Abstract: Received signals of the respective sub-carriers are multiplied by a weighting controlled for each sub-carrier, using a weighting control part 2-8 and multipliers 2-9, so that the mean square error between the signals following despreading and the signals that are actually transmitted is minimized. Afterward, MMSE combining is performed.

Abstract: A channel estimation circuit (101) of the present invention includes: a tentative channel estimation unit (102) for performing channel estimation by making use of a received signal and outputting the result of estimation as a tentative channel estimation signal; a noise/interference power estimation unit (103) for estimating noise and interference power by making use of the received signal and outputting the result of estimation as a noise/interference power estimation signal; a threshold decision unit (104) for establishing a threshold signal by making use of the noise/interference power estimation signal to output the threshold signal; and an effective path detection unit (105) for outputting, as a channel estimation signal, paths of the tentative channel estimation signal that remains after noise paths having powers smaller than the threshold signal have been removed.

Abstract: A MIMO multiple transmission device, comprising a packet data block generator (111) for generating a packet data block as a resent unit for hybrid ARQ; a CRC adder (112) for adding an error detection code; a channel encoder (113) for performing channel encoding, the packet data block generator, the CRC adder and the channel encoder being coupled in series in one or more data streams; a parallel-to-serial converter (114) for converting output of the channel encoder to serial form; an interleaver between transmission streams (115) for performing interleaving between transmission streams on outputs from the parallel-to-serial converter; a serial-to-parallel converter (116) for converting outputs from the interleaver between transmission streams to parallel form; a coding rate changer (117) for changing a coding rate; and a data modulator (119) for modulating data, the coding rate changer and the data modulator being connected in series in plural data streams divided by the serial-to-parallel converter.

Abstract: A radio transmitter-receiver wherein a pilot symbol is used in the transmitter that has undergone M-chip spreading on the frequency axis and N-chip spreading on the time axis by a spreading code of M×N chip length (where M and N are any integers equal to or greater than 2), and in the receiver, a spreading code that is not used in spreading said pilot signal is used as a despreading code to despread a received signal and then estimate noise and interference power. The spreading code that is used to spread the pilot symbol and the despreading code that is used in despreading are assigned so as to be orthogonal even if only in N chips on the time axis.

Abstract: A receiver, comprising a plurality of antennas configured to receive signals that are obtained by multiplying a plurality of data symbols transmitted over a plurality of data channels using spreading codes for each of the data channels, the data symbol being transmitted over a plurality of sub-carriers having different frequencies; a spreading code multiplier configured to multiply reception signals received by the plurality of antennas using spreading codes for the data channels corresponding to the reception signals; a weight controller configured to adjust antenna weights by which a reception signal received by each antenna is to be multiplied, and sub-carrier weights by which a reception signal received over each sub-carrier is to be multiplied; a weight multiplier configured to multiply the reception signals by the antenna weights and the sub-carrier weights adjusted by the weight controller; and a combining unit configured to combine the reception signals multiplied by the antenna weights and the sub-ca

Abstract: A pilot extract section 14 extracts a pilot signal from received signal. An adder 21 in-phase adds a plurality of correlated values of pilot signals for respective subcarriers. Delay devices 201-1 to 201-6 temporarily maintain one in-phase added value. Multiplier 202-1 to 202-6 multiplies a predetermined coefficient to the in-phase added value that is output from the delay device. The predetermined coefficient reflects the result, which is obtained by correcting for multiple times the difference of channel variation in the different subcarriers that is generated when noise power per one subcarrier is calculated. Each of the multiplying results is added by an adder 24, and is squared by a square device 25. A cumulative adder 26 cumulative-adds the squared values for the whole subcarrier. A multiplier 203 averages by multiplying predetermined values to the cumulative-added values.

Abstract: A signal separation device is disclosed that is able to reduce a number of calculations required when separating a received signal transmitted from transmission devices into the individual transmission signal. The signal separation device includes a signal point derivation unit that multiplies the received signal with respective elements of a unitary matrix, and derives at least one received-signal signal point on a signal constellation diagram; a definition unit that defines plural sections on the signal constellation diagram, each of the sections including a predetermined number of signal points; a detection unit that detects a received-signal section from the sections, the received-signal section including the received-signal signal point; a selection unit that selects signal points in the received-signal section as candidates of the received-signal signal point; and a determination unit that determines the transmission signals based on the selected signal points.

Abstract: A noise power estimation apparatus is disclosed. The noise power estimation apparatus includes: a part for calculating correlation between a received signal and a pilot signal so as to obtain a received power of the pilot signal for each path; a part for removing a multipath interference component from the received power of the pilot signal by using a predetermined power ratio between the pilot signal and a data signal so as to obtain a corrected received power of the pilot signal; a part for estimating an estimated total power of the pilot signal and the data signal included in the received signal based on the corrected received power and the predetermined power ratio; and a part for subtracting the estimated total power from a total power of the received signal so as to obtain a noise power.

