1,080 research outputs found
Minimum power multicasting with delay bound constraints in Ad Hoc wireless networks
In this paper, we design a new heuristic for an important extension of the minimum power multicasting problem in ad hoc wireless networks. Assuming that each transmission takes a fixed amount of time, we impose constraints on the number of hops allowed to reach the destination nodes in the multicasting application. This setting would be applicable in time critical or real time applications, and the relative importance of the nodes may be indicated by these delay bounds. We design a filtered beam search procedure for solving this problem. The performance of our algorithm is demonstrated on numerous test cases by benchmarking it against an optimal algorithm in small problem instances, and against a modified version of the well-known Broadcast Incremental Power (BIP) algorithm 20 for relatively large problems
Analysis of Performance of Dynamic Multicast Routing Algorithms
In this paper, three new dynamic multicast routing algorithms based on the
greedy tree technique are proposed; Source Optimised Tree, Topology Based Tree
and Minimum Diameter Tree. A simulation analysis is presented showing various
performance aspects of the algorithms, in which a comparison is made with the
greedy and core based tree techniques. The effects of the tree source location
on dynamic membership change are also examined. The simulations demonstrate
that the Source Optimised Tree algorithm achieves a significant improvement in
terms of delay and link usage when compared to the Core Based Tree, and greedy
algorithm
On application of least-delay variation problem in ethernet networks using SDN concept
The goal of this paper is to present an application idea of SDN in Smart Grids, particularly, in the area of L2 multicast as defined by IEC 61850-9-2. Authors propose an Integer Linear Formulation (ILP) dealing with a Least-Delay-Variation multicast forwarding problem that has a potential to utilize Ethernet networks in a new way. The proposed ILP formulation is numerically evaluated on random graph topologies and results are compared to a shortest path tree approach that is traditionally a product of Spanning Tree Protocols. Results confirm the correctness of the ILP formulation and illustrate dependency of a solution quality on the selected graph models, especially, in a case of scale-free topologies
A heuristic multicast algorithm to support QoS group communications in heterogeneous network
2005-2006 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe
Protocols for collaborative applications on overlay networks.
Third, we address the limitations of traditional multicasting models. Towards this, we propose a model where a source node has different switching time for each child node and the message arrival time at each child depends on the order in which the source chooses to send the messages. This model captures the heterogeneous nature of communication links and node hardware on the overlay network. Given a multicast tree with link delays and generalized switching delay vectors at each non-leaf node, we provide an algorithm which schedules the message delivery at each non-leaf node in order to minimize the delay of the multicast tree.First, we consider the floor control problem wherein the participating users coordinate among themselves to gain exclusive access to the communication channel. To solve the floor control problem, we present an implementation and evaluation of distributed Medium Access Control (MAC) protocols on overlay networks. As an initial step in the implementation of these MAC protocols, we propose an algorithm to construct an efficient communication channel among the participating users in the overlay network. We also show that our implementation scheme (one of the first among decentralized floor control protocols) preserves the causal ordering of messages.Our research is focused on the development of algorithms for the construction of overlay networks that meet the demands of the distributed applications. In addition, we have provided network protocols that can be executed on these overlay networks for a chosen set of collaborative applications: floor control and multicasting. Our contribution in this research is four fold.Fourth, we address the problem of finding an arbitrary application designer specific overlay network on the Internet. This problem is equivalent to the problem of subgraph homeomorphism and it is NP-Complete. We have designed a polynomial-time algorithm to determine if a delay constrained multicasting tree (call it a guest) can be homeomorphically embedded in a general network (call it a host). A delay constrained multicasting tree is a tree wherein the link weights correspond to the maximum allowable delay between the end nodes of the link and in addition, the link of the guest should be mapped to a shortest path in the host. Such embeddings will allow distributed application to be executed in such a way that application specific quality-of-service demands can be met. (Abstract shortened by UMI.)Second, we address the problem of designing multicasting sub-network for collaborative applications using which messages are required to arrive at the destinations within a specified delay bound and all the destinations must receive the message from a source at 'approximately' the same time. The problem of finding a multicasting sub-network with delay and delay-variation bound has been proved to be NP-Complete in the literature and several heuristics have been proposed
A heuristic multicast algorithm to support QoS group communications in heterogeneous network
2005-2006 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
QoS-VNS-CS: QoS constraints Core Selection Algorithm based on Variable Neighborhood Search Algorithm
Within the development of network multimedia technology, more and more real-time multimedia applications arrive with the need to transmit information using multicast communication. Multicast IP routing is an important topic, covering both theoretical and practical interest in different networks layers. In network layer, there are several multicast routing protocols using multicast routing trees different in the literature. However PIM-SM and CBT protocols remains the most used multicast routing protocols; they propose using a shared Core-based Tree CBT. This kind of tree provides efficient management of multicast path in changing group memberships, scalability and performance. The prime problem concerning construction of a shared tree is to determine the best position of the core. QoS-CS’s problem (QoS constraints core Selection) consists in choosing an optimal multicast router in the network as core of the Shared multicast Tree (CBT) within specified QoS constraints associated. The choice of this specific router, called RP in PIM-SM protocol and core in CBT protocol, affects the structure of multicast routing tree, and therefore influences performances of both multicast session and routing scheme. QoS-CS is an NP complete problem need to be solved through a heuristic algorithm, in this paper, we propose a new core Selection algorithm based on Variable Neighborhood Search algorithm and new CMP fitness function. Simulation results show that good performance is achieved in multicast cost, end-to-end delay, tree construction delay and others metrics
Algorithmic Aspects of Energy-Delay Tradeoff in Multihop Cooperative Wireless Networks
We consider the problem of energy-efficient transmission in delay constrained
cooperative multihop wireless networks. The combinatorial nature of cooperative
multihop schemes makes it difficult to design efficient polynomial-time
algorithms for deciding which nodes should take part in cooperation, and when
and with what power they should transmit. In this work, we tackle this problem
in memoryless networks with or without delay constraints, i.e., quality of
service guarantee. We analyze a wide class of setups, including unicast,
multicast, and broadcast, and two main cooperative approaches, namely: energy
accumulation (EA) and mutual information accumulation (MIA). We provide a
generalized algorithmic formulation of the problem that encompasses all those
cases. We investigate the similarities and differences of EA and MIA in our
generalized formulation. We prove that the broadcast and multicast problems
are, in general, not only NP hard but also o(log(n)) inapproximable. We break
these problems into three parts: ordering, scheduling and power control, and
propose a novel algorithm that, given an ordering, can optimally solve the
joint power allocation and scheduling problems simultaneously in polynomial
time. We further show empirically that this algorithm used in conjunction with
an ordering derived heuristically using the Dijkstra's shortest path algorithm
yields near-optimal performance in typical settings. For the unicast case, we
prove that although the problem remains NP hard with MIA, it can be solved
optimally and in polynomial time when EA is used. We further use our algorithm
to study numerically the trade-off between delay and power-efficiency in
cooperative broadcast and compare the performance of EA vs MIA as well as the
performance of our cooperative algorithm with a smart noncooperative algorithm
in a broadcast setting.Comment: 12 pages, 9 figure
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