Relative Delay Penalty Research Articles

The Multiple Implied Overlay Tree P2P Progressive Transmission Method of Mixed Subdivision Mesh

This paper presents a progressive transmission method of mixed subdivision mesh based on multiple implied overlay tree P2P network. Peer-to-Peer networks are widely used in media transmission because of its excellent network scalability. Scalable media service, especially mixed subdivision mesh is proposed to adapt to different terminal processing abilities. For stratified characteristics of progressive mesh, we use multiple implied tree cover P2P technology to transmit 3D mesh of mixed subdivision model. It effectively realizes to reduce MAX, average system load link and lower the average Relative delay penalty. Finally a complete set of solution is given, which is proved to be an effective method by simulation experiment.

Reliable Application Layer Multicast Over Combined Wired and Wireless Networks

During the last several years, the Internet has evolved from a wired infrastructure to a hybrid of wired and wireless domains by spreading worldwide interoperability for microwave access (WiMAX), Wi-Fi, and cellular networks. Therefore, there is a growing need to facilitate reliable content delivery over such heterogeneous networks. On the other hand, application layer multicast (ALM) has become a promising approach for streaming media content from a server to a large number of interested nodes. ALM nodes construct a multicast tree and deliver the stream through this tree. However, if a node leaves, it cannot deliver the stream to its descendant nodes. In this case, quality-of-service (QoS) is compromised dramatically. Especially, this problem is exacerbated in wireless networks because of packet errors and handovers. In order to cope with this problem, multiple-tree multicasts have been proposed. However, existing methods fail to deliver contents reliably in combined wired and wireless networks. In this paper, we propose a method to ensure the robustness of node departure, while meeting various bandwidth constraints by using layered multiple description coding (LMDC). Finally, we evaluate the proposed method via extensive simulations by using the network simulator (ns-2). By comparing our proposed method with the existing ones, we demonstrate that our method provides better performance in terms of total throughput, relative delay penalty (RDP), and relative delay variation (RDV). The results indicate that our approach is a more reliable content delivery system when compared with contemporary methods in the context of heterogeneous networks containing wired and wireless environments.

Fuzzy priority based overlay multicast

Among the existing overlay multicast protocols, the Priority-based directed minimum Spanning Tree (PST) is designed for Distributed Interactive Applications (DIAs), and it uses priority to quantify the relationship between two nodes and guarantees the nodes with high priority receiving data in a short delay. Since the priority is calculated only from the distance between the nodes’ avatars, and the available bandwidth (avail-bw) of nodes is not considered in multicast tree building, PST cannot use avail-bw efficiently and in some cases the priority might be calculated inaccurately. In this paper we propose a novel overlay multicast protocol named Fuzzy priority based Overlay Multicast (FOM), which adopts a fuzzy mechanism to accurately calculate the priority by taking all the attributes of avatars into consideration, and utilizes priority, delay, and avail-bw synthetically to build multicast trees. When avail-bw is insufficient to build a multicast tree, a priority based filtering mechanism is implemented to rebuild it. The simulation results show that with group number and observation region increasing, FOM has the best performance on tree build rates, mean relative delay penalty, and mean bandwidth usage percentage, and it is more suitable for DIAs than protocols ALMI and PST.

Lateral error recovery for media streaming in application-level multicast

We consider media streaming using application-level multicast (ALM) where packet loss has to be recovered via retransmission in a timely manner. Since packets may be lost due to congestion, node failures, and join and leave dynamics, traditional "vertical" recovery approach where upstream nodes retransmit the lost packets is no longer effective. We therefore propose lateral error recovery (LER). In LER, hosts are divided into a number of planes, each of which forms an independent ALM tree. Since error correlation across planes is low, a node effectively recovers its error by "laterally" requesting retransmission from nearby nodes in other planes. We present analysis on the complexity and recovery delay on LER. Using Internet-like topologies, we show via simulations that LER is an effective error recovery mechanism. It achieves low overhead in terms of delivery delay (i.e., relative delay penalty) and physical link stress. As compared with traditional recovery schemes, LER attains much lower residual loss rate (i.e., loss rate after retransmission) under a certain deadline constraint. The performance can be substantially improved in the presence of some reliable proxies.

Robust and efficient path diversity in application-layer multicast for video streaming

Application-layer multicast (ALM), as alternative to IP multicast, provides group communication without the need for network infrastructure support. To improve the reliability of ALM service, path diversity has been studied and two schemes to construct diverse paths for hosts are proposed. One is the random multicast forest (RMF) and the other is topology-aware hierarchical arrangement graph (THAG). RMF makes the paths from the media source to a participating host diverse by selecting parents for each host randomly, while THAG makes the paths node-disjoint by constructing multiple independent multicast trees, where any interior node in a multicast tree will be leaf node in all the other multicast trees. Topology-awareness is implemented in both schemes to make them efficient for media delivery. We compare the reliability and efficiency of THAG and RMF through extensive simulation. The results show that the reliability of THAG has been improved up to 20% compared with RMF. The efficiency metrics, such as relative delay penalty, link stress, and delay variation among different trees in THAG, are also smaller than or almost the same as that in RMF. The results indicate that THAG is a reliable and efficient ALM scheme for streaming media service.