5,409 research outputs found

    Information Gathering in Ad-Hoc Radio Networks with Tree Topology

    Full text link
    We study the problem of information gathering in ad-hoc radio networks without collision detection, focussing on the case when the network forms a tree, with edges directed towards the root. Initially, each node has a piece of information that we refer to as a rumor. Our goal is to design protocols that deliver all rumors to the root of the tree as quickly as possible. The protocol must complete this task within its allotted time even though the actual tree topology is unknown when the computation starts. In the deterministic case, assuming that the nodes are labeled with small integers, we give an O(n)-time protocol that uses unbounded messages, and an O(n log n)-time protocol using bounded messages, where any message can include only one rumor. We also consider fire-and-forward protocols, in which a node can only transmit its own rumor or the rumor received in the previous step. We give a deterministic fire-and- forward protocol with running time O(n^1.5), and we show that it is asymptotically optimal. We then study randomized algorithms where the nodes are not labelled. In this model, we give an O(n log n)-time protocol and we prove that this bound is asymptotically optimal

    Information gathering in ad-hoc radio networks with tree topology

    Get PDF
    We study the problem of information gathering in ad-hoc radio networks, focusing on the case when the network forms a tree, with edges directed towards the root. Initially, each node has a rumor, and we aim to deliver all rumors to the root as quickly as possible without knowing the tree's topology in advance. In the deterministic case, where nodes are labeled with small integers, we give an -time protocol for the model with unbounded message size, and an -time protocol for bounded message size. We also consider fire-and-forward protocols, in which nodes can transmit only their own rumor or the rumor received in the previous step. We give a deterministic fire-and-forward protocol with running time , and show that it is asymptotically optimal. We also present a randomized -time protocol in the model without node labels or aggregation, and show that it is asymptotically optimal

    Latency Optimal Broadcasting in Noisy Wireless Mesh Networks

    Full text link
    In this paper, we adopt a new noisy wireless network model introduced very recently by Censor-Hillel et al. in [ACM PODC 2017, CHHZ17]. More specifically, for a given noise parameter p[0,1],p\in [0,1], any sender has a probability of pp of transmitting noise or any receiver of a single transmission in its neighborhood has a probability pp of receiving noise. In this paper, we first propose a new asymptotically latency-optimal approximation algorithm (under faultless model) that can complete single-message broadcasting task in D+O(log2n)D+O(\log^2 n) time units/rounds in any WMN of size n,n, and diameter DD. We then show this diameter-linear broadcasting algorithm remains robust under the noisy wireless network model and also improves the currently best known result in CHHZ17 by a Θ(loglogn)\Theta(\log\log n) factor. In this paper, we also further extend our robust single-message broadcasting algorithm to kk multi-message broadcasting scenario and show it can broadcast kk messages in O(D+klogn+log2n)O(D+k\log n+\log^2 n) time rounds. This new robust multi-message broadcasting scheme is not only asymptotically optimal but also answers affirmatively the problem left open in CHHZ17 on the existence of an algorithm that is robust to sender and receiver faults and can broadcast kk messages in O(D+klogn+polylog(n))O(D+k\log n + polylog(n)) time rounds.Comment: arXiv admin note: text overlap with arXiv:1705.07369 by other author

    Message and time efficient multi-broadcast schemes

    Full text link
    We consider message and time efficient broadcasting and multi-broadcasting in wireless ad-hoc networks, where a subset of nodes, each with a unique rumor, wish to broadcast their rumors to all destinations while minimizing the total number of transmissions and total time until all rumors arrive to their destination. Under centralized settings, we introduce a novel approximation algorithm that provides almost optimal results with respect to the number of transmissions and total time, separately. Later on, we show how to efficiently implement this algorithm under distributed settings, where the nodes have only local information about their surroundings. In addition, we show multiple approximation techniques based on the network collision detection capabilities and explain how to calibrate the algorithms' parameters to produce optimal results for time and messages.Comment: In Proceedings FOMC 2013, arXiv:1310.459

    Energy Consumption Of Visual Sensor Networks: Impact Of Spatio-Temporal Coverage

    Get PDF
    Wireless visual sensor networks (VSNs) are expected to play a major role in future IEEE 802.15.4 personal area networks (PAN) under recently-established collision-free medium access control (MAC) protocols, such as the IEEE 802.15.4e-2012 MAC. In such environments, the VSN energy consumption is affected by the number of camera sensors deployed (spatial coverage), as well as the number of captured video frames out of which each node processes and transmits data (temporal coverage). In this paper, we explore this aspect for uniformly-formed VSNs, i.e., networks comprising identical wireless visual sensor nodes connected to a collection node via a balanced cluster-tree topology, with each node producing independent identically-distributed bitstream sizes after processing the video frames captured within each network activation interval. We derive analytic results for the energy-optimal spatio-temporal coverage parameters of such VSNs under a-priori known bounds for the number of frames to process per sensor and the number of nodes to deploy within each tier of the VSN. Our results are parametric to the probability density function characterizing the bitstream size produced by each node and the energy consumption rates of the system of interest. Experimental results reveal that our analytic results are always within 7% of the energy consumption measurements for a wide range of settings. In addition, results obtained via a multimedia subsystem show that the optimal spatio-temporal settings derived by the proposed framework allow for substantial reduction of energy consumption in comparison to ad-hoc settings. As such, our analytic modeling is useful for early-stage studies of possible VSN deployments under collision-free MAC protocols prior to costly and time-consuming experiments in the field.Comment: to appear in IEEE Transactions on Circuits and Systems for Video Technology, 201
    corecore