The problem of detecting T-wave alternans (TWA) in ECG signals has received considerable attention in the biomedical community. This paper introduces a Bayesian model for the T waves contained in ECG signals. A block Gibbs sampler was recently studied to estimate the parameters of this Bayesian model (including wave locations, amplitudes and shapes). This paper shows that the samples generated by this Gibbs sampler can be used efficiently for TWA detection via different statistical tests constructed from odd and even T-wave amplitude samples. The proposed algorithm is evaluated on real ECG signals subjected to synthetic TWA and compared with two classical algorithms.

Space Wire is a wormhole network standard scheduled to be used as the sole on-board network for future satellites by the ESA. As the network will be shared by real-time and non real-time traffic, network designers require a tool to check that temporal constraints are verified for all the urgent messages. Previously, we proposed a model for a best-effort worm-hole network based on Network Calculus theory. This model is based on new network element that we call the Wormhole Section. Here, we show how to combine Wormhole Section elements to compute the end-to-end service curve offered to a flow and illustrate its use on a industrial case study.

Coastal altimetric waveforms may be corrupted by peaks. A simple parametric model was recently introduced to model peaky altimetric waveforms. This model assumes that the received altimetric waveform is the sum of a Brown echo and a Gaussian peak. This model has provided interesting results for symmetric peaks affecting altimetric signals. However, it is not appropriate for altimetric signals corrupted by asymmetric peaks. This paper studies a Brown with asymmetric Gaussian peak model for parameter estimation of altimetric waveforms. The parameter estimation problem is solved by a maximum likelihood estimator relying on an optimization algorithm. The performance of the proposed model and the resulting estimation strategy is evaluated via simulations conducted on synthetic and real data.

This paper proposes a spectral- and power- efficient code division multiplexing (CDM) scheme based on code shift keying (CSK) for the down-link of a communication system subject to additive Gaussian noise (e.g., the forward link of a satellite communication system). In a CSK system, each active user is assigned a set of sequences taken from Gold codes and their cyclic shifts. Spectral efficiency can be achieved by multiplexing several CSK modulators. We first define the corresponding Maximum-Likelihood (ML) decoder, showing that it can be efficiently implemented through a Sphere Decoding (SD) algorithm. An approximate performance analysis of the proposed scheme is given, and validated through numerical simulations, showing that larger spectral efficiencies also lead to increased power efficiencies.

The SpaceWire network standard is promoted by the ESA and is scheduled to be used as the sole on-board network for future satellites. This network uses a wormhole routing mechanism that can lead to packet blocking in routers and consequently to variable end-to-end delays. As the network will be shared by real-time and non real- time traffic, network designers require a tool to check that temporal constraints are verified for all the critical messages. Network Calculus can be used for evaluating worst- case end-to-end delays. However, we first have to model SpaceWire components through the definition of service curves. In this paper, we propose a new Network Calculus element that we call the Wormhole Section. This element allows us to better model a wormhole network than the usual multiplexer and demultiplexer elements used in the context of usual Store-and-Forward networks.

Broadcasting systems have to deal with channel diversity in order to offer the best rate to the users. Hierarchical modulation is a practical solution to provide several rates in function of the channel quality. Unfortunately the performance evaluation of such modulations requires time consuming simulations. We propose in this paper a novel approach based on the channel capacity to avoid these simulations. The method allows to study the performance in terms of spectrum efficiency of hierarchical and also classical modulations combined with error correcting codes. Our method will be applied to the DVB-SH standard which considers hierarchical modulation as an optional feature.

The Stokes decomposition theorem deals with the electrical field E-->=X,Y of a light beam. The theorem asserts that a beam can be viewed as the sum of two differently polarized parts. This result was recently discussed for light in the frame of the unified theory of coherence. We study the general case of an electromagnetic wave which can be in radio, radar, communications, or light. We assume stationary components with any power spectrum and finite or infinite bandwidth. We show that an accurate definition of polarization and unpolarization is a key parameter which rules the set of solutions of the problem. When dealing with a ``strong definition'' of unpolarization, the problem is treated in the frame of stationary processes and linear invariant filters. When dealing with a ``weak definition'', solutions are given by elementary properties of bidimensional random variables.

In networks with very large delay like satellite IPbased networks, standard TCP is unable to correctly grab the available resources. To overcome this problem, Performance Enhancing Proxies (PEPs), which break the end-to-end connection and simulate a receiver close enough to the sender, can be placed before the links with large delay. Although splitting PEPs does not modify the transport protocol at the end nodes, they prevent the use of security protocols such as IPsec. In this paper, we propose solutions to replace the use of PEPs named SatERN. This proposal, based on Explicit Rate Notification (ERN) protocols over IP, does not split connections and is compliant with IP-in- IP tunneling solutions. Finally, we show that the SatERN solution achieves high satellite link utilization and fairness of the satellite traffic.

This paper introduces a new error correction strategy using cyclic redundancy checks (CRC) for a trellis coded system in the presence of bit stuffing. The proposed receiver is designed to simultaneously demodulate, decode and correct the received message in the presence of bit stuffing. It is based on a Viterbi algorithm exploiting the conditional transitions of an appropriate extended trellis. The receiver is evaluated with automatic identification system (AIS) messages constructed with a 16 bit CRC and a Gaussian Minimum Shift Keying (GMSK) modulation. The stuffed bits are inserted after any sequence of five consecutive bits 1 as requested by the AIS recommendation. Simulation results illustrate the algorithm performance in terms of packet error rate. A gain of more than 2,5 dB is obtained when compared to the conventional GMSK receiver.