Abstract: The invention relates to a method of estimating symbols carried by a digital signal that is received by a receiver over a communication channel (5), said symbols being multiplexed on orthogonal frequency sub-carriers. The inventive method comprises the following steps in relation to each symbol carried by the digital signal, consisting in: performing at least two transforms towards the frequency domain (8,9) on a portion of the received signal essentially corresponding to the symbol, said transforms being performed with a determined time lag (10) therebetween; estimating the parameters (r0, r1, . . . , rn, r?0, r?1, . . . , r?n) of the communication channel from pre-determined binary information contained in the digital signal; and estimating the symbol from a combination of the result of each of the transforms performed and the estimated communication channel parameters.

Abstract: Systems and methods of data transmission are disclosed. In an embodiment, at least two transmitters are selectively activated and at least one transmitter is deactivated at a serial interface to transmit data via at least two distinct lines.

Abstract: A process for decoding a signal being representative of a Space Time or Frequency Block coding during two signaling periods (STBC) or two parallel channels (SFBC) is provided. The process receives an OFDM signal received from at least one antenna. The process also performs an OFDM demodulation in order to generate N frequency domain representations of the received signal. Then the process performs a decoding process on said OFDM demodulated signal and groups the received signal in word code, Y=(y1, y2), to represent the signal that was received during two signaling periods (STBC) or two parallel channels (SFBC). The word code is then decoded into a matrix after which a lattice reduction algorithm is applied to the matrix in order to transform the matrix into a reduced matrix having a near orthogonal vector. Then it performs a detection process on the reduced matrix to improve noise and interference immunity.

Abstract: In some embodiments, a synchronizing circuit includes at least one synchronization device that operates at a lower clock frequency than another synchronization device in the synchronization circuit. In at least one embodiment of the invention, a method includes sampling a first signal at a first frequency to thereby generate a plurality of sampled versions of the first signal. The first frequency is a frequency of a clock signal divided by N. N is a number greater than one. The method includes sampling a second signal at the frequency of the clock signal. The second signal is based on sequentially selected ones of the plurality of sampled versions of the first signal to thereby generate an output version of the first signal.

Abstract: The present invention provides a method and device for obtaining precoding matrix. A network apparatus comprises a plurality of groups of cross-polarized linear array antennas. The method comprises: obtaining first channel indicating information indicating a first code word; obtaining second channel indicating information indicating a second code word; determining the precoding matrix, according to the first channel indicating information and the second channel indicating information, the first code word and/or the second code word comprises phase shifts and/or amplitude differences among the plurality of groups of cross-polarized linear array antennas.

Abstract: A wireless communication apparatus includes: plural antennas; a channel matrix acquiring unit acquiring a channel matrix for each sub-carrier; a channel matrix encoding unit encoding the acquired channel matrix of each sub-carrier, by decomposition from signals in fixed-point representation into data and amplitude parts with a predetermined bit width; and a channel matrix information delivery unit delivering the encoded channel matrix information to a communication party. The encoding unit retrieves a first maximum value as the maximum of channel matrix elements in all sub-carriers, in plural levels, and determines an amplitude part and a normalization coefficient for normalizing channel matrix elements to a data part having the predetermined bit width, based on a ratio between a second maximum value as the maximum of channel matrix elements with respect to each sub-carrier and the first maximum value, and multiples channel matrix elements by the normalization coefficient to obtain a data part.

Abstract: Methods of transmitting a plurality of communications signals over a plurality of discontiguous bandwidth segments in a frequency band include defining a plurality (NFFT) of orthogonal subcarriers across the frequency band, defining a plurality (N) of available physical subcarriers from among the orthogonal subcarriers. The available physical subcarriers are distributed among, the plurality of discontiguous bandwidth segments. The methods further include spreading the data symbols for each user and combining the spread data symbols to provide composite data signals. The composite data signals are converted to parallel input signals and interleaved. The interleaved signals are assigned to the N available physical subcarriers. Related transmitters, receivers and communications systems are also disclosed.

Abstract: Communication devices and methods are disclosed, wherein a test signal is generated at a first frequency and a higher harmonic of said test signal is received and processed at a second frequency higher than said first frequency.

Abstract: Amplitude-modulation (AM) to AM (AMAM) predistortion data is obtained from an AMAM predistorter. When applied to a digital quadrature signal, the AMAM predistortion data predistorts in-phase (I) and quadrature (Q) data words in a digital quadrature modulator. AM to phase-modulation (AMPM) predistortion data is obtained that is associated with the AMAM predistortion data and a frequency change or a phase shift in a local oscillator (LO) signal is compelled in accordance with the AMPM predistortion data. The frequency-changed or phase-shifted LO signal is provided to a digital upconverter such that an output signal of the digital upconverter is linearized with respect to at least phase distortion in the digital upconverter.

Abstract: A method of equalizing an OFDM signal received over a transmission channel defined by a channel matrix includes: windowing the received signal in the time domain with at least two different tapers to obtain at least two tapered received signals; stacking the tapered received signals in the form of a joint matrix equation [ y 1 ? y ? ? y ? ] = [ D 1 ? D ? ? D ? ] ? y = [ D 1 ? D ? ? D ? ] ? ( Hx + ? ) with y being the received signal, ? being the number of tapers, D? being the ?th taper in form of a diagonal matrix, y? being the ?th tapered received signal, H being the channel matrix, x being the time domain transmitted signal, ? being optional noise; and solving said joint matrix equation for x as a least squares problem.

