Abstract: A multi-carrier receiver system and method for receiving a transmission frequency multi-carrier signal include a feedforward cancellation loop. A frequency conversion circuit generates an intermediate frequency (IF) multi-carrier signal based on the transmission frequency multi-carrier signal. The feedforward cancellation loop generates an amplitude corrected multi-carrier signal based on the IF multi-carrier signal such that the amplitude corrected multi-carrier signal has a reduced dynamic range with respect to the IF multi-carrier signal. A primary A/D converter having a significantly lower dynamic range requirements can therefore generate a digital multi-carrier signal based on the amplitude corrected multi-carrier signal. The feedforward cancellation loop therefore enables the primary A/D converter to process multi-carrier signals without the need for large dynamic range requirements.

Abstract: A method and apparatus for carrierless amplitude and phase CAP encoding of data in a manner avoiding the use of pulse shaping filters for in-phase and quadrature impulse signals. Specifically, in-phase and quadrature vector arithmetic structures (VAS) to adapt respective in-phase and quadrature impulse components to produce appropriate shaped in-phase and quadrature components.

Abstract: In a system for modulating an RF carrier, the RF carrier is fed through a lowpass filter and phase shifted approximately ?90 degrees. The RF carrier is also fed through a high pass filter and phase shifted approximately +90 degrees. A switch connected to the output of the lowpass filter and connected to the output of the highpass filter, selects and outputs either the ?90 degree phase shifted carrier output from the lowpass filter or the +90 degree phase shifted carrier output from the highpass filter depending on a switching state determined by data bit information received at a data port to produce a BPSK modulated RF carrier. Two such BPSK modulators may be combined using lowpass and highpass filters to form a QPSK modulator. Two such QPSK modulators may be combined with an attenuator to form a QAM modulator.

Abstract: The present invention includes a transceiver and a method of operating the same that includes in the transmitter a power control circuit that operates on an analog differential signal containing data packets individually. The power control circuit initially transmits a series of data symbols with known values, periodically strobes the transceiver system for correct power levels and incrementally increases the power level of the transceiver until the optimal gain is reached, without exceeding the maximum output power.

Abstract: A wireless receiver for receiving an incoming signal having spatial and temporal diversity. The receiver uses noise-based prescaling of multiple receiver chain signals for optimally combining the receiver chain signals in a composite equalized signal and uses noise-based time-varying postscaling the equalized signal. The receiver determines noise-based scale factors by comparing signal symbols to dispersed replica symbols of a training sequence for the incoming signal.

Abstract: Sample values of an input information signal are obtained at sampling instants. For each of a plurality of states at a sampling instant, an optimum path metric value is determined. For each of the plurality of states a best predecessor state at he directly preceding sampling instant is determined. A state at the sampling instant identifies a sequence of n subsequent bits, where n is larger than 3, and sequences of n subsequent bits having n?1 directly successive bits of the same binary value ar allocated to the same state. The best path is established from the state at the sampling instant having the lowest optimum path metric value, back in time towards a previous sampling instant via best predecessor states, established earlier for earlier sampling instants, to establish an optimum state at the previous sampling instant. Then at least one bit of the n bits of the sequence of bits corresponding to the established optimum state at the previous sampling instant is output.

Abstract: A sliding-window multi-carrier communication system is described, wherein the carriers are orthogonal in a local sense, but not necessarily in a global sense. In one embodiment, the system allows a reduction of the length of the basis function time as compared to conventional OFDM systems. In some circumstances, the symbol time can be reduced almost to the basis function length even though the delay spread from channel-to-channel is significant. In one embodiment, a discrete Fourier transform DFT is used in the sliding-window receiver. In one embodiment, the DFT produces M outputs (one output for each of M channels) for each time-domain input. In one embodiment, the DFT produces outputs for M channels from N samples, where N is a basis function length. In one embodiment, the sliding-window receiver provides an adjustable basis-function length. In one embodiment, the basis-function length can be separately selected for each channel.

Abstract: A receiver chain (53) for use in a wireless communication system includes a compact, highly correlated, multi-element antenna. The multiple antenna elements (34) and (35) are configured to receive a signal from at least one base station. The highly correlated signals output from the antenna elements (34 and 35) are optimally combined in a controller (55) using a set of weighting factors. The set of weighting factors for each base station signal is determined in response to the spatial signatures of the received signals.

Abstract: An improved method of decoding the Partial-Response Signaling type inter-bin distortion in receiver-end windowed DMT system is disclosed. The method exploits the Maximum Likelihood Sequence Estimation, which yields certain improvements over the conventional DFE-type decoding of PRS signals. Simulation results are shown for the case wherein AWGN is substantially the only impairment. Since in this case the noise samples at the neighboring frequency bin outputs bear correlation of the same type as the correlation introduced among data symbol samples, a trellis imbedded noise prediction/cancellation approach has been devised. It has been shown that performance degradation can be reduced from almost 8 dB to just 1 dB, compared to performance figures with no windowing. Possible applications of this method are for xDSL and wireless OFDM systems.

Abstract: A transceiver includes a receiver section and a transmitter section. The receiver section includes a clocking circuit, a serial-to-parallel module, and compensation. The transmitter section includes a clocking circuit, parallel-to-serial module, and compensation. The compensation within the receiver section and transmitter section compensates for integrated circuit (IC) processing limits and/or integrated circuit (IC) fabrication limits within the clocking circuits, serial-to-parallel module, and parallel-to-serial module that would otherwise limit the speed at which the transceiver could transport data.

