Showing papers by "Marco Zennaro published in 2015"

On the design of smart parking networks in the smart cities: an optimal sensor placement model

Abstract: Smart parking is a typical IoT application that can benefit from advances in sensor, actuator and RFID technologies to provide many services to its users and parking owners of a smart city. This paper considers a smart parking infrastructure where sensors are laid down on the parking spots to detect car presence and RFID readers are embedded into parking gates to identify cars and help in the billing of the smart parking. Both types of devices are endowed with wired and wireless communication capabilities for reporting to a gateway where the situation recognition is performed. The sensor devices are tasked to play one of the three roles: (1) slave sensor nodes located on the parking spot to detect car presence/absence; (2) master nodes located at one of the edges of a parking lot to detect presence and collect the sensor readings from the slave nodes; and (3) repeater sensor nodes, also called “anchor” nodes, located strategically at specific locations in the parking lot to increase the coverage and connectivity of the wireless sensor network. While slave and master nodes are placed based on geographic constraints, the optimal placement of the relay/anchor sensor nodes in smart parking is an important parameter upon which the cost and efficiency of the parking system depends. We formulate the optimal placement of sensors in smart parking as an integer linear programming multi-objective problem optimizing the sensor network engineering efficiency in terms of coverage and lifetime maximization, as well as its economic gain in terms of the number of sensors deployed for a specific coverage and lifetime. We propose an exact solution to the node placement problem using single-step and two-step solutions implemented in the Mosel language based on the Xpress-MPsuite of libraries. Experimental results reveal the relative efficiency of the single-step compared to the two-step model on different performance parameters. These results are consolidated by simulation results, which reveal that our solution outperforms a random placement in terms of both energy consumption, delay and throughput achieved by a smart parking network.

On Real-Time Performance Evaluation of Volcano-Monitoring Systems With Wireless Sensor Networks

Abstract: A volcanic eruption early warning has to be launched with effectiveness and within the shortest time possible, which imposes the requirement of using real-time (RT) systems. In this setting, volcano-monitoring systems using wireless sensor networks (WSNs) may play a key role. Previous work did not report detailed-enough performance evaluation, in order to identify their main constraints as RT systems, either in simulation tools or in testbed scenarios. The aim of this paper was to identify the optimum number of sensors to be deployed a posteriori , based on simulation results considering throughput, packet loss, and end-to-end delay, as metrics to satisfy the RT requirements. We corroborated the simulation results obtained by a testbed deployment within a controlled environment. We determined that optimal scenario for volcano monitoring is a random topology, and the results show that 12 nodes should be deployed as maximum to satisfy the RT constraints. To test the system in a real scenario, 10 sensors were deployed in a strategic area at Cotopaxi Volcano, and information was collected during three days of continuous monitoring. This information was sent to a remote surveillance laboratory located 45 km away from the station placed at the volcano using WiFi-based long-distance technology. Our study shows that the coordinator node is the main bottleneck in the real application scenario, given that its processing rate provokes an excessive time delay near to 3 s, which has to be solved to satisfy the RT requirements. We conclude that a comprehensive study, including simulation, testbed, and in-situ deployment, provides valuable information for the specifications to be accounted in permanent WSN RT volcano monitoring.

On the Scalability of Constructive Interference in Low-Power Wireless Networks

Abstract: Constructive baseband interference has been recently introduced in low-power wireless networks as a promising technique enabling low-latency network flooding and sub-μs time synchronisation among network nodes. The scalability of this technique has been questioned in regards to the maximum temporal misalignment among baseband signals, due to the variety of path delays in the network. By contrast, we find that the scalability is compromised, in the first place, by emerging fast fading in the composite channel, which originates in the carrier frequency disparity of the participating repeaters nodes. We investigate the multisource wave problem and show the resulting signal becomes vulnerable in the presence of noise, leading to significant deterioration of the link whenever the carriers have similar amplitudes.

Energy-efficient Internet of Things monitoring with low-capacity devices

Abstract: The Internet of Things (IoT) allows users to gather data from the physical environment. While sensors in public spaces are already widely used, users are reluctant to deploy sensors for shared data at their homes. The deployment of IoT nodes at the users premises presents privacy issues regarding who can access to their data once it is sent to the Cloud which the users cannot control. In this paper we present an energy-efficient and low cost solution for environmental monitoring at the users home. Our system is built completely with open source components and is easy to reproduce. We leverage the infrastructure and trust of a community network to store and control the access to the monitored data. We tested our solution during several months on different low-capacity single board computers (SBC) and it showed to be stable. Our results suggest that this solution could become a permanently running service in SBCs at the users homes.

