Buy The Rumor, Sell The News! What About Takeover Rumors?

This paper attempts to quantify the short-term impact of takeover rumors on target stock prices. The study was conducted on the French stock market between 1997 and 2011 and concerns 200 rumors that appeared in the media (news agencies, newspapers, and Web sites). Our results show that this particular kind of information has a significant impact on the prices of target companies around and after the date of rumor appearance. The best performance of target shares is observed 50 days after the dissemination of the rumors in the media, with an average return of 4%. This performance is mainly explained by three components:  credibility, rumor characteristics, and the anticipated effects of the takeover bid.

Analysis of Mobile Ad-hoc Network Routing Protocols in Random Graph Models

We analyze the performance of ad-hoc routing as defined in MANet IETF working group in the random graph model. In particular we analyze the performance of a reactive protocol DSR and of a pro-active protocol OLSR. The random graph model is defined by the number of nodes n, and link probabili- ty p. We give the asymptotic evaluation of the flooding distance which is used in DSR and the multi-point relay flooding used in OLSR

TAR channel access mechanism for VANET safety-critical situations

International audienceVehicular Ad-hoc Network (VANET) is among the most relevant forms of mobile ad-hoc networks. VANET helps improving traffic safety and efficiency. By exchanging information between each others, vehicles can warn drivers or even prepare for dangerous situation. These warnings can be about critical situations like vehicles merging in a highway. Detecting and warning about such situations require a reliable communication between vehicles increasing thus the need for an efficient medium access control (MAC) protocol. In this paper, we propose to apply Transmit And Reserve (TAR), an ad-hoc medium access protocol, to vehicular communications. We integrated TAR into NS-3 simulator and evaluated its performance compared to IEEE 802.11 DCF in a vehicular network context. The evaluation results show that TAR is an efficient medium access protocol for VANET critical situations as it increases the throughput reduces the medium access delays and provides close to optimal short term fairness

Increasing Reliability of a TSCH Network for the Industry 4.0

International audienceTime Slotted Channel Hopping (TSCH) networks are emerging as a promising technology for the Internet of Things and the Industry 4.0 where ease of deployment, reliability, short latency, flexibility and adaptivity are required. Our goal is to improve reliability of data gathering in such wireless sensor networks. We present three redundancy patterns to build a reliable path from a source to a destination. The first one is the well-known two node-Disjoint paths. The second one is based on a Triangular pattern, and the third one on a Braided pattern. A comparative evaluation is carried out to analyze the reliability achieved, the number of failures tolerated, the number of message copies generated and the energy consumed by each node to ensure that at least one copy of the message is delivered to the destination. These results are validated by simulations

OLSR improvement for distributed traffic applications

PosterInternational audienceThis paper presents the experimental framework currently being developed at INRIA on mobile traffic applications using ad hoc communication. In this paper we propose a set of modifications to the OLSR protocol in order to adapt it to vehicle ad hoc networks. This work is the fruit of a collaboration between two INRIA research teams: HIPERCOM and IMARA. HIPERCOM is working on ad hoc routing protocols and IMARA is working on intelligent vehicles

Duplicate address detection and autoconfiguration in OLSR

Mobile Ad hoc NETworks (MANETs) are infrastructure-free, highly dynamic wireless networks, where central administration or configuration by the user is very difficult. In hardwired networks nodes usually rely on a centralized server and use a dynamic host configuration protocol, like DHCP , to acquire an IP address. Such a solution cannot be deployed in MANETs due to the unavailability of any centralized DHCP server. For small scale MANETs, it may be possible to allocate free IP addresses manually. However, the procedure becomes impractical for a large-scale or open system where mobile nodes are free to join and leave. Most of the autoconfiguration algorithms proposed for ad hoc networks are independent of the routing protocols and therefore, generate a significant overhead. Using the genuine optimization of the underlying routing protocol can significantly reduce the autoconfiguration overhead. One of the MANET protocols which have been recently promoted to RFC is the OLSR routing protocol , on which this article focuses. This article aims at complementing the OLSR routing protocol specifications to handle autoconfiguration. The corner stone of this autoconfiguration protocol is an advanced duplicate address detection algorithm. Under well defined assumptions, we prove the correctness of the the proposed autoconfiguration protocol

An Advanced Configuration and Duplicate Address Detection mechanism for a multi-interface OLSR Network

Mobile Ad hoc NETworks (MANETs) are infrastructure-free, highly dynamic wireless networks, where central administration or configuration by the user is very difficult. In hardwired networks nodes usually rely on a centralized server and use a dynamic host configuration protocol, like DHCP, to acquire an IP address. Such a solution cannot be deployed in MANETs due to the unavailability of any centralized DHCP server. For small scale MANETs, it may be possible to allocate free IP addresses manually. However, the procedure becomes impractical for a large-scale or open system where mobile nodes are free to join and leave. Numerous dynamic addressing schemes for ad hoc networks have been proposed. These approaches differ in a wide range of aspects, such as the usage of centralized servers or full decentralization, hierarchical structure or flat network organization, and explicit or implicit duplicate address detection. In this paper we will present a complete and optimized version of the auto-configuration solutions for OLSR , that we have already proposed in and . This solution works in the case of a nodes having multiple interfaces, and is based on an efficient Duplicate Address Detection(DAD) algorithm which takes advantage of the genuine optimization of the OLSR routing protocol. A proof of the correct operation of the proposed solution is given and the communication overhead induced is evaluated

Multicast Optimized Link State Routing

This document describes the Multicast extension for the Optimized Link State Routing protocol (MOLSR). MOLSR is in charge of building a multicast structure in order to route multicast traffic in an ad-hoc network. MOLSR is designed for mobile multicast routers, and works in a heterogenous network composed of simple unicast OLSR routers, MOLSR routers and hosts. In the last part of this document we introduce also a Wireless Internet Group Management Protocol (WIGMP). It offers the possibility for OLSR nodes (without multicast capabilities) to join multicast groups and receive multicast data

Ad hoc communication between intelligent vehicles

International audienceWireless ad hoc networks are composed of mobile autonomous nodes, and can work without any fiwed infrastructure or centralised entity. Moreover, they are adaptive and self-configurating. These kind of networks are well suited for inter-vehicles communication and information exchange (used for tele-traffic management for example). Depending on the context, some of these information need to be sent to almost all the network, and other information need to be sent to a smaller subset of vehicles

Securing the OLSR routing protocol with or without compromised nodes in the network

The primary issue with respect to securing Mobile Ad hoc NETworks (MANETs) is that of ensuring network integrity even when the network is subject to attacks to break its connectivity. In this research report, we study how to secure the OLSR routing protocol . We first analyse the attacks that can be launched against the network integrity. We then present mechanisms for ensuring that only ``trusted'' nodes are admitted into the network and, subsequently, are the only nodes used to forward traffic. We also present mechanisms for detecting and dealing with scenarios where ``trusted'' nodes have become compromised