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Vehicular communications are becoming a reality due to the investments by stakeholders like car manufacturers and Public Transport Authorities. The building blocks of the "Vehicle Grid" (radios, Access Points, spectrum, standards, etc.) are coming into place enabling a broad gamut of applications that range from navigation safety, intelligent transport, entertainment and urban sensing. Vehicular protocols and applications, however, must be carefully tested before deployment in the urban grid and introduction to the users. This validation must be carried out progressively in simulation, emulation and small scale testbed environments. In this paper we discuss the important role of the vehicular testbed in validating models and protocols before deployment in large scale scenarios. We illustrate the concept using two case studies that were carried out in the UCLA open vehicular testbed. © 2012 IEEE.

International audience; One fundamental limit for synchronizing a packet trace is that the two measurement systems that can be used to timestamp the packets, the operating system and the network interface, have mutually exclusive properties. The OS clock can be stabilized over the long run but the OS timestamps are not accurate; the PHY timestamps are accurate but they show a drift. To leverage the best features of both systems, we propose to stabilize the OS clock with a GPS and to remap the PHY timestamps over the OS/GPS time. This method is well suited for challenged scenarios like VANETs as no signaling is needed between nodes. We apply our approach to VANET monitoring and evaluate it on packet traces collected from our testbed. The results show that our solution reduces the mean synchronization error to 3 μs.

International audience; Mobility has become a basic premise of network communications, thereby requiring a native integration into 5G networks. Despite numerous efforts to propose and standardize effective mobility-management models for IP, the result is a complex, poorly flexible set of mechanisms. The natural support for mobility offered by ICN (Information Centric Networking) makes it a good candidate to define a radically new solution relieving limitations of the traditional approaches. If consumer mobility is supported in ICN by design, in virtue of its connectionless pull-based communication model, producer mobility is still an open challenge. In this work, we look at two prominent ICN architectures, CCN (Content Centric Networking) and NDN (Named Data Networking) and we propose MAP-Me, an anchor-less solution to manage micro-mobility of content producers via a name-based CCN/NDN data plane, with support for latency-sensitive streaming applications. We analyze MAP-Me performance and provide guarantees of correctness, stability, and bounded stretch, which we verify on real ISP topologies. Finally, we set up a comprehensive simulation environment in NDNSim 2.1 for MAP-Me evaluation and comparison against the existing classes of solutions, including a realistic trace-driven car-mobility pattern under a 802.11n radio access. The results are encouraging and highlight the superiority of MAP-Me in terms of user performance and network cost metrics. All the code is available as open-source.

This paper presents a preliminary experiment done to identify potential problems and issues in setting up a testbed for air pollution measurement and modeling. Our final testbed, part of a joint research activity between the University of Bologna and the Macao Polytechnic Institute, will be composed of three lines of the air pollution sensors Canarin II and it will be used to produce spatio-temporal open data to test third-party air pollution models. Here, we present a preliminary experiment based on a single line of sensors, showing interesting insights into the actual open challenge of air pollution modeling techniques validation, taking into account the effects of air pollutant emissions sources, meteorology, atmospheric concentrations and urban vegetation.

Mobility and ambient conditions are key factors in urban environments, affecting well-being and quality of life. In this context, sensors, smart mobility, networks, connectivity can play a significant and strategic role, being exploited with the aim of improving data and information available to public administration and to each citizen. In this way, they can be supported in having more sustainable and aware behaviours and in getting useful information and services, improving their daily activities. In this paper, we present a prototype of smart bike eco-system, designed with the aim of collecting, aggregating and sharing data about air pollution and about the urban environment, which can be exploited in a smart mobility context thanks to sensor and vehicular networks.

Climate change and higher level of pollutants are affecting our heritage affect the conservation abilities and endangering centuries old buildings and artifacts. Governments and conservation agencies alike are scrambling to monitor and prevent disasters that would result in the loss of precious cultural artifacts. Sensing technologies, on one side, and new restoration techniques on the other, are in being used in this effort however they result in high costs and complex installation logistics. In this paper we present a pollution monitoring study for the Biblioteca Joanina, a baroque library situated in University of Coimbra that has been inducted in the UNESCO world's heritage list in 2013. In contrast with current practices the study has been conducted using a low-cost sensing platform, namely CANARIN II, built in a joint effort by the Sorbonne Universite, the Macao Polytechnic Institute and the Asian Institute of Technology (Thailand). Our study shows that is possible to use low-cost platform for cultural heritage monitoring and preservation and how it can support decision makers in execute simple policy changes and yet achieve substantial impacts in the preservation efforts.

