Networked Drones for Industrial Emergency Events

Uncontrolled emissions of gases from industrial accidents and disasters result in huge loss of life and property. Such extreme events require a quick and reliable survey of the site for effective rescue strategy planning. To achieve these goals, a network of unmanned aerial vehicles can be deployed that survey the affected region and identify safe and danger zones. Although single UAV-based systems for gas sensing applications are well-studied in literature, research on the deployment of a UAV network for such applications, which is more robust and fault tolerant, is still in infancy. The objective of this project is to design a system that can be deployed in emergency situations to provide a quick survey and identification of safe and dangerous zones in a given region that contains a toxic plume without making any assumptions about plume location. We focus on an end-to-end solution and formulate a two-phase strategy that can not only guarantee detection/acquisition of plume but also its characterization with high spatial resolution. To guarantee coverage of the region with a certain spatial resolution, we set up a vehicle routing problem. To overcome the limitations imposed by limited range of sensors and drone resources, we estimate the concentration map by using Gaussian kernel extrapolation. Finally, we evaluate the suggested framework in simulations. Our results suggest that this two-phase strategy not only gives better error performance but is also more efficient in terms of mission time. Moreover, the comparison between 2-phase random search and 2-phase uniform coverage suggest that the latter is better for single drone systems whereas for multiple drones the former gives reasonable performance at low computational cost

Elastic Rate Limiting for Spatially Biased Wireless Mesh Networks

International audienceIEEE 802.11-based mesh networks can yield a throughput distribution among nodes that is spatially biased, with traffic originating from nodes that directly communicate with the gateway obtaining higher throughput than all other upstream traffic. In particular, if single-hop nodes fully utilize the gateway's resources, all other nodes communicating with the same gateway will attain very little (if any) throughput. In this paper, we show that it is sufficient to rate limit the single-hop nodes in order to give transmission opportunities to all other nodes. Based on this observation, we develop a new rate limiting scheme for 802.11 mesh networks, which counters the spatial bias effect and does not require, in principle, any control overhead. Our rate control mechanism is based on three key techniques. First, we exploit the system's inherent priority nature and control the throughput of the spatially disadvantaged nodes by only controlling the transmission rate of the spatially advantaged nodes. Namely, the single-hop nodes collectively behave as a proxy controller for multi-hop nodes in order to achieve the desired bandwidth distribution. Second, we devise a rate limiting scheme that enforces a utilization threshold for advantaged single-hop traffic and guarantees a small portion of the gateway resources for the disadvantaged multi-hop traffic. We infer demand for multi-hop flow bandwidth whenever gateway resource usage exceeds this threshold, and subsequently reduce the rates of the spatially advantaged single-hop nodes. Third, since the more bandwidth the spatially disadvantaged nodes attain, the easier they can signal their demands, we allow the bandwidth unavailable for the advantaged nodes to be elastic, i.e., the more the disadvantaged flows use the gateway resources, the higher the utilization threshold is. We develop an analytical model to study a system characterized by such priority, dynamic utilization thresholds, and control by proxy. Moreover, we use simulations to evaluate the proposed elastic rate limiting technique

Proceedings of the Third Edition of the Annual Conference on Wireless On-demand Network Systems and Services (WONS 2006)

Ce fichier regroupe en un seul documents l'ensemble des articles accéptés pour la conférences WONS2006/http://citi.insa-lyon.fr/wons2006/index.htmlThis year, 56 papers were submitted. From the Open Call submissions we accepted 16 papers as full papers (up to 12 pages) and 8 papers as short papers (up to 6 pages). All the accepted papers will be presented orally in the Workshop sessions. More precisely, the selected papers have been organized in 7 session: Channel access and scheduling, Energy-aware Protocols, QoS in Mobile Ad-Hoc networks, Multihop Performance Issues, Wireless Internet, Applications and finally Security Issues. The papers (and authors) come from all parts of the world, confirming the international stature of this Workshop. The majority of the contributions are from Europe (France, Germany, Greece, Italy, Netherlands, Norway, Switzerland, UK). However, a significant number is from Australia, Brazil, Canada, Iran, Korea and USA. The proceedings also include two invited papers. We take this opportunity to thank all the authors who submitted their papers to WONS 2006. You helped make this event again a success

Enforceable Quality of Service Guarantees for Bursty Traffic Streams

Providing statistical quality-of-service guarantees introduces the conflicting requirements for both deterministic traffic models to isolate and police users and statistical multiplexing to efficiently utilize and share network resources. We address this issue by introducing two schemes for providing statistical services to deterministically policed sources: (1) adversarial mode resource allocation in which we bound the stochastic envelopes of policed streams and provide a statistical service for adversarial or worst case sources and (2) non-adversarial mode allocation in which we approximate the stochastic envelopes of policed, but non-worst-case streams in order to exploit a further statistical multiplexing gain in the typical case. Our key technique is to study the problem within the domain of deterministic and stochastic traffic envelopes, which allows us to explicitly consider sources with rate variations over multiple time scales, obtain results for any deterministic traffic model, and apply accurate admission control tests for buffered priority schedulers. We evaluate the scheme’s performance with experiments using traces of compressed video and show that substantial statistical multiplexing gains are achieved

Resource Allocation for Multimedia Traffic Flows using Rate-Variance Envelopes

In order for networks to support the delay and loss requirements of interactive multimedia applications, resource management algorithms are needed that efficiently allocate network resources. In this paper, we introduce a new resource allocation scheme based on rate-variance envelopes. Such envelopes capture a flow's burstiness properties and autocorrelation structure by characterizing the variance of its rate distribution over intervals of different length. From this traffic characterization, we develop a simple and efficient resource allocation algorithm for static priority schedulers by employing a Gaussian approximation over intervals and considering a maximal busy period. Our approach supports heterogeneous quality of service requirements via our consideration of prioritized service disciplines, and supports heterogeneous and bursty traffic flows via our general framework of traffic envelopes. To evaluate the scheme, we perform trace-driven simulation experiments with long traces ..