Abstract: An apparatus and a method for transmission encoding a message with space-time turbo code using feedback information of the channel gain or the phase in digital mobile communication system having a plurality of transmit antennas are disclosed.

Abstract: A digital lock detector for a phase-locked loop. The PLL generates a feedback clock according to a reference clock. The digital lock detector includes a match detector and an arbiter. When a first clock transitions, the match detector checks that whether a second clock transitions in a predetermined time window or not. The match detector generates a match signal if the second clock transitions in the predetermined time window. The arbiter counts a number of the successive match signals and generates a lock signal to indicate a lock state when the number exceeds a first predetermined number.

Abstract: A method of and system for determining the time required for a digital bit or bit stream to traverse a round-trip path from a source transceiver to at least one destination transceiver and back is disclosed. The relative timing of the transmitted bit or bit stream is compared to the return bit or bit stream using a high speed comparison configuration so as to provide in substantially real-time various measurements related to or derived from the time required to traverse the round trip path, including distance measurement in indoor positioning, real-time locating, adaptive cruise control, intelligent transportation systems, robotics, collision avoidance, personnel accountability, emergency location, search/rescue. In addition, a method of and system for determining the distance between transceivers, and a method of and system for determining the angular position of a transceiver with respect to at least two other transceivers are disclosed.

Abstract: A method is provided for self-calibrating the mismatch and the direct current (DC) offset occurring in a mobile transceiver. The transmitter of the mobile terminal is used as a signal generator and the receiver thereof is used as a response characteristic measurer. The baseband processor calibrates the mismatch and the DC offset for the receiving and transmitting sides using a test signal received from the transmitter. When multiple input subcarriers are used in a mixer present on a reception stage, self-calibration is performed using multiple received test signals obtained from one transmission test signal.

Abstract: A frequency-shift-keying demodulator including a phase shifter for shifting the phase of an input signal by a predetermined degree and outputting a shifted signal, a combining unit for combining the input signal and the shifted signal and for outputting a corresponding signal, and a low-pass filter for filtering the signal output by the combining unit and outputting a low-pass filtered signal, the bandwidth of the low-pass filter being matched with the bandwidth of a data signal included in the input signal, such that the combining unit includes at least one adder for adding the input signal and the shifted signal, and outputting an added signal, and at least one square law detector for receiving the added signal output by the adder and outputting a squared signal which is the square of the added signal, wherein the combining unit outputs the squared signal to the low-pass filter.

Abstract: A method for correcting a soft decision value includes: demodulating a reception signal, which is coded by an error correction code and modulated in order to represent one or multiple bits with one symbol; generating the soft decision value, which is used in decoding of the error correction code; multiplying the soft decision value by a weight factor to correct the soft decision value; estimating an amplitude of the reception signal in every predetermined measurement time period; and variably setting the weight factor in a symbol unit in accordance with an estimating result so that a corrected soft decision value approaches to a predetermined amplitude range.

Abstract: Methods and systems for filtering an input signal include receiving a first demodulated signal produced by multiplying a first generated signal with a received input signal, receiving a second demodulated signal produced by multiplying a second generated signal with the received input signal, and producing first and second filtered output signals by applying a transfer function to the first and second demodulated signals, wherein the transfer function comprises a first filtering coefficient, wherein the first filtering coefficient defines a matrix comprising one or more non-symmetrical terms. An application of the transfer function can compensate for one or more of an amplitude mismatch between the first and second generated signals, a phase mismatch between the first and second generated signals, and one or more frequency handling characteristics of channels used to produce the first and second demodulated signals.

Abstract: A method for de-spreading spread data includes receiving a data stream by multiple access communication where the received data stream is spread using a pseudo-noise (PN) code; multiplying a first portion of the received data stream including data from a first user by a first portion of a PN signal to obtain a first product; providing the first product to a first counter; multiplying a second portion of the received data stream including data from a second user by the first portion of the PN signal to obtain a second product; providing the second product to a second counter; and determining whether the first portion of the PN signal and the second portion of the PN signal produce valid sequences based at least in part on the first product and the second product.

Abstract: An equalization apparatus and method estimate a channel response based on a received signal and a reference signal. Equalization processing estimates intersymbol interference with the received signal based on a channel response estimation results. A decoding error is detected based on the equalization processing to provide an error detection result. A power level threshold for the channel response estimation result is controlled based on the channel response estimation result of the received signal and the error detection result. The number of states for the equalization processing is determined, the number of taps employed in the equalization process is determined, and the number of taps used when the channel response is estimated is determined.

Abstract: An apparatus and method are provided for estimating a Carrier-to-Interference-and-Noise Ratio (CINR) in a communication system based on Orthogonal Frequency Division Multiplexing (OFDM) or Orthogonal Frequency Division Multiple Access (OFDMA). In the communication system, all base stations boost a power level for a preamble or pilot by B dB. Accordingly, a received signal power level and a received interference level are boosted by B dB, but a noise level is not boosted. Transmission power for a preamble or pilot interval is boosted as compared with that for the data interval. After an interference and noise level is estimated from a preamble or pilot, the interference and noise level estimate of the preamble or pilot is corrected by taking into account a boosting level of the preamble or pilot.

Abstract: A high speed data link includes transmitter equalization and (passive) receiver equalization to compensate for frequency distortion of the data link. In one embodiment, the transmitter equalization is performed with a de-emphasis circuit. The transmitter de-emphasis circuit pre-distorts an input signal to compensate for at least some of the frequency distortion in the data caused by the transmission line. The (passive) receive equalization circuit further compensates for the frequency distortion at the output of the transmission line to flatten the amplitude response of the output signal, and thereby reduce inter-symbol interference, improve media reach and improve the bit error rate (BER).