Abstract: A sync mark detector identifies a sync mark in an incoming bitstream of a communications channel. A bit comparing circuit compares the sync mark bit-by-bit to the incoming bitstream if channel irregularities do not exist. A symbol comparing circuit compares the sync mark symbol-by-symbol to the incoming bitstream if channel irregularities do exist. The bit comparing circuit implements a bit level matching rule. The symbol comparing circuit implements a symbol level matching rule. The bit comparing circuit generates a sync mark found state when the bit level matching rule is satisfied. The symbol comparing circuit generates a sync mark found state when the symbol level matching rule is satisfied. Post coding such as NRZ, INRZI, or NRZI can be used.

Abstract: The in-band adjacent-channel digital audio broadcasting system includes a scrambling unit for scrambling a signal to be broadcasted, thereby generating a scrambled signal; an outer coding unit for performing a first encoding of the scrambled signal, thereby generating an outer encoded signal; an outer interleaving unit for performing a first interleaving of the outer encoded signal a byte by byte basis, thereby generating an outer interleaved signal; an inner coding unit for performing a second encoding the outer interleaved signal, thereby generating an inner encoded signal; an inner interleaving unit for performing a second interleaving of the inner encoded signal, thereby generating an inner interleaved signal; a modulating unit for modulating the inner interleaved signal, thereby generating an orthogonal frequency division multiplexing (OFDM) symbols; a guard interval inserting unit for inserting a guard interval between the OFDM symbols in order to eliminate an inter-symbol interference, thereby generati

Abstract: A half-rate clock and data recovery circuit includes a phase detector capable of operating at a half-rate, a charge pump circuit, a low pass filter, and a voltage controlled oscillator. The phase detector includes a selector circuit which receives uninverted and inverted signals from respective latches of the phase detector and an uninverted and inverted half-rate clock and outputs uninverted and inverted retimed signals supplied to the charge pump so that the charge pump produces a full-rate output in response to a half-rate input. The circuit provides greater operating margin.

Abstract: An improved digital capacitive isolation barrier system is provided that is suitable for use in a telephone or modem where the locally powered circuits must be effectively isolated from the public telephone system, while permitting data transfer across the barrier. In particular, an automatic ADC offset calibration system is provided for determining the magnitude of the ADC offset signal required in the system during a calibration operation, and for providing the calibrated ADC offset signal during normal operation of the isolation barrier system. A modified hybrid circuit is provided for isolating the system input from the telephone line during calibration, and for completing the calibration loop. Fixed bias signals are also provided for the ADC and for a DAC in the system. In a preferred embodiment, the ADC is located on the isolated side of the isolation barrier, while the integrator and register that determine and hold the offset signal are located on the powered side of the isolation barrier.

Abstract: A method of adjusting the weights of a blind equalizer. In the blind equalizer, an error signal e(n) is reset to zero as soon as the error signal e(n) reaches a predetermined value such as a maximum error signal value so that the weight vector W(n+1) is unaffected by the error signal e(n). Furthermore, the error signal e(n) is also reset to zero as soon as a second slicer output r2(n) changes from the original value due to an adjustment or transmission error and results in an inaccuracy of error signal e(n) so that the weight vector W(n+1) is unaffected by the error signal e(n).

Abstract: A direct current (DC) offset estimation, frequency offset estimation, and compensation system (200), receives data packet (204) with preamble (206). A DC offset estimator (210) and a frequency offset estimator (212) operate concurrently to produce estimates of DC and frequency offsets of the data packet (204), which are determined from a portion of the preamble (206) as it is received. As the data packet (204) is received, a compensator (214) receives the estimates of DC and frequency offsets and compensates the remaining portion of the data packet (204) to produce a DC and frequency compensated data packet (218). Concurrent operation of the DC estimator (210) and the frequency offset estimator (212) advantageously allows more time to produce the estimates of DC and frequency offsets.

Abstract: A communication system for transmitting encoded signals over a communication channel is disclosed. The system includes a transmitter, which has a source that is configured to output a message signal, and an encoder that is configured to generate a code word in response to the message signal. The code word is based upon a stacking construction that is generalized for the communication channel. The communication channel is characterized as a multi-input multi-output (MIMO) block fading channel. The transmitter also includes a modulator that is configured to modulate the code word for transmission over the communication channel. Further, the transmitter includes a plurality of transmit antennas that are configured to transmit the modulated code word over the communication channel. The system also includes a receiver, which has a plurality of receive antennas. The receiver is configured to receive the transmitted code word via the plurality of receive antennas.

Abstract: To transmit information with the aid of a transmit signal exhibiting a number of frequency-specific subcarriers from a first unit to a second unit via a transmission medium, the frequency-selective transmission characteristics of the transmission medium are determined in the first unit and then the subcarriers of the transmit signal are adapted to the transmission characteristics determined. All subcarriers of the transmit signal can be advantageously modulated with the same number of modulation levels as a result of which maximum utilization of the transmission resources of the transmission medium is achieved.

Abstract: In a communications device having a physical layer device and a processing device connected to the physical layer device, the number of input/output (I/O) ports required for communication between the devices in the gigabit range is substantially reduced by utilizing millivolt differential I/O drivers and receivers. In addition, a calibration feedback loop synchronizes the data and clock signals on the processing device, thereby eliminating the need to recover the clock on the processing device.

Abstract: Improved branch metrics for Viterbi decoders in CDMA systems take into account the time dependency of the variance of the multiple access interference in any user's signal after the single-user detector, and the time dependency of the residual multiple access interference in any user's signal after subtractive interference cancellation is applied in two-stage detectors. The (residual) multiple access interference can be modeled as a Gaussian random variable with time dependent variance. Modeling the RMAI in such a way reduces the bit error rate in CDMA systems.