Eads Secure Networks

Cassidian Sas

Eads Telecom

Cassidian Finland Oy

Airbus Ds Sas

Christophe Brutel

Philippe Mege

Pierre-Yves Le Gal

Christophe Molko

Marc Mouffron

Pierre-Yves Legal

This transmission comprising a first transmission of a packet (), comprising the steps consisting in: a first processing () of said packet () to obtain a first packet (); and a coding () of the first packet (); wherein, when the first coded packet is received erroneous, the method comprises a second transmission of said packet, comprising: the steps implemented in the transmitter, consisting in: a second processing () of said packet () to obtain a second packet (); and a coding () of the second packet (); and the steps implemented in the receiver, consisting in: a modification of the first and/or the second coded packets to obtain two packets in which the difference due to the first and second processings is compensated for: a combination () of both packets according to a HARQ procedure; and a decoding () of the combined packet.

Data packet transmission method

An emission chain, comprising a processing pathway for an input signal which includes a digital signal decomposition according to N signal components, with N an integer greater than or equal to 2. The N signal components being converted from a digital form into an analog form and following distinct physical pathways that induce first respective delays on the N signal components. A delayed input signal is obtained by applying a second delay (&#x3c4;) having a value greater than or equal to the maximum value of the first delays. Next, N correction delays (&#x3c4;&#x2212;&#x3c4;) are applied respectively to the N signal components based on a comparison between said input signal delayed by the second delay and the signal to be emitted. Finally, the signal to be provided to a power amplifier is obtained by combining the N signal components obtained on completion of the previous step.

Correction of distortions in an emission chain

A signal is received in a telecommunication network in the form of P signals received on P corresponding antennas, where P is greater than or equal to 1. The received signals correspond to a multi-carrier signal transmitted in the form of flames comprising symbols occupying corresponding positions distributed along a time axis and along a frequency axis; a frame comprising M blocks each having at least N reference symbols. The reference symbols in each of the blocks satisfy a first maximum spacing between each other along the time axis and a second maximum spacing between each other along the frequency axis, less than a first value and a second value respectively, M being an integer number equal to at least two. M estimated noise power values are determined at frame level, each related to one of the M emitted reference symbol blocks. Values of the estimated noise power for the other symbols in the frame are then obtained from the determined estimated noise power values.

Noise power interpolation in a multi-carrier system

A signal is received by P antennas. It includes frames having symbols occupying respective positions distributed along an axis of time and of frequency, a frame including M blocks having N reference symbols M groups of P weighting coefficients are determined, each one of the groups relating to one of the blocks emitted, with the coefficients of a group being associated to the blocks which are received on the P antennas and which correspond to the block emitted relating to the group. The coefficients are determined so as to increase via a threshold value, an error value for each block emitted, between the reference symbols of the block emitted, and the symbols obtained using the symbols received on each antenna at the positions of reference symbols corresponding to the block emitted and the associated coefficients. Then, weighting coefficients are obtained for the other symbols of the frame Finally, a composite signal is generated by summing up the symbols received respectively weighted by the associated weighting coefficients.

OFDM reception in multi-antenna mode

A transmission chain comprises a power amplifier adapted for receiving as input a signal to be amplified Sw(t) and for providing as output an amplified signal Dw(t); a predistortion module comprising a linearization unit adapted for applying a predistortion coefficient W(t) to an input signal S(t), and a unit for determining said predistortion coefficient. The input signal S(t) is received and the amplified signal Dw(t) is received through a return pathway, at the level of the unit for determining the predistortion coefficient, and the predistortion coefficient is determined on the basis of a comparison between the input signal and the amplified signal. Next, at the level of the linearization unit, the predistortion coefficient is applied to the input signal to provide as output the signal to be amplified. The determining unit determines the predistortion coefficient on the basis of a first-order approximation of the input signal.

Linearization in a transmission chain

The invention provides a multicarrier system constructed on a time-frequency lattice defined comprising frames having MxN symbols distributed over M subcarriers each of which is divided into N specific symbol times. Each frame comprises P pilot symbols distributed time-wise and frequency-wise so as to cover the frame in a meshed structure, so that, in particular, some at least of the M subcarriers contain no pilot symbol and/or that no pilot symbol should be transmitted to some at least of the N symbol times. The invention also relates to a method for tracking a transmission channel using such a signal, and a device for implementing the method.

Multicarrier signal, method of tracking a transmission channel based on such a signal and device therefor

A method for estimating a transmission channel from a multicarrier signal transmitted through said transmission channel, comprising real pilot symbols and so-called pure imaginary pilot symbols, consists in selecting one or several values zof the received signal corresponding respectively to one or several real pilot symbols, and one or several values zof the received signal corresponding respectively to one or several pure imaginary pilot symbols. The pilot symbols are sufficiently close both in frequency and in time such that it can be assumed that the fading of the signal through the transmission channel has a complex value &#x3b1; substantially identical for the symbols. An estimated value {circumflex over (&#x3b1;)} of &#x3b1; for the pilot symbols concerned is then determined by minimizing a least square equation involving the values zand the values z.

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Cagnes, France

Christophe Brutel