Gossiping in chordal rings under the line model

The line model assumes long distance calls between non neighboring processors. In this sense, the line model is strongly related to circuit-switched networks, wormhole routing, optical networks supporting wavelength division multiplexing, ATM switching, and networks supporting connected mode routing protocols. Since the chordal rings are competitors of networks as meshes or tori because of theirs short diameter and bounded degree, it is of interest to ask whether they can support intensive communications (typically all-to-all) as efficiently as these networks. We propose polynomial algorithms to derive optimal or near optimal gossip protocols in the chordal ring

Minimum-cost line broadcast in paths

AbstractUnder the line communication protocol, calls can be placed between pairs of non-adjacent sites over a path of lines connecting them; only one call can utilize a line at any time. This paper addresses questions regarding the cumulative cost, i.e., sum of lengths of calls, of broadcasting under the line protocol in path networks. Let Pn be the path with n vertices, and Cn be the cost of an optimal, line broadcast scheme from a terminal vertex in path Pn. We show that a minimum-cost line broadcast scheme from any source vertex in Pn has cost no more than Cn and no less than Cn − n + 2 for any n ⩾ 2 and any time t > [log2n]. We derive a closed-form expression for the minimum cost of a minimum-time line broadcast from a terminal vertex in certain paths and relate this to costs from nearby sources

Structure of Heterogeneous Networks

Heterogeneous networks play a key role in the evolution of communities and the decisions individuals make. These networks link different types of entities, for example, people and the events they attend. Network analysis algorithms usually project such networks unto simple graphs composed of entities of a single type. In the process, they conflate relations between entities of different types and loose important structural information. We develop a mathematical framework that can be used to compactly represent and analyze heterogeneous networks that combine multiple entity and link types. We generalize Bonacich centrality, which measures connectivity between nodes by the number of paths between them, to heterogeneous networks and use this measure to study network structure. Specifically, we extend the popular modularity-maximization method for community detection to use this centrality metric. We also rank nodes based on their connectivity to other nodes. One advantage of this centrality metric is that it has a tunable parameter we can use to set the length scale of interactions. By studying how rankings change with this parameter allows us to identify important nodes in the network. We apply the proposed method to analyze the structure of several heterogeneous networks. We show that exploiting additional sources of evidence corresponding to links between, as well as among, different entity types yields new insights into network structure

Minimum-time multidrop broadcast

AbstractThe multidrop communication model assumes that a message originated by a sender is sent along a path in a network and is communicated to each site along that path. In the presence of several concurrent senders, we require that the transmission paths be vertex-disjoint. The time analysis of such communication includes both start-up time and drop-off time terms. We determine the minimum time required to broadcast a message under this communication model in several classes of graphs

Optical control plane: theory and algorithms

In this thesis we propose a novel way to achieve global network information dissemination in which some wavelengths are reserved exclusively for global control information exchange. We study the routing and wavelength assignment problem for the special communication pattern of non-blocking all-to-all broadcast in WDM optical networks. We provide efficient solutions to reduce the number of wavelengths needed for non-blocking all-to-all broadcast, in the absence of wavelength converters, for network information dissemination. We adopt an approach in which we consider all nodes to be tap-and-continue capable thus studying lighttrees rather than lightpaths. To the best of our knowledge, this thesis is the first to consider “tap-and-continue” capable nodes in the context of conflict-free all-to-all broadcast. The problem of all to-all broadcast using individual lightpaths has been proven to be an NP-complete problem [6]. We provide optimal RWA solutions for conflict-free all-to-all broadcast for some particular cases of regular topologies, namely the ring, the torus and the hypercube. We make an important contribution on hypercube decomposition into edge-disjoint structures. We also present near-optimal polynomial-time solutions for the general case of arbitrary topologies. Furthermore, we apply for the first time the “cactus” representation of all minimum edge-cuts of graphs with arbitrary topologies to the problem of all-to-all broadcast in optical networks. Using this representation recursively we obtain near-optimal results for the number of wavelengths needed by the non-blocking all-to-all broadcast. The second part of this thesis focuses on the more practical case of multi-hop RWA for non- blocking all-to-all broadcast in the presence of Optical-Electrical-Optical conversion. We propose two simple but efficient multi-hop RWA models. In addition to reducing the number of wavelengths we also concentrate on reducing the number of optical receivers, another important optical resource. We analyze these models on the ring and the hypercube, as special cases of regular topologies. Lastly, we develop a good upper-bound on the number of wavelengths in the case of non-blocking multi-hop all-to-all broadcast on networks with arbitrary topologies and offer a heuristic algorithm to achieve it. We propose a novel network partitioning method based on “virtual perfect matching” for use in the RWA heuristic algorithm

Automatic Optimisation of Reliable Collaborative Services in OLSR Mobile Ad Hoc Networks

International audienceFuture Network based Operations (NbO) will strongly rely on Mobile Ad hoc Networks (MANET), due to urban area, tactical mobility and assymetric operation management. These networks will support multiple collaborative services, such as sensor to shooters, reachback, maintenance of Common Operational Picture (COP). Both networks and services will have to be managed with no or limited operator intervention, still providing reliable behavior in spite of aggressive environments. At routing level, we present how to preserve 2-connectivity by adapting the Optimised Link State Routing Protocol (OLSR). We also introduce the concept of active subnet management to retrieve maximal operational gain from collaborative services. Following a constraint solving method, the paper shows how to maximise the subnet of actors, while satisfying 2-connectivity, reactivity and communication quality constraints. We demonstrate the approach on simulating real world NbO

Cooperative Channel State Information Dissemination Schemes in Wireless Ad-hoc Networks

This thesis considers a novel problem of obtaining global channel state information (CSI) at every node in an ad-hoc wireless network. A class of protocols for dissemination and estimation are developed which attempt to minimize the staleness of the estimates throughout the network. This thesis also provides an optimal protocol for CSI dissemination in networks with complete graph topology and a near optimal protocol in networks having incomplete graph topology. In networks with complete graph topology, the protocol for CSI dissemination is shown to have a resemblance to finding Eulerian tours in complete graphs. For networks having incomplete graph topology, a lower bound on maximum staleness is given and a near optimal algorithm based on finding minimum connected dominating sets and proper scheduling is described in this thesis

EASR: Graph-based Framework for Energy Efficient Smart Routing in MANET using Availability Zones

Energy consumption in MobileAdhoc Network (MANET) is a topic of research from more than a decade. Althoughthere are multiple archival of literatures, that have proposed variousenergy-efficient algorithms for reducing the energy consumption to improveenergy efficiency. Establishing correct and reliable route is important designissue in MANET, but a more challenging goal is to provide energy efficientroute. But, it was observed that majority of such energy efficient routingprotocols just give symptomatic solution which addresses and mitigated theenergy issues overlooking various associated issues like quality of services.Moreover, in majority of research previous studies it is found that AODV andDSDV are highly in adoption rate among the researcher for solving energy issuesusing routing protocols. This manuscript after reviewing some of thesignificant literatures in past explored issues in existing AODV and DSDVand  proposes a novel energy efficientrouting protocols by incorporating a new actor called availability zone. Theproposed model shows better energy efficiency and QoS compared to AODV andDSDV