Abstract: A transmitting apparatus includes a first OFDM modulator that generates a first OFDM modulation signal by modulating a first information signal using a first modulation scheme, the first OFDM modulation signal having a plurality of subcarriers. A second OFDM modulator generates a second OFDM modulation signal by modulating a second information signal using the first modulation scheme, the second OFDM modulation signal having a plurality of subcarriers, and that generates a third OFDM modulation signal by changing a second position in an in-phase quadrature-phase plane in which a signal point of the second OFDM modulation signal is positioned, to a third position, the third position being different from a first position in the in-phase quadrature-phase plane in which a signal point of the first OFDM modulation signal is positioned. A multiplexer generates a multiplexed signal to be transmitted in a common frequency band, by multiplexing the first OFDM modulation signal and the third modulation signal.

Abstract: In a multivalue modulation type with one pilot symbol inserted for every 3 or more symbols, signal points of each one symbol immediately before and after a pilot symbol are modulated using a modulation type different from that for pilot symbols. In this way, it is possible to suppress deterioration of the accuracy in estimating the reference phase and amount of frequency offset by pilot symbols and improve the bit error rate characteristic in the signal to noise ratio in quasi-coherent detection with symbols whose symbol synchronization is not completely established.

Abstract: A radio communication apparatus capable of switching modulation schemes includes a QPSK modulation signal generator configured to modulate transmission data by a QPSK modulation scheme and to output a QPSK modulation signal. A 64QAM modulation signal generator is configured to modulate transmission data by a 64QAM scheme and to output a 64QAM modulation signal. A radio processor is configured to receive, as an input, the QPSK modulation signal or the 64 QAM modulation signal and to output a transmission signal. A transmission power amplifier is configured to amplify a power of the transmission signal. The QPSK modulation signal generator and the 64QAM modulation signal generator perform gain control so as to make an average transmission power of the 64QAM modulation signal smaller than an average transmission power of the QPSK modulation signal.

Abstract: On a transmitting side, a spread modulated signal that has undergone spread spectrum processing and an information modulated signal that has not undergone spread spectrum processing are multiplexed in a same frequency band. On the receiving side, the specific modulated signal is first demodulated by a spread spectrum demodulation section, then a replica signal of the specific modulated signal is generated by a spread spectrum modulated signal regeneration section, and the information signal that has not undergone spread spectrum processing is extracted by eliminating the replica signal from the multiplex signal. Thus, even when a large number of information signals are transmitted in a same frequency band, these signals can be separated and demodulated satisfactorily on the receiving side.

Abstract: In a wireless communication apparatus adopting a time division duplex system for executing transmission and reception using a plurality of antennas, deviation of amplitude and phase occurring between transmission and reception circuits is detected and corrected using a communication signal. Channel estimation means 105 detects channel information based on reception output of reception circuits 104-1 to 104-N provided in a one-to-one correspondence with a plurality of antennas 101-1 to 101-N. Correction value detection means 110 finds a correction value for correcting deviation occurring between each of transmission circuits 103-1 to 103-N and each of the reception circuits 104-1 to 104-N based on the channel information. A wireless communication apparatus 100 transmits an already known signal (training signal) to a base station with which the wireless communication apparatus conducts communications.

Abstract: In a multivalue modulation type with one pilot symbol inserted for every 3 or more symbols, signal points of each one symbol immediately before and after a pilot symbol are modulated using a modulation type different from that for pilot symbols. In this way, it is possible to suppress deterioration of the accuracy in estimating the reference phase and amount of frequency offset by pilot symbols and improve the bit error rate characteristic in the signal to noise ratio in quasi-coherent detection with symbols whose symbol synchronization is not completely established.

Abstract: A communication method of a base station transmits a modulation signal based on an OFDM (orthogonal frequency division multiplexing) scheme to a plurality of communication terminals. The method includes using a transmission frame on which a first subcarrier group and a second subcarrier group are arranged, the first subcarrier group on which a signal using a first transmission scheme is arranged, and the second subcarrier group on which a signal using a second transmission scheme different from the signal using the first transmission scheme in transmission quality is arranged. The method also includes determining, on a per frame basis, which subcarrier group is allocated to each of the plurality of communication terminals and how many subcarriers are allocated to said each of the plurality of communication terminals, and forming the transmission frame based on the determined information. The method further includes transmitting the modulation signal using the transmission frame.

Abstract: In a wireless communication apparatus adopting a time division duplex system for executing transmission and reception using a plurality of antennas, deviation of amplitude and phase occurring between transmission and reception circuits is detected and corrected using a communication signal. Channel estimation means 105 detects channel information based on reception output of reception circuits 104-1 to 104-N provided in a one-to-one correspondence with a plurality of antennas 101-1 to 101-N. Correction value detection means 110 finds a correction value for correcting deviation occurring between each of transmission circuits 103-1 to 103-N and each of the reception circuits 104-1 to 104-N based on the channel information. A wireless communication apparatus 100 transmits an already known signal (training signal) to a base station with which the wireless communication apparatus conducts communications.

