Abstract: A digital wireless communication apparatus includes a first modulator that modulates a pilot symbol according to a first modulation scheme, and a second modulator that modulates specific symbols according to a second modulation scheme, the second modulation scheme being different than the first modulation scheme. A third modulator modulates symbols other than the pilot symbol and the specific symbols according to a third modulation scheme, the third modulation scheme being different than the first and second modulation schemes. A timing controller controls timing such that the specific symbols are inserted immediately before and after the pilot symbol. The signal points of the specific symbols are allocated on an imaginary line that connects the origin point and a signal point of the pilot symbol on a signal space diagram.

Abstract: A peak power suppressing apparatus capable of improving the reception error rate characteristic of an apparatus on a reception side. In this apparatus, a clipping part (102) clips an input signal, thereby suppressing the peak power of the signal. A subtracting circuit (104) extracts an in-band distortion component of the peak power suppressed signal. A subtracting circuit (111) subtracts the extracted in-band distortion component from the peak power suppressed signal, thereby removing the residual distortion component in the band of the peak power suppressed 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 phase/amplitude control section controls the phase and amplitude of at least one of the signals: a distributed signal distributed by a modulation signal distributor and a reference signal based on an orthogonal base-band signal. A signal combiner combines a combinatory signal according to the distributed signal and the reference signal whose phase and amplitude have been controlled. A reference table updating section updates non-linear distortion compensating data according to the combinatory signal subjected to A/D conversion and the orthogonal base-band signal. With this configuration, since a known signal component is removed from the combinatory signal, the change amount of the signal input to the A/D converter of a feedback system circuit is reduced and the A/D converter of the feedback system circuit need not have a wide dynamic range performance.

Abstract: A transmitting method and a transmitter apparatus, which need no manual adjustment, are disclosed. A delay amount is automatically adjusted such that an out-of-band distortion component of a transmission signal is minimized, and a correct timing is produced by the method and the apparatus. In this transmitter apparatus, a first delay adjusts a control timing over a voltage that controls a power amplifier, and a distributor distributes an output from the power amplifier in order to feedback parts of the output. A distortion adjusting units calculating a distortion component of the transmission signal by using the signal fed back by the distributor, and adjusts automatically a delay amount of the first delay so as to minimize the distortion component. This structure allows eliminating manual adjustment, and obtaining high power-efficiency with fewer distortions.

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: A coefficient computing section, for computing a characteristic reverse to an input/output characteristic of the power amplifier, is configured by a fixed coefficient storing section and an error coefficient computing section. The fixed coefficient storing section is previously stored with the characteristic reverse to a pre-measured input/output characteristic. The error coefficient computing section computes an error coefficient between a characteristic stored in the fixed coefficient storing section and a current characteristic of the power amplifier. When the determining section determines that the adjacent-channel leak current power ratio is greater than a predetermined value, an operation halt is instructed to the power amplifier.

Abstract: An average signal point amplitude detection section 15A determines an average position of I and Q components when a received QPSK modulated signal is demodulated and a threshold calculation section 15B determines threshold ths on an IQ plane based on the average signal point position of the received QPSK modulated signal and a theoretical distribution position on the IQ plane of signal points of a 16-value QAM signal. Then, a threshold decision section 14A makes a threshold-decision on the I and Q components of sequentially received QPSK modulated signals using this threshold ths and thereby calculates a simulated bit error rate of the 16-value QAM signal.

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 digital reception apparatus includes a receiver that processes a received signal and a distortion corrector that corrects a non-linear distortion of the processed received signal, introduced by the receiver. The receiver may include an amplifier, a quadrature demodulator and/or a quantizer. The distortion corrector includes a distortion estimator that estimates the distortion and outputs a correcting signal based on an inverse distortion characteristic of the receiver, and a distortion compensator that multiplies the received signal and the correcting signal to remove the non-linear distortion from the received signal, to obtain a corrected received signal. The corrected signal is output to a demodulator, which performs demodulation processing on the corrected signal, and thereby obtains a demodulated signal.

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: In a radio communication method whereby adaptive modulation is performed, a method is used whereby pilot symbol signal points are arranged in the in-phase-quadrature plane (IQ plane) so that the reception sensitivity of a receiving apparatus is made optimal in the respective modulation methods while maintaining the average transmission output power of the transmitting apparatus at a fixed level. By this means, it is possible to arrange pilot symbol signal points and improve the reception sensitivity characteristics of a receiving apparatus while maintaining the average transmission output power of the transmitting apparatus at a fixed level.

