Daniele Brevi

A Methodology for the Analysis of 802.11a Links in Industrial Environments

Wireless solutions are becoming more and more attractive for the communication systems of manufacturing plants. If the advantages of wireless are clear and have been extensively discussed, also the drawbacks need to be considered and, among them, the impact of an industrial environment on error rate and throughput of the wireless links. These performance aspects get even more critical when developing wireless solutions for safety-critical industrial communications and using off-the-shelf components. The first step in evaluating these solutions is to characterize the channel behavior of the selected wireless platform for a set of real-life scenarios representative of different operating conditions. We present a methodology and software tool aimed at analyzing WLAN channel behaviors and we apply it to evaluate the use of 802.11a consumer chipsets for a typical safety critical industrial plant application.

Comparative characterization of four antennas for VANETs by on-field measurements

Vehicular ad-hoc networks (VANETs) have been extensively studied by simulations and trials and are getting closer and closer to the practical deployment. Despite this, only few studies have investigated the issues of antenna placement, even if it is far from being negligible: depending on the antenna position, a stronger or a weaker signal may be received and the overall effectiveness of safety messages carried by VANETs may get affected. This paper aims at digging into the problem of antenna placement for VANETs by a field-test comparative analysis of four candidate antennas, differing in their design and, particularly, in their positions.

A drone-based image processing system for car detection in a smart transport infrastructure

In this paper we present a car detection system prototyped within an experimental project. It analyzes video streams recorded by drones flying over an urban environment. The intended final goal is the automatic provision of helpful information, such as the available parking spaces and the level of congestion of the streets. The system has been tested both in a desktop PC and on an embedded system. The experimental results show a significant accuracy and prove the feasibility of novel on-board services.

A Hybrid Cloud Infrastructure for the Optimization of VANET Simulations

Cloud computing is becoming increasingly popular for the provisioning of computing resources, in particular, through scientific tools that perform modeling or simulations. Vehicular Ad-Hoc Networks (VANETs) are mobile ad hoc networks which are meant to support primarily safety warnings and to manage challenging conditions to improve our transportation experience. This is a challenging context where large amounts of data need to be elaborated and analyzed in order to fully understand protocol and phenomena behaviors. In fact, VANET simulations are typically computationally intensive problems, and lend themselves for execution on distributed systems. A new hybrid cloud infrastructure is here presented to help and support the simulation science. This architecture optimizes the scheduling and execution of a batch of simulations, increasing the overall performance, in terms of simulation time and costs. Results clearly highlight the potentiality of this technology, proving as a valuable tool for network simulations.

Viability and guidelines for the effective integration of consumer WiFi in industrial plants

Wireless solutions are becoming frequent in manufacturing plants: the introduction of wireless in industrial automated processes requires solutions which fulfill industrial environmental and electromagnetic requirements and meet reliability and communication performance typically required by control loops. In this paper these issues are discussed and set by a practical case involving WiFi transceivers, requiring an EMC (Electromagnetic Compatibility) industrial certification and almost deterministic near real-time guarantees. The solution here presented shows how the above two goals can be achieved using cheap off-the-shelf components: the EMC conditions are satisfied thanks to practical tricks (proposed as guidelines), while near real-time performance is enabled by proper configurations of IEEE 802.11e parameters.

Hybrid localization solutions for robotic logistic applications

This paper presents some results concerning rovers localization, achieved within the framework of the Italian Regional project MACP4Log [1]. This project investigates the coordination of a team of rovers that delivers assistance services in the context of logistic spaces. The issue of single rover localization is a service prerequisite which is faced by different approaches. First a WiFi-based localization technique is examined: it involves building a radio map of the Received Signal Strength (RSS) in the considered environment and, afterwards, setting the problem of localization as an optimization problem: given a RSS, the function is reversed to get the estimated position of the rover. Finally the proposed WiFi technique is integrated with a particle filter algorithm following both a “loose” and a “tight” coupling approaches, integrating radio information at two different levels. Experimental results in monodimensional and bidimensional environments validate these approaches and allow a comparative analysis among them.

Wireless for the factory: The Wi-Fact analysis

Wireless in shop-floors is a bet: it outlines the possibility of making automation more flexible and to simplify plant reconfiguration. However, the specific context subtends several challenging requirements, which the available off-the-shelf solutions are not 100%-ready to cope with. By the way, the potential benefits of wireless for automation are so significant that it is worth investigating novel techniques to enforce the available wireless transceivers, so as to make them suitable for factories. The Italian regional project Wi-Fact is putting under close scrutiny the context of wireless automation to identify the most significant threats and proposing solutions to stem them. This paper take stock of the project achievements at its mid-term turning point.

Design and Quantitative Assessment of a Novel Hybrid Cloud Architecture for VANET Simulations

Vehicular Ad-hoc NETworks (VANETs) are ad hoc networks aimed at improving the safety and efficiency of transportation in the near future. Despite the availability of results from field trials, simulations still play an unequalled role in the comprehensive understanding of complex and crowded VANET scenarios. Even more, VANET simulations are typically computationally intensive problems and lend themselves for execution on distributed systems. This paper presents a new architecture optimizing the scheduling and execution of a batch of simulations over a hybrid cloud. Results reveal that, in case of multiple simulations to be executed, the overall performance can deeply benefit from a distributed approach, reducing time and costs.

MS-Aloha: Preliminary analysis of its suitability for wireless automation

This paper deals with the adoption of wireless communications in industrial automation. Most diffuse wireless systems require the deployment of a fixed infrastructure, with sufficient nodes acting as coordinators; this approach is typically applied also in automation. Conversely, a decentralized wireless solution is here proposed: it is based on a synchronous and connection-oriented protocol studied for vehicular communications. The protocol, called MS-Aloha, guarantees a multi-hop coordination with dynamic resource reservation, spatial slot re-use and hidden terminals prevention. The proposed solution has been modeled and simulated in order to quantitatively demonstrate how much its determinism and multi-hop coordination can be beneficial to the automation, in comparison to CSMA/CA. The simulated scenarios address the evaluation of the latency, delay variation, and delivery rate in critical conditions involving hidden terminals and close to congestion.

Exploring TV white spaces for the mitigation of AIS weaknesses

Ship Reporting Systems (SRSs) are aimed at a safer sailing, by providing a timely description of the sea traffic. Automatic Identification System (AIS) is the most known SRS and works in the VHF band: given the limited available bandwidth, AIS mainly addresses pure line-of-sight scenarios and neglects security aspects. Specifically to overcome the current limitations of AIS and make it more robust and reliable, new solutions are being investigated. This paper explores for the first time the potential role of white-space frequencies as an auxiliary channel, bearing Out-Of-Band signals required to make AIS more versatile. The simulation analyses confirm the applicability of this band and outline possible future studies and activities.