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France Telecom

Alcatel Mobile Communication France

Conservatoire National Des Arts Et Metiers (cnam)

Orange

Maurice Bellanger

Pierre Siohan

Frederic Gourgue

Tich T Dao

Rodolphe Legouable

Chrislin Lele

Vincent Bruneau

Sabrina Azrouf

Rodophe Legouable

A system includes at least a transmitter having a serial-to-parallel converter, an iFFT block and a frequency de-spreader device that applies each signal that results from multiplying a data sample by one of the predetermined frequency coefficients of the prototype filter of a synthesis filter bank to one of the inputs of the iFFT block presenting a size that is strictly greater than the number of subchannels. Also described is a system including at least one receiver including a serial-to-parallel converter, a FFT block presenting a size that is strictly greater than the number of subchannels of the system, and a frequency de-spreader device that multiplies the signal from each output of the FFT block by one of predetermined frequency coefficients of the prototype filter of an analysis filter bank and sums the results of these multiplications to deliver at least a portion of the output signal from the receiver.

Systems for the multicarrier transmission of digital data and transmission methods using such systems

A transmission system includes an emitter () that includes an iFFT block () coupled to a set of memories (-) feeding a weighted summation device (). Switches () are introduced at the intput of the memories, in order to load the set of samples provided by the iFFT block when the first symbol is fed to the input of the emitter. This system may also include a receiver () that includes a set of memories (-) feeding a weighted summation device () coupled to a FFT block (). Switches () are introduced at the input of the memories in order to load the set of samples received, corresponding to the first transmitted symbol. A method of transmission with preloading of the memories that is extended to OQAM modulation and MIMO systems is also described.

Multicarrier digital signal transmission system using filter banks and memory preloading for initialization

A method and apparatus are provided for transmitting a multicarrier spread-spectrum signal formed by a temporal succession of multicarrier symbols, using OQAM modulation and a plurality of inter-orthogonal spreading codes. The method includes spreading at least one complex-value data symbol, representative of a source data signal to be transmitted, over a set of sub-carriers of at least one multicarrier symbol, each of the sub-carriers modulating a complex value.

Methods for transmitting and receiving a multicarrier spread-spectrum signal, corresponding signal, computer program products and transmission and reception devices

An emitter converts a serial input data stream into a set of parallel substreams. An OQAM modulator () receives and supplies each substream to an input of a synthesis filter bank (). Synchronization input(s) of the filter bank receive an OQAM signal that carries a data sequence. This sequence contains frame, superframe and hyperframe synchronization patterns, and specifies the number of bits allocated to each subchannel. A receiver () includes an analysis filter bank () that decomposes the multicarrier signal into a set of elementary signals for each subchannel. A synchronizing processing block () receives output(s) of the filter bank for synchronization subchannel(s). The block () includes a first cascade of blocks that control receiver sampling times, and a second cascade of blocks that extract synchronization patterns and subchannel bit assignment data. Other filter bank outputs are each coupled to a cascade subchannel equalizer () followed by a data extractor () and a parallel-to-serial converter ().

Multicarrier digital transmission system using an OQAM transmultiplexer

A signal processing system involving a least squares method where the system is structured around a microprocessor and includes memory zones 130, 140 and 250 which include Tables for facilitating the signal processing. Input signals are normalized before being applied to the Tables. Use of one of the Tables (130) is made easier by the normalization. The other Tables are involved in rotation processes in the selected least squares algorithm.

Signal processing system involving a least squares method

A signal form synthesizer comprises a digital generator circuit (1) for generating the synthesis signal to produce a first series of digital samples which are representative of this signal and formed by binary words of N bits, and a digital-to-analog converter circuit (30) for producing an analog version of this signal. Furthermore, there is provided an assembly (40) for filtering in accordance with a band-pass characteristic curve the samples of the first series and for supplying to said digital-to-analog converter circuit (30) a second series of samples formed by binary words of N' bits, where N.gtoreq.N'. A negative feedback loop (45) subtracts the samples of the second series from the samples of the first series.

Signal form synthesizer arrangement, transmitter station and receiver

The analog-to-digital converter receives an analog input signal (x(t)) to produce a digital error signal (y(t)). It comprises a subtractor (1) to calculate the difference between the input signal and a reference signal (Ur(t)), a converter subsystem (2, 3, 4) to produce the error signal from said difference and a feedback loop to produce the reference signal by means of a digital-to-analog converter (5) which delivers a comparison signal (Uc(t)) in response to the error signal. In accordance with the invention, the input signal (x(t)) is assigned a center frequency (f.sub.0), the feedback loop comprises a displacement unit (7) for displacing the frequency response of the digital-to-analog converter (5) from the null frequency towards the center frequency (f.sub.0), said displacement unit producing the reference signal (Ur(t)) from the comparison signal (Uc(t)).

Modulated feedback loop analog-to-digital converter

A filter for implementing a least squares method receives samples x(n+1) and produces error signals e(n+1) based on reference signals y(n+1). Filtered samples y(n+1) are available at an output 28. The filtered samples are calculated based on: angle functions .theta..sub.i (i=1 to n) that form part of rotation matrices; a gain vector G.sub.N (n+1) that is based on the rotation matrices; and the error signals. Because the filtered samples are available the filter is suitable for use in an equalizer in which the reference signal is formed by from the filtered signals, as well as in other applications such as echo cancelers.

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Paris, France

Maurice Bellanger