Alcatel

Alcatel Italia S.p.a.

Stmicroelectronics S.r.l.

Arnaldo Spalvieri

Roberto Pellizzoni

Roberto Valtolina

Franco Guglielmi

Carlo Luschi

Morena Ferrario

Andrea Sandri

Maurizio Bolla

Angelo Leva

Massimo Brioschi

Marco Odoni

Giovanni Paltenghi

Alessandro Colombo

Domenico Farnese

Giovanni Mendola

Gianluigi Redaelli

Sergio Gulino

Leonardo Rossi

A method of detecting sequences of multi-level encoded symbols. The multi-level encoded symbols are mapped and modulated with a modulation scheme having a number of constellation points identified by a sequence of bits arranged in at least a first and a second group. The first group is encoded with a first encoding scheme, and the second group is encoded with a second coding scheme, and the multi-level encoded symbols are transmitted by multiple transmitting sources and received as a received vector by multiple receiving elements. A first set of candidate sequences is selected and a first set of probability information is calculated for the first set of candidate sequences. Then the first group of bits of the symbols are decoded. The decoded bits of the first group are re-encoded and used to select a sub-set of constellation points. A second set of candidate sequences is selected based on this sub-set of constellation points and a second set of probability information is calculated for the second set of candidate sequences. Finally, the second group of bits of the symbols are decoded.

Method and apparatus for multiple antenna communications, and related systems and computer program

A method for reducing the peak-to-average power ratio (PAR) of a multicarrier signal in transmitter/receiver systems. The method comprises the steps of: providing, in transmission, a digital signal to be transmitted; and subjecting such a signal to be transmitted to a Fourier transform in order to obtain a modulated signal. It is characterized by the steps of generating an anti-peak signal; summing said anti-peak signal with said modulated signal; and transmitting the sum signal. The invention provides a transmitter and a receiver for implementing the method. Through the use of the invention, the PAR is reduced as compared with the known techniques.

Method of reducing the peak-to-average power ratio of a fourier transform-generated multi-carrier signal in transmission systems

A method and apparatus is described for the automatic delay compensation in space diversity radio transmissions. The method includes the steps of: a) receiving a first analog signal and a second analog signal, a possible delay being between the first and second signals; b) sampling the first and the second analog signals to obtain a first digital signal and a second digital signal, respectively; c) sending the digital signals to respective equalizers, and the steps of d) digitally delaying one of the first digital signal and the second digital signal by a period equal to an integral multiple of the sampling period, and e) recoverying, at the equalization phase, the residual difference between the imposed delay and the actual one.

Method and apparatus for automatic delay compensation in space diversity radio transmissions

Disclosed is a method for controlling the peak power of a filtered signal in a single carrier data transmission system. The method comprises the steps of receiving a digital sequence () from a data source; generating a new digital sequence (a(k)); shaping filtering () the new digital sequence (a(k)) and producing a filtered digital sequence (y(k)) Characterized in that the step of generating a new digital sequence (a(k)) comprises the steps of: encoding data by an algebraic error correcting code (); and performing a bit modification () by deliberately adding errors in such a way that the peak power of the filter signal affected by the deliberately introduced errors is lower than the peak power of the signal unaffected by errors. Disclosed is also a circuit for performing the method.

Method and circuit for controlling the peak power of a filtered signal in a single carrier data transmission system

A method is provided for realizing, in a radio transmission system, a carrier synchronization and for cancelling one or more co-channel interfering signals from a received main signal, in which a synchronous down-conversion of the received main signal and of each of the interfering signal is performed to obtain respective intermediate frequency signals; and then a synchronous demodulation of the intermediate frequency signals so obtained is carried out.

Method and device for synchronization and cancellation of a plurality on interfering signals in radio transmission with frequency reuse

Described is a method for the clock-pulse selection in a baseband combiner of a space-diversity receiver. The method provides for driving the clock recovery circuit by means of the main signal, filtered and sampled, or by the diversity signal, filtered and sampled as well, and it is characterized by calculating the average power of the equalized main signal and the average power of the equalized diversity signal; and by driving the clock recovery circuit by means of the signal chosen according to a comparison between the average powers of the signals at the output of the equalizers. Advantageously, the invention provides for a hysteresis on the power comparison and guarantees a soft change with respect to the selection performed at the preceding time of processing.

