Ulrich Sorger

CrowdSenSim: a Simulation Platform for Mobile Crowdsensing in Realistic Urban Environments

Smart cities take advantage of recent Information and Communication Technology (ICT) developments to provide added value to existing public services and improve quality of life for the citizens. The Internet of Things (IoT) paradigm makes the Internet more pervasive where objects equipped with computing, storage, and sensing capabilities are interconnected with communication technologies. Because of the widespread diffusion of IoT devices, applying the IoT paradigm to smart cities is an excellent solution to build sustainable ICT platforms. Having citizens involved in the process through mobile crowdsensing (MCS) techniques augments capabilities of these ICT platforms without additional costs. For proper operation, MCS systems require the contribution from a large number of participants. Simulations are therefore a candidate tool to assess the performance of MCS systems. In this paper, we illustrate the design of CrowdSenSim, a simulator for mobile crowdsensing. CrowdSenSim is designed specifically for realistic urban environments and smart cities services. We demonstrate the effectiveness of CrowdSenSim for the most popular MCS sensing paradigms (participatory and opportunistic), and we present its applicability using a smart public street lighting scenario.

Coherent receiver for AIS satellite detection

AIS is a universal shipborne Automatic Identification System recently introduced for traffic monitoring and safety at sea. Ships exchange navigational information to identify and localize vessels in a short range to avoid collisions. AIS signals use Gaussian Minimum Shift Keying (GMSK) for transmission.

Turbo decoding: Why stopping-criteria do work

The convergence of iterative decoding schemes is considered. The class of dually coupled codes is recalled, being a super class to both turbo and LDPC codes. It is proven that the output L-values of a turbo decoder cannot grow to infinity, while those of an LDPC decoder can. Finally, a new decoder parameter is introduced by which the convergence behavior can be controlled.

MPTCP: Concept of a flow control protocol based on multiple paths for the next generation internet

This contribution is attempting to provide the fundamental basis of a new transmission control protocol designed for the next generation Internet and based on TCP. The TCP protocol is not capable to carry out all the traffic generated by the Internet as it leads to congestion and packet loss out of the quality of service required specially for critical connections that need to be treat with a higher priority. In this paper, we focus on a new protocol design for the next generation Internet. This protocol has been developed in order to avoid or reduce the congestions appearance and the high variability of the Internet traffic. It should be applied preferentially for connections that require a high level of security and performance. We suggest a TCP protocol based on multiple paths MPTCP for a data transmission between two network entities in a well-defined environment. This work is based on a theoretical modeling.

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

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

Computation of distributions and their moments in the trellis

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Route diversity: A future for transmission protocols?

aaS) 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.

Reduced State M-ary Iterative Channel and Data Estimation without Prefilter using Proportionate Algorithm

Consider a function whose set of vector arguments with known distribution is described by a trellis. For a certain class of functions, the distribution of the function values can be calculated in the trellis. The forward/backward recursion known from the BCJR algorithm [2] is generalized to compute the moments of these distributions. In analogy to the symbol probabilities, by introducing a constraint at a certain depth in the trellis we obtain symbol distributions and symbol moments, respectively. These moments are required for an efficient implementation of the discriminated belief propagation algorithm in [8], 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 actually providing a generalization of the Viterbi algorithm [10].

Doppler-variant modeling of the vocal tract

This contribution is attempting to show how a route diversity can improve the traffic behavior of a connection between two network entities. The most used transmission protocols TCP and UDP control the quasi-totality of the Internet traffic. However they are not capable to carry out all the traffic generated by the Internet as they lead to congestion and packet loss out of the quality of service required specially for critical connections that need to be treat with a higher priority. In this paper, we focus on multipath routing and multipath transport protocols that seem to be a relevant solution to avoid the drawbacks generated by the use of a single path by each connection packet. Pushing connection packets on multiple paths during all the data transaction should bring a better QoS. We mention a new protocol design for the next generation Internet. This protocol has been developed in order to avoid or reduce the congestions appearance and the high variability of the Internet traffic. We suggest a TCP protocol based on Multiple Paths MPTCP for a data transmission between two network entities in a well-defined environment. A simulator has been developed in order to evaluate the gain provided by the route diversity.

Maximum-likelihood channel estimation using the spreading matrix in fast time-variant frequency selective channels

The technique presented here improves a previously proposed iterative channel data estimation (ICDE) technique in M-ary data transmission over time-variant frequency selective channels by using a proportionate sample adaptive filter for channel tracking on a per-survivor processing (PSP) basis. Henceforth, we call the approach using proportionate algorithm P-ICDE. The data detector is a simple M-algorithm with extended metric calculation that minimizes the expectation of the Euclidian distance between received signal and convolution of channel and data hypotheses. For low velocities, the technique can work with an initial channel estimate as data detector only, simply as M- algorithm with extended metric. Known techniques, such as delayed decision feedback sequence estimation (DDFSE), optionally with reduced state sequence estimation (RSSE) or adaptive state allocation (ASA), for comparison, reduce the complexity of the Viterbi detector by shortening of the channel impulse response or applying decision feedback on the trellis. In order to keep the performance loss low, a minimum-phase overall impulse response, achieved by an allpass approximating front-end prefilter (FEP), is crucial for these techniques. Our detector, however, works without FEP, which, if block adapted, would lead to severe degradation in fast fading. The detector can work with 3-5 states only, depending on the quality of the channel estimates, the multipath profile of the channel and the symbol constellation.