How to Choose the Relevant MAC Protocol for Wireless Smart Parking Urban Networks?

Parking sensor network is rapidly deploying around the world and is regarded as one of the first implemented urban services in smart cities. To provide the best network performance, the MAC protocol shall be adaptive enough in order to satisfy the traffic intensity and variation of parking sensors. In this paper, we study the heavy-tailed parking and vacant time models from SmartSantander, and then we apply the traffic model in the simulation with four different kinds of MAC protocols, that is, contention-based, schedule-based and two hybrid versions of them. The result shows that the packet interarrival time is no longer heavy-tailed while collecting a group of parking sensors, and then choosing an appropriate MAC protocol highly depends on the network configuration. Also, the information delay is bounded by traffic and MAC parameters which are important criteria while the timely message is required.Comment: The 11th ACM International Symposium on Performance Evaluation of Wireless Ad Hoc, Sensor, and Ubiquitous Networks (2014

Performance Comparison of Contention- and Schedule-based MAC Protocols in Urban Parking Sensor Networks

Network traffic model is a critical problem for urban applications, mainly because of its diversity and node density. As wireless sensor network is highly concerned with the development of smart cities, careful consideration to traffic model helps choose appropriate protocols and adapt network parameters to reach best performances on energy-latency tradeoffs. In this paper, we compare the performance of two off-the-shelf medium access control protocols on two different kinds of traffic models, and then evaluate their application-end information delay and energy consumption while varying traffic parameters and network density. From the simulation results, we highlight some limits induced by network density and occurrence frequency of event-driven applications. When it comes to realtime urban services, a protocol selection shall be taken into account - even dynamically - with a special attention to energy-delay tradeoff. To this end, we provide several insights on parking sensor networks.Comment: ACM International Workshop on Wireless and Mobile Technologies for Smart Cities (WiMobCity) (2014

Router deployment of Streetside Parking Sensor Networks in Urban Areas

The deployment of urban infrastructure is very important for urban sensor applications. In this paper, we studied and introduced the deployment strategy of wireless on-street parking sensor networks. We defined a multiple-objective problem with four objectives, and solved them with real street parking map. The results show two sets of Pareto Front with the minimum energy consumption, sensing information delay and the amount of deployed routers and gateways. The result can be considered to provide urban service roadside unit or be taken into account while designing a deployment algorithm.Comment: UM - Urban Modelling Symposium, Oct 2014, Lyon, France. \<http://urbanmodelling.sciencesconf.org/\&g

WDM Mesh Networks with Dynamic Traffic

This article presents a mathematical model that results in a low-cost network design to satisfy a set of point-to-point demands that arrive and leave the network along of time. It considers the problem of routing working traffic and assigning wavelengths in an all-optical network avoiding if possible that wavelengths assignment changes and flow rerouting. The model allows to know when a reconfiguration/expansion is needed. The model provides a physical network configuration selecting a lowest cost set of components of the network (subnetworks and OXCs) with sufficient capacities to attend the demands and the required wavelengths in all time

Smart cities ou human city, gouverner la ville par les data

National audienceGouverner la ville en se fondant sur des données est bien loin d'être une nouveauté : les cartographies, les données statistiques de l'INSEE, les enquêtes ménage déplacement, les observations du trafic routier, les archives municipales, etc. sont un vaste fonds de données à la disposition des services et des élus pour nourrir leurs réflexions et étayer leurs décisions. Ce qui change, et renouvelle parfois profondément les modalités de gouvernance, c'est la nature des données disponibles : nombre, hétérogénéité, fréquence de mise à jour, granularités spatiales, temporelles et sociales, précision, origines. Le chapitre « Les acteurs privés de la ville numérique » d'Antoine Courmont aborde la diversité des acteurs produisant ces données et les conséquences sur la gouvernance des villes