We present the design and implementation of ParkMaster, a system that leverages the ubiquitous smartphone to help drivers find parking spaces in the urban environment. ParkMaster estimates parking space availability using video gleaned from drivers' dash-mounted smartphones on the network's edge, uploading analytics about the street to the cloud in real time as participants drive. Novel lightweight parked-car localization algorithms enable the system to estimate each parked car's approximate location by fusing information from phone's camera, GPS, and inertial sensors, tracking and counting parked cars as they move through the driving car's camera frame of view. To visually calibrate the system, ParkMaster relies only on the size of well-known objects in the urban environment for on-the-go calibration. We implement and deploy ParkMaster on Android smartphones, uploading parking analytics to the Azure cloud. On-the-road experiments in three different environments comprising Los Angeles, Paris and an Italian village measure the end-to-end accuracy of the system's parking estimates (close to 90%) as well as the amount of cellular data usage the system requires (less than one mega-byte per hour). Drill-down microbenchmarks then analyze the factors contributing to this end-to-end performance, as video resolution, vision algorithm parameters, and CPU resources.

In the last several years the awareness about pollution levels and other natural hazards has risen significantly. Millions of citizens globally pay daily attention to air quality and other factors such as for instance UV index and pollens. This new need has been so far met by a plethora of smartphone applications that leverage data collected by the city-operated stations or, in some cases, community-based stations located at the user premises. In this work we exploit recent advances in micro-controllers and sensing technologies to design and implement a personal pollution awareness system tiny enough to be embedded into user accessories. In particular, we will introduce the concept and the architecture of our prototype and show the preliminary results we collected using this prototype.

The need for Internet access from moving vehicles has been steadily increasing in the past few years. Solutions that rely on cellular connectivity are becoming impractical to deploy due to technical and economic reasons. Car-Fi proposes an approach that leverages existing home Wi-Fi access points configured in dual-access mode, in order to offload all data traffic from the congested and expensive cellular infrastructure to whatever Wi-Fi network is available. Thanks to an improved scanning algorithm and numerous optimizations to the connection setup, Car-Fi makes downloading large amounts of data from a moving car feasible.

International audience; Mobility has become a basic premise of almost any network communication, thereby requiring a native integration into next generation 5G networks. Despite the numerous efforts to propose and to standardize effective mobility management models for IP, the result is a very complex, poorly flexible set of mechanisms not suitable for the design of a radio-agnostic 5G mobile core. The natural support for mobility, security and storage offered by ICN (Information-Centric Networking) architecture, makes it a good candidate to define a radically new solution relieving limitations of traditional approaches. If consumer mobility is supported in ICN by design in virtue of its connectionless pull-based communication model, producer mobility still appears to be an open challenge. In this work we describe an initial proposal for an anchor-less approach to manage producer mobility via Interest Up-dates/Notifications in the data plane, even in presence of latency-sensitive applications. We detail the different operations triggered by producer movements and position our contribution in the context of existing alternatives, by discussing either user performance and network metrics.

Cloud computing allows user to access remote hardware, data and software through the network. However, many of these resources today are found on mobiles. For example, modern vehicles provide powerful platforms for computation, data delivery, storage, and sensing. This paper introduces the notion of Mobile Cloud computing to tap mobile resources. As an example, we describe the Pies-on-Wheels service, a Vehicular Cloud service that delivers images on demand to citizens by using vehicles' on board cameras. A server (eg taxi dispatcher or Navigator Server) accepts requests from members and assigns the photo clicking task to vehicles close to the target. The feasibility of the Pies-on-Wheels service is demonstrated in a San Francisco scenario using published taxicab routes. © 2013 IEEE.

