Patent application number | Description | Published |
20090180566 | TRANSMISSION APPARATUS AND A RECEPTION APPARATUS IN A MULTICARRIER TRANSMISSION SYSTEM AND A TRANSMISSION METHOD AND A RECEPTION METHOD USING THE MULTICARRIER TRANSMISSION SYSTEM - An object is to reduce inter-carrier interference caused by frequency fluctuations, amplitude fluctuations, phase fluctuations, or the like without reducing a transmission efficiency. On a receiving end, a canceling filter section ( | 07-16-2009 |
20090268837 | MULTICARRIER MODULATION SCHEME AS WELL AS TRANSMISSION APPARATUS AND RECEPTION APPARATUS USING THE SCHEME - An object is to generate a pilot signal for estimating transmission characteristic of a transmission channel which is suitable for the OFDM/OQAM multicarrier modulation. A phase reference pilot symbol of which a modulation amplitude is suppressed to zero, and an amplitude reference pilot signal obtained through modulation performed by using an amplitude known to a reception end are transmitted from a transmission end, and the transmission characteristic of the transmission channel is estimated and compensated by using the phase reference pilot signal and the amplitude reference pilot signal at the reception end. Thus, it is possible to simplify frame generation process performed at the transmission end, and reduce transmission power for the phase reference pilot signal. | 10-29-2009 |
20100316164 | Methods and Apparatus for Reducing Average-to-Minimum Power Ratio in Communications Signals - A baseband circuit for a communications transmitter includes a baseband modulator, a pulse-shaping filter, and an AMPR reduction circuit. The baseband modulator is configured to generate a sequence of symbols formatted in accordance with a non-constant envelope modulation scheme. The pulse-shaping filter is configured to band-limit the sequence of samples to provide a sequence of samples. The AMPR reduction circuit is configured to analyze and modify one or more samples in the sequence of samples, if a sample in the sequence of samples that has been previously analyzed by the AMPR reduction circuit is determined to have a magnitude less than a predetermined low-magnitude threshold. | 12-16-2010 |
20110116535 | METHODS AND APPARATUS FOR REDUCING THE AVERAGE-TO-MINIMUM MAGNITUDE RATIO OF COMMUNICATIONS SIGNALS IN COMMUNICATIONS TRANSMITTERS - A communications transmitter configured to reduce the average-to-minimum magnitude ratio (AMR) of a communications signal includes a symbol mapper, a pulse-shaping filter, an AMR reduction circuit, and a modulator. The symbol mapper operates to generate a sequence of symbols from a binary-source data stream containing a message to be transmitted, and the pulse-shaping filter generates a baseband signal based on the sequence of symbols. The AMR reduction circuit is configured to compare a magnitude of a local minimum of samples of the baseband signal to various magnitude threshold levels, and to modify the baseband signal in one of two manners depending on the relationship of the magnitude of the local minimum and the various threshold levels. Finally, the modulator operates to modulate a carrier signal based on the modulation information contained in the modified baseband signal. | 05-19-2011 |
20110305171 | TRANSMISSION CIRCUIT AND TRANSMISSION METHOD - A transmission circuit that performs modulation based on a phase difference signal and an amplitude signal includes an asymmetrical phase rotation device. The asymmetrical phase rotation device performs an operation of subtracting 2π from a value of the phase difference signal when the value of the phase difference signal is greater than a predetermined positive threshold value, or an operation of adding 2π to the value of the phase difference signal when the value of the phase difference signal is less than a predetermined negative threshold value. Accordingly, the transmission circuit has distortion reduction characteristics improved uniformly over a range of frequencies higher or lower than a carrier wave band. | 12-15-2011 |
20110305292 | NONLINEAR FILTER AND TRANSMISSION CIRCUIT - A nonlinear filter includes: a determination unit that determines, based on I and Q signals inputted into the determination unit, whether or not to perform pulse insertion; a rotation detector that detects a rotation direction of the I and Q signals on an IQ plane with respect to the origin of the IQ plane; a pulse generator that generates, when the determination unit determines to perform the pulse insertion, a pulse of which at least one of the direction and the magnitude is determined in accordance with at least the detected rotation direction; and an adder that inserts the pulse into the I and Q signals and outputs resultant I and Q signals. | 12-15-2011 |
20120076220 | TRANSMISSION APPARATUS AND A RECEPTION APPARATUS IN A MULTICARRIER TRANSMISSION SYSTEM AND A TRANSMISSION METHOD AND A RECEPTION METHOD USING THE MULTICARRIER TRANSMISSION SYSTEM - Inter-carrier interference caused by frequency fluctuations, amplitude fluctuations, phase fluctuations, or the like is reduced without reducing a transmission efficiency. A receiving end has a canceling filter section that alleviates the inter-carrier interference caused by the frequency fluctuations, the amplitude fluctuations, the phase fluctuations, or the like through filtering processing. A transmitting end has a precoding section that facilitates determination of demodulation data in a vector demodulation section on the receiving end through precoding processing. Or, the receiving end has a trellis decoding section that decodes the demodulation data through trellis decoding processing. | 03-29-2012 |
20120094727 | POWER AMPLIFICATION CIRCUIT AND COMMUNICATION APPARATUS - Provided is a power amplification circuit capable of quickly and highly accurately preventing an output power and a current of a power amplifier from fluctuating when an antenna load changes. A power amplifier | 04-19-2012 |