Nortel Networks Corporation

Alcatel Lucent

Hassan El Nahas El Homsi

Moussa Abdi

Alexandre Jard

Jean-Marc Corbel

A spread spectrum modulator converts input sequences composed of digital symbols into n&#x2267;2 spread-spectrum sequences. The spread spectrum modulator can generate spreading code and can combine the spreading code with the input sequences to produce the n spread spectrum sequences for transmission from n respective antennas of a radio transmitter. Each spread spectrum sequence corresponds to a sum of at least two contributions mutually shifted by a time substantially less than the duration of a symbol, each contribution being the product of a version of one of the n input sequences times the spreading code.

Spread spectrum modulator and demodulator

In a spread spectrum digital radio communication receiver, a propagation profile of a propagation channel between a sender and the receiver, including at least one propagation path associated with a reception energy, is determined, data relating to an energy distribution in the propagation profile are measured, and information symbols carried by a signal received originating from the sender over the propagation channel are estimated, by applying to the signal a processing taking into account a predetermined maximum number of propagation paths, the propagation paths taken into account being chosen according to a criterion selected from several criteria as a function of the measured data relating to the energy distribution in the propagation profile.

Method of processing a signal by a radio receiver and radio receiver for the implementation of the method

A signal received by a base station is fed to a set of filters matched to spreading codes allocated to pilot channels originating from radio terminals. The outputs from the matched filters are processed so as to estimate parameters comprising, for each channel, eigenvectors representing propagation paths associated with respective amplitudes of reception along these paths. The processing of the output signals from the matched filters comprises an estimation of parameters for a first channel received with a fairly high power by the base station, a correction of the output from the matched filter of a second channel having less energy, taking account of at least one of the eigenvectors of the first channel, and an estimation of parameters for this second channel on the basis of the modified output from said matched filter.

Signal processing method and apparatus for a spread spectrum radio communication receiver

The received radio signal includes contributions from a plurality of channels multiplexed by respective spreading codes. A matched filter receiver is allocated to each multiplexed channel to estimate an impulse response of the channel and to provide first soft estimates of symbols transmitted on the channel. The first soft estimates provided by the matched filter receivers are processed to obtain a corrected soft estimate of at least one symbol transmitted on a channel. That processing includes subtracting from the first soft estimate of the symbol at least one term equal to the product of a decision value assigned to another symbol transmitted on another channel, determined from a soft estimate obtained previously for said other transmitted symbol, and a correlation between two generalized codes associated respectively with said symbol and with said other symbol. The generalized code associated with a symbol transmitted on a channel is a convolution of the estimated impulse response of said channel and Q samples of the spreading code of the channel which correspond to said symbol.

Method and device for radio signal reception

A base station having N transmission antennas () broadcasts M beacon signals (CPICH, CPICH), with 1&#x3c;M&#x3c;N. Each beacon signal is associated with a distribution vector (a, b) with N components and is applied to each of the antennas after weighting by a component of this vector. A mobile terminal in communication with the base station evaluates the reception of the M beacon signals so as to determine feedback data communicated to the base station. The latter causes the distribution vectors associated with the M beacons to vary over time, and processes the feedback data successively received so as to determine a respective weighting coefficient (w&#x2212;w) for each of the N antennas relative to the mobile terminal. A transmitted dedicated radio signal destined for the mobile terminal is applied to each of the N transmission antennas after weighting by the coefficient determined for this antenna.

Radio station with closed-loop transmission diversity, and process for controlling transmission from such a station

A digital signal available at the output of a filter matched to a spreading code in a spread spectrum receiver comprises successive blocks each corresponding to a sequence of symbols sent by a transmitter. Statistical parameters representing a channel having at least one propagation path between the transmitter and the receiver are estimated, and each block of the digital signal is processed so as to estimate instantaneous amplitudes of reception of the symbols of the corresponding sequence sent by the transmitter. The processing of a block comprises the prior estimation of information symbols of the corresponding sequence, then the estimation of the instantaneous amplitudes as a function of the digital signal of the block, of the estimated statistical parameters, of the symbols of the sequence which are known a priori and of the previously estimated symbols.

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Paris, France

Hassan El Nahas El Homsi