International audience; Vehicular networks are intended to support a safer and more comfortable driving experience both through vehicle-to-infrastructure communication and, even more interesting, vehicle-to-vehicle ad-hoc networking. In the latter case, the focus will be on getting a content of interest from a specific geographic region, rather than communicating to a predetermined host. As current IP-based protocols are specifically designed for conversations between hosts, innovative solutions have to be devised. To this aim, we consider the Named Data Networking paradigm and propose a named-data approach efficiently mapping bi-dimensional geographic areas into a uni-dimensional naming scheme.

MoViT is a distributed software suite for the emulation of mobile wireless networks. MoViT provides researchers and developers with a virtualized environment for developing and testing mobile applications and protocols for any hardware and software platform that can be virtualized. The distributed nature of MoViT allows for the emulation of mobile networks of arbitrary size. Additionally, the network connectivity is shaped transparently such that the connectivity observed by each virtual node resembles that of a physical mobile network. In this paper we present the MoViT architecture, the models used to emulate the wireless channel, the details of our initial implementation and, finally, the results of our evaluation regarding the scalability, realism, and versatility of MoViT. © 2012 ACM.

In this paper, we propose a simple and effective method to extend digital maps with the location and timing of stop-signs and traffic lights in a city, given GPS traces collected by on-road vehicles. Our system finds the location and timing of traffic lights and stop-signs using a small number of traces per road segment. We developed and evaluated the system by applying it to two sets of GPS traces -open street map, a multicity, publicly available database of GPS traces, and a set of traces collected in west Los Angeles. Evaluation results show that our system can estimate the location of stop-signs with as little as 5 traversal per road segment and the location/timing of traffic lights with as little as 7 traversals, with more than 90% accuracy. © 2010 IEEE.

The comparison of different applications and protocols in vehicular ad hoc networks (VANETs) is a very difficult task. This is mainly due to the nature of VANET, for which it is virtually impossible to replicate the same exact environment in two separate experiments. This paper introduces a flexible experiment structure that will allow different protocols to be compared in the same mobility pattern and channel conditions in VANET. A virtualized environment is setup on each node where the combination of Xen and Gentoo software is used to create multiple virtual guests. All virtual guests on the same machine use different protocols and share the wireless interface. We compare the widely recognized ad-hoc routing protocols AODV and OLSR to demonstrate the novelty of our system. Experiment results show that even with arbitrary external interference and mobility pattern, meaningful comparisons between different protocols can be carried out. © 2010 IEEE.

Vehicular communications are becoming a reality under the push of increased transportation safety requirements and huge investments of several actors in the field like car manufacturers and Public Transport Authorities. As a consequence, the building blocks of the "Vehicle Grid" (radios, Access Points, spectrum, standards, etc.) will soon be in place enabling a broad gamut of applications ranging from automatic safety systems, intelligent transport, entertainment, urban sensing and environmental protection/monitoring. In this paper, we take a visionary look at "Vehicular Grid" and we argue that the cooperation of pure ad-hoc vehicle-to-vehicle communications and roadside infrastructure is fundamental to broaden the supported applications. The paper further describes the activities carried out at UCLA to deploy an open testbed integrating ad hoc vehicle-to-vehicle communications and a wireless mesh backhaul based on MobiMESH hardware/software solutions. © 2010 IEEE.

This paper presents an ad-hoc vehicular protocol to support the logistics of first responders. First responders often travel several kilometers to reach an area impacted by an accident or other emergency. The street-path between an emergency responder and an operational field often includes densely populated areas with busy vehicular traffic. It is key that emergency vehicles are able to traverse them safely and as quickly as possible. Vehicular communications is essential for supporting this traversal. Traditionally, this communication is accomplished through intense sirens and lights. Our protocol improves upon traditional techniques by forwarding a first responder's current location and estimated path over an adhoc vehicular network. Vehicles lying along this path receive packets and take appropriate actions giving way to an emergency vehicle. Our protocol improves over traditional methods in two ways. First, packets propagated over a vehicular network affords a more timely notification withoug congesting the network. In addition, notifications supply vehicles with a first responders GPS location and intended path traversal. These two improvements allow vehicles to safely and efficiently clear pathways long before an emergency vehicle's arrival. © 2010 IEEE.