Abstract: A method for receiving data transmitted wirelessly includes receiving information indicating a device type associated with a wireless communication device and, based on the device type associated with the wireless communication device, deciding to request information indicating a set of possible data values associated with transmissions from the wireless communication device. The method further includes receiving information indicating the set of possible data values and receiving a data transmission from the wireless communication device that comprises encoded data bits. Additionally, the method includes attempting to decode the data transmission using the set of possible data values.

Abstract: Embodiments of the present invention provide a multipath searching method and a multipath searcher, to improve accuracy of delay estimation, thereby improving performance of a receiver. The method includes: performing processing on received signals ri(t) and pilot sequences pi(t) to obtain upsampling signals y(?); subtracting contribution values of a current multipath waveform to other multipath waveforms by using a raised cosine function with a peak position set to zero and according to a global maximum value of |y(?)|2 and a total of M sampling points {circumflex over (?)}1(m) near the global maximum value, to obtain an upsampling signal yL(?) having a minimum residual in M groups of upsampling signals yL(m)(?); and obtaining a time delay power spectrum of the upsampling signal yL(?) having the minimum residual.

Abstract: A wideband microwave digital receiver comprises an antenna, an amplifier, and a digital IFM device for measuring the frequency of the received signal or signals. A consistency indicator indicates the consistency of the frequency measurements and is calculated by analyzing the values taken by said measurements obtained over two consecutive transforms. The presence of signal pulses at the input of the receiver is detected when said indicator signals the consistency of at least one frequency measurement.

Abstract: Methods and systems for I/Q mismatch calibration and compensation for wideband communication receivers may comprise receiving a plurality of radio frequency (RF) channels, downconverting the received plurality of received RF channels to baseband frequencies, determining and removing average in-phase (I) and quadrature (Q) gain and phase mismatch of the downconverted channels, determining a residual phase and amplitude tilt of the downconverted channels with removed average I and Q gain and phase mismatch, and compensating for said residual phase and amplitude tilt I and Q gain and phase mismatch of the downconverted channels. The determined phase tilt may be compensated utilizing a phase tilt correction filter, which may comprise one or more all-pass filters. The average I and Q gain and phase mismatch may be determined utilizing a blind source separation (BSS) estimation algorithm.

Abstract: An embodiment may include circuitry to generate and/or receive, at least in part, a signal that may include at least one waveform. The at least one waveform may include at least one portion followed by at least one other portion. The at least one portion may include a plurality of levels to be compared to data encoding levels to determine whether the plurality of levels satisfy ratios determined based at least in part upon the plurality of levels and the data encoding levels. The at least one other portion may include maximum and minimum data encoding levels to facilitate emphasis measurement. Many alternatives, variations, and modifications are possible.

Abstract: A computer-implemented method and system for generating large families of sequences with desirable properties for many applications, including communications and radar applications, applies constraints to a sequence in the Zak space, modulates the constrained sequence in the Zak space, and determines permutations of the modulated sequence in the Zak space. The constraints are associated with predetermined properties, including predetermined autocorrelation and cross-correlation properties. Other embodiments of the computer-implemented method and system transform an input sequence into a transformed sequence using the finite Zak transform and determine at least one other different sequence based on the transformed sequence. The at least one other different sequence can be determined by collecting a plurality of sequences that are finitely supported on an algebraic line in the Zak space and modulating and/or determining permutations of some or all of the sequences.

Abstract: A cellular communication system comprises a Multiple-In Multiple-Out (MIMO) transmitter and receiver. The MIMO transmitter comprises a message generator for generating MIMO messages comprising selected training sequences and transceivers transmitting the messages on a plurality of antennas. The training sequences are selected by a midamble selector from a set of training sequences in response to an associated antenna on which the message is to be transmitted. The set of training sequences is associated with the cell of the MIMO transmitter and comprises disjoint subsets of training sequences for each of the plurality of antennas. The receiver comprises a transmit antenna detector which determines which antenna of the MIMO transmitter the message is transmitted from in response to the training sequence of the received message.

Abstract: A transmitter with modulation comprising a phase changing stage having a first switch and a second switch coupled t the first switch, a first transistor and a second transistor individually coupled to the each switch. The transmitter is configured to receive a phase changing signal having a first state and a second state. The first switch is configured t operate in an opposing manner to the second switch such that only the first transistor is configured to be turned on i the first state and only the second transistor is configured to be turned on in the second state upon receipt of the phase changing signal by the switches so as to achieve a change in an output phase of the transmitter when the phase changing signal switches from the first state to the second state.

Abstract: A method for removing distortions in a transmitted signal transmitted by a high power amplifier in a satellite communications system. The method characterizes the high power amplifier to define a series of Volterra coefficients and uses those coefficients in an equalizer in a receiver in the communications system to remove the distortions. The equalizer is a non-linear soft interference cancellation and minimum mean square error equalizer that employs three processing operations including parallel soft interference cancellation, minimum mean square error filtering and a priori log-likelihood ratio calculations.

Abstract: In a wireless apparatus, a first receiver receives, from a wireless reception apparatus, a transmit beam pattern with better reception quality among transmit beam patterns of a transmitter switched to by a first switching unit. A generation unit generates a transmit beam pattern obtained by rotating a phase of the received transmit beam pattern. A second switching unit switches a transmit beam pattern of the transmitter to the received transmit beam pattern and the generated transmit beam pattern. A second receiver receives, from the wireless reception apparatus, the transmit beam pattern of a combination with better reception quality out of combinations of the switched transmit beam patterns and receive beam patterns switched to by the wireless reception apparatus. A setting unit sets a transmit beam pattern of the transmitter in the transmit beam pattern received by the second receiver.