Abstract: A signal processing system includes an AGC and pre-echo cancellation system for receiving an analog signal, amplifying signal magnitude (over all frequencies) to a pre-determined level by AGC, and removing the immediate transmit pulse from this received signal by pre-echo canceller to provide a second analog signal. The signal processing system also includes a summer for receiving the analog signal; a feed forward equalization (FFE) unit for receiving a signal from the summer; and a slicer for receiving a signal from the FFE unit and providing an output signal. The signal processing system also includes an Echo and NEXT or FEXT cancellation system for receiving the output signal and for providing a signal to the summer for canceling the echo and crosstalk in the signal processing system. The Echo and crosstalk components associated with a signal processing system can be subtracted prior to the FFE.

Abstract: Systems, apparatuses, and methods for low wander timing generation and/or recovery are disclosed here. In one aspect, embodiments of the present disclosure include a communication system for high speed communications between a first location and a second location. The communication system, may include a transmitter module at the first location associated a first clock and/or a receiver module at the second location associated with the second clock.

Abstract: An apparatus and method of an OFDM system for compensating IQ imbalance. The apparatus includes a mixer module for mixing a wireless signal to generate a pair of in-phase and quadrature-phase analog signals; an in-phase and quadrature-phase imbalance parameter estimation unit coupled to the mixer module for estimating a gain compensation value and a phase compensation value; and a signal compensation module coupled to the in-phase and quadrature-phase imbalance parameter estimation unit for compensating the pair of in-phase and quadrature-phase analog signals for gain imbalance and phase imbalance, according to the gain compensation value and the phase compensation value respectively.

Abstract: A method and transceiver for wireless multicarrier communications. At the transmitter side, conventional OFDM symbols, after inverse fast Fourier Transform, are scrambled in time domain and then guard-interval (GI) inserted, up-converted at the carrier frequency for transmission. At the receiver side, after GI removal and frequency domain channel equalization, the received signal is transformed into time-domain by inverse fast Fourier Transform. The time-domain equalized signal is descrambled in time domain and then transformed back to the frequency domain before it is rate-matched, demodulated and decoded. This time-domain scrambling and descrambling method can be used in a wireless OFDM system such as WLAN, cellular OFDM, and MC-CDMA.

Abstract: A method of controlling a digital demodulator (922) coupled to an equalizer (930) includes the steps of generating an equalizer value (930A), filtering (944) the equalizer value (930A) to obtain a post filter output, subtracting the equalizer output signal (930C) from the decoded data (930D) and generating an error value (924A). The post filter output is correlated (948) with the error value (924A) to obtain a correlated value (74A). A control signal is developed from the correlated value and is used to adjust the digital demodulator (922).

Abstract: A transmission apparatus includes a frame configuration determiner that determines a modulation scheme, from among a plurality of modulation schemes. A first symbol generator modulates a transmission signal according the modulation scheme determined by the frame configuration determiner to generate a first symbol, the first symbol being a first quadrature baseband signal. A second symbol generator modulates a pilot signal in accordance with a specific modulation scheme to generate a second symbol. A third symbol generator generates a third symbol to be inserted immediately before or immediately after the second symbol, the third symbol being different from the first symbol. On a signal space diagram, the third symbol generator arranges a signal point of the third symbol on a virtual line that links an origin with a signal point of the second symbol.

Abstract: The received signal y0(t) is modulated by M-ary-QAM method. The same signal is received by the receiver 0 and receiver 1 through different paths. First, the receiver 0 detects the received signal and calculates a posteriori probabilities for the detected signal. These a posteriori probabilities are sent to the receiver 1. The receiver 1 detects the same signal and calculates second a posteriori probabilities using the probabilities sent from the receiver 0. The second a posteriori probabilities are sent to the receiver 0 and used to calculate third a posteriori probabilities in the receiver 0. These processes are repeated several times. Finally, both a posteriori probabilities of the receiver 0 and 1 are combined to decide the received signals.

Abstract: An apparatus for estimating a channel from a transmitting point to a receiving point in an environment, in which at least two transmitting points spaced apart from each other are present, the transmitting point having associated therewith a pilot sequence, wherein the pilot sequences are different from each other, having a provider for providing an input signal, the input signal including a superposition of signals from the transmitting points, a multiplier for providing a number of copies of the input signal, the number of copies being equal to the number of transmitting points, for each copy of the input signal, a transformer for transforming the copy or a signal derived from the copy to obtain a transformed signal, the transformer being operative to apply a transform algorithm which is based on a Fourier transform, and for each transformed signal, an extractor extracting a portion of the transformed signal.

Abstract: A wireless communication apparatus performs fast control even on a large phase rotation of a received signal to synchronize the frequency of a received signal with a specified frequency. A symbol-phase-difference detector detects an intersymbol phase difference of an input signal demodulated by a quadrature demodulator. When a minute-phase-error detector detects an intersymbol minute phase error between symbols whose phase difference has been detected by the symbol-phase-error detector, an oversampling/phase-rotational-amount detecting section detects an intersymbol phase rotational amount of the received signal by oversampling the received signal at a rate higher than a symbol rate. A coarse-phase-error detector detects a coarse phase error between symbols whose phase difference has been detected by the oversampling/phase-rotational-amount detecting section. A frequency control amount calculator computes a frequency control amount for the process station to control the frequency of the input signal.