Lors du développement d’un nouvel avion, la phase précédant l’obtention du certificat de navigabilité est basée sur de nombreux essais au sol ou en vol. Dans le domaine spatial, le lancement est l’une des phases les plus critiques pour les systèmes et des essais au sol particulièrement rigoureux sont donc réalisés afin de vérifier que la charge utile ne sera pas endommagéeDes milliers de capteurs de pression ou de jauges de contrainte sont ainsi utilisés par les industriels du secteur pour ce type d’essais. Mais tous ces éléments sont aujourd’hui connectés par des fils, ce qui engendre des contraintes de temps, de coût et de limitation du nombre de capteurs. Leur remplacement par des réseaux de capteurs sans fil est une solution évidente qui permet également d’augmenter le nombre de points de mesure. Cependant, il n’existe aujourd’hui aucun protocole permettant de répondre aux attentes et besoins des professionnels de l’aéronautique et du spatial. Les travaux présentés dans cette thèse ont ainsi vocation à répondre aux besoins d’un canal de communication très haut débit, basse consommation, à faible puissance d’émission, fiable et autorisant un grand nombre de nœuds. Un prototype de couche physique basée sur un système OFDM ultra large bande a été réalisé, testé et validé, et permet d’atteindre un débit de plus de 200 Mbits/s. / To evaluate a system's compliance with its specified requirements, Hardware System Testing is conducted on the complete and integrated system. This phase is essential in all industry branches, especially in the very regulated and critical aerospace world. In the final phase of the development of an airplane, flight test equipment gathers and analyzes data during flight to evaluate the flight characteristics of the aircraft and validate its design, including safety aspects. One of the most critical tests is the measure of the pressure around the wings during flight. All new aircrafts are computer designed with the use of virtual wind tunnels. So very accurate measures have to be done on the aircraft to validate the model before the aircraft can be industrially produced. In the case of satellites, vibration and mechanical stress are two critical phenomena a satellite endures during launch. This is leading to the necessity for accurate ground tests using strain gauges or thermal sensors before allowing a launch. All such systems used by aircraft and satellite manufacturers today are wired systems. Sensors put around the wings or inside the satellite compartments are wired to a concentrator inside the cabin or the operator’s room. Although good performances are observed in terms of measurement accuracy, these systems have strong drawbacks. The two most important ones are the weight and the cost of both the systems and their installation. An additional drawback concerning its use on aircrafts is due to the installation of a system that increases the weight of the aircraft and immobilizes it during many weeks due to the routing of every cable inside the wings. The cost and the complexity of such systems don’t allow a great number of measurement points. The replacement of conventional measurement networks by wireless sensor networks is not an obvious solution. Despite the great interest in wireless sensor networks in the recent years, the technological barriers are still very numerous and there is currently no protocol to meet the expectations and needs of aviation professionals. The work presented in this thesis aims to meet the needs of a high-speed, low power consumption, low emission and reliable communication layer. Measurements have been performed in real conditions using commercial devices based on the protocol MB-OFDM/Wimedia, the most common standard that approach the need expressed, and have served to define the basis of the study and have helped to select best development tracks. Measurements have demonstrated also the specificity of the propagation channel. In order to reduce the time between the choice of algorithms and their testing in real conditions, it became necessary to use a design flow called Specification - Exploration – Improvement based on automatic synthesis tools. This development cycle has identified specific material needs for the design of the demonstrator.The physical layer is based on an OFDM system and UWB to achieve a data rate of over 150 Mb/s. A fully functional demonstrator, implemented on FPGA and composed of four communicating nodes was presented and has been used to validate the physical layer. Finally first steps to develop a digital ASIC are presented to achieve the goal of low power consumption

