Abstract: A noise cancellation method includes: inputting an interference wave signal detected near a receiver section, and changing the phase and the amplitude of the input signal to generate a cancellation signal that cancels the input signal; performing correlation calculations on a signal obtained by adding the cancellation signal to a communication signal received by the receiver section and a code replica of a PRN code used for the communication signal, within a given correlation calculation target range that is included within a code phase range and a frequency range; and performing the correlation calculations within a non-signal range outside the correlation calculation target range, and controlling a phase shift amount and an amplitude change rate of the input signal based on the correlation calculation result.

Abstract: A video encoding method and apparatus is shown wherein image information is represented as a plurality of pixels, the pixels are organized into blocks, pixels transposition is performed on image information at the boundaries of the blocks, the blocks are transform coded and quantized. Pixel transposition involves transposition of alternate pixels at the boundaries of blocks with pixels of neighboring blocks found in a pre-determined direction. The pre-determined direction may be fixed by a system or may be applied on an image by image basis. In the event that the pre-determined direction is not established by a system, a pixel transposition circuit includes a transposition keyword in the output bit stream which is used by a decoded to determine the direction of pixel transposition.

Abstract: A discriminator for a code tracking block of a navigation satellite system (NSS) receiver is provided. This discriminator can advantageously use only four complex correlators, i.e. early (E), prompt (P), late (L), and one of very early (VE) and very late (VL), while providing optimized multipath mitigation. This NSS discriminator can be derived from the first-order derivative of a Teager-Kaiser (TK) operator. This differential TK (DiffTK) discriminator is more sensitive to multipath dispersions than other discriminators or correlators, thereby providing enhanced performance in the presence of multipath.

Abstract: A system is provided for performing downlink beamforming based on information fed back by a mobile station. The mobile station includes a channel matrix generation unit to generate a channel matrix with respect to channels ranging from a base station to a mobile station, the base station including multiple transmission antennas, a codebook updating unit to generate a second codebook including a plurality of second codeword matrixes based on the generated channel matrix and a first codebook including a plurality of first codeword matrixes, a codeword selection unit to select at least one transmission codeword matrix from among the plurality of second codeword matrixes, a transmission unit to transmit an index of the selected transmission codeword matrix to the base station, and a receiving unit to receive data transmitted from the base station via the multiple transmission antennas.

Abstract: A digital demodulator adapted in a receiver and a digital demodulation method are provided. The digital demodulator includes: a phase splitter, a complex multiplier, an AFC, a limiter, a phase detector, a re-tracker, a post-multiplier and an oscillator. The phase splitter generates a complex signal from the input signal. The complex multiplier multiplies the complex signal by both first and second phase signals to generate first and second base band signals. The AFC generates a first output signal. The limiter generates a trend signal and the re-tracker generates a tuning signal from the first output signal. The phase detector multiplies the trend and second base signal and adjusts the multiplied signal based on the tuning signal. The oscillator generates the first and second phase signals according to the output of the phase detector. The post-multiplier multiplies the trend signal by the first and second base band signals for output.

Abstract: In an ADPLL frequency synthesizer where a frequency control word is changed from FCW0 to FCW2, a control sensitivity estimation section firstly measures oscillatory frequencies f1L and f1H obtained, respectively, when frequency control words FCW1L and FCW1H being used as dummies are set, and then measures an oscillatory frequency f2 obtained when a frequency control word FCW2 is set. Thereafter, based on values of the oscillatory frequencies f1L, f1H and f2, the control sensitivity estimation section calculates a control sensitivity KDCO2 obtained when the frequency control word FCW2 is set. Based on a value of the control sensitivity KDCO2, the loop filter determines values of filter coefficients ?2 and ?2 so as to be equal to a natural frequency ?n and a damping factor ?, respectively, both of which have been previously designed.

