimic as legitimate flow. The proposed method achieves highest classification accuracy for DDoS flooding attacks with less than 1% of false positive rate.

Longer life time is the primary goal of interest in Wireless Sensor Networks (WSNs). Communication dominates the power consumption among all the activities in WSNs. The classical sleep and wake up scheduling scheme at the application layer is believed to be one of the best power saving schemes for dense WSNs. These schemes reduce redundant transmissions, and as a result, prolong the network life time. This chapter analyzes the effect of density on inter cluster and intra cluster communication and evaluates a hybrid cross layer scheduling schemes to enhance the life time of the WSNs. In the conventional scheduling schemes at the application layer, all the nodes whose area are covered by their neighbors are put to sleep in order to prolong the life time of the WSNs. The hybrid cross layer scheme in this chapter suggests that instead of putting the redundant nodes to sleep if they are used for some other energy intensive tasks, for example the use of redundant nodes as relay stations in inter cluster communication, will be more energy efficient compare to the conventional application layer scheduling schemes in WSNs. Performance studies in the chapter indicate that the proposed communication strategy is more energy efficient than the conventional communication strategies that employ the sleep/wake up pattern at application layer.

It is a common case in Public Safety Networks (PSNs) that a user equipment (UE) instead of a base station (BS) acts as the multicast transmitter. In the network physical (PHY) layer, we adopt the fountain coding method to reduce network burden and energy consumption of UEs. However, current LTE standards support Quality of Service (QoS) controls only for unicast communications. To satisfy the QoS requirements of emergency group communications, an effective opportunistic multicast scheduling scheme is investigated at the MAC layer which can minimize the delay of a multicast. To further improve multicast throughput, Device-to-Device (D2D) relaying technique is also integrated into the proposed multicast scheduling scheme, which can combat the multicast bottleneck when one or very few receivers are with very poor channel conditions. The simulation results verify the effectiveness of the proposed D2D relaying based multicast service in LTE based PSNs.

무선 인터넷 프록시 서버 클러스터링에서 저장공간을 최소화하기 위해서는 URL 해싱기법을 가진 Layer 7 부하분산기가 필요하다. 서버 클러스터 앞단에 위치한 Layer 4 부하분산기는 TCP 또는 UDP와 같은 트랜스포트 계층에서 컨텐츠 내용을 확인하지 않고 사용자 요청들을 똑같은 컨텐츠를 가진 서버들에게 분배한다. 서버 클러스터 앞단에 위치한 Layer 7 부하분산기는 응용계층에서 사용자 요청을 분석하여 요청 컨텐츠 유형에 따라 해당되는 서버들에게 분배한다. Layer 7 부하분산기를 이용하면 서버들이 배타적으로 각기 다른 컨텐츠를 가지게 할 수 있어서 서버들 저장공간을 최소화할 수 있으며 전체 클러스터 성능을 향상할 수 있다. 그러나 Layer 7 부하분산기는 응용계층에서 사용자 요청을 분석하는데 요구되는 큰 처리 부담으로 인해 Layer 4 부하분산기와 다르게 확장성이 제한된다. 본 논문에서는 그 확장성 제한을 극복하기 위해서 분산형 Layer 7 부하분산기를 제안한다. 종래의 방법에서는 한 대의 Layer 7 부하분산기 를 사용하는데 본 논문에서 제안한 방법에서는 서버 클러스터 앞에 한 대의 Layer 4 부하분산기를 설치하고 서버들에게 Layer 7 부하분산기들을 각각 설치한다. 클러스터 기반의 무선 인터넷 프록시 서버에서 종래의 방법을 리눅스기반의 Layer 7 부하분산기인 KTCPVS를 이용하여 구현하였다. 본 논문에서 제안한 방법에서는 리눅스기반의 Layer 4 부하분산기인 IPVS를 사용하고 각 서버들에게 Layer 7 부하분산기인 KTCPVS를 설치하여 같이 동작하게 구현하였다. 실험은 16대의 컴퓨터를 사용하여 수행되었고, 실험 결과에 의하면 제안 방법이 종래 방법에 비해 서버 대수가 증가함에 따라 확장성 및 높은 성능 향상률을 가짐을 확인하였다. A Clustering based wireless internet proxy server needs a layer-7 load balancer with URL hashing methods to reduce the total storage space for servers. Layer-4 load balancer located in front of server cluster is to distribute client requests to the servers with the same contents at transport layer, such as TCP or UDP, without looking at the content of the request. Layer-7 load balancer located in front of server cluster is to parse client requests in application layer and distribute them to servers based on different types of request contents. Layer 7 load balancer allows servers to have different contents in an exclusive way so that it can minimize the total storage space for servers and improve overall cluster performance. However, its scalability is limited due to the high overhead of parsing requests in application layer as different from layer-4 load balancer. In order to overcome its scalability limitation, in this paper, we propose a distributed layer-7 load balancer by replacing a single layer-7 load balancer in the conventional scheme by a single layer-4 load balancer located in front of server cluster and a set of layer-7 load balancers located at server cluster. In a clustering based wireless internet proxy server, we implemented the conventional scheme by using KTCPVS(Kernel TCP Virtual Server), a linux based layer-7 load balancer. Also, we implemented the proposed scheme by using IPVS(IP Virtual Server), a linux-based layer-4 load balancer, installing KTCPVS in each server, and making them work together. We performed experiments using 16 PCs. Experimental results show scalability and high performance of the proposed scheme, as the number of servers grows, compared to the conventional scheme.

Multicasting is the data distribution from one sender to a group of receivers. Traditionally multicasting is implemented at network layer, in the way that routers perform membership management, maintain data delivery path, and replicate and forward data. IP multicast is the most efficient way for group data distribution. However, it has been shown that it is extremely difficult to deploy IP multicast at a large scale. Therefore an alternative has been proposed to shift multicast support to the application layer. This approach expects end-hosts participating in the application to perform multicast functions. This is application layer multicasting (ALM). This paper proposes a proxy-based single source ALM protocol which targets media streaming applications, where latency is the overlay building metric. A text-based message exchange application is implemented based on this protocol. Some measurements are taken both on the intranet and on the Internet. And some performance data are provided. Finally we concluded our research

Application layer (AL) multicast protocols emerged, and in large number, as a response to the slow deployment of IP multicast. However, the gain of different AL multicast mechanisms, in terms of resources consumption over uni-cast, is questionable. In this paper, we investigate the efficiency of AL multicast protocol NICE, in terms of the number of hops a packet traverses on its path toward the destinations. We propose four alternative algorithms for the creation of NICE overlay and compare their efficiency to the efficiency of unicast, IP multicast, and another two previously evaluated AL multicast protocols (MCAN and Scribe). Further, we investigate the influence of the underlying topology awareness on the efficiency. Our analysis has been performed via simulations, as well as via measurements on the PlanetLab network. We show that the NICE structure achieves better results than MCAN and scribe