[pt] As comunicações sem fio são um dos pilares do desenvolvimento das novas gerações de comunicações móveis. Cada geração tem usado alguma técnica de acesso múltiplo para aproveitar os recursos do canal. Esta dissertação apresenta uma análise de duas técnicas de multiplexação ortogonal. Ambas técnicas implementam a transmissão em blocos, onde uma delas se combina com a abordagem Code Division Multiple Access (CDMA), enquanto a outra usa a técnica de transmissão multiportadora Orthogonal Frequency Division Multiplexing (OFDM). O desempenho e a ocupação espectral de ambas técnicas e as suas vantagens são analisados neste trabalho. Expressões analíticas para a Densidade Espectral de Potência dos sinais foram obtidas e permitiram estabelecer comparações entre os dois métodos. O estudo dessas técnicas de multiplexação é realizado em diferentes canais de propagação para avaliar o comportamento de ambos sistemas de uma forma geral. Os três tipos de canais avaliados neste trabalho são: linear e invariante no tempo, linear e variante no tempo e, finalmente, não linear e invariante no tempo. Cada tipo de canal foi modelado em forma matricial para ambos sistemas de forma independente. As simulações consideram os equalizadores Zero Forcing e Minimum Mean Square Error, assumindo um canal conhecido. / [en] Wireless communications are one of the pillars of the development of the new generations of mobile communications. Each generation has used some multiple access technique to take advantage of the channel s resources. This dissertation presents an analysis of two orthogonal multiplexing techniques. Both techniques implement block transmission, where one is combined with the Code Division Multiple Access (CDMA) approach, while the other uses the multicarrier transmission technique Orthogonal Frequency Division Multiplexing (OFDM). The performance and spectral occupation of both techniques and their advantages are analyzed. Analytical expressions for the Power Spectral Density of the signals were obtained, which allowed establishing comparisons between both methods. The study of these multiplexing techniques is carried out in different propagation channels to evaluate the behavior of both systems in general. The three types of channels evaluated in this work are linear and time-invariant, linear and time-variant and, finally, non-linear and time-invariant. Each type of channel was modeled in matrix form for both systems independently. The simulations consider the Zero Forcing and Minimum Mean Squared Error equalizers, assuming a known channel.

ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada / This paper introduces a study of the feasibility and initial hardware design for transmitting data over aircraft power lines. The intent of this design is to significantly reduce the wiring in the aircraft instrumentation system. The potential usages of this technology include Common Airborne Instrumentation System (CAIS) or clock distribution. Aircraft power lines channel characteristics are presented and Orthogonal Frequency Division Multiplexing (OFDM) is introduced as an attractive modulation scheme for high-speed power line transmission. A design of a full-duplex transceiver with accurate frequency planning is then discussed. A general discussion of what communications protocols are appropriate for this technology is also provided.

ITC/USA 2009 Conference Proceedings / The Forty-Fifth Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2009 / Riviera Hotel & Convention Center, Las Vegas, Nevada / This paper provides an introduction to the Orthogonal Frequency Division Multiplexing (OFDM) scheme which has been proposed for future aeronautical telemetry applications. OFDM offers the potential for high data rates on radio channels with multipath such as aeronautical telemetry channels. This paper provides in introduction to OFDM and demonstrates how orthogonality is maintained over multipath channels by the introduction of a guard band and by the inclusion of a cyclic prefix. The simulation of OFDM in multipath is simulated and performance results are presented that show the degradation of this scheme on a multipath channel with and without the guard band and the cyclic prefix.

The division of computer engineering at Linköping’s university is currentlydeveloping an innovative parallel DSP processor architecture called ePUMA. Onepossible future purpose of the ePUMA that has been thought of is to implement itin base stations for mobile communication. In order to investigate the performanceand potential of the ePUMA as a processing unit in base stations, a model of theLTE physical layer uplink receiving chain has been simulated in Matlab and thenpartially mapped onto the ePUMA processor.The project work included research and understanding of the LTE standard andsimulating the uplink processing chain in Matlab for a transmission bandwidth of5 MHz. Major tasks of the DSP implementation included the development of a300-point FFT algorithm and a channel equalization algorithm for the SIMD unitsof the ePUMA platform. This thesis provides the reader with an introduction tothe LTE standard as well as an introduction to the ePUMA processor. Furthermore,it can serve as a guidance to develop mixed point radix FFTs in general orthe 300 point FFT in specific and can help with a basic understanding of channelequalization. The work of the thesis included the whole developing chain from understandingthe algorithms, simplifying and mapping them onto a DSP platform,and testing and verification of the results.

The focus of this thesis is peak-to-average power ratio (PAPR) reduction in cooperative wireless networks which exploit orthogonal frequency division multiplexing in transmission. To reduce the PAPR clipping is employed at the source node. The first contribution focuses upon an amplify-and-forward (AF) type network with four relay nodes which exploits distributed closed loop extended orthogonal space frequency block coding to improve end-to-end performance. Oversampling and filtering are used at the source node to reduce out-of-band interference and the iterative amplitude reconstruction decoding technique is used at the destination node to mitigate in-band distortion which is introduced by the clipping process. In addition, by exploiting quantized group feedback and phase rotation at two of the relay nodes, the system achieves full cooperative diversity in addition to array gain. The second contribution area is outage probability analysis in the context of multi-relay selection in a cooperative AF network with frequency selective fading channels. The gains of time domain multi-path fading channels with L paths are modeled with an Erlang distribution. General closed form expressions for the lower and upper bounds of outage probability are derived for arbitrary channel length L as a function of end-to-end signal to noise ratio. This analysis is then extended for the case when single relay selection from an arbitrary number of relay nodes M is performed. The spatial and temporal cooperative diversity gain is then analysed. In addition, exact form of outage probability for multi-path channel length L = 2 and selecting the best single relay from an arbitrary number of relay nodes M is obtained. Moreover, selecting a pair of relays when L = 2 or 3 is additionally analysed. Finally, the third contribution context is outage probability analysis of a cooperative AF network with single and two relay pair selection from M available relay nodes together with clipping at the source node, which is explicitly modelled. MATLAB and Maple software based simulations are employed throughout the thesis to support the analytical results and assess the performance of algorithms and methods.