On the impact of propagation models on TV white spaces measurements in Africa

Abstract: Currently, use of geo-location databases is the preferred method for detecting TV white spaces by white space devices in the United States of America. The approach protects TV transmitters and receivers from interference sufficiently by keeping a record of the TV transmitters' information, and relying on propagation models to determine the protection area of the TV transmitters. Thus accurate radio propagation by the propagation models is the key to determining the protection area of the TV transmitters. How accurate the propagation models determine the protection area is largely dependent on the terrain characteristics and environmental factors that vary widely from one area to another. These propagation models have been tested in different regions of the world but scarcely in the developing world where white space is assumed to provide broadband connectivity. As such, it is unclear at the moment how accurate the geo-location databases will detect TV white spaces in the developing world. Therefore, this paper argues that unless thorough tests have been conducted with the propagation models in the developing world, the use of geo-location databases in predicting TV white spaces in those regions may not produce optimal results.

From the chairs

Abstract: The 2014 Community College National Legislative Summit (NLS) comes at a time when federal policy makers will be considering legislative and funding issues that will impact our institutions and students both now and well into the future. As Congress works to determine priorities concerning higher-education reform, your voice can play an essential role in determining the course of our nation relative to America’s skilled workforce and global competitiveness.

Deploying clouds in the Guifi community network

Abstract: This paper describes an operational geographically distributed and heterogeneous cloud infrastructure with services and applications deployed in the Guifi community network. The presented cloud is a particular case of a community cloud, developed according to the specific needs and conditions of community networks. We describe the concept of this community cloud, explain our technical choices for building it, and our experience with the deployment of this cloud. We review our solutions and experience on offering the different service models of cloud computing (IaaS, PaaS and SaaS) in community networks. The deployed cloud infrastructure aims to provide stable and attractive cloud services in order to encourage community network user to use, keep and extend it with new services and applications.

Exploring TV White Spaces for Use in Campus Networks

Abstract: University campuses are busy places for wireless client traffic coming from Wi-Fi connections and other wireless devices that contend for the 2.4 GHz frequencies space that most campus Wi-Fi networks use currently. This is making the 2.4 GHz frequency unsuitable for Wi-Fi connection due to too much interference from other devices as well as from Wi-Fi connections themselves. TV white space could provide a suitable alternative to campus Wi-Fi networks because of its better signal propagation characteristics as compared to 5 GHz frequencies, which is currently being used as an alternative. As a first step towards white space management to prepare Africa’s university campuses networks for the migration from analog to digital TV, this paper presents the results of an investigation that was conducted to look at the spatial distribution of white spaces frequencies around two university campuses in Cape Town-South Africa to assess if they are useful enough to be used for university campuses to complement Wi-Fi networks.

The cloudy distribution in community network clouds in Guifi.net

Abstract: This demo paper presents Cloudy, a Debian-based distribution to build and deploy clouds in community networks. The demonstration covers the following aspects: Installation of Cloudy, the Cloudy GUI for usage and administration by end users, demonstration of Cloudy nodes and services deployed in the Guifi community network.

RFTrack: TVWS Spectrum Measurements using Android Phones

Abstract: Despite successful trials in several Developing Countries, TVWS has not gained the amount of attention that it deserves. One of the reasons is the lack of awareness by both the general public and the spectrum regulators about the abundance of idle spectrum. Traditionally, spectrum measurements required expensive instruments and considerable operator's expertise. This has changed with the emergence of low cost spectrum analyzers that are also easier to operate. In this paper we present an Android application called RFTrack that measures spectrum using a low-cost spectrum analyzer and geo-tags the data using the phone's GPS. Data is stored in the internal memory. Once an Internet connection is available, the program sends data to a server that presents the results in an easy-to-understand way. After having performed some measurement campaigns with this set up, we believe that this is a useful tool to demonstrate the existence of significant swats of of underutilized spectrum, especially in rural areas of developing countries.

WHITENET: A white space network for campus connectivity using spectrum sensing design principles

Abstract: To this day, the technical challenges of accessing TV white spaces through spectrum sensing can be summed up into its inability to provide maximum protection to primary users from interference. Yet, off-the-shelf spectrum sensing devices, which are emerging on the market at low cost, and the low computation and implementation complexities of the sensing technique, make them more and more attractive to the developing world. Building upon "WhiteNet", a white space network management platform for campus connectivity, this paper proposes design principles that can be incorporated in a spectrum sensing-based white space identification system to minimise probability ofcausing interference to primary users. The principles are designed around the cooperative spectrum sensing model to further reduce chances of interference to primary users. Evaluation of the principles was done using real-world indoor measurements and based on a real TV transmitter-allocation at the University of the Western Cape in Cape Town, South Africa. The results reveal the relevance of using these design principles in white space networking using the emerging White-Fi protocol to boost the capacity of current Wi-Fi campus networks.