Construction of Application-Layer Multicast Trees for Message Distribution

The geographically distributed system can be interconnected via an overlay multicast network. In this overlay network the multicast data are routed and replicated on the application layer along a multicast tree. This paper presents the techniques of the network reduction and the multicast tree construction. The multicast tree in the form of shortest path tree (SPT) can be build up upon the linear programming formulation. To control the load of each host, the additional constraints on the maximal number of directly outgoing connections and integer variables are added and subsequently form the degree-bounded shortest path tree problem (db-SPT). This theoretically based problem is formulated in integer linear programming framework

In order to reduce the relative intensity noise (RIN) in the interferometric signal of the fiber optic gyroscope (FOG), an adaptive noise subtraction method is presented, which aims to overcome to the drawbacks that the fixed delay time and gain of the digital noise subtraction method. The drawbacks will make the performance of FOG to be degraded greatly in the changing environment. In the paper the adaptive noise subtraction system based on the recursive least squares algorithm (RLS) is formed in FPGA, in which the interferometric signal is regarded as the signal source, and RIN in the free end of the optical fiber coupler of FOG is looked as the noise reference signal. The two critical parameters that minimum delay time and its varying range result from measuring the minimum and maximum delay times of the interferometric signal in a certain temperature range. The off-line and on-line temperature experimental results verify the capability of adapting to the environmental temperature. DOI : http://dx.doi.org/10.11591/telkomnika.v12i1.3373

This article presents a new heuristic algorithm called DDBMA lDynamic Delay Bounded Multicast Algorithmr to construct a minimum-cost multicast tree. The heuristic depends on l1r bounded delay along paths from source nodes to destination node; l2r minimum cost of the multicast tree; l3r dynamic multicast tree status which is maintained by updating the existing multicast tree when nodes in the network request to join or leave. Copyright © 1999 John Wiley & Sons, Ltd.

Minimum-energy broadcast and multicast in wireless networks: An integer programming approach and improved heuristic algorithms

This paper presents a new heuristic algorithm called DDBMB (dynamic delay bounded multicast algorithm) to construct a minimum cost multicast tree. The heuristic depends on: (A) bounded delay along paths from source node to each destination node; (B) minimum cost of the multicast tree where the algorithm starts with the minimum delay tree and monotonically decreases the cost iteratively to construct a delay bounded minimum cost tree; and (C) dynamic multicast tree status which is maintained by updating the existing multicast tree when nodes in the network request join or leave. The construction of such constrained multicast tree is known as an NP-complete problem. Compared with other existing relative algorithms, the heuristic demonstrates a better average case behavior and can be very close to having a minimum cost depending on the delay bounds imposed.

Circuit delay calculation considering data dependent delays

A delay-constrained and priority-aware channel assignment algorithm for efficient multicast in wireless mesh networks

For many multimedia multicast applications, especially those requiring real-time traffic, it is important that the maximum delay bound requirement between any pair of group members be satisfied. Most studies on multicast routing have been based on a single multicast tree (a shortest path tree or a minimal Steiner tree) approach. By using only a single multicast tree for a multicast group, satisfying the maximum delay bound requirement is nearly impossible. To fulfill these requirement, we adopt the multiple multicast tree concept whose disadvantage is the high tree maintenance cost. Since the tree maintenance cost is proportional to the number of multicast trees for a multicast group, it is necessary to minimize the number of multicast trees. In this paper, we formulate the delay-bounded multicast tree (DBMT) problem whose main objectives are to satisfy an application's maximum delay bound among the group members and to minimize the number of multicast trees needed for a group communication. We categorize the DBMT problem according applications' needs into two subproblems, the shortest path tree-based DBMT (SPT DBMT) and the minimal Steiner tree-based DBMT (MST DBMT) problems. For the DBMT subproblems, we prove the NP-hardness and propose heuristic algorithms. For the performance analysis, simulations were performed.

Quality of service (QoS) provisioning generally assumes more than one QoS measure which implies that QoS routing can be categorized as an instance of routing subject to multiple constraints: delay-jitter, bandwidth, cost, etc. We study the problem of constructing multicast trees to meet the QoS requirements of real-time interactive applications where it is necessary to provide bounded delays and bounded delay variation among the source and all destinations while keeping overall cost of the multicast tree low. The main contribution of our work is a new strategy for constructing multiconstrained multicast trees. We first derive mathematically a new Delay-Variation Estimation Scheme and prove its efficiency. Thereafter, we propose a simple and competitive (in terms of system running time) heuristic algorithm, for delay and delay variation constrained routing problem based on the proposed delay-variation estimation scheme and using the Extended Prim-Dijkstra tradeoffs' algorithm. Besides, our algorithm uses cost information only from neighboring nodes as it proceeds which makes it more practical from an implementation point of view. Our contribution also extends previous works in providing some properties and analyses of delay bounded paths satisfying delay variation constraints.

