Serge Fdida

SIMPS: using sociology for personal mobility

Assessing mobility in a thorough fashion is a crucial step toward more efficient mobile network design. Recent research on mobility has focused on two main points: analyzing models and studying their impact on data transport. These works investigate the consequences of mobility. In this paper, instead, we focus on the causes of mobility. Starting from established research in sociology, we propose SIMPS, a mobility model of human crowds with pedestrian motion. This model defines a process called sociostation, rendered by two complimentary behaviors, namely socialize and isolate, that regulate an individual with regard to her/his own sociability level. SIMPS leads to results that agree with scaling laws observed both in small-scale and large-scale human motion. Although our model defines only two simple individual behaviors, we observe many emerging collective behaviors (group formation/splitting, path formation, and evolution).

A preferential attachment gathering mobility model

In this letter we propose a mobility model using preferential attachment via objects called attractors. We introduce a new kind of mobility we call Gathering Mobility, where nodes, although independent, exhibit a collective behavior. We show that this model, called Pragma, achieves a scale-free spatial distribution in the situation of population growth.

GPS-free-free positioning system for wireless sensor networks

Positioning systems are important components of many communication architectures. The traditional global positioning system (GPS) is impractical in many situations, which makes the need for relative measurement-based approaches. Existing relative solutions lead to good results but generally require that nodes are embedded with specific capabilities. in this paper, we propose GPS-free-free, a simple positioning system based on distances in number of hops between nodes. GPS-free-free make very loose assumptions (only neighborhood discovery) and does not require the computation of complex algorithms. We show through simulations that GPS-free-free leads to good placement results at very low signaling over-head.

Reconsidering microscopic mobility modeling for self-organizing networks

Mobility modeling is a critical step in the design of mobile self-organizing networks. With the emergence of small-scale and short-range wireless communication devices, the communication sphere shrinks (radio range or sensing range), which leads to an increase in the need for fine-grained representations of mobility. In fact, mobility models must scale accordingly to the application and reflect real scenarios in which wireless devices are deployed. Currently, self-organizing networks are evaluated using mobility models that do not represent the precise motion of mobile individuals at small scales. In this article we present a new class of mobility models, namely, behavioral mobility (BM) models, which decomposes mobility into simple atomic individual behaviors. Combined, these behaviors yield realistic displacement patterns by reproducing the mobility observed at small scales in every day life, in both space and time

Evaluation of cross-layer rate-aware routing in a wireless mesh network test bed

Real deployments of wireless multihop networks, by Internet service providers (ISPs), have been slowed down by their poor performance and unreliability. The research community has already proved that efficient cross-layer routing, in particular rate-aware routing, can significantly improve performances. Nevertheless, this work has been done mainly by simulations, seldom being implemented in a real environment. We present in this paper the results we obtained by comparing the performances of the traditional routing approach based on the hop-count metric and the cross-layer routing approach based on the transmission rate metric. These measurements have been done on the MeshDVNet test bed we deployed in our laboratory. As a routing protocol, we used two versions (with and without cross-layer metric) of MeshDV, a simple routing protocol expressly designed for wireless mesh networks (WMNs). As our tests clearly show, cross-layer rate-aware metric gives important improvements, in both connectivity and throughput.

Dissecting the routing architecture of self-organizing networks

The proper operation of self-organizing networks (SONs) relies on the autonomous behavior of their individual nodes. Routing in such networks has been a challenging task since their conception, due to their nontraditional characteristics and design requirements. Although a large amount of routing architectures and protocols for SONs has been proposed, very little work has been done on the fundamental characteristics that make a routing strategy efficient for a particular network and/or design requirement. Contrary to traditional techniques where the routing architecture is structured as a single unit, we suggest in this article that routing be thought of as a combination of four main architectural components, namely, addressing, dissemination, discovery, and forwarding. This logical decomposition offers significant advantages from both the analysis and the design perspectives. We conclude from our observations that routing architectures should be scenario-driven, in the sense that the configuration parameters are not necessarily universally good for all application scenarios

Multicast for RSVP switching: An extended multicast model with QoS for label swapping in an IP over ATM environment

The ubiquity of IP associated with the acknowledgment of ATM as a key switching technology has motivated an increasing interest towards the design of a more efficient way of operating IP over ATM networks. This approach is known under the name Label Swapping. A few studies have addressed the primary issue of providing simultaneously quality of service and multicast. We propose a solution where we mix an RSVP architecture with one Label Swapping technique called IP Switching. We discuss problems that arise when using cut-through associated with an RSVP multicast model and propose an application for an IPv6 environment over an ATM switching hardware.

Implicit merging of overlapping spontaneous networks [mobile ad hoc networks]

Due to mobility, spontaneous networks composed of nodes following similar group mobility patterns are likely to overlap. Previous solutions invariably considered overlapping as a permanent state where the networks combine to form a new network. In this paper, we propose a more realistic model where merging is either permanent or transient. Our contributions are twofold. First, we introduce a methodology to identify transient merging and detect implicit permanent merging. Second, we propose an efficient routing protocol between merging networks while in the transient state. Our approach is completely distributed and incurs low routing control overhead. We also investigate a solution to prevent respective intra-network communications from interfering.

Practical DHT-based location service for wireless mesh networks

Mobility management in Wireless Mesh Networks (WMN) is a hot topic still lacking a final, widely accepted, and deployed solution. The major drawbacks of existing proposals is the fact that they rely on some sort of flooding-based technique and very often they need support from end-users devices. Flooding in wireless environments leads to increased latency and broadcast storm problems, thus providing low performances. In this paper, we argue that a DHT-based approach can overcome such limitations and provide an effective solution to the mobility management problem. A preliminary evaluation of our DHT-based scheme on a real WMN test-bed shows encouraging results when compared to previous solutions.

An Absration Layer for Neighborhood Discovery and Cross-Layer Metrics

Topology-awareness is an important feature of communication algorithms and protocols for wireless multi-hop networks. In its basic form, topology-awareness requires nodes to know their immediate neighbors and, if possible, the quality of the links between them. In general, neighborhood discovery is done by routing protocols; the problem with such an approach is that fundamental changes in node characteristics require revisiting the routing protocol, especially if this latter relies on cross-layer metrics. In this paper, we propose an abstraction layer that performs neighborhood discovery and link quality assessment. In this way, neighborhood discovery is decoupled from the upper layers. Our abstraction layer stands as an active building block for the implementation of routing protocols or any other IEEE 802.11 communication algorithm for wireless multi-hop networks. It provides an updated list of neighbors, along with several statistics about link quality that can be used, for instance, to compute cross-layer metrics.