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

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

Affective life, "vulnerable" youths, and international volunteering in a residential care programme in Cusco, Peru

This paper critically engages with the implications of the "affect turn" in the geographies of development and volunteering. By way of considering "affective life" at a residential youth care centre in Peru through an ethnographic study, we aim to contribute to current discussions of "(self‐)transformation" taking place through affectivity in the experience of volunteering. Conceptually, our approach to investigating "affective life" and volunteering involves two steps. First, we critically review this body of work's recent focus on the individualistic mode of volunteer self‐transformation in encountering "vulnerable others." We identify the need to think about affect and embodiment also from the perspectives of the "vulnerable" groups whose lives are entangled with the presence of international volunteering. Second, we argue for an affect‐informed approach to socio‐politically shaped vulnerability, with a particular emphasis on lived experiences and affective capacities related to enduring social and material conditions. Against the backdrop of marginalisation of adolescent mothers from rural and indigenous backgrounds, many of whom are survivors of sexual abuse, we analyse the experiences of these youths living at a specific residential care centre and interacting with volunteers on a daily basis. In doing so, we employ a series of perspectives from the residents, while taking into account the organisational environment. We also show the complex ways in which resident–volunteer encounters are at play in life‐enhancing affective states, capacities, and relations emerging among the residents. Our findings on the residents' self‐ and shared capacity of transformation highlights the importance of attending to the spatialities of affective life in academic work focused on the contemporary geographies of international volunteering

Urban Infrastructure Deployment for Wireless On-Street Parking Sensor Networks

International audienceThe deployment strategy of wireless applications in metropolitan areas is essential for their efficiency and functionality. In this paper, we introduce and study a deployment strategy for wireless on-street parking sensor networks. We define a multiple-objective problem in our analysis, and solve it with two real-world street parking maps. We present the results on the tradeoff among minimum energy consumption, sensing information delay and the amount of deployed mesh routers and Internet gateways, i.e., the cost of city infrastructure. These results yield engineering insights for appraising and deploying city mesh infrastructure to provide smart parking services to urban users. We also analyze these tradeoffs to see how different urban layouts affect the optimal solutions

A Survey of Smart Parking Solutions

International audienceConsidering the increase of urban population and traffic congestion, smart parking is always a strategic issue to work on, not only in the research field but also from economic interests. Thanks to information and communication technology evolution, drivers can more efficiently find satisfying parking spaces with smart parking services. The existing and ongoing works on smart parking are complicated and transdisciplinary. While deploying a smart parking system, cities, as well as urban engineers, need to spend a very long time to survey and inspect all the possibilities. Moreover, many varied works involve multiple disciplines, which are closely linked and inseparable. To give a clear overview, we introduce a smart parking ecosystem and propose a comprehensive and thoughtful classification by identifying their functionalities and problematic focuses. We go through the literature over the period of 2000-2016 on parking solutions as they were applied to smart parking development and evolution, and propose three macro-themes: information collection, system deployment, and service dissemination. In each macro-theme, we explain and synthesize the main methodologies used in the existing works and summarize their common goals and visions to solve current parking difficulties. Lastly, we give our engineering insights and show some challenges and open issues. Our survey gives an exhaustive study and a prospect in a multidisciplinary approach. Besides, the main findings of the current state-of-the-art throw out recommendations for future research on smart cities and the Internet architecture

Traffic Modeling and Analysis in the Performance of Parking Sensor Networks

Network traffic model is a critical problem for urban application, 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 node density. From the simulation results, we highlight some limits induced by node density, occurrence frequency and non-uniform characters of event-driven applications. When it comes to real-time urban services, a protocol selection shall really 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.Les réseaux de capteurs sans fil sont essentiels au développement des villes intelligentes. Pour les étudier, les modèles de trafic employés sont cruciaux pour prendre en compte les spécificités des applications urbaines, ainsi que la diversité et la densité des noeuds. Dans ce travail, nous comparons les performances de deux protocoles classiques de contrôle d'accès au médium (MAC) sur deux modèles de trafic différents. Nous nous intéressons à leur performances en termes d'efficacité énergétique et de délai d'acheminement de l'information en fonction de l'intensité de l'activité mesurée et de la densité du réseau. Nous mettons en évidence les limites de pertinence de chaque approche et en dérivons des conseils sur les paramètres à utiliser en fonction de la situation ainsi que des perspectives vers des protocoles s'adaptant aux conditions réelles de l'activité mesurée

Fenrir: Blockchain-based Inter-company App-Store for the Automotive Industry

International audienceFrom a software evolution perspective, more actors are integrating the in-vehicle software development cycle. In this process, software deployment mechanisms must include more complex techniques to meet the software verification and traceability levels required by industry safety and security constraints. In this context, we propose Fenrir, a public inter-automaker blockchain-based application store framework in which each automaker retains software installability control. This application store also aims to ensure traceability and security, while also keeping the solution light in terms of both energy consumption and computing requirements, to be used in constrained environments. We implemented Fenrir in a heterogeneous architecture composed of both on-board (bearing an ARM Cortex-A53 chipset, already deployed in cars) and off-board (Amazon EC2) nodes for a realistic automotive use-case scenario, in which we evaluated its performance and energy consumption. We demonstrate that the overheads added by our solution for an entire software deployment pipeline-comprising both deployment and usage of already deployed software packages-depends mainly on the verification mechanism, whose impact is not significant, i.e., 3.8% for the worst-case scenario and 0.3% for a typical scenario

Single-Cell Transcriptional Analysis of Normal, Aberrant, and Malignant Hematopoiesis in Zebrafish

Hematopoiesis culminates in the production of functionally heterogeneous blood cell types. In zebrafish, the lack of cell surface antibodies has compelled researchers to use fluorescent transgenic reporter lines to label specific blood cell fractions. However, these approaches are limited by the availability of transgenic lines and fluorescent protein combinations that can be distinguished. Here, we have transcriptionally profiled single hematopoietic cells from zebrafish to define erythroid, myeloid, B, and T cell lineages. We also used our approach to identify hematopoietic stem and progenitor cells and a novel NK-lysin 4+ cell type, representing a putative cytotoxic T/NK cell. Our platform also quantified hematopoietic defects in rag2E450fs mutant fish and showed that these fish have reduced T cells with a subsequent expansion of NK-lysin 4+ cells and myeloid cells. These data suggest compensatory regulation of the innate immune system in rag2E450fs mutant zebrafish. Finally, analysis of Myc-induced T cell acute lymphoblastic leukemia showed that cells are arrested at the CD4+/CD8+ cortical thymocyte stage and that a subset of leukemia cells inappropriately reexpress stem cell genes, including bmi1 and cmyb. In total, our experiments provide new tools and biological insights into single-cell heterogeneity found in zebrafish blood and leukemia