Recent advances in portable technologies suggest that ad hoc networks will finally move out from the research and military harbors to the commercial world. In particular, vehicular safety and entertainment applications are mature for the market. Several major manufacturer are considering vehicular communications as an opportunity to increase the profitability and marketability of their vehicles. In this phase, simulations are essential to evaluate the performance of protocols and applications large urban Ad Hoc and Vehicular networks. This paper tackles on the long overdue issue of an high fidelity propagation model for urban ad hoc networks. In particular, we propose CORNER a low computational cost yet accurate urban propagation prediction technique for ad hoc networks in urban scenarios. We also provide validation of the model through a side-to-side comparison of real experiments and simulations. ©2010 IEEE.

The investigation around the use of peer-to-peer in IPTV environments goes on. The debate about the best compromise between the cost reduction offered by the peer-to-peer (P2P) approach and the quality requirements by the mass market is still open. Though some successful protocols are already worldwide used, there are still issues and optimization problems to solve. The main contribution of this work has been the deployment on PlanetLab (Plab) of a large testbed in order to investigate the performance of [P2P client - streaming player] systems in static and dynamic overlays: the goal was to recreate a real IPTV-like heterogeneous scenario with home users enjoying the same stream and cooperating via P2P. IPTV needs bandwidth and computational resources that single peers often struggle to provide. We chose the SopCast client for our experiments, mainly because of its popularity and its flexibility. Although SopCast analysis was not our main research purpose, we are able to point out some of its characteristics by observing its behavior in large and dynamic overlay, with different churn patterns (i.e. zapping channel behaviors). ©2009 IEEE.

In 2003, transportation activities accounted for 27 percent of the U.S. total greenhouse gasses (GHG) up from the 24.8 percent in 1990 [1]. The 1990 - 2007 United States inventory of GHG Emissions shows that, in 2007, transportation activities, were responsible 1,892.2 Millions of metric tons of CO2 or 28 percent of the U.S. CO2 emissions [2]. Gasoline burning vehicles are clearly in the limelight as a major source of GHG. While, industry and academia are striving to design clean burning and electrical vehicles however this process is costly and will require few decades for zero-emission vehicles to hit the mainstream market. In this paper we argue that, vehicles, one of today's human liabilities, can become one of tomorrow's assets today's pollution war through the integration of information and communication technologies at every every stage of the transport production chain. Cooperative sensing, close loop actuators, wireless communication technologies and event-driven policies should all concur to build an optimized cyber-physical transportation network optimized for service and pollution. This approach poses many technological, behavioral, and policy challenges; however we believe it could result in cleaner, more health-conscious and less congested cities. The last century was marked by unpredictably large changes of the hearth temperature and sea levels. Between early 1900s and 2000s the average temperature of the earth surface has risen by 0.74C and the sea levels rose 10cm. Observing the data scientists expect an additional 2C to 4C and a further major increase in sea levels by 2100. Climate changes of this amplitude are closely related to major disruptions in the food chain and can potentially cause the extinction of several plants and animal species[10]. The main reason for the raising thermometer lies in 150 years industrialization: the burning of massive and ever increasing quantities of oil, gasoline, and coal, the continuous quest for land at forests' expenses, and the practice of certain intense farming methods. These activities carry the principal responsibility for the enormous amount of "greenhouse gases" in the atmosphere, especially carbon dioxide, methane, and nitrous oxide[11][8]. In western countries the road transportation sector accounts for a large share of the GHG emissions thus the urgency for its redesign. In the United States, for instance, road-transportation contributes for 28 percent of the total emissions. In particular, 33 percent of road-transportation emissions are due passenger cars, 28 percent due to light duty trucks, and SUVs, 28 percent pickup trucks and minivans, 21 percent freight trucks, and 8 percent commercial aircraft [2]. The United Nations Framework Convention on Climate Change found similar ratios for most of the industrialized countries[8]. A major inversion of the trend will happen with the advent of zero-emission vehicles that are expected to hit the mass-market in about two decades; thus a natural question is what we can do now? We believe the road-transportation system as it is known today is obsolete and offers numerous improvement opportunities. In particular, smart vehicles can closely cooperate with an intelligent road infrastructure to reduce pollution emissions and, in general, to sense the city environmental health. Cooperative urban sensing, performed by vehicles and the urban mesh infrastructure, will be at the heart of the intelligent city traffic management with the aim of reducing pollution, fuel consumption and traffic delays. We envision vehicles as a key component of a city wide distributed sensor system able to track down pollution hot-spots and take an active role in reducing citizens exposure to pollutants. The enabling technology is already available and largely deployed in our cars. Furthermore, recent advances in vehicular communications, cooperative sensing and computer vision paved the ground for a new deal that aims at pollution control and traffic management. In this white-paper, we explore the challenges and research opportunities to transform today's basic transportation infrastructure in a sophisticated dynamic cyber-physical system. Intelligent traffic lights together with in-vehicle sensors, dynamic engines, close-loop navigation devices, will be the pivotal to ensure greener, less-polluting traffic in the city. Copyright 2009 ACM.

