Optimal algorithms for dissemination of information in generalized communication modes

Communication in the two-way listen-in vertex-disjoint paths mode

Optimal algorithms for dissemination of information in some interconnection networks

A line-broadcasting model in a connected graph G = ( V , E ) , | V | = n , is a model in which one vertex, called the originator of the broadcast, holds a message that has to be transmitted to all vertices of the graph through placement of a series of calls over the graph. In this model, an informed vertex can transmit a message through a path of any length in a single time unit, as long as two transmissions do not use the same edge at the same time. Farley [6] has shown that the process can be completed within at most ⌈ log 2 n ⌉ time units from any originator in a tree (and thus in any connected undirected graph) and that the cumulative cost of broadcasting one message from any vertex, that is, the total number of edges used, is at most ( n − 1 ) ⌈ log 2 n ⌉ . In this article, we present lower and upper bounds for the cumulative cost to broadcast one message in a complete k-ary tree, k ≥ 2 , from any vertex using the line-broadcasting model. We prove that if B(u) is the minimum cumulative cost of line-broadcast in a graph G = ( V , E ) from an originator u ∈ V using the line-broadcasting model, then ( 2 − o ( 1 ) ) n ≤ B ( u ) ≤ ( 2 + o ( 1 ) ) n , where u is any vertex in a complete k-ary tree. Furthermore, for certain conditions, B(u) is about ( 2 − o ( 1 ) ) n . © 2015 Wiley Periodicals, Inc. NETWORKS, Vol. 67(2), 139–147 2016

Multistage interconnection networks are used as a medium for interconnecting processors and memories in multiprocessor systems. Multistage interconnection networks are an effective substitute for crossbar switches, used in telephone network systems and parallel computers, due to their low cost, better performance and easy maintainability. In this paper, we propose new fault-tolerant hybrid multistage interconnection networks obtained from shuffle exchange gamma interconnection network (SEGIN) and logical neighborhood network named as shuffle exchange gamma logical neighborhood interconnection network (SEGLNIN). We evaluated the performance of SEGLNIN in terms of disjoint paths, reliability and hardware cost and compared it with some well-known MINs like shuffle exchange network (SEN), shuffle exchange network with one extra stage (SEN +) and shuffle exchange network with two extra stages (SEN + 2), SEGIN-1, and SEGIN-2. The results illustrate that the performance of the proposed SEGLNIN is better than that of the compared networks in terms of reliability and disjoint paths.

A pyramid organization is a hierarchical structure based on the principle of unity of command (Koontz, 1980) that every member except the top in the organization should have a single immediate superior. On the other hand an organization characterized by System 4 (Likert, 1976) has a structure in which relations between members of the same section are added to the pyramid organization structure. Members of middle layers of System 4 which are both members of the upper units and chiefs of the lower units are called linking pins, and this type of organization is called a linking pin organization. In the linking pin organization there exist relations between each superior and his direct subordinates and those between members which have the same immediate superior. The linking pin organization structure can be expressed as a structure where every pair of siblings which are nodes which have the same parent in a rooted tree is adjacent, if we let nodes and edges in the structure correspond to members and relations between members in the organization respectively. Then the linking pin organization structure is characterized by the number of subordinates of each member, that is, the number of children of each node and the number of levels in the organization, that is, the height of the rooted tree, and so on (Robbins, 2003; Takahara & Mesarovic, 2003). Moreover, the path between a pair of nodes in the structure is equivalent to the route of communication of information between a pair of members in the organization, and adding edges to the structure is equivalent to forming additional relations other than those between each superior and his direct subordinates and between members which have the same direct subordinate. The purpose of our study is to obtain an optimal set of additional relations to the linking pin organization such that the communication of information between every member in the organization becomes the most efficient. This means that we obtain a set of additional edges to the structure minimizing the sum of lengths of shortest paths between every pair of all nodes. We have obtained an optimal depth for a model of adding edges between every pair of nodes with the same depth to a complete K-ary linking pin structure of height H(H = 2, 3, ...) where every pair of siblings in a complete K-ary tree of height H is adjacent (Sawada, 2008). A complete K-ary tree is a rooted tree in which all leaves have the same depth and all internal nodes have K(K = 2, 3, ...) children (Cormen et al., 2001). Figure 1 shows an example

An almost complete (or 2-complete) tree is a binary search tree in which any two external nodes are no more than two levels apart. While complete binary search trees have an amortized update cost of Θ(n), we demonstrate that almost complete binary search trees have an amortized update cost of O(log2 n). Thus, they are an attractive alternative for those situations that require fast retrieval, that is, log n+O(1) comparisons, and have few updates.KeywordsBalance TreeBinary Search TreeExternal NodeBalance CriterionInsertion AlgorithmThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

This paper concentrates on the set $$\mathcal {V}_n$$ of weighted Dyck paths of length 2n with special restrictions on the level of valleys. We first give its explicit formula of the counting generating function in terms of certain weight functions. When the weight functions are specialized, some connections are builded between $$\mathcal {V}_n$$ and other classical combinatorial structures such as (a, b)-Motzkin paths, q-Schröder paths, Delannoy paths and complete k-ary trees. Some bijections are also established between these settings and $$\mathcal {V}_n$$ subject to certain special weight functions.

Global edge alliances in graphs

In this paper, we consider the problem of finding the minimum number of searchers to sweep networks/graphs with special topological structures. Such a number is called the search number. We first study graphs, which contain only one cycle, and present a linear time algorithm to compute the vertex separation and the optimal layout of such graphs; by a linear-time transformation, we can find the search number of this kind of graphs in linear time. We also investigate graphs, in which every vertex lies on at most one cycle and each cycle contains at most three vertices of degree more than two, and we propose a linear time algorithm to compute their search number and optimal search strategy. We prove explicit formulas for the search number of the graphs obtained from complete k-ary trees by replacing vertices by cycles. We also present some results on approximation algorithms.

