Faster Gossiping in Bidirectional Radio Networks with Large Labels

We consider unknown ad-hoc radio networks, when the underlying network is bidirectional and nodes can have polynomially large labels. For this model, we present a deterministic protocol for gossiping which takes $O(n \lg^2 n \lg \lg n)$ rounds. This improves upon the previous best result for deterministic gossiping for this model by [Gasienec, Potapov, Pagourtizis, Deterministic Gossiping in Radio Networks with Large labels, ESA (2002)], who present a protocol of round complexity $O(n \lg^3 n \lg \lg n)$ for this problem. This resolves open problem posed in [Gasienec, Efficient gossiping in radio networks, SIROCCO (2009)], who cite bridging gap between lower and upper bounds for this problem as an important objective. We emphasize that a salient feature of our protocol is its simplicity, especially with respect to the previous best known protocol for this problem

Information Gathering in Ad-Hoc Radio Networks with Tree Topology

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

The Cost of Global Broadcast Using Abstract MAC Layers

We analyze greedy algorithms for broadcasting messages throughout a multi-hop wireless network, using a slot-based model that includes message collisions without collision detection. Our algorithms are split formally into two pieces: a high-level piece for broadcast and a low-level piece for contention management. We accomplish the split using abstract versions of the MAC layer to encapsulate the contention management. We use two different abstract MAC layers: a basic non-probabilistic one, which our contention management algorithm implements with high probability, and a probabilistic one, which our contention management algorithm implements precisely. Using this approach, we obtain the following complexity bounds: Single-message broadcast, using the basic abstract MAC layer, takes time O(D log(n/epsilon) log(Delta)) to deliver the message everywhere with probability 1 - epsilon, where D is the network diameter, n is the number of nodes, and Delta is the maximum node degree. Single-message broadcast, using the probabilistic abstract MAC layer, takes time only O((D + log(n/epsilon)) log(Delta)). For multi-message broadcast, the bounds are O((D + k' Delta) log(n/epsilon) log(Delta)) using the basic layer and O((D + k' Delta log(n/epsilon)) log(Delta)) using the probabilistic layer,for the time to deliver a single message everywhere in the presence of at most k' concurrent messages

Faster deterministic gossiping in directed ad-hoc radio networks

Abstract. We study the gossiping problem in directed ad-hoc radio networks. Our main result is a deterministic algorithm that solves this problem in an n-node network in time O(n 4/3 log 4 n). The algorithm allows the labels (identifiers) of the nodes to be polynomially large in n, and is based on a novel way of using selective families. The previous best general (i.e., dependent only on n) deterministic upper bounds were O(n 5/3 log 3 n) for networks with polynomially large node labels [1], and O(n 3/2 log 2 n) for networks with linearly large node label

Distributed computation on unreliable radio channels

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 169-175).An important topic in wireless networking is the development of reliable algorithms for environments suffering from adversarial interference. This term captures any type of channel disruption outside the control of the algorithm designer-from contention with unrelated devices to malicious jamming. In this thesis, we provide four contributions toward a comprehensive theoretical treatment of this topic. First, we detail a formal modeling framework. This framework is general enough to describe almost any radio network studied to date in the theory literature. It can also precisely capture the often subtle details of adversarial behavior. In addition, we prove a pair of composition results that allow a layered strategy for designing radio network algorithms The results can be used to combine an algorithm designed for a powerful channel with an implementation of this channel on a less powerful channel. Next, we formalize adversarial interference with the definition of the t-disrupted channel. We then define the more powerful (t, b, p)-feedback channel, and provide both a randomized and deterministic implementation of the latter using the former. To emphasize the utility of this layered approach, we provide solutions to the set agreement, gossip, and reliable broadcast problems using the powerful feedback channel. Combined with the implementation algorithms and composition results, this automatically generates solutions to these problems for the less powerful, but more realistic, t-disrupted channel. Finally, we define a variant of the modeling framework that captures the attributes of an ad hoc network, including asynchronous starts and the lack of advance knowledge of participating devices.(cont.) Within this new framework, we solve the wireless synchronization problem on a t-disrupted channel. This problem requires devices to agree on a common round numbering scheme. We conclude by discussing how to use such a solution to adapt algorithms designed for the original model to work in the ad hoc variant.by Calvin Newport.Ph.D