France Telecom

Wavecom

Matra Communication

France Telecom and Telediffusion De France

Michel Alard

Nathalie Goudard

Damien Castelain

Jean-Francois Helard

Alexandre Rouxel

Pierre Combelles

Franck Bietrix

Dominique Lacroix-Penther

Jean-Luc Foure

A method is provided for extracting a sequence of pilot symbols enabling to estimate the transfer function of a transmission channel. At least a radiocommunication device communicates through the channel with a remote station, the latter regularly delivering to the radiocommunication device a reference pattern. The structure of the reference pattern is variable, depending on at least one characteristic of the transmission channel.

Method for extracting a variable reference pattern

A multicarrier signal, which includes a temporal succession of symbols formed by a set of data elements, each of said data elements modulating a carrier frequency of the signal. The data elements include reference elements called pilots, whereof the value in transmission is known to at least one receiver designed to receive the signal and informative data elements, whereof the value in transmission is not known a priori to the at least one receiver. One of the caffier frequencies is modulated, at a given time, by one of the data elements, being called a carrier. At least one constraint is imposed on the value of at least one of the informative data elements, so as to reduce, in reception, at least one term of interference affecting at least one of the pilots.

Distributed pilot multicarrier signal designed to limit interference affecting said pilots

The invention concerns a method for estimating the transfer function of a multicarrier signal transmission channel consisting of a temporal succession of symbols of a set of data elements, each of the data elements modulating a carrier frequency of the signal, the data elements comprising pilots and so-called informative data elements. The invention is characterized in that said method comprises: a step which consists in determining a set of two-dimensional discrete prolate spheroidal sequences (DPSS); a step which consists in writing the transfer function in the form of a combination of at least some of the two-dimensional discrete prolate spheroidal sequences (DPSS); a step which consists in time-based and frequency-based two-dimensional interpolation of at least some of the coefficients of the combination, so as to obtain an estimation of the transfer function at any point of a time-frequency network.

Method for estimating the transfer function of a multicarrier signal transmission channel and corresponding receiver

The invention concerns a cellular radio telephone signal comprising a symmetrical two-way main channel, including a main uplink and a main downlink, in particular transmitting low or medium speed data and signaling and control data, and comprising at least one additional channel solely assigned to the downlink, transmitting in particular, high speed data transmission. At one given time, all or part of said supplementary channel transmission capacity can be dynamically allocated to a particular mobile station. Information for retrieving data intended for a particular mobile station and carried by said supplementary channel can be transmitted among said main downlink signaling and control data.

Cellular radio signal with additional channel assigned to downlink, corresponding method, system and base station

This invention concerns a multicarrier signal designed to be transmitted to digital receivers, especially in a non-stationary transmission channel. The multicarrier signal corresponds to the frequency multiplexing of several elementary carriers. Each of the several elementary carriers corresponds to a series of symbols. The multicarrier signal is built on a non-orthogonal time-frequency lattice with a density two.

Prototype signals construction for multicarrier transmission

Construction of a multicarrier signal

Digital PSK-type demodulator having clock recovery before carrier

Decoding apparatus provides the maximum likelihood decoding of a sequence of samples of the type implementing a Viterbi type of decision algorithm that defines an initial decoding trellis. Sub-sampling apparatus sub-samples the initial trellis by a ratio p to preserve nodes corresponding to one sample out of p consecutive samples. This sub-sampling apparatus associates a p order antecedent node to each preserved node. Trace-back apparatus traces an optimal path back in the sub-sampled trellis by associating the p order antecedent node for each preserved node. The trace back apparatus designates at least the last two nodes of the optimal path. Over-sampling apparatus over-samples the designation of the last two nodes of the optimal path. The factor p is an integer greater than 1 selected so that there is a single path between a node and its p order antecedent in the initial trellis. Hence the bit rate is increased by a factor p, without loss of information.

Method of maximum likelihood decoding with sub-sampled decoding trellis,

The relay base of the invention comprises a receive antenna connected to a receiver coupling member associated with receiver members connected to respective digital processing units. The digital processing units are connected to transmitter members via link lines each of which is associated with one of the digital processing units and all of the transmitted members via parallel connections, each transmitter member including a switching member causing one of the link lines to be put into communication with the associated transmitter member.

Growing community of inventors

Paris, France

Michel Alard