Abstract: A new multiuser detection scheme EPIC (Equalized Parallel Interference Cancellation) is disclosed. A rake receiver signal zRake output by a rake receiver is detected, which receives a spread spectrum composite signal r comprising plural user signals b1,b2, . . . ,bK that have been spread with spreading codes. At first, first hard-decision values bRake are produced on the basis of the rake receiver outputs. Then, first parallel interference cancellation values are produced on the basis of the first hard-decision values, and second hard-decision values bPIC are produced on the basis of the first parallel interference cancellation values. After that, the first and second hard-decision values are combined for producing first combination values, and second parallel interference cancellation values are on the basis of the first combination values.

Abstract: A method for equalizing data and systems utilizing the method. The method of this invention for equalizing (by shortening the channel response) data includes minimizing a function of the data and a number of equalizer characteristic parameters, where the function utilizes cyclic differences of equalized data. Updated equalizer characteristic parameters are then obtained from the minimization and an initial set of equalizer characteristic parameters. Finally, the received data is processed utilizing the equalizer defined by the minimization. The method of this invention can be implemented in an equalizer and the equalizer of this invention may be included in a system for receiving data.

Abstract: Non-systematic and non-linear PC-TCM (Parallel Concatenate Trellis Coded Modulation). A non-systematic and non-linear PC-TCM code is presented that provides quite comparable performance to turbo encoding using only systematic and linear trellis codes (e.g., convolutional codes). The non-systematic and non-linear PC-TCM described herein may be modified to support a wide variety of code rates (e.g., rate 2/3, 5/6, 8/9, and 3/4 among other rates) and also a wide modulation types (e.g., 8 PSK (8 Phase Shift Key) and 16 QAM (16 Quadrature Amplitude Modulation) among other modulation types). In one embodiment, a non-systematic and non-linear PC-TCM presented herein comes to within approximately 0.15 dB of a systematic and linear turbo code. A design approach is presented that allows for the design of such non-systematic and non-linear PC-TCM codes and several exemplary embodiments are also presented that have been designed according to these presented principles.

Abstract: A receiver may reduce phase noise in phase-encoded communications signals using symmetrical averaging to estimate phase shift correction. In one embodiment, a receiver, such as a quadrature amplitude modulation receiver may include a decision feedback equalizer and a filter of low complexity to receive a phase modulated incoming signal. Using a combination of phase shift difference estimates prior and subsequent to a decision point for the received symbols, the filter may derive another estimate of the phase shift relative to the estimated phase shift by the equalizer.

Abstract: A method for interference suppression for TDMA and/or FDMA transmission, which at least approximately can be described as pulse amplitude modulation, with an arbitrary number of receive antennas. The method comprises filtering of at least one complex-valued received signal ri[k] of one receive antenna with a filter with complex-valued coefficients fi[k] for generation of at least one output signal yi[k], forming at least one projection of at least one output signal yi[k] onto a vector pi which is assigned to this output signal yl [k], summing of a majority, especially all of the output signals yi[k] for forming a sum signal s[k], and feeding the sum signal s[k] into a device for detection, especially equalization. A system for interference suppression for TDMA and/or FDMA transmission is also disclosed.

Abstract: The invention concerns a data transmission device comprising a turbo coder (22) comprising an interleaver operating on two interleaving blocks and means (26) for producing symbols from said codes (D, Y1, Y2) supplied by the turbo coder The device comprises means (28) for inserting a synchronising sequence into said symbols at a site having a predetermined relationship position relative to the symbols produced with the codes associated with a common interleaving block.

Abstract: A channel impulse response for a channel is determined by determining an initial channel impulse response estimate based upon a stored training sequence and a received signal, by thresholding the initial channel impulse response estimate, by estimating a noise variance for the channel based upon the stored training sequence, the thresholded initial channel impulse response estimate, and the received signal, by determining an inverse of a covariance matrix based on the estimated noise variance and the thresholded initial channel impulse response estimate, by updating the channel impulse response based on the inverse covariance matrix, the stored training sequence, and the received signal, and by thresholding the updated channel impulse response estimate.

Abstract: A method for conveying digital data from a transmitter (20) to a receiver (40) includes specifying a spectral filtering profile to be applied in conveying the data. A sequence of input symbols is generated (22) at the transmitter, corresponding to the data to be conveyed. The input symbols are precoded at the transmitter using Tomlinson-Harashima precoding (25) responsive to the specified profile, so as to generate a corresponding sequence of precoded symbols. The precoded symbols are filtered (26) in accordance with the specified profile. The precoded and filtered symbols are decoded at the receiver so as to recover the data therefrom.

Abstract: Techniques for preceding data for a multipath channel in a MIMO system. In one method, data is coded in accordance with one or more coding schemes to provide coded data, which is further modulated (i.e., symbol mapped) in accordance with one or more modulation schemes to provide modulation symbols. An estimated response of the MIMO channel is obtained (e.g., provided by a receiver), and an equivalent channel response is derived based on the estimated MIMO channel response and a response of a feed-forward filter of a decision feedback equalizer. The modulation symbols are then precoded based on the equivalent channel response to provide precoded symbols, which are further preconditioned based on the estimated MIMO channel response (e.g., using spatio-temporal pulse-shaping) to provide preconditioned symbols for transmission over the MIMO channel. The feed-forward filter may be adapted based on a minimum mean square error (MMSE) criterion.