WSN-inspired Sleep Protocols for Heterogeneous LTE Networks

International audienceThe tremendous increase of the traffic demand in cellular networks imposes a massive densification of the traditional cellular infrastructure. The network architecture becomes heterogenous, in particular 4G networks where LTE micro eNodeBs are deployed to strengthen the coverage of macro eNodeBs. This densification yields major issues related to the energy consumption of the infrastructure. Indeed, there is fixed and significant amount of energy required to run each additional node, whatever the traffic load of the network. Mitigating this fixed energy consumption is therefore a major challenge from a societal and economical viewpoint. Extensive researches about energy-saving highlight that to save energy the better strategy is to switch off the radio part of nodes. This is the heart of wireless sensor networks energy-saving strategies, even though the objective for WSN is to maximize the battery life of each individual nodes. In this paper, we develop a parallel between the principles of WSN protocols and the requirements of cellular infrastruc- tures. We then propose a distributed and localized algorithm to dynamically switch off and on the micro eNodeBs of an LTE heterogeneous network following the traffic demand evo- lution in time and analyze it in terms of energy savings. We show that one can expect energy savings of approximately 12% when implementing sleep modes whereas the energy cost for sending the traffic decreases by 24%

Une ville intelligente et démocratique donne forcément une place centrale à la formation

Tribune pour la section "Cities" du Monde.Beaucoup de citadins restent exclus du déploiement de la « ville intelligente », faute d’une sensibilisation aux enjeux du numérique. Une nécessité républicaine pourtant, estime Hervé Rivano dans cet épisode de l’Abécédaire de la ville, à la lettre « A », comme ville « apprenante ».National audienc

IoB-DTN: a lightweight DTN protocol for mobile IoT Applications to smart bike sharing systems

International audienceInformation and communication are key to the intelligent city of tomorrow. Many technologies have been designed to connect smart devices to the Internet. In particular, public transport systems have been used to collect data from mobile devices. Public bike sharing systems have been introduced as part of the urban transportation system and could be used as the support of a mobile sensor network. In this paper, we introduce the "Internet of Bikes" IoB-DTN protocol which applies De-lay/Disruption Tolerant Network (DTN) paradigm to the Internet of Things (IoT) applications running on urban bike sharing system based sensor network. We evaluate the performance of three variants of IoB-DTN with four buffer management policies. Our results show that limiting the number of packet copies sprayed in the network and prioritizing generated packets against relayed ones, improves on low loss rate and delivery delay in urban bicycle scenario

About the Capacity of Flat and Self-Organized Ad Hoc and Hybrid Networks

Ad hoc networking specific challenges foster a strong research effort on efficient protocols design. Routing protocols based on a self-organized structure have been studied principally for the robustness and the scalability they provide. On the other hand, self-organization schemes may decrease the network capacity since they concentrate the traffic on privileged links. This paper presents four models for evaluating the capacity of a routing schemes on 802.11 like networks. Our approach consists in modeling the radio resource sharing principles of 802.11 like MAC protocols as a set of linear constraints. We have implemented two models of fairness. The first one assumes that nodes have a fair access to the channel, while the second one assumes that on the radio links. We then develop a pessimistic and an optimistic scenarii of spatial re-utilization of the medium, yielding a lower bound and an upper bound on the network capacity for each fairness case. Our models are independent of the routing protocols and provide therefore a relevant framework for their comparison. We apply our models to a comparative analysis of the well-known shortest path base flat routing protocol OLSR against two main self-organized structure approaches, VSR, and Wu & Li's protocols. This study concludes on the relevance of self-organized approaches from the network capacity point of view

Wireless Backhaul Networks: Minimizing Energy Consumption by Power-Efficient Radio Links Configuration

In this work, we investigate on minimizing the energy consumption of a wireless backhaul communication network through a joint optimization of data routing and radio configuration. The backhaul network is modeled by a digraph in which the nodes represent radio base stations and the arcs denote radio links. According to the scenario under consideration, a power-efficient configuration can be characterized by a modulation constellation size and a transmission power level. Every link holds a set of power-efficient configurations, each of them associating a capacity with its energy cost. The optimization problem involves deciding the network's configuration and flows that minimize the total energy expenditure, while handling all the traffic requirements simultaneously. An exact mathematical formulation of the problem is presented. It relies on a minimum cost multicommodity flow with step increasing cost functions, which is very hard to optimize. We then propose a piecewise linear convex function, obtained by linear interpolation of power-efficient configuration points, that provides a good approximation of the energy consumption on the links, and present a relaxation of the previous formulation that exploits the convexity of the energy cost functions. This yields lower bounds on the energy consumption, and finally a heuristic algorithm based on the fractional optimum is employed to produce feasible solutions. Our models are validated through extensive experiments that are reported and discussed. The results verify the potentialities behind this novel approach. In particular, our algorithm induces a satisfactory integrality gap in practice