Abstract: An adaptive MAP channel decoding apparatus and method in a mobile communication system. In the adaptive MAP channel decoding apparatus, a channel estimator calculates channel noise power and a scaling factor, a controller determines an operation mode by checking accumulated channel noise power and the scaling factor, and a MAP channel decoder performs a MAP decoding operation with an E function including a log function in a static channel mode and an E function free of a log function in a time-varying channel mode.

Abstract: In a multivalue modulation type with one pilot symbol inserted for every 3 or more symbols, signal points of each one symbol immediately before and after a pilot symbol are modulated using a modulation type different from that for pilot symbols. In this way, it is possible to suppress deterioration of the accuracy in estimating the reference phase and amount of frequency offset by pilot symbols and improve the bit error rate characteristic in the signal to noise ratio in quasi-coherent detection with symbols whose symbol synchronization is not completely established.

Abstract: A communication system (10) includes a communication bus (16) through which a power/voltage transmitter (44) conveys electrical energy and messages to a plurality of units (18, 20). The power/voltage transmitter (44) includes components for adjusting voltage of the electrical energy past a first predetermined threshold to provide a first type message frame and modulating the voltage of the electrical energy during the first type message frame to convey a first type message. The power/voltage transmitter (44) also includes components for adjusting the voltage past a second predetermined threshold to provide a second type message frame and modulating the voltage of the electrical energy during the second type message frame to convey a second type message.

Abstract: A method of generating values of a predistortion look up table for linearization of a transmitter. The method includes accumulating a plurality of pairs of values representing input and output values of samples entering one or more non-linear elements of the transmitter, fitting the pairs of values into a parameteric model of at least one of the one or more non-linear elements, so as to determine values for the parameters of the parameteric model, and generating values of the look up table responsive to the fitted parameteric model.

Abstract: In a multivalue modulation type with one pilot symbol inserted for every 3 or more symbols, signal points of each one symbol immediately before and after a pilot symbol are modulated using a modulation type different from that for pilot symbols. In this way, it is possible to suppress deterioration of the accuracy in estimating the reference phase and amount of frequency offset by pilot symbols and improve the bit error rate characteristic in the signal to noise ratio in quasi-coherent detection with symbols whose symbol synchronization is not completely established.

Abstract: An adaptive data slicer which functions to adapt to changes in the properties of a signal input thereto by producing a near optimal slicing threshold in accordance with the input signal for use in a decision circuit. The slicing level is considered optimal when its use in the decision circuit minimizes the bit error probability. The data slicer utilizes two peak detectors, a maximum peak detector for detecting the highest levels of the input signal and a minimum peak detector for detecting the lowest levels of the input signal.

Abstract: A method and device for measuring frequency instability noise &Dgr;TRMS from a source includes measuring the signal to noise ratio SRN1 at the output from a circuit having an input to receive a frequency input signal ft, an output to supply an output signal, and a sequencing input to receive a clock signal, and determining the signal to noise ratio SRN2 at the output from the circuit, the input signal being the frequency input signal ft and the clock signal being a signal coming from the source. The frequency instability noise &Dgr;TRMS is then calculated from SRN1, SRN2 and ft.

Abstract: An arrangement for synchronization of nodes in VDSL-systems, or more exactly, synchronization of optical VDSL-nodes which share a common part of a cable in the access network between subscribers and a local station. A time synchronization is provided towards an external system, for instance GPS, which gives a time reference by which the different nodes can be synchronized. The synchronization reduces the near end cross-talk between the VDSL-systems in the different nodes. Preferably, each respective node includes a receiver for a synchronization signal and an internal oscillator with high stability to deliver a stable clock signal.

Abstract: A method and apparatus to transmit turbo-encoded data in a multitone channel assigns the original data and selected parity bits across multitone subchannels allowing transmission of an entire turbo-encoded block withing one or few symbol time frame. Parity bits are selected by a procedure using data derived by optimization using simulation of a single-channel system. The optimization determines, for a specified bit error rate, for each possible number of information bits per symbol, the code rate corresponding to the lowest signal-to-noise ratio. Alternatively, in the simulation non-identical integer values may be applied to the channels to approximate non-integer values of code rate and information bits-per-channel in the aggregate. The optimized data are used to determine an optimal code rate and SNR for each channel. In assigning the respective bits to the channels, the number of parity bits in each channel are shared.

Abstract: A method for transfer of digital data, comprising a succession of one values and zero values, across a capacitive interface. The interface includes a first capacitor and a second capacitor in parallel, linking a first circuit to a second circuit. First digital data is transferred from the first circuit to the second circuit, and a reference clock is provided by the first circuit and transmitted with the first data to the second circuit for recovery thereby. A first set of bi-level signals representing the zero values of the first data is applied to the first capacitor, such that a repeating level transition of the reference clock corresponds to a first level transition of the first set of bi-level signals. A second set of bi-level signals representing the one values of the first data is applied to the second capacitor, such that the repeating transition of the reference clock corresponds to a second level transition of the second set of bi-level signals. The clock and data are then recovered.

Abstract: A method and device for improving DFE performance in a trellis coded system by placing a short adaptive predictive filter after the DFE in order to whiten the error sequence at the output of the DFE.

