Isabelle Guérin-Lassous

ECOFEN: An End-to-end energy Cost mOdel and simulator For Evaluating power consumption in large-scale Networks

Wired networks are increasing in size and their power consumption is becoming a matter of concern. Evaluating the end-to-end electrical cost of new network architectures and protocols is difficult due to the lack of monitored realistic infrastructures. We propose an End-to-End energy Cost mOdel and simulator For Evaluating power consumption in large-scale Networks (ECOFEN) whose users entries are the network topology and traffic. Based on configurable measurement of different network components (routers, switches, NICs, etc.), it provides the power consumption of the overall network including the end-hosts as well as the power consumption of each equipment over time.

Energy-efficient bandwidth reservation for bulk data transfers in dedicated wired networks

The ever increasing number of Internet-connected end-hosts calls for high-performance end-to-end networks, which in turn leads to an increase in the energy consumed by the networks. Our work deals with the energy-consumption issue in dedicated networks with bandwidth provisioning and in-advance reservations of network equipments for Bulk Data transfers.First, we propose an end-to-end energy-cost model of such networks, which describes the energy consumed by a transfer for all the crossed equipments. This model is then used to develop a complete energy-efficient framework adapted to Bulk Data Transfers over dedicated networks. This framework enables switching unused network portions off during certain periods of time to save energy. This framework is also endowed with prediction algorithms to avoid useless switching off and with adaptive scheduling management to optimize the energy used by the transfers. Through network simulations, we show that, under given load and topology, the proposed framework can achieve 35% energy savings compared to the current approach, with no energy-management system.

Available bandwidth estimation in GPSR for VANETs

This paper proposes an adaptation of the collision probability used in the measure of the available bandwidth designed for Mobile Ad hoc Networks (MANETs) and which is described in ABE~\cite{abe}. Instead, we propose a new ABE+ that includes a new function to estimate the probability of losses. This new function has been specially designed for Vehicular Ad hoc Networks, to be suited to the high mobility and variable density in vehicular environments. In this analysis we do not only consider the packet size, but also other metrics, such as, density and speed of the nodes. We include the ABE+ algorithm in the forwarding decisions of the GBSR-B protocol~\cite{TrippLatin12}, which is an improvement of the well-known GPSR protocol. Finally through simulations, we compare the performance of our new ABE+ compared to the original ABE. These results show that ABE+ coupled with GBSR-B achieves a good trade-off in terms of packet losses and packet end-to-end delay.

Evaluation and comparison of MBAC solutions

Admission control is a mechanism used to restrict access to a computer network to some flows based on the current utilization level of the network resource. By regulating the number of on-going flows, admission control aims at preventing overloading, congestion and performance collapses, so that, accepted flows receive a sufficient level of Quality of Service (QoS). In this paper, we evaluate three existing measurement-based admission control (MBAC) solutions, and we compare their efficiency in the context of semantic networks. Semantic networks refer to networks that autonomously acquire a knowledge on the on-going traffic as well as on any new incoming flow requesting admission. In this framework, we configure the three MBAC solutions in a way they have an identical target in terms of maximum tolerable packet loss rate or maximum tolerable packet queueing delay. We evaluate the solutions performance analytically or by simulation, and compare them to the “ideal” admission control. The results show that one solution, outperforms the others in meeting the target performance.1

KBAC: Knowledge-Based Admission Control

Many methods have been proposed in the literature to perform admission control in order to provide a sufficient level of Quality of Service (QoS) to accepted flows. In this paper, we introduce a novel data-driven method based on a time-varying model that we refer to as Knowledge-Based Admission Control solution (KBAC). Our KBAC solution consists of three main stages: (i) collect measurements on the on-going traffic over the communication link; (ii) maintain an up-to-date broad view of the link behavior, and feed it to a Knowledge Plane; (iii) model the observed link behavior by a mono-server queue whose parameters are set automatically and which predicts the expected QoS if a flow requesting admission were to be accepted. Our KBAC solution provides a probabilistic guarantee whose admission threshold is either expressed, as a bounded delay or as a bounded loss rate. We run extensive simulations to assess the behavior of our KBAC solution in the case of a delay threshold. The results show that our KBAC solution leads to a good trade-off between flow performance and resource utilization. This ability stems from the quick and automatic adjustment of its admission policy according to the actual variations on the traffic conditions.

Comparison of Two Self-organization and Hierarchical Routing Protocols for Ad Hoc Networks

In this article, we compare two self-organization and hierarchical routing protocols for ad hoc networks. These two protocols apply the reverse approach from the classical one, since they use a reactive routing protocol inside the clusters and a proactive routing protocol between the clusters. We compare them regarding the cluster organization they provide and the routing that is then performed over it. This study gives an idea of the impact of the use of recursiveness and of the partition of the DHT on self-organization and hierarchical routing in ad hoc networks.

Hierarchical modeling of IEEE 802.11 multi-hop wireless networks

IEEE 802.11 is implemented in many wireless networks, including multi-hop networks where communications between nodes are conveyed along a chain. We present a modeling framework to evaluate the performance of flows conveyed through such a chain. Our framework is based on a hierarchical modeling composed of two levels. The lower level is dedicated to the modeling of each node, while the upper level matches the actual topology of the chain. Our approach can handle different topologies, takes into account Bit Error Rate and can be applied to multi-hop flows with rates ranging from light to heavy workloads. We assess the ability of our model to evaluate loss rate, throughput, and end-to-end delay experienced by flows on a simple scenario, where the number of nodes is limited to three. Numerical results show that our model accurately approximates the performance of flows with a relative error typically less than 10%.

Towards a passive measurement-based estimator for the standard deviation of the end-to-end delay

In this paper, we propose an algorithm to estimate the second moment of the end-to-end delay experienced by the packets of a flow based only on delay measurements locally collected by the network nodes. Our solution estimates the standard deviation of the end-to-end delay in an easy and computationally efficient way. Based on thousands of simulations using a real-life trace, our solution is found to be accurate, typically differing by only a few percent from the actual value of the standard deviation of the end-to-end delay.

Physics-Based Swarm Intelligence for Disaster Relief Communications

This study explores how a swarm of aerial mobile vehicles can provide network connectivity and meet the stringent requirements of public protection and disaster relief operations. In this context, we design a physics-based controlled mobility strategy, which we name the extended Virtual Force Protocol (VFPe), allowing self-propelled nodes, and in particular here unmanned aerial vehicles, to fly autonomously and cooperatively. In this way, ground devices scattered on the operation site may establish communications through the wireless multi-hop communication routes formed by the network of aerial nodes. We further investigate through simulations the behavior of the VFPe protocol, notably focusing on the way node location information is disseminated into the network as well as on the impact of the number of exploration nodes on the overall network performance.

Modeling of IEEE 802.11 multi-hop wireless chains with hidden nodes

In this paper, we follow up an existing modeling framework to analytically evaluate the performance of multi-hop flows along a wireless chain of four nodes. The proposed model accounts for a non-perfect physical layer, handles the hidden node problem, and is applicable under workload conditions ranging from flow(s) with low intensity to flow(s) causing the network to saturate. Its solution is easily and quickly obtained and delivers estimates for the expected throughput and for the datagram loss probability of the chain with a good accuracy.