Abstract: The present invention relates to a method and a circuitry for estimating a spreading factor and/or data transmission rate in a communication system that employs variable data transmission rates. A received transmission signal is analyzed in order to estimate noise variances for those spreading factors that are possible for a data frame in the signal. The estimate is based on information that is determined by assuming that the smallest possible spreading factor was used for the transmission of the signal. The estimates are then scaled by predefined constants, each of the constants depending on the respective possible spreading factor. The smallest one of the scaled estimates is determined, whereafter the most probable spreading factor of the received data frame is determined based on the smallest variance estimate.

Abstract: A method and apparatus for monitoring and adjusting an analog signal of an operating circuit. The apparatus includes a control circuit, an analog-to-digital converter, and a comparator. The control circuit has an analog generator for generating the analog signal and an adjusting circuit for adjusting the strength of the analog signal. The analog-to-digital converter receives the analog signal and converts the analog signal to a digital signal. The comparator then compares the value of the digital signal to a predetermined value and generates a comparator signal. The adjusting circuit then receives the comparator signal and adjusts the strength of the analog signal based upon the value of the comparator signal. The method includes generating the analog signal, converting the analog signal to a digital signal, comparing the value of the digital signal to a predetermined value and adjusting the strength of the analog signal.

Abstract: An automatic level control circuit exhibits a closed loop response that does not change as a function input power operating point. This allows the designer to set the closed loop response and have that response held fixed with respect to input power operating point. The loop response depends solely on the loop error and the loop gain. The loop error is scaled with the iterative loop stress signal.

Abstract: A OAM receiver includes a source of a received hierarchical OAM signal. The hierarchical OAM signal represents successive data points in the I-Q plane, each data point being in one of four quadrants. Circuitry, coupled to the hierarchical OAM signal source, calculates the location in the I-Q plane of the center-of-gravity of successive received data points in a quadrant. A level 1 decoder is responsive to a received data point and detects the quadrant in the I-Q plane of a received data point. Further circuitry, coupled to the hierarchical OAM signal source and responsive to the calculating circuitry, translates the received data point in the I-Q plane such that the center-of-gravity of the detected quadrant is translated to the origin of the I-Q plane. A level 2 decoder is then responsive to the translated data point for detecting the quadrant of the translated data point.

Abstract: New systems and methods are provided which use a new pulse shape which performs better in certain circumstances than the raised cosine pulse.

Abstract: A method and apparatus for data and clock recovery in a biphase-coded data signal is described, in which the data signal is sampled using a sampling frequency that is greater than twice the bit frequency of the data signal. The bit limits of the data signal are then determined from the sampling values and used to recover the both the data bits and the corresponding bit clock pulse of the data signal.

Abstract: A signal compensation circuit and associated method dynamically compensate for signal baseline wandering in a transmission line. The compensation circuit has a detection circuit and a correction circuit. The detection circuit first compares a transmission signal with a reference level and generates a comparison result. The correction circuit then corrects the transmission signal according to the comparison result. The compensation circuit can adjust its compensation over time based on the quality of the transmission signal.

Abstract: The present invention provides an amplifying apparatus including, two amplifiers for receiving input signals in common and for outputting their respective amplified signals, a combiner for combining the output signals of the two amplifiers and for outputting a combined signal, the amplifying apparatus which inhibit the distortion component in the output of amplifiers in the transition state. This amplifying apparatus comprises, a predistortion unit for determining a distortion compensation component based on the output of the combiner and for predistorting the input based on the determined distortion compensation component, and a gain control unit for attenuating the inputs to set lower than in the steady state by reducing the gain in the transition from two amplifier operation to one amplifier operation, or in the transition from one amplifier operation to two amplifier operation, or at the time of removal or attachment the amplifiers.

Abstract: In an apparatus for generating a transmit sequence comprising information from a plurality of information channels, a first means serves for generating a plurality of different candidate channel sequences from information of a first information channel of the plurality of information channels using a first code sequence associated with the first information channel, wherein each candidate channel sequence carries the same information as the information of the first information channel. A second means is provided to provide at least one candidate channel sequence for a second information channel from the plurality of information channels using a second code sequence associated with the second information channel and differing from the first code sequence. To receive an optimum transmit sequence resulting in a minimum out-of-band radiation combined sequences are examined, wherein each combined sequence may be obtained by a combination of at least one candidate channel sequence from each information channel.

Abstract: Techniques for processing a data transmission at the transmitter and receiver. In an aspect, a time-domain implementation is provided which uses frequency-domain singular value decomposition and “water-pouring” results to derive time-domain pulse-shaping and beam-steering solutions at the transmitter and receiver. The singular value decomposition is performed at the transmitter to determine eigen-modes (i.e., spatial subchannels) of the MIMO channel and to derive a first set of steering vectors used to “precondition” modulation symbols. The singular value decomposition is also performed at the receiver to derive a second set of steering vectors used to precondition the received signals such that orthogonal symbol streams are recovered at the receiver, which can simplify the receiver processing. Water-pouring analysis is used to more optimally allocate the total available transmit power to the eigen-modes, which then determines the data rate and the coding and modulation scheme to be used for each eigen-mode.

Abstract: In an automatic gain control circuit of a demodulating circuit, power values of pieces of symbol information I and Q of in-phase components and quadrature components of a modulated signal are calculated, a power difference between each power value and an ideal power value is detected, and an AGC control signal is produced to adjust a gain of the modulated signal according to the AGC control signal in a demodulating system including the demodulating circuit. Therefore, when an amount of noise included in the modulated signal is low, an average value of the power differences is reduced to zero, and the modulated signal can be correctly demodulated to a demodulated signal. To correctly demodulate the modulated signal including a large amount of noise, after the conversion of the AGC control signal, a sweep counter value is added to the AGC control signal so as to minimize a bit error rate of the demodulated signal.