Abstract: Amplitude phase distortion adding sections are provided for the power amplifiers on the antenna arrays greater in amplitude weighting while amplitude distortion adding sections are provided for the power amplifiers on the antenna arrays smaller in amplitude weighting. Due to this, because a required amount of distortion compensation is made based on each antenna array, there is no bad effect upon the adjacent other antenna array, suppressing the deterioration in beam control accuracy. This, also, reduces the size of the apparatus and improves the power efficiency on the array antenna apparatus overall.

Abstract: Frame configuration determination section 101 judges a communication situation based on the transmission path information indicating the level of fluctuations of the transmission path due to fading and data transmission speed information indicating the transmission speed of the transmission data based on the level of the reception signal and determines the interval of inserting a known pilot symbol and the modulation system of a transmission digital signal. Quadrature baseband modulation section 102 modulates the transmission digital signal to a quadrature baseband signal according to the modulation system indicated from frame configuration determination section 101. Pilot symbol generation section 103 generates a pilot symbol known between the transmitting and receiving sides. Frame configuration section 104 inserts the known pilot symbol output from pilot symbol generation section 103 at the insertion interval instructed from frame configuration determination section 101 to configure a frame.

Abstract: QPSK modulated quadrature baseband signal generating section 301 generates a QPSK modulated quadrature baseband signal. 8PSK modulated quadrature baseband signal generating section 302 generates an 8PSK modulated quadrature baseband signal. Based on the modulation scheme determined information, in-phase component switching section 304 and quadrature component switching section 305 switch between the QPSK modulated quadrature baseband signal, 8PSK modulated quadrature baseband signal and pilot symbol to output to radio section 306. Radio section 306 performs the predetermined radio processing on the baseband signal to output a transmission signal. The transmission signal is amplified in power amplifier 307, and the amplified transmission signal is transmitted from transmission antenna 309. It is thereby possible to take into account both the improvement in the data transmission rate, and the benefit and convenience in terminals.

Abstract: A phase/amplitude control section controls the phase and amplitude of at least one of the signals: a distributed signal distributed by a modulation signal distributor and a reference signal based on an orthogonal base-band signal. A signal combiner combines a combinatory signal according to the distributed signal and the reference signal whose phase and amplitude have been controlled. A reference table updating section updates non-linear distortion compensating data according to the combinatory signal subjected to A/D conversion and the orthogonal base-band signal. With this configuration, since a known signal component is removed from the combinatory signal, the change amount of the signal input to the A/D converter of a feedback system circuit is reduced and the A/D converter of the feedback system circuit need not have a wide dynamic range performance.

Abstract: A coefficient computing section, for computing a characteristic reverse to an input/output characteristic of the power amplifier, is configured by a fixed coefficient storing section and an error coefficient computing section. The fixed coefficient storing section is previously stored with the characteristic reverse to a pre-measured input/output characteristic. The error coefficient computing section computes an error coefficient between a characteristic stored in the fixed coefficient storing section and a current characteristic of the power amplifier. When the determining section determines that the adjacent-channel leak current power ratio is greater than a predetermined value, an operation halt is instructed to the power amplifier.

Abstract: A transmitting method and a transmitter apparatus, which need no manual adjustment, are disclosed. A delay amount of a delay means is automatically adjusted such that an out-of-band distortion component of a transmission signal is minimized, and a correct timing is produced by the method and the apparatus. In this transmitter apparatus, a first delay means adjusts a control timing over a voltage that controls a power amplifying means, and a distributor distributes an output from the power amplifying means in order to feedback parts of the output. A distortion adjusting means calculates a distortion component of the transmission signal by using the signal fed back by the distributor, and adjusts automatically a delay amount of the first delay means so as to minimize the distortion component. This structure allows eliminating manual adjustment, and obtaining high power-efficiency with fewer distortions.

Abstract: An average signal point amplitude detection section 15A determines an average position of I and Q components when a received QPSK modulated signal is demodulated and a threshold calculation section 15B determines threshold ths on an IQ plane based on the average signal point position of the received QPSK modulated signal and a theoretical distribution position on the IQ plane of signal points of a 16-value QAM signal. Then, a threshold decision section 14A makes a threshold-decision on the I and Q components of sequentially received QPSK modulated signals using this threshold ths and thereby calculates a simulated bit error rate of the 16-value QAM 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.