Collaborative Data Delivery for Smart City-oriented Mobile Crowdsensing Systems

in IEEE Global Communications Conference (GLOBECOM), Abu Dhabi, UAE, 2018 (2018, December)

The huge increase of population living in cities calls for a sustainable urban development. Mobile crowdsensing (MCS) leverages participation of active citizens to improve performance of existing sensing ... [more ▼]

The huge increase of population living in cities calls for a sustainable urban development. Mobile crowdsensing (MCS) leverages participation of active citizens to improve performance of existing sensing infrastructures. In typical MCS systems, sensing tasks are allocated and reported on individual-basis. In this paper, we investigate on collaboration among users for data delivery as it brings a number of benefits for both users and sensing campaign organizers and leads to better coordination and use of resources. By taking advantage from proximity, users can employ device-to-device (D2D) communications like Wi-Fi Direct that are more energy efficient than 3G/4G technology. In such scenario, once a group is set, one of its member is elected to be the owner and perform data forwarding to the collector. The efficiency of forming groups and electing suitable owners defines the efficiency of the whole collaborative-based system. This paper proposes three policies optimized for MCS that are compliant with current Android implementation of Wi-Fi Direct. The evaluation results, obtained using CrowdSenSim simulator, demonstrate that collaborative-based approaches outperform significantly individual-based approaches. [less ▲]

A New Synchronization Method for Three - phase Grid - tied LC-Filtered Voltage Source Inverters

in International Journal of Emerging Engineering Research and Technology (2017), 5(5), 7-15

In order to identify and to track the phase angle and magnitude of the grid voltage, several synchronization methods exist, among which the phase-locked loop (PLL) algorithm is the most popular. This ... [more ▼]

In order to identify and to track the phase angle and magnitude of the grid voltage, several synchronization methods exist, among which the phase-locked loop (PLL) algorithm is the most popular. This paper presents a new synchronization method for grid-tied voltage source inverters (VSIs) based on the intrinsic inverter synchronous reference frame. The absolute phase angle of the grid voltage is not required but its voltage direct and quadrature components into the well-known inverter frame. The advantages of this method is its low computational load with a reduced number of control parameters, as well as its robustness and effectiveness. This property makes it very convenient for embedded control systems with limited computing resources. Simulations and experimental test results are presented to prove the performance of the proposed method. [less ▲]

Assessing Performance of Internet of Things-based Mobile Crowdsensing Systems for Sensing as a Service Applications in Smart Cities

in 8th IEEE International Conference on Cloud Computing Technology and Science (CloudCom) (2016, December)

The Internet of Things (IoT) paradigm makes the Internet more pervasive. IoT devices are objects equipped with computing, storage and sensing capabilities and they are interconnected with communication ... [more ▼]

The Internet of Things (IoT) paradigm makes the Internet more pervasive. IoT devices are objects equipped with computing, storage and sensing capabilities and they are interconnected with communication technologies. Smart cities exploit the most advanced information technologies to improve public services. For being effective, smart cities require a massive amount of data, typically gathered from sensors. The application of the IoT paradigm to smart cities is an excellent solution to build sustainable Information and Communication Technology (ICT) platforms and to produce a large amount of data following Sensing as a Service (S^2aaS) business models. Having citizens involved in the process through mobile crowdsensing (MCS) techniques unleashes potential benefits as MCS augments the capabilities of existing sensing platforms. To this date, it remains an open challenge to quantify the costs the users sustain to contribute data with IoT devices such as the energy from the batteries and the amount of data generated at city-level. In this paper, we analyze existing solutions, we provide guidelines to design a large-scale urban level simulator and we present preliminary results from a prototype. [less ▲]

Untraceable VoIP Communication based on DC-nets

E-print/Working paper (2016)

Untraceable communication is about hiding the identity of the sender or the recipient of a message. Currently most systems used in practice (e.g., TOR) rely on the principle that a message is routed via ... [more ▼]