Abstract: An update algorithm for equalizer coefficients in a communications system using phase correction symbols. Instead of using a traditional all symbols slicer update algorithm, the equalizer is updated during phase correction symbols for optimal performance in low signal-to-noise ratio conditions. In lower signal-to-noise ratio conditions, the equalizer uses a phase correction circuit to compensate for distortion caused by a communication channel when a demodulated data stream contains an unknown phase offsets resulting from a fast dynamic distortion. More specifically, the phase correction circuit uses a phase correction signal to correct for the unknown phase offsets in a demodulated data stream in lower signal-to-noise ratio conditions. The equalizer then corrects for distortion caused by the communication channel based upon the phase corrected demodulated data stream.

Abstract: A multi-stage CFR estimation method for multi-band OFDM-based UWB systems is provided. The method includes obtaining a CFR estimation ?r(1) by performing LS estimation using a channel estimation sequence from a received OFDM-UWB frame; obtaining a CFR estimation ?r(2) by applying a frequency-domain smoothing to the CFR estimation ?r(1) with a first smoothing factor; obtaining a frame header which contains OFDM symbols transmitted with frequency-domain spreading on each OFDM symbol, and detecting signal signs based on a combination of two spread signals of the same OFDM symbol in the frame header with a decision directed mode and the CFR estimation ?r(2) assisted; obtaining a CFR estimation ?r(3) by using the signs and a finite-alphabet feature of the detected transmitted signals; obtaining a CFR estimation ?r(4) by applying a frequency-domain smoothing to the CFR estimation ?r(3) with a second smoothing factor; and obtaining a CFR estimation ?r by averaging the CFR estimations ?r(2) and ?r(4).

Abstract: A method of generating a reference signal includes acquiring a base sequence and acquiring a reference signal sequence with a length N from the base sequence. Good PAPR/CM characteristics of the reference signal can be kept to enhance performance of data demodulation or uplink scheduling.

Abstract: A common phase value of pilot subcarriers of a received data symbol (n) is estimated and used for correcting the phase of all subcarriers of the data symbol, wherein, with a time-variant frequency of the local oscillator (VCO), the estimated noisy phase values (?n) are used directly for the phase and frequency correction, whereas with a time-invariant frequency after the VCO, a corrected phase value ({circumflex over (?)}n) is determined from the estimated phase values of the current data symbol (?n) and earlier data symbols (?m) in a linear FIR filter arrangement (17-20) and is used for the phase correction.

Abstract: An input bit stream is phase rotated by reversing bit pairs and inverting bits. The manipulated bit stream is mapped to a symbol and the mapped symbol is converted to the time domain such that an output of the time domain conversion is an ordered set of N samples that allow efficient cyclic prefix insertion without rotation at the symbol level. A first portion of the set of samples is stored in a buffer, and the complete set of samples is output followed by the buffered first portion of the set of samples for transmission. The set of samples can be NIFFT samples of an OFDM symbol and the first portion can be NCP samples that make up the cyclic prefix CP. Re-ordering the bits can be done by swapping bit pairs and inverting one of the swapped pairs, or by trivial (1, ?1, ?j) phase rotation. The buffer is ¼ the length of prior art OFDM buffers and CP-related processing delays are significantly reduced.

Abstract: An adaptive channel estimator for estimating channel frequency responses when receiving OFDM symbols. The adaptive channel estimator comprises a channel estimator and a channel tracking module. The channel estimator generates one first channel frequency response for each OFDM symbol when operated in the first mode, and generates the channel frequency responses of a second channel frequency response for every N-th OFDM symbols when operated in the second mode, wherein N is a constant integer exceeding one and j is a non-negative integer. The channel tracking module indicates a channel status, and controls the channel estimator to operate in a first mode or a second mode according to the channel status.

Abstract: A method and OFDM receiver for estimating timing offset are provided. The method includes receiving OFDM data to calculate frequency offset between a transmitter carrier frequency and a receiver carrier frequency, determining first timing offset based on the frequency offset, compensating the OFDM data with the first timing offset, estimating a residual common phase based on the compensated OFDM data, determining second timing offset based on the residual common phase, and compensating the OFDM data with the second timing offset, if the frame symbol index exceeds the predetermined data length.