Method for clock-pulse selection in a baseband combiner and related baseband combiner

A method is described for managing and monitoring the performances in digital radio systems. The idea of the invention provides for identifying the type of distorting phenomenon that possibly affects the monitored radio channel; in this way it is also possible to univocally connect, apart from the cause of degrade, the system performances with one of the performance monitoring methods commonly usable. In practice, the invention utilizes two distinct thresholds, each specific to the related corrupting source, and above all it provides an effective technique for discriminating which of the two thresholds is to be compared with the measure of the quality chosen. In a first preferred embodiment of the invention, the type of distortion present in the channel is identified on the basis of the error autocorrelation test at the threshold decision circuit.

Method of managing and monitoring performances in digital radio systems

Adaptive digital pre-correction of nonlinearities introduced by power amplifiers

A method and/or system for the stable operation of fractionally spaced equalizers available in digital signal receivers, having a plurality of equalization coefficients, said equalization coefficients being updatableby minimizing a proper cost function and stabilizable through a proper change of said cost function, said change of said cost function requiring the use of a virtual noise matrix. According to the invention, the cost function (J) for the updating of the coefficients of the fractionally spaced equalizer (FSE) is changed by adding a cyclostationary virtual interference &lsqb;v(t)&rsqb;.

Method for stabilizing the operation of fractionally spaced sequalizer in digital signal receivers

The invention concerns a method of controlling the minimal distance between successive errors in digital radio transmissions when multilevel modulations are used. With such a method the errors are spaced according to the needs, with an extremely reduced use of hardware with respect to prior art techniques. The method is characterized in that, in transmission a differential delay, i.e. different from flow to flow, is applied to each parallel flow not yet modulated, and in reception a differential delay is applied to each demodulated flow in such a way that the overall delay applied to each flow, i.e. the sum of the delay applied in transmission and the delay applied in reception, is constant and equal for all the flows.

Method and system for controlling the minimal distance between

The present invention relates to a method of fractionally spaced adaptive equalization which allows the achievement of the performances of the optimal linear receiver with a high degree of stability of the control algorithms. The technique is applicable to a generic communication system. The present method provides a fractionally spaced equalizer which is perfectly stable and has a good convergence rate without introducing any deterioration of the performances with respect to the optimal receiver and with an extremely low increase in the complexity of realization as compared to the prior art techniques. The invention is based upon the introduction of a whitening filter of the input signal to a fractionally spaced equalizer stabilized with the tap-leakage technique, where the whitening filter is a device able to make the power spectrum density of the signal--repeated with a period equal to the reciprocal of the signalling interval--constant.

Fractionally spaced equalizing circuits and method

Efficiency of a digital link, e.g., a microwave link, is improved by coding numeric signals for transmission so as to transmit selected sequences, in terms of peak power of a filtered signal, for transmission through the link. The most favorable numeric sequences may be encoded by baseband numeric coding.

Method and circuits for the transmission and reception of numeric

The invention relates to a baseband signal combiner and to a sampler typically used in radio relay systems and also in generic communication systems. In order to avoid temporary failures in the free space links, space and/or frequency diversity techniques are used, which consist in the use of two suitably spaced receive antennas or of two transmission frequencies. By suitably combining the signals thus received, the failures in radio links can be redued. The invention provides the use of a particular algorithm of the type CMA (Constant Modulus Algorithm) which, being independent of the combined signal phase, does not interact with the carrier recovery circuits. Moreover, by also applying the same algorithm to the sampler, the cooperation of the two circuits for the optimization of the output signal is obtained.

Method and circuits for combining baseband signals and recovery of clock

The invention relates to a method of reducing the peak power of a signal at the output of the transmit filter of a digital link, e.g. a microwave link. The invention is characterized by the use of a coding in transmission and a decoding in reception, adapted to reduce the peak power of the filtered signal. In the disclosed embodiment, not intended to be limiting, the encoder and the decoder can be realized through simple maps insertable in the baseband part of the system.

Method and circuits for reducing the peak power of the filtered signal

The present invention concerns a method and a system for demodulating mutually interfering signals according to a suitable synchronism bond between said signals. With such a system a complete decoupling of the demodulators of said signals is obtained. The system is characterized in that on each polarization there is at least a pair of demodulators, a first pair operate a baseband conversion of both signal H and V using the carrier recovery circuit driven by data of one of the two signals (e.g. V) and a second pair operate still a baseband conversion of both signals H and V but using said carrier recovery circuit now driven by data of the other signal (e.g. H).

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Milan, Italy

Arnaldo Spalvieri