Speech is the primary and most common and efficient mode of communication between human beings. It is the real natural language. For educated people the other mode of communication is writing. People write in textual language. It is not only desirable but also essential at least for the common illiterate mass of the developing countries that the information dissemination be made via speech mode which is the most natural mode of human communication. With the unprecedented expansion of Information Technology (IT) invading the life of the common man it is only natural that an IT solution will be available for this. Speech synthesis, the automatic and artificial generation of the speech signal by a machine, is this solution.

In wireless multi-hop networks, a fundamental problem is to disseminate continuous data traffic from a source node to all other network nodes, which is known as the broadcast problem. Such a problem becomes even more complicated in wireless multi-hop networks with energy-harvesting capabilities at nodes when facing the interaction between stochastics of traffic arrivals at the source and randomness of energy-harvesting process at nodes. In such networks, the energy consumable at a node cannot exceed the amount of the energy harvested at the node. In this paper, we investigate the throughput-optimal broadcast problem in time-varying directed acyclic wireless multi-hop networks with such energy harvesting constraints. The topologies of such networks change dynamically with time while satisfying the directed acyclic property and the energy arrival time and harvested amount at a node are random, which causes the consumable energy in each time slot to fluctuate with time. Existing throughput-optimal broadcast algorithms did not consider such energy-harvesting constraints in their designs and therefore their throughput-optimal properties do not hold anymore in such a network. In this paper, we characterize the energy-harvesting uncertainties at nodes by using time-varying per-slot-based supportable transmission rates of wireless links. We consider the time-varying property of supportable link transmission rates caused by energy-harvesting dynamics in the per-slot transmission scheduling and propose an online max-weight broadcast algorithm. We derive a tight upper bound of broadcast capacity of the wireless networks under study in this paper and further prove that our proposed algorithm is throughput-optimal. We evaluate the throughput and latency performance of the proposed algorithm by simulations and the simulation results affirm our theoretical analysis.

Technological evolution and in particular the development of the Internet of Things (IoT) has paved the way for material prosperity and a better standard of living. A critical factor in the effectiveness of emerging IoT applications, which heavily rely on sensor information flow, is the development of a functional and efficient Wireless Sensor Network. Additionally, the levels of automation are conducive to usability and time efficiency by reducing the need for human intervention, as well as increasing the rate at which experiments can be carried out. In current work, an already installed infrastructure on the Ionian University campus is considered and enhanced, with the goal of elevating accessibility and user-friendliness, by designing a web platform. The presented platform enables the remote development, execution and monitoring of simple but necessary network-based algorithms using a custom language, without requiring code to be uploaded to remote nodes. As a proof of concept, three information dissemination algorithms are implemented and provided as example templates for users, promoting simultaneously ease of use.

IEEE 802.16j Mobile Multihop Relay Standard defines multi-hop relay operation in a WiMAX system. It uses a novel synchronous multicast and broadcast transmission mechanism to achieve macro diversity. With the newly introduced synchronous delivery constraint, the multicast data delivery algorithm should be designed differently to enhance system performance. This paper provides Multi-Rate Selection Algorithm (MRSA) for multicast and broadcast (MBS) data delivery. It could reduce the data distribution delay from the BS to all the RSs. Besides, we also propose the path selection algorithm to further improve the effectiveness of MRSA. Our simulation results show that using MRSA with our shortest-path path selection algorithm, the delay for data delivery in 802.16j MBS system could be greatly reduced. The proposed scheme could achieve the performance closed to the optimal solutions. To the authors' best knowledge, this is the first research work to investigate the IEEE 802.16j multicast and broadcast problem.

The use of reversible nonlinear interface devices (RNIs) to design optical interconnection networks for single instruction multiple data (SIMD) machines is proposed. An optical two-by-two switch requires four RNI devices. This design is shown. The basic two-by-two optical switches can be used to construct small and medium-size optical crossbar networks. The performances of the optical versions of Benes, Clos, shuffle exchange, and delta networks are compared. >

In this paper, we present the first algorithm for exactly implementing the abstract MAC (absMAC) layer in the physical SINR model. The absMac layer, first presented by Kuhn et al. in [15], provides reliable local broadcast communication, with timing guarantees stated in terms of a collection of abstract delay functions, such that high-level algorithms can be designed in terms of these functions, independent of specific channel behavior. The implementation of absMAC layer is to design a distributed algorithm for the local broadcast communication primitives over a particular communication model that defines concrete channel behaviors, and the objective is minimizing the bounds of the abstract delay functions. Halldorsson et al. [10] have shown that in the standard SINR model (synchronous communication, without physical carrier sensing or location information), there cannot be efficient exact implementations. In this work, we show that physical carrier sensing, a commonly seen function performed by wireless devices, can help get efficient exact implementation algorithms. Specifically, we propose an algorithm that exactly implements the absMAC layer. The algorithm provides asymptotically optimal bounds for both acknowledgement and progress functions defined in the absMAC layer. Our algorithm can lead to many new faster algorithms for solving high-level problems in the SINR model. We demonstrate this by giving algorithms for problems of Consensus, Multi-Message Broadcast and Single-Message Broadcast. It deserves to point out that our implementation algorithm is designed based on an optimal algorithm for a General Local Broadcast (GLB) problem, which takes the number of distinct messages into consideration for the first time. The GLB algorithm can handle much more communication scenarios apart from those defined in the absMAC layer. Simulation results show that our proposed algorithms perform well in reality.