Using OLSR Multipoint Relays (MPRs) to estimate node positions in a Wireless Mesh Network

In this paper we address in this paper the problem of nodes localization in wireless heterogeneous networks, focussing particularly on selection methods to estimate position. The OLSR routing protocol uses special nodes called Multipoint Relay (MPR) nodes to broadcast control messages within the network. We propose a novel approach based on using these Multipoint Relay (MPR) nodes as anchor nodes to estimate nodes positions. We evaluate its performance by simulation and compare it to other selection techniques such as convex hull selection and greedy selection

Geometric Bucket Trees: Analysis of Linear Bucket Tree

International audienceWe analyse the average number of buckets in a Linear Bucket tree created by $n$ points uniformly dispatched on an interval of length $y$. A new bucket is created when a point does not fall in an existing bucket. The bucket is the interval of length 2 centered on the point. We illustrate this concept by an interesting tale of how the moon's surface took on its present form. Thanks to an explicit Laplace transform of the Poissonized sequence, and the use of dePoissonization tools, we obtain the explicit asymptotic expansions of the average number of buckets in most of the asymptotic regimes relative to $n$ and $y$

An Efficient Simulation Model for Wireless LANs Applied to the IEEE 802.11 Standard

In this research report, we propose a simple simulation model for wireless LANs. In wireless LANs, contrary to LANs different transmission results can be observed by network nodes. This phenomenon is the result of radio propagation laws where the signal decay is by far more important than on cables. This leads to new and interesting modelization and simulation problems. In this article we propose a simple but general physical model to take into account radio propagation. We then apply this model to the study of the IEEE 802.11 standard. We show how IEEE 802.11 can be efficiently modeled and simulated. This allows us to offer a detailed study of the standard. We will give performance evaluations of the IEEE 802.11 DS standard with transmisson rate 1, 2, 5.5 or 11 Mbit/s which take into account the exact protocol overhead. We also study special behaviour as broadcast transmission, performance with hidden nodes, spatial reuse

Red list and checklist of the planthoppers and leafhoppers

Erstmalig wird für das Land Berlin eine Rote Liste der Zikaden vorgelegt, außerdem eine aktualisierte Gesamtartenliste. Von insgesamt 337 Arten gelten demnach 39 Arten als verschollen, 25 als vom Aussterben bedroht (Kategorie 1), 5 als stark gefährdet (Kategorie 2) und 15 als gefährdet (Kategorie 3). 20 Arten gelten als gefährdet mit unbekannten Ausmaß (Kategorie G), 14 Arten als extrem selten (Kategorie R), 12 Arten wurden auf die Vorwarnliste gesetzt (Kategorie V) und für 14 Arten wurde der Befund „Daten defizitär“ gestellt (Kategorie D). Für drei Arten wurde eine besondere Verantwortlichkeit Berlins festgestellt, die Schmuckseggenzirpe (Cicadula ornata), die Braune Kragenzirpe (Anoplotettix fuscovenosus) und die Dünenzirpe (Pinumius areatus). Die beiden erstgenannten kommen deutschlandweit nur in Berlin vor, die letztere weist hier Schwerpunktvorkommen auf.We present, for the first time, a Red List of the planthoppers and leafhoppers of the federal state of Berlin, as well as an updated checklist. Altogether 337 species have been recorded so far, 39 of them are considered as regionally extinct (category 0), 25 as critically endangered (category 1), 5 as endangered (category 2), 15 as vulnerable (category 3), 20 as indeterminate (category G), 14 rare (category R), 12 near-threatened (category V). The data base is deficient (category D) for 14 further species. Berlin is assigned a particular responsibility for conservation of Cicadula ornata, Anoplotettix fuscovenosus and Pinumius areatus. The first two species are in Germany so far only known from Berlin. For the latter species most recent German records are from Berlin

In memoriam Prof. Dr. rer. nat. Hildegard Strübing (8.5.1922 - 18.5.2013), with a complete bibliography

An obituary for Hildegard Strübing (1922 - 2013

Throughput in multihop CSMA mobile adhoc network

A lot of research has been done in routing protocols for ad-hoc network especially at the IETF in the working group MANET. These studies have mostly focused on the conception of routing protocols for mobile radio networks where the radio channel capacity is generally limited. The present article does not target the study of these routing protocols but investigate how carrier sense multiple access (CSMA) protocols can be tuned to optimize the network throughput. We buid two models of interference of simultaneous transmissions and conduct simple computations to guide our optimizations. The first interference model only considers the strongest interferer as the second one takes into account all the contributions. We use simulations to test our optimizations results. The result of this paper is a guide to optimize CSMA multihop networks; the obtained results show that a good tuning of CSMA protocols in term of carrier sense threshold and transmission range allows one to gain a lot of network throughput (up to 9

Vehicular Ad-hoc Networks: Point-to-Point, Emergency and Broadcast Communications

International audienceThe aim of this paper is to analyze the Aloha medium access (MAC) scheme in one-dimensional, linear networks, which might be an appropriate assumption for Vehicular Ad-hoc NETworks (VANETs). The locations of the vehicles are assumed to follow a homegeneous Poisson point process. Assuming powerlaw mean path-loss and independent point-to-point fading we study performance metrics based on the signal-over-interference and noise ratio (SINR). In contrast to previous studies where the receivers are at a fixed distance from the transmitter, we assume here that the receivers are the nearest neighbors of the transmitters in the Poisson process and in a given direction. We derive closed formulas for the capture probability and for the density of progress of a packet sent by a given node. We compute the mean delay to send a packet transmitted at each slot until successful reception. We also evaluate an upper bound to discover the neighborhood within a given space interval. We show that we can include noise in the previous models

Stack Algorithms in Implicit Framing, Free Access and Blocked Access for CATV Networks

In this paper we present in the framework of access protocols for Cable TV (CATV) networks performant and easy implementation of stack algorithms with an implicit framing scheme. We use a stack algorithm with a single interleaved process in a free or blocked access mode. We show that the blocked access can be implemented to have a deterministic behaviour. We show that a dynamic tuning of the access persistence parameter $R$ improves the performance both in terms of throughput and delays