An increasing adoption of digital signal processing (DSP) in optical fiber telecommunication has brought to the fore several interesting DSP enabled modulation formats. One such format is orthogonal frequency division multiplexing (OFDM), which has seen great success in wireless and wired RF applications, and is being actively investigated by several research groups for use in optical fiber telecom. In this dissertation, I present three implementations of OFDM for elastic optical networking and distributed network control. The first is a field programmable gate array (FPGA) based real-time implementation of a version of OFDM conventionally known as intensity modulation and direct detection (IMDD) OFDM. I experimentally demonstrate the ability of this transmission system to dynamically adjust bandwidth and modulation format to meet networking constraints in an automated manner. To the best of my knowledge, this is the first real-time software defined networking (SDN) based control of an OFDM system. In the second OFDM implementation, I experimentally demonstrate a novel OFDM transmission scheme that supports both direct detection and coherent detection receivers simultaneously using the same OFDM transmitter. This interchangeable receiver solution enables a trade-off between bit rate and equipment cost in network deployment and upgrades. I show that the proposed transmission scheme can provide a receiver sensitivity improvement of up to 1.73 dB as compared to IMDD OFDM. I also present two novel polarization analyzer based detection schemes, and study their performance using experiment and simulation. In the third implementation, I present an OFDM pilot-tone based scheme for distributed network control. The first instance of an SDN-based OFDM elastic optical network with pilot-tone assisted distributed control is demonstrated. An improvement in spectral efficiency and a fast reconfiguration time of 30 ms have been achieved in this experiment. Finally, I experimentally demonstrate optical re-timing of a 10.7 Gb/s data stream utilizing the property of bound soliton pairs (or "soliton molecules") to relax to an equilibrium temporal separation after propagation through a nonlinear dispersion alternating fiber span. Pulses offset up to 16 ps from bit center are successfully re-timed. The optical re-timing scheme studied here is a good example of signal processing in the optical domain and such a technique can overcome the bandwidth bottleneck present in DSP. An enhanced version of this re-timing scheme is analyzed using numerical simulations.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / This paper presents a mathematical model for Coded Orthogonal Frequency Division Multiplexing (COFDM) in frequency selective multipath encountered in aeronautical telemetry. The use of the fast Fourier transform (FFT) for modulation and demodulation is reviewed. Error control coding with interleaving in frequency is able to provide reliable data communications during frequency selective multipath fade events. Simulations demonstrate QPSK mapped COFDM performs well in a multipath fading environment with parameters typically encountered in aeronautical telemetry.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / In this paper, we propose applying the spatio-temporal signal processing and OFDM techniques to a multiple-antenna system in order to achieve high data rate and high performance transmission capability. In order to perform real time processing for this system, we also propose a complexity reduced QR beamforming algorithm. The performance of the proposed system has been investigated for a two-ray frequency-selective fading model by extensive computer simulations. These results show that significant benefits can be realized in terms of lower bit error rate and higher data transmission rate.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Three Quadrature Phase Shift Keying (QPSK) mapped COFDM systems demonstrating a continuum of complexity levels are simulated over an evolving three ray model of the multipath fading channel with parameters interpolated from actual channel sounding experiments. The first COFDM system uses coherent QPSK and convolutional coding with interleaving in frequency, channel equalization and soft decision decoding; the second uses convolutional coding with interleaving in frequency, Differential Phase Shift Keying (DPSK) and soft decision decoding; the third system uses a quaternary BCH code with DPSK mapping and Error and Erasure Decoding (EED). All three systems are shown to be able to provide reliable data communication during frequency selective fade events. Simulations demonstrate QPSK mapped COFDM with reasonable complexity performs well in a multipath frequency selective fading environment under parameters typically encountered in aeronautical telemetry.