Untraceable communication is about hiding the identity of the sender or the recipient of a message. Currently most systems used in practice (e.g., TOR) rely on the principle that a message is routed via several relays to obfuscate its path through the network. However, as this increases the end-to-end latency it is not ideal for applications like Voice-over-IP (VoIP) communication, where participants will notice annoying delays if the data does not arrive fast enough. We propose an approach based on the paradigm of Dining Cryptographer networks (DC-nets) that can be used to realize untraceable communication within small groups. The main features of our approach are low latency and resilience to packet-loss and fault packets sent by malicious players. We consider the special case of VoIP communication and propose techniques for a P2P implementation. We expose existing problems and sketch possible future large-scale systems composed of multiple groups. [less ▲]

A Hidden Markov Model to detect relevance in nancial documents based on on/off topics

in European Conference on Data Analysis (2014)

Automated text classification has gained a significant attention since a vast amount of documents in digital forms are widespread and continuously increasing. Most of the standard classification posit the ... [more ▼]

Automated text classification has gained a significant attention since a vast amount of documents in digital forms are widespread and continuously increasing. Most of the standard classification posit the independence of the terms-features in document, which is unrealistic considering the sophisticated structure of the language. Our research concerns the discovery of relevance in documents, which adequately refers to a sufficient number of thematic themes (or topics) that are either `on' or `off'. `On topics' are semantically close with a domain specific discourse, whereas `Off topics' are not considered to be on documents. As a rather promising approach, we have modelled a stochastic process for term sequences, where each term is conditionally dependent of its preceeding terms. Hidden Markov Models hereby provide a reliable potential to incorporate language and domain dependencies for a classification. Terms are deterministically associated with classes to improve the probability estimates for the infrequent words. In the paper presentation, we demonstrate our approach and motivate its eligibility by the exploration of annotated Thomson Reuters news documents; in particular, the `on topic' documents discourse the monetary policy of Federal Reserves. We estimate the transition and emission probabilities of our model on a training set of both on and off topic documents and evaluate the accuracy of our approach using 10-fold cross validation. This work is part of the interdisciplinary research project ESCAPE, which is funded by the Fonds National de la Recherche. We kindly thank our colleagues from the Dept. of Finance for their support. [less ▲]

Coherent Receiver for AIS Satellite Detection

in Proceedings of 4th International Symposium on Communications, Control and Signal Processing (ISCCSP) (2010)

Multiple Decision Feedback Equalizer for Satellite AIS Coherent detection

in Multiple Decision Feedback Equalizer for Satellite AIS Coherent detection (2010)

Slotted Packet Counting Attacks on Anonymity Protocols

in The proceedings of the Australasian Information Security Conference (2009)

In this paper we present a slotted packet counting attack against anonymity protocols. Common packet counting attacks make strong assumptions on the setup and can easily lead to wrong conclusions, as we ... [more ▼]

In this paper we present a slotted packet counting attack against anonymity protocols. Common packet counting attacks make strong assumptions on the setup and can easily lead to wrong conclusions, as we will show in our work. To overcome these limitations, we account for the variation of traffic load over time. We use correlation to express the relation between sender and receiver nodes. Our attack is applicable to many anonymity protocols. It assumes a passive attacker and works with partial knowledge of the network traffic. [less ▲]

Functions on Probabilistic Graphical Models

in Proceedings of the International Multiconference on Computer Science and Information Technology IMCSIT 2009 (2009)

Computation of Moments in the Trellis

in Proceedings of IEEE International Symposium on Information Theory (2008)

Decisions on sources with memory transmitted over independent channels can be taken by employing trellis calculations. In this paper, it is shown that for a certain class of functions their moments can be ... [more ▼]

Decisions on sources with memory transmitted over independent channels can be taken by employing trellis calculations. In this paper, it is shown that for a certain class of functions their moments can be computed in the trellis, too. This is done by generalizing the forward/backward recursion known from the BCJR algorithm [1]. In analogy to the symbol probabilities, by introducing a constraint at a certain depth in the trellis we obtain symbol moments. These moments are required for an ef?cient implementation of the discriminated belief propagation algorithm in [2], and can furthermore be utilized to compute conditional entropies in the trellis. The moment computation algorithm has the same asymptotic complexity as the BCJR algorithm. It is applicable to any commutative semi-ring, thus also providing a generalization of the Viterbi algorithm [3]. [less ▲]