Low complexity partial selected mapping for PAPR reduction of OFDM system

International audienceWe present partial blind selected mapping method (P-BSLM) as a probabilistic OFDM-PAPR reduction method. The P-BSLM method generates more candidates than the classical SLM (C-SLM) method while using the same number of IFFT computations. Moreover, common stage computation in an IFFT process can reduce the computational complexity. More candidates increase the PAPR reduction capability, and give a better error performance in the presence of non-linear amplifier. This method has the maximum spectral efficiency without side information, and the phase sequence can be correctly detected using partial blind phase sequence detection

Bit Error Rate Calculation for a Multiband Non Coherent On-Off Keying Demodulation

International audienceThe purpose of this paper is to calculate the bit error rate (BER) of a multiband non coherent on-off keying (OOK) demodulation. The results fit perfectly the simulations of the system. It allows us to study the influence of the filter and the decimation factor on the modulation performance. It is also possible to optimize the system, by means of other criteria (e.g. system complexity, jammer sensitivity) thus avoiding time consuming simulations

Robust Detection of Binary CPMs With Unknown Modulation Index

International audienceWe consider soft-output detection of a binary continuous phase modulation (CPM) generated through a low-cost transmitter, thus characterized by a significant modulation index uncertainty, and sent over a channel affected by phase noise. The proposed detector is designed by adopting a simplified representation of a binary CPM signal with the principal component of its Laurent decomposition and is obtained by using the framework based on factor graphs and the sum-product algorithm. It does not require an explicit estimation of the modulation index nor of the channel phase and is very robust to large uncertainties of the nominal value of the modulation index. Being soft-output in nature, this detector can be employed for iterative detection/decoding of practical coded schemes based on a serial concatenation, possibly through a pseudo-random interleaver, of an outer encoder and a CPM modulation forma

Binary Continuous Phase Modulations Robust to a Modulation Index Mismatch

International audienceWe consider binary continuous phase modulation (CPM) signals used in some recent low-cost and low-power consumption telecommunications standard. When these signals are generated through a low-cost transmitter, the real modulation index can end up being quite different from the nominal value employed at the receiver and a significant performance degradation is observed, unless proper techniques for the estimation and compensation are employed. For this reason, we design new binary schemes with a much higher robustness. They are based on the concatenation of a suitable precoder with binary input and a ternary CPM format. The result is a family of CPM formats whose phase state is constrained to follow a specific evolution. Two of these precoders are considered. We will discuss many aspects related to these schemes, such as the power spectral density, the spectral efficiency, simplified detection, the minimum distance, and the uncoded performance. The adopted precoders do not change the recursive nature of CPM schemes. So these schemes are still suited for serial concatenation, through a pseudo-random interleaver, with an outer channel encoder

Confidence Level for Finite Blocklength Ultra Reliable Communication over Fading Channels

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Etude d'un algorithme itératif d'annulation de repliement spectral lors d'une conversion A/N parallèle

International audienceLa réalisation de convertisseurs analogique-numérique à architecture parallèle hybride doit apporter une attention particulière à la conception des bancs de filtres analogiques et numériques, afin d’obtenir une reconstruction du signal la plus parfaite possible. On se propose dans cet article d’étudier une alternative à cette conception, qui relâcherait les contraintes du banc de filtres en les compensant par un traitement numérique sur le signal après conversion. On montre qu’une telle alternative reste pour l’instant trop sensible aux erreurs de réalisation

Synchronisation de Trame pour les Transmissions de Paquets Courts

International audienceWe consider the transmission of successive short packets. Each of them combines information to be transmitted (codeword) with information for synchronizing the frame (SW). For short packets, the cost of including SW is no longer negligible and its design requires careful optimization. In particular, a trade-off arises depending on the way the total transmit power is split among the SW and the codeword, or on the way the total frame length is split among the SW length and the codeword length. Assuming optimal finite-length codes, we develop tight upper bounds on the probability of erroneous synchronization, for both frames with concatenated SW and frames with superimposed SW. We use these bounds to optimize this trade-off. Simulation results show that the proposed bounds and analysis have practical relevance for short-packet communication system design.Nous considérons la transmission continue de paquets de petite taille, constitués d'informations de synchronisation (SW) et d'in-formation à transmettre (mot de code). Pour les paquets courts, le sur-coût apporté par SW n'est plus négligeable : un compromis s'impose en fonction de la façon dont la puissance d'émission totale est répartie entre SW et le mot de code, ou de la façon dont la longueur totale est répartie sur SW et sur le mot de code. En supposant des codes à longueur finie optimaux, nous développons des bornes supérieures sur la probabilité d'erreur de synchronisation dans deux cas distincts : le cas où SW est concaténé aux symboles codés et le cas où SW est superposé aux symboles codés. Puis nous utilisons ces bornes pour caractériser ce compromis. Les résultats de simulation montrent que les bornes et l'analyse proposées sont pertinentes et facilitent la conception de systèmes de communication à paquets courts

How lattice codes compare to conventional FEC/modulation schemes ?

International audienceIn this presentation, we propose a multilevel lattice construction, employing binary Reed-Muller codes, for the Gaussian and the Rayleigh block fading channels. The construction is performed on a binary two-dimensional lattice partition chain, and a capacity-achieving code is used for each stage. The lattice construction based on number-theoretical con- cepts is explained, and the system's performance is shown for various codeword lengths

Frame Length Reduction for Massive-Machine Communications

International audience-Machine type communications (MTC) require short-length frames to improve the latency and to achieve high reliability when combined to advanced automatic request (ARQ) mechanisms. The use of short frames has a direct impact on the physical layer, especially on the forward-error correction code (FEC) performance. In this article, lattice based codes are used to achieve an efficient joint decoding of the code and the modulation. The linear group structure of lattices makes it possible to design a decoder based on a sphere decoder. To improve the performance for lower spectral efficiencies, the decoder design takes into account the inevitable lattice shaping processing of the transmitter. With a small number of dimensions, the frame lengths are very short and well suited to MTC. A comparison in frame error rate is performed between the proposed lattice code and an LTE inspired baseline, designed upon the LTE turbo code. Simulation results show that for equivalent spectral efficiencies, a gain in frame length is obtained. This frame length reduction can be employed for increasing the number of users in a machine type communication system