Line broadcasting in cycles

AbstractBroadcasting is the process of transmitting information from an originating node (processor) in a network to all other nodes in the network. A local broadcast scheme only allows a node to send information along single communication links to adjacent nodes, while a line broadcast scheme allows nodes to use paths of several communication links to call distant nodes. The minimum time possible for broadcasting in a network of n nodes when no node is involved in more than one communication at any given time is ⌊ log n⌋ phases. Local broadcasting is not sufficient, in general, for broadcasting to be completed in minimum time; line broadcasting is always sufficient. An optimal line broadcast is a minimum-time broadcast that uses the smallest possible total number of communication links. In this paper, we give a complete characterization of optimal line broadcasting in cycles, and we develop efficient methods for constructing optimal line broadcast schemes

Broadcasting in cycles with chords

Broadcasting is the process of information dissemination in which one node, the originator, knows a single piece of information and using a series of calls must inform every other node in the network of this information. We assume that at any given time, a node can communicate the message to another node, with which it shares an edge, by acting as either a sender or receiver, but not both. Multiple message broadcasting considers the case when the originator has m messages, where m \u3e 1, to disseminate. Whereas broadcasting limits the communication of a message from one node to another node via a single edge, line broadcasting allows one node to send a message to any other node in the network as long as a simple path exists between the sending node and the receiving node and every edge along the path is not in use.;In this dissertation, we consider the problem of broadcasting in a cycle with chords and we develop broadcast schemes for this type of network.;We begin by investigating the problem of broadcasting in a cycle with one and two chords, respectively. Then, we consider the problem of multiple message broadcasting in cycles with one and two chords. Finally, we consider the problem of line broadcasting in cycles with chords.;Through our investigations, we develop two algorithms for the problem of broadcasting in a cycle with one and two chords, respectively and we analyze the correctness and complexity of these algorithms. Then, we discuss problems associated with multiple message broadcasting in cycles with one and two chords. Finally, we use techniques developed for line broadcasting in cycles to create minimum time broadcast schemes for cycles through the addition of chords.;Using techniques developed in this dissertation, we are able to broadcast in minimum time in cycles with chords. In cycles whose size is a power of 2, we have proved that the number of chords that we add to the cycle is the minimum number of chords required to broadcast in minimum time in such a cycle

Assessment of radio frequency exposures in schools, homes, and public places in Belgium

Characterization of exposure from emerging radio frequency (RF) technologies in areas where children are present is important. Exposure to RF electromagnetic fields (EMF) was assessed in three "sensitive" microenvironments; namely, schools, homes, and public places located in urban environments and compared to exposure in offices. In situ assessment was conducted by performing spatial broadband and accurate narrowband measurements, providing 6-min averaged electric-field strengths. A distinction between internal (transmitters that are located indoors) and external (outdoor sources from broadcasting and telecommunication) sources was made. Ninety-four percent of the broadband measurements were below 1 V m(-1). The average and maximal total electric-field values in schools, homes, and public places were 0.2 and 3.2 V m(-1) (WiFi), 0.1 and 1.1 V m(-1) (telecommunication), and 0.6 and 2.4 V m(-1) (telecommunication), respectively, while for offices, average and maximal exposure were 0.9 and 3.3 V m(-1) (telecommunication), satisfying the ICNIRP reference levels. In the schools considered, the highest maximal and average field values were due to internal signals (WiFi). In the homes, public places, and offices considered, the highestmaximal and average field values originated from telecommunication signals. Lowest exposures were obtained in homes. Internal sources contributed on average more indoors (31.2%) than outdoors (2.3%), while the average contributions of external sources (broadcast and telecommunication sources) were higher outdoors (97.7%) than at indoor positions (68.8%). FM, GSM, and UMTS dominate the total downlink exposure in the outdoor measurements. In indoor measurements, FM, GSM, and WiFi dominate the total exposure. The average contribution of the emerging technology LTE was only 0.6%

Making Transport Safer: V2V-Based Automated Emergency Braking System

An important goal in the field of intelligent transportation systems (ITS) is to provide driving aids aimed at preventing accidents and reducing the number of traffic victims. The commonest traffic accidents in urban areas are due to sudden braking that demands a very fast response on the part of drivers. Attempts to solve this problem have motivated many ITS advances including the detection of the intention of surrounding cars using lasers, radars or cameras. However, this might not be enough to increase safety when there is a danger of collision. Vehicle to vehicle communications are needed to ensure that the other intentions of cars are also available. The article describes the development of a controller to perform an emergency stop via an electro-hydraulic braking system employed on dry asphalt. An original V2V communication scheme based on WiFi cards has been used for broadcasting positioning information to other vehicles. The reliability of the scheme has been theoretically analyzed to estimate its performance when the number of vehicles involved is much higher. This controller has been incorporated into the AUTOPIA program control for automatic cars. The system has been implemented in Citroën C3 Pluriel, and various tests were performed to evaluate its operation

Combinatorial Channel Signature Modulation for Wireless ad-hoc Networks

In this paper we introduce a novel modulation and multiplexing method which facilitates highly efficient and simultaneous communication between multiple terminals in wireless ad-hoc networks. We term this method Combinatorial Channel Signature Modulation (CCSM). The CCSM method is particularly efficient in situations where communicating nodes operate in highly time dispersive environments. This is all achieved with a minimal MAC layer overhead, since all users are allowed to transmit and receive at the same time/frequency (full simultaneous duplex). The CCSM method has its roots in sparse modelling and the receiver is based on compressive sampling techniques. Towards this end, we develop a new low complexity algorithm termed Group Subspace Pursuit. Our analysis suggests that CCSM at least doubles the throughput when compared to the state-of-the art.Comment: 6 pages, 7 figures, to appear in IEEE International Conference on Communications ICC 201

The dynamics of television advertising with boundedly rational consumers

The paper adapts a static model of television advertising into a dynamic scenario. In its original form, the model consists on a profit maximization problem of a television network working in a competitive environment. The network sells commercial time to advertisers and tries to minimize the effects of viewers’ aversion to ads. Viewers are assumed heterogeneous with regard to the preferences over the types of products companies sell through ad time. Into this framework we introduce an intertemporal rule reflecting the possible preference changes of consumers (these are boundedly rational and their utility for different types of products varies over time). The introduction of the intertemporal rule originates interesting dynamic results, namely in what concerns the evolution over time of crucial variables like the total time of broadcasting that networks allocate to advertising or the amount of revenues that satisfies the profit maximization condition. As in the original model, attention will be given to the possibility, that cable television allows, of ad addressability.Television advertising; Networks’ profit maximization; Heterogeneous viewers; Ad addressability; Bounded rationality; Nonlinear dynamics