Perfect tag identification protocol in RFID networks

Radio Frequency IDentification (RFID) systems are becoming more and more popular in the field of ubiquitous computing, in particular for objects identification. An RFID system is composed by one or more readers and a number of tags. One of the main issues in an RFID network is the fast and reliable identification of all tags in the reader range. The reader issues some queries, and tags properly answer. Then, the reader must identify the tags from such answers. This is crucial for most applications. Since the transmission medium is shared, the typical problem to be faced is a MAC-like one, i.e. to avoid or limit the number of tags transmission collisions. We propose a protocol which, under some assumptions about transmission techniques, always achieves a 100% perfomance. It is based on a proper recursive splitting of the concurrent tags sets, until all tags have been identified. The other approaches present in literature have performances of about 42% in the average at most. The counterpart is a more sophisticated hardware to be deployed in the manufacture of low cost tags.Comment: 12 pages, 1 figur

Target DoA estimation in passive radar using non-uniform linear arrays and multiple frequency channels

In this paper we present a robust approach for target direction of arrival (DoA) estimation in passive radar that jointly exploits spatial and frequency diversity. Specifically we refer to a DVB-T based passive radar receiver equipped with a linear array of few antenna elements non-uniformly spaced in the horizontal dimension, able to collect multiple DVB-T channels simultaneously. We resort to a maximum likelihood (ML) approach to jointly exploit the target echoes collected across the antenna elements at multiple carrier frequencies. Along with an expected improvement in terms of DoA estimation accuracy, we show that the available spatial and frequency diversity can be fruitfully exploited to extend the unambiguous angular sector useful for DoA estimation, which represent an invaluable tool in many applications. To this purpose, a performance analysis is reported against experimental data collected by a multi-channel DVB-T based passive radar developed by Leonardo S.p.A

Minimum Message Waiting Time Scheduling in Distributed Systems

In this paper, we examine the problem of packet scheduling in a single-hop multichannel system, with the goal ofminimizing the average message waiting time. Such an objective function represents the delay incurred by the users before receivingthe desired data. We show that the problem of finding a schedule with minimum message waiting time is NP-complete, by means ofpolynomial time reduction of the time table design problem to our problem. We present also several heuristics that result in outcomesvery close to the optimal ones. We compare these heuristics by means of extensive simulations

Computationally effective range migration compensation in PCL systems for maritime surveillance

In this paper, we consider the possibility of extending the coherent processing interval (CPI) as a way to improve target detection capability in passive radars for maritime surveillance applications. Despite the low velocity of the considered targets, range walk effects could limit the performance of the system when long CPIs are considered. To overcome these limitations while keeping the computational load controlled, we resort to a sub-optimal implementation of the Keystone Transform (KT), based on Lagrange polynomial interpolation, recently presented by the authors and successfully applied against aerial targets. Following those promising results, we extend the proposed approach to a coastal surveillance scenario. In the considered case, since longer CPI values are used, the proposed strategy appears to be even more attractive with respect to a conventional KT implementation based on the Chirp-Z Transform interpolation. In fact, comparable detection performance are obtained with a remarkable computational load saving. In detail, the effectiveness of the proposed approach is demonstrated against experimental data provided by Leonardo S.p.A., using a DVB-T based passive radar

Minimizing the Message Waiting Time in Single-Hop Multichannel Systems

In this paper, we examine the problem of packet scheduling in a single-hop multichannel systems, with the goal of minimizing the average message waiting time. Such an objective function represents the delay incurred by the users before receiving the desired data. We show that the problem of finding a schedule with minimum message waiting time, is NP-complete, by means of polynomial time reduction of the time table design problem to our problem. We present also several heuristics which result in outcomes very close to the optimal ones. We compare these heuristics by means of extensive simulations

Measuring IEEE 802.11p Performance for Active Safety Applications in Cooperative Vehicular Systems

Abstract-In this paper, we present a measurement study of application layer performance in IEEE 802.11p vehicular networks. More specifically, our focus is on active safety applications, which are based on the exchange of beacon messages containing status information between close-by vehicles. We consider two performance metrics relevant to active safety applications: the first is application-layer goodput, which can be used to optimize congestion control techniques aimed at limiting the beaconing load on the wireless channel; the second is the beacon reception rate, which is useful to estimate the level of situation awareness achievable onboard vehicles. Our measurements were conducted using a prototypal, 802.11p compliant communication device developed by NEC, in both stationary and mobile V2V scenarios, and disclosed several useful insights on 802.11p application-level performance. To the best of our knowledge, the ones presented in this paper are the first application-level measurements of IEEE 802.11p based vehicular networks reported in the literature