Heuristic algorithms for packing of multiple-group multicasting

Building a multicast tree in an overlay network is the major problem in application layer multicast. In a selfish overlay network, the end hosts may not be cooperative. They are willing to maximize their own benefits instead of being loyal to the protocol or altruistically contributing to the benefits of the whole overlay network. In this paper, we design a strategyproof mechanism in building a truthful minimum cost multicast tree in the mesh-tree way, which could simplify the overlay construction and maintenance. We model the network in both simple and general cost model. We conduct simulation to study the relationship between utility of cheating node and other nodes

Recently, application-layer multicast (ALM) has emerged as a means to solve most of the problems of IP-based multicast. Topology-aware approach of ALM is more attractive because it exploits underlying network topology data to construct multicast overlay networks. In this paper, a novel overlay network construction mechanism called balanced multi-domain topology-aware grouping (BMTAG) is introduced. BMTAG adopts a special node (domain monitor) to be the parent of all other nodes in the same domain. The mechanism can not only save the time used to discover the topology and execute the path matching algorithm but also lower the depth of the multicast tree. Building a multicast tree with balanced traffic to avoid the bottleneck is another purpose of BMTAG. Simulation results show that BMTAG can get higher performance than TAG especially when the group size is large or the percentage of domain nodes is high.

In peer-to-peer (P2P) applications, a group of multiple peer processes (peers) are required to cooperate with each other. In this paper, we discuss a heterogeneous hybrid time group communication (HHT) protocol which takes advantage of the linear time (LT) and physical time (PT) to causally order messages in a scalable heterogeneous group. It depends on accuracy of each physical clock and minimum delay time between a pair of peers how messages can be ordered. In this paper, we consider a heterogeneous type of group where the clock accuracy of each peer and the minimum delay time between every pair of peers are not the same. In group protocols, even if a pair of messages are ordered in the protocol, the messages may not be causally ordered. Thus, some messages are unnecessarily ordered in the protocols. In this paper, we show the number of messages to be unnecessarily ordered can be reduced in the HHT protocol. In a scalable group, it is not easy, maybe impossible for each peer to hold information on the clock accuracy and minimum delay time of every peer. In this paper, we newly consider a two-layered model of a heterogeneous group to reduce the information which each peer has to hold.

This paper aims to provide a smart design to improve the efficiency of surface permanent magnet synchronous motor. An efficient design strategy involving penalty approaches are considered for extracting all the possible parameter combinations and the solutions in the infeasible region. We compare the performance of tree heuristic optimization algorithms and six penalty methods. The heuristic optimization algorithms are: particle swarm optimization, differential search algorithm, and tree seed algorithm. The penalty methods are: three of which are static penalty approaches, two of dynamic penalty approaches, and Deb’s rule. Besides, the optimized motor design is tested with finite element analysis. Two conclusions were drawn from the experiments. First, heuristic algorithms using penalty approaches had significantly better performance compared to standard and popular heuristic algorithms. This emphasizes the importance of using heuristic algorithms with penalty approaches in SPMSM design optimization. Second, the compatibility of design optimization and numerical analysis results are acceptable and highly satisfactory for surface permanent magnet synchronous motor design. According to the analytical design, a 4% improvement in efficiency was achieved with the proposed approach.

When renovating a pedestrian area, it is crucial to maintain as normal as possible an operation while the renovation activities are underway. Usually the area is divided into several zones to accommodate the renovation in sections. A zone closure forces the users to take an alternative route that could be longer or more congested. The impact of such rerouting must be minimized by properly planning the work crews. In this paper, the author proposed a model using simulation to estimate the impact of the extra walking distance on pedestrians, and ant colony optimization to search for the nearoptimal work crew schedule. The author applied the model to the renovation of a public pedestrian area in a villa resort. It provides a near-optimal work schedule for a variety of work crews with minimal walking time delay for the pedestrians. This model takes into account total walking time delay, average delay per person, and total duration in order to evaluate all alternatives to allow both owner and contractor to decide the appropriate work schedule.