Minimum mean-square-error expression of LMMSE channel estimation in SISO OFDM systems

International audienceAn expression of the minimum mean square error (MMSE) of the linear MMSE channel estimation is given in the case of a non-invertible channel covariance matrix, as in single-input single-output (SISO) OFDM system. A matrix expression, already proposed for a multi-input multi-output OFDM system in a previous article, is not valid in SISO. A new proof is then proposed, by deriving a scalar expression of the MMSE, which leads to solve an optimisation problem. Furthermore, we show that the proposed solution is the global minimum. Simulations validate the proposed development

A Soft-Output STBC Decoder for Aeronautical Telemetry, Journal of Telecommunications and Information Technology, 2020, nr 1

Alamouti encoding is a well-known space time block encoding technique used to improve the received signal quality in Rayleigh fading channels. In aeronautical telemetry, this encoding technique is applied to shaped offset quadrature phase shift keying tier generation (SOQPSK-TG) modulation in order to handle the two-antenna issue. It is provided for in telemetry-related IRIG standards. In this paper, we propose a unique decoding architecture for Alamouti-encoded SOQPSK-TG signals, taking advantage of pulse amplitude modulation decomposition with soft and hard outputs. We exploit this result to obtain a Viterbi algorithm (VA) for hard decoding and a soft output Viterbi algorithm (SOVA) for soft and hard decoding, with a twofold benefit: operation using one trellis structure, unlike decoders that are based on the 8-waveforms cross-correlated trellis-coded quadrature modulation (XTCQM) approximation, and very attractive bit error rate performance, as well as a complexity trade-o

System size and centrality dependence of the balance function in A + A collisions at sqrt s NN = 17.2 GeV

Electric charge correlations were studied for p+p, C+C, Si+Si and centrality selected Pb+Pb collisions at sqrt s_NN = 17.2$ GeV with the NA49 large acceptance detector at the CERN-SPS. In particular, long range pseudo-rapidity correlations of oppositely charged particles were measured using the Balance Function method. The width of the Balance Function decreases with increasing system size and centrality of the reactions. This decrease could be related to an increasing delay of hadronization in central Pb+Pb collisions

Contribution à l'étude des modulations multiporteuses OFDM / OQAM et OFDM suréchantillonnées

Actuellement, pour la transmission dans des canaux multi-trajets, le choix de la modulation se base surtout sur des schémas de transmission multiporteuse du fait de leur robustesse vis-à-vis de la sélectivité fréquentielle. Parmi ces solutions, la modulation OFDM est la modulation de référence. Mais cette modulation, basée sur une mise en forme spectrale rectangulaire, possède des inconvénients notables comme une densité spectrale de puissance ayant des lobes secondaires très élevés. D'autres modulations ont alors été développées pour lutter contre ce problème, parmi lesquelles l'OFDM/OQAM et l'OFDM suréchantillonné, ceci au prix de nouvelles contraintes. L'objectif de cette thèse est d'étudier ces modulations avec forme d'onde sur plusieurs aspects critiques des transmissions. Nous nous focalisons ainsi sur l'étude de la densité spectrale de puissance, du PAPR et de sa réduction, et de l'estimation de canal. Une application au courant porteur en ligne est enfin réalisée.Nowadays, for the transmission over multipath fading channel, the choice of multicarrier solutions becomes more and more frequent because of their remarkable robustness with respect to frequency selective distortions. The OFDM solution then stands for a reference modulation. However, this modulation, based on a rectangular pulse shape, exhibits some noticeable drawbacks, like a power spectral density with high sidelobes. In order to cope with this problem, new solutions have been developed using non-rectangular pulse shapes. Nevertheless, modulations like OFDM/OQAM and oversampled OFDM lead to specific constraints. This Ph.D. thesis aims at studying these pulse-shaped multicarrier modulations on several critical aspects of transmission. We focus on the study of the power spectral density, the PAPR and its reduction, and the channel estimation problem. We finally apply these solutions to power line communications.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Theoretical bit error floor analysis of 16 QAM OFDM signal with channel estimation using polynomial interpolation

International audienceThis paper deals with a bit error rate (BER) floor performance analysis for orthogonal frequency division multiplexing (OFDM) systems using pilot-aided channel estimation with polynomial interpolations.Such a performance analysis has been previously undertaken in the literature, but is limited to binary phase shift keying (BPSK) and 4-quadrature amplitude modulation (4-QAM) constellations.The main contribution of this paper is then to analyze the BER floor achieved by a 16-QAM OFDM signal in a Rayleigh channel. To achieve this, the binary error probability is obtained by carrying out the analysis on maximum significant bits (MSB) and least significant bits (LSB). The MSB leads to the similar results as those obtained in 4-QAM, but very specific developments are required to obtain the error probability of the LSB. Numerical results show that the proposed BER performanceanalysis is valid for the 16-QAM constellation

Use of OFDM/OQAM modulation for dynamic spectrum insertion in cognitive radio

Le principe de la "cognitive radio" réside dans l'exploitation par un utilisateur secondaire des ressources spectrales inutilisées par un utilisateur principal au sein d'un standard de télécommunication. Lorsque ces bandes libres sont détectées, la transmission d'information de l'utilisateur secondaire doit être réalisée grâce à une modulation performante. Parmi les diverses solutions possibles, les modulations multiporteuses sont les plus indiquées. Aussi l'OFDM/OQAM, par l'utilisation possible de formes d'onde bien localisées en temps et en fréquence, apparaît comme une solution très intéressante au problème de l'insertion dans le spectre. Diverses simulations permettent de montrer un net avantage de cette solution comparativement à d'autres modulations multiporteuses

A Soft-Output STBC Decoder for Aeronautical Telemetry

Alamouti encoding is a well-known space time block encoding technique used to improve the received signal quality in Rayleigh fading channels. In aeronautical telemetry, this encoding technique is applied to shaped offset quadrature phase shift keying tier generation (SOQPSK-TG) modulation in order to handle the two-antenna issue. It is provided for in telemetry-related IRIG standards. In this paper, we propose a unique decoding architecture for Alamouti-encoded SOQPSK-TG signals, taking advantage of pulse amplitude modulation decomposition with soft and hard outputs. We exploit this result to obtain a Viterbi algorithm (VA) for hard decoding and a soft output Viterbi algorithm (SOVA) for soft and hard decoding, with a twofold benefit: operation using one trellis structure, unlike decoders that are based on the 8-waveforms cross-correlated trellis-coded quadrature modulation (XTCQM) approximation, and very attractive bit error rate performance, as well as a complexity trade-off

Joint Channel Estimation and Detection ofSOQPSK Using the PAM Decomposition

International audienc