The IPERMOB System for Effective Real-Time Road Travel Time Measurement and Prediction

Accurate, real-time measurement and estimation of road travel time is considered a central problem in the design of advanced Intelligent Transportation Systems. In particular, whether eective, real-time collection of travel time measurements in a urban area is possible is, to the best of our knowledge, still an open problem. In this paper, we introduce the IPERMOB system for efficient, real-time collection of travel time measurements in urban areas through vehicular networks. We demonstrate that travel time measurements can be accurately estimated onboard GPS-equipped vehicles, and delivered to a centralized server within a few seconds by sending a single message. Furthermore, in IPERMOB locations of travel time checkpoints can be dynamically changed through software reconfiguration, thus at a very limited cost as compared to the enormous costs of, say, installing and/or changing location of automatic vehicle identification equipment. We demonstrate the effectiveness of our approach through extensive travel time collection campaigns. In particular, our technique is shown to estimate travel time with an accuracy below 1%, with two-, three-orders of magnitude savings in both communication and storage resources with respect to existing techniques based on centralized collection of GPS traces. In the last part of the paper, we further show how real-time travel time measurements can be exploited to perform accurate, short range travel time predictions in situations where existing travel time prediction approaches are challenged (e.g., in presence of traffic congestion). The effects of vehicular network penetration rate on accuracy of travel time prediction are also discusse

Assessing the Performance of a MIMO SDR Testbed with Dual Transceiver Implementation

Software Defined Radio testbeds are becoming increasingly used in the wireless networking community, given their feature of leaving wireless network designer full control of the PHY layer. On the other hand, SDR testbeds are formed of very complex software/hardware tools, in which implementation bugs are likely and difficult to identify. For this reason, assessment of the results provided by an SDR platform should be a fundamental, preliminary step in the performance evaluation process. In this paper, we provide a thorough assessment of the MIMONet SDR platform for network-level exploitation of MIMO technology. To assess the platform, we have used two different implementations of an OFDM transceiver: one based on Matlab, the other on the GNU Radio software. We have then crossvalidated performance by means of extensive measurements using the two alternative implementations. We have also designed and implemented a fine grained SNR and BER estimation methodology, that allowed us to carefully validate performance of the two software implementations against theoretical predictions. When collectively considered, the results of our measurements promote MIMONet as the first SDR testbed with carefully validated performance

Understanding the Roles of the Hedgehog Signaling Pathway during T-Cell Lymphopoiesis and in T-Cell Acute Lymphoblastic Leukemia (T-ALL)

The Hedgehog (HH) signaling network is one of the main regulators of invertebrate and vertebrate embryonic development. Along with other networks, such as NOTCH and WNT, HH signaling specifies both the early patterning and the polarity events as well as the subsequent organ formation via the temporal and spatial regulation of cell proliferation and differentiation. However, aberrant activation of HH signaling has been identified in a broad range of malignant disorders, where it positively influences proliferation, survival, and therapeutic resistance of neoplastic cells. Inhibitors targeting the HH pathway have been tested in preclinical cancer models. The HH pathway is also overactive in other blood malignancies, including T-cell acute lymphoblastic leukemia (T-ALL). This review is intended to summarize our knowledge of the biological roles and pathophysiology of the HH pathway during normal T-cell lymphopoiesis and in T-ALL. In addition, we will discuss potential therapeutic strategies that might expand the clinical usefulness of drugs targeting the HH pathway in T-ALL

Chapter A statistical information system in support of job policies orientation

A significant problem for labour market policies relies on the individuation of the most advisable skills to have and to enhance through focused training offers. Vocational training systems and institutions are called to answer the question posed by every person looking for a new job or professional opportunities: which are the skills-to-have to enhance the professional profile? Many efforts have been made to answer this question, mainly designing predictive models; however, these models are often limited to specific economic sectors and usually don’t adopt a country-specific perspective. This paper proposes a recommendation system oriented to specific users: once that the user has described his/her skills profile, the system suggests the skills that, once got, will fit with the most frequent job vacancies. In this proposal perspective, the skills are proposed regardless of the economic sector, and they are compatible with the characteristics of the specific country labour market. In this contribution, we will focus on the Italian market; the recommendation system is based on the job ads published by Italian companies on various websites for both 2019 and 2020 after the skills required for each job offer have been mapped to one of the skills presented in the classification of European Skills/ competence, qualifications ad Occupations (ESCO)