Mesh-based Multicast Protocols Research Articles

K-Tree: A multiple tree video multicast protocol for Ad hoc wireless networks

In this paper, we address the problem of video multicast over Ad hoc wireless networks. Multicasting is an efficient means of one-to-many communication and is typically implemented by creating a multicast tree. Video multicasting demands high quality of service with a continuous delivery to receivers. However, most of the existing multicast solutions do not guarantee this because they are not resilient to mobility of the nodes and do not exploit error-resilient nature of recently available video coding techniques. Uninterrupted video transmission requires continuous reachability to receivers which emphasizes the usage of path-diversity. Hence, we propose a multiple tree multicast protocol which maintains maximally node-disjoint multicast trees in the network to attain robustness against path breaks. We further enhance the robustness by using the error-resilient multiple description coding (MDC) for video encoding. We prove that finding a given number of node-disjoint multicast trees for a multicast session in a given network is NP-Hard. Then we propose a protocol called K-Tree which maintains the maximal node-disjointedness property of K trees by using a distributed online heuristic. Through extensive simulation experiments, we show how the proposed protocol improves the video quality as we use two or three trees instead of a single tree for multicasting video stream. We also show, through simulations, that the protocol efficiently, in terms of overhead, provides high quality video as compared to an existing two tree video multicast protocol and a well known mesh-based multicast protocol.

High-throughput multicast routing metrics in wireless mesh networks

The stationary nature of nodes in a mesh network has shifted the main design goal of routing protocols from maintaining connectivity between source and destination nodes to finding high-throughput paths between them. Numerous link-quality-based routing metrics have been proposed for choosing high-throughput routing paths in recent years. In this paper, we study routing metrics for high-throughput tree or mesh construction in multicast protocols. We show that there is a fundamental difference between unicast and multicast routing in how data packets are transmitted at the link layer, and accordingly how the routing metrics for unicast routing should be adapted for high-throughput multicast routing. We propose a low-overhead adaptive online algorithm to incorporate link-quality metrics to a representative multicast routing protocol. We then study the performance improvement achieved by using different link-quality-based routing metrics via extensive simulation and experiments on a mesh-network testbed, using ODMRP as a representative multicast protocol. Our extensive simulation studies show that: (1) ODMRP equipped with any of the link-quality-based routing metrics can achieve higher throughput than the original ODMRP. In particular, under a tree topology, on average, ODMRP enhanced with link-quality routing metrics achieve up to 34% higher throughput than the original ODMRP under low multicast sending rate; (2) the improvement reduces to 21% under high multicast sending rate due to higher interference experienced by the data packets from the probe packets; (3) heavily penalizing lossy links is an effective way in the link-quality metric design to avoid low-throughput paths; and (4) the path redundancy from a mesh data dissemination topology in mesh-based multicast protocols provides another degree of robustness to link characteristics and reduces the additional throughput gain achieved by using link-quality-based routing metrics. Finally, our experiments on an eight-node testbed show that on average, ODMRP using SPP and PP achieves 14% and 17% higher throughput over ODMRP, respectively, validating the simulation results.

An adaptive redundancy protocol for mesh based multicasting

Mesh-based multicast routing protocols for multi-hop wireless ad hoc networks (MANETs) build multiple paths from senders to receivers. Higher redundancy results in higher reliability because packets can be delivered even in the presence of links breaking. However, in less dynamic environments, in which links break less frequently, the additional redundancy may not be needed in terms reliability and may significantly increase overhead. This paper investigates the tradeoffs between reliability and efficiency in mesh-based multicast protocols for MANETs. We introduce an adaptive mesh-based multicast mechanism that controls mesh redundancy based on link reliability in the neighborhood of the node. Mesh redundancy is measured by the number of paths from each receiver to the core of the group’s mesh, which serves as the address of the group. We introduce a metric called Mesh Reliability Index (MRI), which allows nodes to estimate the reliability of the mesh in their neighborhood, and determine whether redundancy needs to be increased or decreased. Through simulations, we compare the performance of the adaptive mesh-building protocol against the non-adaptive version (which builds the mesh with maximum redundancy), and against ODMRP for a wide range of scenarios with varying mobility, group members, number of senders, traffic load, number of multicast groups and terrain size. Our results show that adjusting mesh redundancy based on link reliability can maintain high packet delivery ratios with less overhead compared to non-adaptive mesh-based multicast protocols.

모바일 애드혹 네트워크를 위한 링 기반 멀티캐스트 라우팅 구조

예상치 못한 에드혹 망의 접속형태의 변경이 동반되는 멀티캐스트 라우팅 프로토콜에 대한 연구에 많은 과제를 남겨놓고 있으며, 다양한 이동 에드혹 망에 적합한 프로토콜에 대한 연구의 필요성이 제기되고 있다. 본 논문에서는 계층적 Eulerian 링 멀티캐스트 구조를 갖는 새로운 프로토콜을 제안한다. 제안한 구조는 Eulerian 링, 계층구조, 멀티캐스트 에이전트를 갖으며 기존의 방법보다 효율적이며 안전한 특성을 갖는다. 제안한 구조는 트리기반 및 메시기만 멀티캐스트 프로토콜과 비교하여 제어트래픽의 양, 점대점 지연, 패킷전송률 등에 있어 우수함은 시뮬레이션을 통해 입증한다. Due to the frequent and unpredictable topology changes, multicast still remains as challenge and no one-size-fits-all protocol could serve all kinds of needs in mobile ad hoc network. In this paper, we propose a novel scheme of Hierarchical Eulerian Ring Oriented Multicast Architecture (HEROMA) over mobile ad hoc network. It has features that concentrate on efficiency and robustness simultaneously. It is also an application-driven proposal for hazard detection. Architectures including Eulerian ring, hierarchy and multicast agent are investigated in detail Simulation results different level of improvements on control traffic, end-to-end delay and packet delivery ratio by comparing with tree-based and mesh-based multicast protocols.