Simulation is essential to evaluate the performance of large scale vehicular networks. It is logistically challenging (and prohibitively expensive) to run tests with more than a few dozens experimental vehicles. Given the critical role of simulation in the evaluation of VANET protocols in large scale scenarios, it is important to guarantee realism of the models. This paper focuses on the accuracy of urban propagation models and their impact on vehicular protocol results. In a city-based vehicular network we compare the predominant Two Ray model and a recently proposed Corner model. We identify a number of factors that undermine the validity of the Two Ray model, for example, the presence of buildings causing propagation disruption and the heavy weight border effects that incorrectly compensate for the presence of hidden terminals in the networks. The paper analyzes a small scale urban vehicular scenario which unveils the issues to be considered in large scale vehicular simulations. ©2009 IEEE.

Multicast streaming is gaining increasing importance in wireless ad hoc networks, in part because ad hoc scenarios often include team activities and the requirement for distribution of audio, video and situation awareness to the members. At the network level, techniques for routing the multimedia streams are quite mature. Much more challenging is the allocation of resources, the fair sharing among streams and the control of congestion. While in rate adaptive UNICAST streams congestion control and fair sharing are accomplished with end-to-end feedback techniques inspired to TCP, the feedback does not scale well in MULTICAST. In fact, it leads to the well knows ACK/NAK "implosion" problem and unfair penalties for heterogeneous receivers. These limitations can be overcome using backpressure from congestion points to the sources - but this approach suffers of latency and cannot rapidly adjust to changes in traffic. Another solution is multilayer adaptive coding. Namely, the encoding adaptation is done locally by dropping layers. It does not require end-to-end feedback nor changes in input rates. Multi-resolution codes are now becoming attractive due to the progress in technology; we expect these to become the prevalent techniques in large scale media distribution. One issue, however, that still remains to be resolved is the fair sharing among competing multicast streams. In this paper we address the congestion control AND fair sharing in a multilayer multicast scenario. We show that lack of proper fairness provisions in the "local adjustments" can lead to serious capture situations, especially in heterogeneous traffic mixes (e.g. voice and video). We then propose a FAIR local adjustment that targets a fair dropping of packets in each interference domain. We show that the scheme can be interpreted as a distributed implementation of a utility function minimization, where the utility is the packet loss subject to fairness bounds across flows. This formulation guarantees stability and convergence of the distributed algorithm. The main contributions of this paper are the low overhead design of the local fairness enforcement algorithm, the utility function framework and the demonstration of convergence via simulation in representative scenarios. Copyright 2008 ACM.

An increasing number of applications have been developed around a GNSS receiver, such as automotive, marine and spacecraft navigation, surveying and mapping, precise time reference and marketing. A key factor that impacts the application's effectiveness and performance is the precision and the trust of positioning. The main contribution of this paper is a novel approach for tracking loads using both GNSS positioning capabilities as well as network-supported location services. The use of these two methods allows us to have an independent cooperative evaluation of the current position of the tracked target. To assure the security of the tracking and tracing application we propose a cooperative certification method to evaluate the one-hop distance between the trucked target and all the cooperative nodes in the truck's view. Since the control center knows the position of every cooperating node, it evaluates a Least Mean Square (LMS) trilateration. This triangulation compared with the position sent by the target allows the control center to make decision on the trucked vehicle. As the results show, the availability of the certification strategy is directly connected to the distribution of the cooperatives nodes. In order to better understand this relationship an analysis has been performed on a scalable network simulator where different mobility scenarios have been considered.