Abstract: This invention provides a reception synchronization control device that controls reception synchronization of demodulated signals to be established, the demodulated signals being obtained by demodulating a phase modulated signal transmitted by a phase modulation, wherein the reception synchronization control device includes a signal level detector that detects signal levels of sampled demodulated signals extracted by sampling analog demodulated signals; a constellation position specifier that specifies constellation positions of plural kinds of data contained in the sampled demodulated signals displayed on a polar coordinates display based on the detected signal levels; and a phase angle difference calculation processor that calculates a difference between a phase angle calculated based on the specified constellation positions and a reference phase angle, thereby controlling the phase angle so that the difference is within a predetermined range.

Abstract: An equalizer is provided, including: a feedback combiner to combine an input signal and a feedback signal to produce a first signal; a delay line to delay the first signal to produce a second signal; a feed-forward combiner to combine the second signal and a feed-forward signal to produce an output signal; an interim decision circuit to extract a sign bit from the first signal; N feedback scaling elements to generate N scaled feedback signals; M feed-forward scaling elements to generate M scaled feed forward signals; a feedback circuit to pass the N scaled feedback signals through feedback delay elements and feedback summing elements to generate the feedback signal in response to the sign bit; and a feed forward circuit to pass the M scaled feed forward signals through feed-forward delay elements and feed-forward summing elements to generate the feed-forward signal in response to the sign bit.

Abstract: The invention relates to a method and a circuit arrangement for deciding a symbol upon the reception of a signal including or coupled with a quadrature signal pair, wherein the decision is made by means of an analysis of the metric of at least one reception point to at least one nominal point in a complex coordinate space, and the metric is analyzed in the non-Cartesian or not exclusively Cartesian complex coordinate space. The decision is made after the analysis, and during the decision process, a second most probable nominal point and a reliability of the decision are determined.

Abstract: A decision feedback equalizer having an adjusting device and method thereof are described. The decision feedback equalizer having an adjusting device includes a feed-forward filter, a decision device, a feedback filter, the adjusting device, and a summation device. The feed-forward filter generates a forwarding signal (Sff) based on an input signal (Si). The decision device generates a first decision (Sd1) signal and a second decision signal (Sd2) which are associated with the summation signal (Ssu). The feedback filter receives the second decision signal (Sd2) for generating a feedback signal (Sfb). The adjusting device adjusts the first decision signal (Sd1) according to a first weighting value (V1) for generating a first adjusted signal (Sa1) and transmitting the first adjusted signal (Sa1) to the feed-forward filter. The adjusting device further adjusts the feedback signal (Sfb) according to a second weighting value (V2) for generating a second adjusted signal (Sa2).

Abstract: The architecture of the present invention is premised upon an algorithm involving integration of oblique correlators and RAKE filtering to null interference from other spread spectrum signals. The oblique correlator is, of course, based on the non-orthogonal projections that are optimum for nulling structured signals such as spread spectrum signals. RAKE filtering is used to rapidly steer the beam of the multi-antenna system and to mitigate the effects of multipath.

Abstract: An apparatus and method for measuring power of carrier channel in question and power leaked from an adjacent channel (leakage power) of a transmitter, and calculating a ratio between the leakage power and the carrier power in the time domain using a digital signal processing technique. The power measurement apparatus includes a frequency mixer which receives a signal from a transmission channel in consideration, an A/D converter for converting an output of the frequency mixer to a digital signal, a Hilbert converter for converting the digital signal into a complex signal, a low pass filter for removing low frequency components from the output signal of the Hilbert converter, a bandpass filter for separating the output of the low pass filter into the carrier power and the leakage power, and a power processing unit for computing the ratio between the leakage power and the carrier power.