Abstract: A method and apparatus for system time alignment is provided. The method and apparatus for a system time alignment provides synchronization between system components even when one or more system components remains in a quiescent mode for an extended period of time. Compensation for changes in propagation delay between system components is provided, even when such changes in propagation delay occur while one or more system components is in a quiescent mode. A searcher (402) searches a raw data signal for a maximal energy, and a shifter (403) shifts a spreading sequence a plurality of times. An accumulator (408) accumulates a plurality of sets of symbols to produce a plurality of symbol energies. A time offset calculator (410) calculates an updated time offset value and an updated system time value and updates a reference position counter (202) and a system time counter (205), respectively, with these values.

Abstract: A method for reducing a current crosstalk interference component from an oscillating multiplex electric current flowing through a magnetic coil of a given electrical circuit originated from an electromagnetic flux emanating from a magnetic coil of a certain neighboring electrical circuit and intercepted by the magnetic coil of the given electrical circuit. The oscillating multiplex electric current has a main current component, related to the given electrical circuit, which is superposed with the current crosstalk interference component. The reduction of the crosstalk interference is achieved by estimating the current crosstalk interference component induced by the certain neighboring electrical circuit, and subtracting this current crosstalk interference component from a multiplex electric current flowing through the magnetic coil of the given electrical circuit by using earlier obtained crosstalk interference estimates.

Abstract: A method and apparatus for a UWB radio utilizing MEMS filtering is described. The method described includes receiving a pulse signal from a transmission station. Once received, a delay line including one or more taps is driven with the pulse signal. Once the pulse signal exits the delay line, the delay line is sampled at each of the taps to determine a time delay and amplitude of each echo in the pulse signal. These steps are repeated for each pulse signal received until a delay/amplitude map of the transmission channel between the stations is complete. Using the echo map, a time delay and amplitude of each echo indicated by the map is determined synthetic and recursive anti-echoes. Accordingly, when transmitting or receiving a signal over the channel, anti-echoes are combined with the signal in order to eliminate channel echoes in a received signal.

Abstract: A wireless transmitter includes a data rate controller operating to predictively determine a traffic channel data rate for a frame of data stream using a previous data rate, transmitted bit energy of a traffic channel, and a target data throughput. The data rate controller includes a selector, a bit energy computer, a predictor, an estimator, and a comparator.

Abstract: A digital audio broadcasting (DAB) receiver designed for receiving a signal with 1536 active carriers generated by an inverse fast Fourier transform (FFT) with 2048 points, includes the usual RF stage (14), an IF filter (20), and a demodulator (22) providing baseband I and Q signals. This is followed by an anti-aliasing filter (28), a sampler (30), and an FFT (32). The FFT is a 4096-point FFT, and is thus twice as long as required, and gathers twice as many points during each symbol period. However this is found to substantially simplify the construction of the IF filter (20) and, more particularly, the anti-aliasing filter (28). For use with real signals rather than quadrature demodulated signals, an 8192-point FFT is employed.

Abstract: An apparatus and method for spread spectrum multiuser communication receivers is disclosed that includes, an adaptive filter adapted to minimize a block error function, wherein the filter tap weights are updated according to a non-linear optimization algorithm adapted for block processing of time-varying data.

Abstract: The invention relates to a digital transmission method, which can be used between two items of computer equipment. This digital transmission mode is characterized in that: the data are transmitted in the form of a series of digital signal frames (8), each frame (8) comprises at least successively, from start to end, frame synchronization signals (10), data signals (12) and control signals (14) for the transmitted data, and the characteristics of the synchronization signals (10) and of the data signals (12) and control signals (14) for the transmitted frames are specific to an item of reference computer equipment and are known to the follower computer equipment.

Abstract: The receiver receives a complex spread spectrum signal modulated using complementary code keying. The received signal is down converted and cross correlated with code words using a Fast Walsh Transform. The peak magnitudes resulting from the Fast Walsh Transform are selected for a period before, during, and after an expected symbol boundary. The relative magnitudes of the early, on-time and late measurements are compared to determine which output has the largest magnitude. If the on-time measurement is the largest, symbol tracking continues without a timing adjustment. If the early measurement has the greatest magnitude, then the tracking timing is adjusted one period downward to shorten the period expected before the next symbol boundary. If the late measurement has the largest magnitude, then the tracking timing is increased by one sample period to increase the period expected before the next symbol boundary. This process repeats itself to provide accurate symbol tracking.

Abstract: A method is disclosed for generating unitary space-time signals for wireless communication using an array of M transmitting antennas. Each unitary space-time signal comprises T symbols. The method can be used to generate arbitrarily large signal constellations. The resulting unitary space-time signals have statistical properties that are favorable for reliable use in communication, and they can lead to very high data transmission rates. The disclosed method involves the mapping of binary strings of data to matrix products of the kind obtained by left-multiplying an initial T×M matrix by an ordered multiplicative sequence of exponentiated T×T unitary matrices, referred to as generator matrices. The result of each such multiplication is a unitary space-time signal matrix that may be transmitted. Each generator matrix corresponds to a single bit or a collection of bits of a binary string that is to be mapped.