Satellite networks have the potentiality to guarantee ubiquitous access to the Internet. Yet, their transmission delay and errors represent still a challenge for researchers and practitioners, especially when considering TCP-based flows. Having efficient means to estimate important channel features such as, for instance, the available bandwidth and the total capacity has been proven to be proficient in improving the performance in this context. To this aim we discuss SBE (Shareable Bandwidth Estimator), a solution able to provide a simple and effective estimation of the bottleneck link capacity minus the simultaneously present uniformly distributed traffic. Simulative experiments prove that our scheme is effective since the very beginning of a connection. Furthermore, SBE can be easily implemented as it requires only sender-side modifications and is based on regular TCP functioning. © 2008 IEEE.

In an urban environment, vehicles can opportunistically exploit infrastructure through open Access Points (APs) to efficiently communicate with other vehicles. This is to avoid long wireless ad hoc paths, and to alleviate congestion in the wireless grid. Analytic and simulation models are used to optimize the communications and networking strategies. For realistic results, one important challenge is the accurate representation of traffic mobility patterns. In this paper we introduce realistic vehicular mobility traces of downtown Portland, Oregon, obtained fromextremely detailed large scale traffic simulations performed at the Los Alamos National Laboratories (LANL). To the best of our knowledge, these are among the most accurate synthetic motion traces available for study, with the exception of actual car trace measurements. The new mobility model is used to evaluate AODV [1] in flat and opportunistic infrastructure routing. To assess the importance of a realistic mobility model for this evaluation, we compare these results with those obtained with CORSIM [2] traces. The paper makes the following contributions: (a) introduction of efficient, opportunistic strategies for extending the AP infrastructure to use vehicle to vehicle paths, and (b) assessment of different mobility models - CORSIM traces and LANL's realistic vehicular traces - in the modeling of different routing strategies. Copyright 2007 ACM.

In [1] we show how vehicles can opportunistically exploit infrastructure through open Access Points (APs) to efficiently communicate with other vehicles. We also highlight the importance of the use of a correct mobility model, since the advantages that may derive from the use of an infrastructure may not be appreciated because of a lack of accuracy. We continue our study based on realistic vehicular mobility traces of downtown Portland, Oregon, obtained from extremely detailed large scale traffic simulations performed at the Los Alamos National Laboratories (LANL). This mobility model is used to evaluate both flat and opportunistic infrastructure routing. We here build upon [1] and extend that work to: (a) assess the impact of a range of mobility models on network performance and; (b) discuss the performance trend we may expect during the day, as urban mobility patterns change. We here compare results obtained with CORSIM [2] traces and Random Waypoint (RWP) [3] to the results obtained with realistic mobility traces. ©2007 IEEE.

This paper proposes a novel architecture, named APOHN, designed for data communications over heterogeneous networks. APOHN enables easy implementation of various existing and upcoming performance optimization solutions with the main objective to keep the standardized TCP/IP reference model untouched. APOHN architecture extends ISO/OSI protocol stack model with an additional layer designed for subnetwork communications and optimized with specific physical subnetwork characteristics in mind. TCP/IP flow speedup, subnetwork flow multiplexing and optimized subnetwork communications result in great performance improvements in heterogeneous networks. Moreover, the support of IPsec enables secure communications. APOHN performance is evaluated through simulations using a combined satellite and WLAN network scenario - commonly used in disaster recovery as well as in a variety of military applications. APOHN constitutes an architectural solution competitive with leading architectures such as Performance Enhancement Proxies (PEP) as well as Delay-Tolerant Networking (DTN).12© 2006 IEEE.

Mobile peer-to-peer systems have recently got in the lime-light of the research community that is striving to build efficient and effective mobile content addressable networks. Along this line of research, we propose a network coding based file swarming protocol targeting vehicular ad hoc networks (VANET). We argue that file swarming protocols in VANET should deal with typical mobile network issues such as dynamic topology and intermittent connectivity as well as various other issues that have been disregarded in previous mobile peer-to-peer researches such as addressing, node/user density, non-cooperativeness, and unreliable channel. Through simulation, we show that the efficiency and effectiveness of our protocol allows shorter file downloading time compared to an existing VANET file swarming protocol. Copyright 2006 ACM.