Abstract: The invention performs orthogonal frequency division multiplex processing on a transmission signal to form an OFDM modulation signal (daubed in FIG.) and performs orthogonal frequency division multiplex processing and code division multiple access processing on a transmission signal to form an OFDM-CDM modulation signal (shaded in FIG.) to transmit the OFDM modulation signal and the OFDM-CDM modulation signal, which makes it possible to transmit data in a very high rate using the OFDM modulation signal while making it possible to transmit data in a higher quality using the OFDM-CDM modulation signal than using the OFDM-modulation signal, although it is slightly inferior to OFDM modulation in terms of high rate transmission.

Abstract: In a multivalue modulation type with one pilot symbol inserted for every 3 or more symbols, signal points of each one symbol immediately before and after a pilot symbol are modulated using a modulation type different from that for pilot symbols. In this way, it is possible to suppress deterioration of the accuracy in estimating the reference phase and amount of frequency offset by pilot symbols and improve the bit error rate characteristic in the signal to noise ratio in quasi-coherent detection with symbols whose symbol synchronization is not completely established.

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: In a multivalue modulation type with one pilot symbol inserted for every 3 or more symbols, signal points of each one symbol immediately before and after a pilot symbol are modulated using a modulation type different from that for pilot symbols. In this way, it is possible to suppress deterioration of the accuracy in estimating the reference phase and amount of frequency offset by pilot symbols and improve the bit error rate characteristic in the signal to noise ratio in quasi-coherent detection with symbols whose symbol synchronization is not completely established.

Abstract: In a multivalue modulation type with one pilot symbol inserted for every 3 or more symbols, signal points of each one symbol immediately before and after a pilot symbol are modulated using a modulation type different from that for pilot symbols. In this way, it is possible to suppress deterioration of the accuracy in estimating the reference phase and amount of frequency offset by pilot symbols and improve the bit error rate characteristic in the signal to noise ratio in quasi-coherent detection with symbols whose symbol synchronization is not completely established.

Abstract: A digital radio communication method includes selecting a modulation scheme for a transmission data signal from among a plurality of modulation schemes. The transmission data signal is modulated according to the selected modulation scheme to generate a first symbol, the first symbol being a first quadrature baseband signal. Further, a pilot signal is modulated according to a specific modulation scheme to generate a second symbol, the second symbol being a second quadrature baseband signal.

Abstract: The invention performs orthogonal frequency division multiplex processing on a transmission signal to form an OFDM modulation signal (daubed in FIG.) and performs orthogonal frequency division multiplex processing and code division multiple access processing on a transmission signal to form an OFDM-CDM modulation signal (shaded in FIG.) to transmit the OFDM modulation signal and the OFDM-CDM modulation signal, which makes it possible to transmit data in a very high rate using the OFDM modulation signal while making it possible to transmit data in a higher quality using the OFDM-CDM modulation signal than using the OFDM-modulation signal, although it is slightly inferior to OFDM modulation in terms of high rate transmission.

Abstract: In a multivalue modulation type with one pilot symbol inserted for every 3 or more symbols, signal points of each one symbol immediately before and after a pilot symbol are modulated using a modulation type different from that for pilot symbols. In this way, it is possible to suppress deterioration of the accuracy in estimating the reference phase and amount of frequency offset by pilot symbols and improve the bit error rate characteristic in the signal to noise ratio in quasi-coherent detection with symbols whose symbol synchronization is not completely established.

Abstract: The invention performs orthogonal frequency division multiplex processing on a transmission signal to form an OFDM modulation signal (daubed in FIG.) and performs orthogonal frequency division multiplex processing and code division multiple access processing on a transmission signal to form an OFDM-CDM modulation signal (shaded in FIG.) to transmit the OFDM modulation signal and the OFDM-CDM modulation signal, which makes it possible to transmit data in a very high rate using the OFDM modulation signal while making it possible to transmit data in a higher quality using the OFDM-CDM modulation signal than using the OFDM—modulation signal, although it is slightly inferior to OFDM modulation in terms of high rate transmission.

Abstract: A digital reception apparatus includes a receiver that performs reception processing on a received signal and an adjuster that adjusts the amplitude of the received signal after the reception processing. A distortion estimator estimates a non-linear distortion of the received signal after the reception processing, the non-linear distortion being caused by the reception processing. A distortion corrector performs a distortion correction on the estimated non-linear distortion. A controller controls the adjuster based on a gain control signal such that the amplitude of a desired signal contained in the received signal after the reception processing and the distortion correction approaches a required level. The distortion estimator estimates the non-linear distortion of the received signal with reference to the gain control signal.

Abstract: A transmission apparatus includes a frame configuration determiner that determines a modulation system, from among a plurality of modulation systems, based on a communication situation. A first symbol generator modulates a digital transmission signal, according to the modulation system determined by the frame configuration determiner and generates a first symbol, the first symbol comprising a first quadrature baseband signal. A second symbol generator modulates a known digital transmission signal between a transmitting side and a receiving side and generates a second symbol, the second symbol comprising a second quadrature baseband signal.

Abstract: A transmission apparatus includes a frame configuration determiner that determines a modulation system from among a plurality of modulation systems on a communication situation. A first symbol generator modulates a digital transmission signal according to the modulation system determined by the frame configuration determiner and generates a first symbol, the first symbol comprising a first quadrature baseband signal. A second symbol generator modulates the digital transmission signal according to a predetermined modulation system and generates a second symbol, the second symbol comprising a second quadrature baseband signal.