Telediffusion De France

Other

France Telecom

Etat Francais

Centre National D'etudes Des Telecommunications

Etat Francais and Telediffusion De France Sa

Bernard Le Floch

Jean-Francois Helard

Bertrand Sueur

Vincent Michon

Marc Riviere

Roselyne Halbert-Lassalle

Damien Castelain

Daniel Pommier

Jean-Michel Lemesle

Jean-Christophe Rault

The invention relates to a signal intended to be transmitted towards a plurality of receivers, of the type comprising at least two source signals and consisting of a plurality of independently modulated substantially orthogonal carrier frequencies distributed over a predetermined frequency band. According to the invention, the frequency band is divided into at least two frequency sub-bands each comprising a set of the substantially orthogonal carrier frequencies, and to each of the sub-bands is allocated one of the source signals, so that a receiver may retrieve from the transmitted signal, by filtration, at least one of the sub-bands and perform demodulation processing only on the carrier frequencies contained in the retrieved sub-bands. The invention also relates to a transmission process as well as to a receiver of such signal.

OFDM signal organized so as to simplify reception

The invention relates to a signal intended to be transmitted towards a plurality of receivers, of the type comprising at least two source signals and consisting of a plurality of independently modulated substantially orthogonal carrier frequencies distributed over a predetermined frequency band. According to the invention, said frequency band (,) is divided into at least two frequency sub-bands (13,-13,) each comprising a set of said substantially orthogonal carrier frequencies (,), and to each of said sub-bands is allocated one of said source signals, so that a receiver may retrieve from the transmitted signal, by filtration, at least one of said sub-bands and perform demodulation processing only on the carrier frequencies contained in the retrieved sub-bands. The invention also relates to a transmission process as well as to a receiver of such signal.

A method for the broadcasting of digital data, intended to be received notably by mobile receivers moving about in an urban environment, that is, under conditions of multiple propagation and in the presence of parasites and jamming, enabling a coherent demodulation under such conditions of reception. This method is one for the broadcasting of digital data, notably for radio broadcasting at a high bit rate towards mobile receivers, of the type providing for the distribution of the data in the form of digital elements in the frequency-time space f-t and the transmission of symbols each constituted by a multiplex of N orthogonal carrier frequencies modulated by a set of digital elements and broadcast simultaneously, certain of the digital elements being reference elements with a value and position in the frequency-time space f-t that are known to the receivers.

Method for the broadcasting of digital data, notably for radio

A method for the broadcasting of digital data, in channels to which multiple paths are assigned, the characteristics of which vary in time, with time-frequency interlacing and assistance in the acquisition of the automatic frequency control. This method is one of the type providing for the distribution of the data in the form of digital elements in the frequency-time space f-t and the transmission of frames of symbols each constituted by a multiplex of N orthogonal carrier frequencies modulated by a set of the digital elements and broadcast simultaneously, the method providing for the transmission of a pattern of frequency synchronization, recurrent in time. It can be applied notably for radio broadcasting at a high bit rate towards mobile receivers, and for example, to COFDM radio broadcasting.

A device for the transmission of digital data with at least two levels of protection, of the type providing for the distribution of the data to be transmitted in the form of digital elements in the time-frequency space and the transmission of symbols each formed by a multiplex of N orthogonal carriers modulated by a set of the digital elements, and transmitted simultaneously, the device including channel encoding means comprising at least two types of modulation and/or at least two encoding efficiency levels. This enables to optimize the use of the transmission channel by assigning differentiated transmission techniques to portions of data of a same digital train as a function of the different levels of protection sought, against transmission errors.

Growing community of inventors

Rennes, France

Bernard Le Floch