This paper introduces a new model for delay/Doppler altimetry, taking into account the effect of antenna mispointing. After defining the proposed model, the effect of the antenna mispointing on the waveform is analyzed with respect to along-track and across-track directions. Two least squaresapproaches are proposed for the estimation of the altimetric parameters. The first algorithm estimates four parameters including the across-track mispointing (which affects the echo’s shape) while the second algorithm considers the mispointing angles provided by the star-trackers and estimates the three remaining parameters. The proposed model and algorithms are validated via simulations conducted on both synthetic and real data.

In this paper, we derive an asymptotic analysis and optimization of coded CPM systems using both unstructured and protograph-based LDPC codes ensembles. First, we present a simple yet effective approach to design unstructured LDPC codes: by inserting partial interleavers between LDPC and CPM, and allowing degree-1 and degree-2 variable nodes in a controlled pattern, we show that designed codes perform that can operate very close to the maximum achievable rates. Finally, the extension to protograph based codes is discussed. We provide some simple rules to design good protograph codes with good threshold properties.

The propagation of a laser beam through the atmosphere leads to spectral widening, which has a detrimental effect on information transmission. In literature the study of laser beam envelope and phase was achieved through demodulation. In this paper we explain that amplitude demodulation in the baseband leads to changes in analytic signals. We give a formula which allows this drawback to be overcome, achieving two demodulations with same frequency and different phases. Examples are given in the Gaussian framework and in the case of random propagation times.

This paper presents a nonlinear mixing model for hyperspectral image unmixing. The proposed model assumes that the pixel reflectances are post-nonlinear functions of unknown pure spectral components contaminated by an additive white Gaussian noise. These nonlinear functions are approximated using second-order polynomials leading to a polynomial postnonlinear mixing model. A Bayesian algorithm is proposed to estimate the parameters involved in the model yielding an unsupervised nonlinear unmixing algorithm. Due to the large number of parameters to be estimated, an efficient Hamiltonian Monte Carlo algorithm is investigated. The classical leapfrog steps of this algorithm are modified to handle the parameter constraints. The performance of the unmixing strategy, including convergence and parameter tuning, is first evaluated on synthetic data. Simulations conducted with real data finally show the accuracy of the proposed unmixing strategy for the analysis of hyperspectral images.

Vector acquisition collects all signals in a given environment, attempting to better identify those that are weakest but most important for navigation and positioning services. This article describes the operation of this methodology incorporating a new implementation algorithm to more efficiently use multiple GNSS signals in challenging environments.

Data gathering and transmission through a communicating network can be obtained thanks to wireless sensor networks and observation satellites. Using both these technologies will allow mankind to build a sustainable future by understanding the world around. In recent years, space actors have demonstrated a will to reuse the developped technologies by creating multiple programs platforms and defining context-agnostic protocols. The goal of this thesis is to study the characteristics of several observation technologies to exploit their similarities. We analyse the existing technologies and architectures in several contexts. Then, we propose a networking architecture handling constraints of most commonly used systems in such a context. The main constraints of observation scenarios are due to the links intermittence and lack of network connectivity. We focus on a solution using the delay tolerant networking concept. In such a context, a path between source and destination might not exist at all time. That is why most proposed protocols send multiple copies of a message to increase the delivery ratio. We wanted to decrease network resource use while keeping a similar performance to increase network efficiency. After having proposed a common architecture, we focused on particularities of each network segment to solve problems locally. Concerning the satellite part, we focused specifically on memory management techniques. We considered a low earth orbit satellite with a limited on-board buffer, gathering data from gateways. The goal is then to select the most urgent messages even though the least urgent ones are sent back to the ground. On the terrestrial sensor network part, we focused on the decrease of network resource use. We used the history of encounters between nodes and analysed the influence of the proportion of memory allocated to acknowledgements on network performance. We achieved better performance than existing solutions and at lower cost. The proposed solutions can be deployed and applied in several applications.

Data gathering and transmission through a communicating network can be obtained thanks to wireless sensor networks and observation satellites. Using both these technologies will allow mankind to build a sustainable future by understanding the world around. In recent years, space actors have demonstrated a will to reuse the developped technologies by creating multiple programs platforms and defining context-agnostic protocols. The goal of this thesis is to study the characteristics of several observation technologies to exploit their similarities. We analyse the existing technologies and architectures in several contexts. Then, we propose a networking architecture handling constraints of most commonly used systems in such a context. The main constraints of observation scenarios are due to the links intermittence and lack of network connectivity. We focus on a solution using the delay tolerant networking concept. In such a context, a path between source and destination might not exist at all time. That is why most proposed protocols send multiple copies of a message to increase the delivery ratio. We wanted to decrease network resource use while keeping a similar performance to increase network efficiency. After having proposed a common architecture, we focused on particularities of each network segment to solve problems locally. Concerning the satellite part, we focused specifically on memory management techniques. We considered a low earth orbit satellite with a limited on-board buffer, gathering data from gateways. The goal is then to select the most urgent messages even though the least urgent ones are sent back to the ground. On the terrestrial sensor network part, we focused on the decrease of network resource use. We used the history of encounters between nodes and analysed the influence of the proportion of memory allocated to acknowledgements on network performance. We achieved better performance than existing solutions and at lower cost. The proposed solutions can be deployed and applied in several applications.

L'invention concerne un procédé et un dispositif d'évaluation prédictive de puissance d'intermodulation dans un dispositif électronique dans lequel une fonction prédictive f permet d'évaluer de façon prédictive des valeurs de puissance d'une composante d'intermodulation produite par une distorsion d'intermodulation d'un signal d'entrée, caractérisé en ce que la fonction prédictive f comprend une partie impaire V obtenue par multiplication d'une fonction impaire F, et d'une fonction G, obtenue par composition d'une fonction g paire à valeurs réelles positives et d'une fonction Q sous forme de série réelle comprenant au moins un terme de degré q appartenant aux réels non-entiers.

The Low Extra Delay Background Transport (LEDBAT) protocol is a recently standardized protocol that aims to offer a scavenger service (i.e. the goal is to exploit the remaining and unused capacity of a link). LEDBAT is a delay-based protocol mainly defined by two parameters: a target queuing delay and a gain. The RFC 6817 provides guidelines to configure both parameters that strongly impact on the LEDBAT behavior in terms of fairness with other protocols. However, these guidelines are questioned by several studies as they might lead to the generation of a non-LBE (Less-than-Best-Effort) traffic. This paper explores the set of optimal parameters allowing LEDBAT protocol to effectively perform as an LBE traffic. We conclude that the optimal couple of target and decrease gain is (5ms; 10). However, we observe that the aggregated use of optimized LEDBAT sources still disturb the overall traffic performance and that the exponential backoff is not an answer to this issue. As a result, we believe that additional strategies to limit the number of LEDBAT flows are required for integrating this protocol at a large scale.

In this paper, we consider the problem of IP packet scheduling over a GSE/DVB-S2 satellite link. Scheduling flows with QoS requirements has been widely addressed in the mobile field, especially in LTE and WiMAX, with emphasis on fairness, efficiency and dynamic adaptation to transmission conditions. We focus on the well-known empirical scheduling rules known as PF, M-LWDF and EXP-PF for both QoS and MODCOD scheduling, and present how they were adapted to GSE/DVB-S2 encapsulation. Some of the challenging issues yielded by DVB-S2 are tackled, such as joint scheduling of both QoS and MODCODs, concatenation of numerous user packets into one BBFrame and fairness issues introduced by the scheduling algorithm, especially when dealing with various transmission scenarios. We show the potential of our scheduling algorithm using several simulations.