Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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 signalling 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 signalling and control data.

Abstract: 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.

Abstract: 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.

Abstract: The invention concerns a method for extracting a sequence of pilot symbols enabling to estimate the transfer function of a transmission channel, at least a radiocommunication device communicating through said channel with a remote station, the latter regularly delivering to said radiocommunication device a reference pattern. The invention is characterised in that the structure of said reference pattern is variable, depending on at least one characteristic of said transmission channel.

Abstract: 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.

Abstract: The invention concerns a multicarrier signal designed to be transmitted to digital receivers, especially in a non-stationary transmission channel, corresponding to the frequency multiplexing of several elementary carriers each corresponding to a series of symbols, two consecutive symbols being separated by a symbol time &tgr;0, a signal in which, firstly, the spacing &ngr;0 between two neighboring carriers is equal to half of the reverse of the symbol time &tgr;0 and, secondly, each carrier undergoes an operation of filtering for the shaping of its spectrum having a bandwidth strictly greater than twice said spacing between carriers &ngr;0 and is spectrum is chosen so that each symbol element is highly concentrated in the temporal domain and in the frequency domain. The invention also concerns the methods for the transmission and reception of such a signal.

Abstract: For demodulating a phase-modulated signal having 2M states of a carrier (M being an integer), the signal is converted into two baseband signals in quadrature. For that, they are multiplied by a signal delivered by a local oscillator at a transposed carrier frequency. Then the baseband signals are digitized by sampling at the clock frequency of the modulating signal. The clock of the signal is recovered by adjusting the phase of a local clock, stabilized at a bit frequency. For that, a minimum value of the intersymbol interference is searched. The signal clock is recovered before the carrier is recovered. Devices for implementing the method are also disclosed.

Abstract: 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.

Abstract: 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.

Abstract: A digital broadcasting process, suitable for digital audiobroadcast, comprises encoding the data in the form of binary words using a redundant code to obtain a sequence of modulation symbols and transmitting the symbols in a plurality of subchannels at different frequencies. The symbols are time interlaced with such a distribution that two adjacent symbols cannot be transmitted in time succession and at the same one of the frequencies. Preferably, a Viterbi decoder is used. Particular construction of an emitter and a receiver are also described.

Abstract: In a broadcasting system with time division multiplexing of digital signals containing a synchronization pattern and analog signals, sync extraction is achieved with a process including detecting the extreme values of the signals to be subjected to decoding, after they have been amplified with a gain G, with a time constant compatible with the low cut off frequencies to be accomodated; the gain G is controlled as a decreasing function of the difference between the extreme values with a time constant greater by several orders of size than the repetition period of the multiplex; before decoding and determination of the extreme values, there is added to the amplified signal a DC component which is a decreasing function of the sum of the extreme values, until the retrieval of the clock signal and identification of the synchronization pattern downstream of the coding.