Abstract: A path searcher (304) used in a receiver includes a power delay profile generating unit (402) configured to generate a power delay profile based on a signal received by the receiver, a sidelobe generating unit (406) configured to identify a sidelobe component of a path contained in the power delay profile based on a response characteristic of a band-limiting filter of the receiver, a sidelobe removing unit (407) configured to remove the sidelobe component from the power delay profile to produce a corrected power delay profile, and a path timing detection unit (408) configured to detect a path timing based on the corrected power delay profile.

Abstract: A channel estimation device is provided to achieve high-precision channel estimation in a MIMO or multicarrier wireless receiver. This channel estimation device is used in the wireless receiver that receives pilot signals through reception antennas. The pilot signals are modulated by a multicarrier method and are transmitted from transmission antennas. The pilot signals are orthogonal to one another. The channel estimation device includes: an estimation unit that determines a channel estimate value for each unit time slot and each unit sub carrier; and an averaging unit that averages the channel estimate values over time slots including a target time slot and sub carriers including a target sub carrier, thereby determining an average channel estimate value.

Abstract: A transmitter (200) used in a wireless communication system based on an orthogonal frequency division multiplexing (OFDM) scheme includes a determination unit (216) configured to determine a spreading factor and an amplitude for a control channel based on at least one of signal quality information and interference information in data transmission, a multiplexing unit (212) configured to multiplex a data channel with the control channel having been code-spread based on the spreading factor and the amplitude, and means (214) configured to modulate the multiplexed signal in the OFDM scheme and transmit the modulated signal as OFDM symbols.

Abstract: A radio communication system having a radio transmitter and a radio receiver and adopting multiple carrier modulation and code spreading modulation methods is disclosed. The radio communication system comprises a selecting unit provided in the radio transmitter or the radio receiver, for selecting an interleaving mode out of plural interleaving modes depending on radio propagation path conditions; a symbol configuration unit provided in the radio transmitter; and a symbol reconfiguration unit provided in the radio receiver. The symbol configuration unit configures information symbols to be transmitted by the radio transmitter in both time and frequency directions in a pattern according to the interleaving mode selected by the selecting unit, and the symbol reconfiguration unit reconfigures information symbols received by the radio receiver in both time and frequency directions in an inverse pattern of the pattern.

Abstract: A signal reception device is disclosed that is capable of detecting symbol synchronization timing with high precision in accordance with a condition of a propagation path even in an environment involving multi-path interference. The signal reception device adopts an OFCDM transmission scheme or a multi-carrier transmission scheme. The signal reception device includes a received signal information calculation unit to calculate received signal information representing a signal reception condition of a received signal; an output combination unit to combine correlation values in a predetermined section obtained by correlation detection based on the received signal information; and a symbol timing detection unit to detect a symbol synchronization timing based on the combined value.

Abstract: The object of the present invention is to prevent continued reception of unreliable information symbols at the receiver apparatus 200 in the OFCDM radio communication system, so that it is possible to improve transmission quality. The radio communication system according to the present invention comprises a transmitter apparatus 100 configured to estimate conditions of propagation paths used in the radio communication, arrange information symbols along the direction of the frequency axis in accordance with a predetermined pattern based on the estimated conditions of propagation paths, and transmit a radio communication signal including the arranged information symbols and a receiver apparatus 200 configured to receive the radio communication signal, and rearrange the information symbol included in the radio communication signal along the direction of the frequency axis in accordance with a reverse pattern to the predetermined pattern.

Abstract: The object of the present invention is to provide a transmitter for multi-carrier transmission for allocating pilot channels to radio frames, in consideration of interference with other pilot channels.

Abstract: A receiver, comprising a plurality of antennas configured to receive signals that are obtained by multiplying a plurality of data symbols transmitted over a plurality of data channels using spreading codes for each of the data channels, the data symbol being transmitted over a plurality of sub-carriers having different frequencies; a spreading code multiplier configured to multiply reception signals received by the plurality of antennas using spreading codes for the data channels corresponding to the reception signals; a weight controller configured to adjust antenna weights by which a reception signal received by each antenna is to be multiplied, and sub-carrier weights by which a reception signal received over each sub-carrier is to be multiplied; a weight multiplier configured to multiply the reception signals by the antenna weights and the sub-carrier weights adjusted by the weight controller; and a combining unit configured to combine the reception signals multiplied by the antenna weights and the sub-ca

Abstract: A radio transmission system is configured to, on the occasion of radio transmission of information between a transmitter and a receiver, perform the radio transmission of information using an orthogonal frequency and code division multiplexing transmission scheme of parallelly transmitting identical information by a plurality of sub-carriers. The radio transmission system has a spreading factor variable control transmitting device for parallelly converting information channel-coded at the transmitter, according to symbols transmitted simultaneously, and for spreading a sequence of parallelized symbols in at least one of a frequency direction and a time direction by a spreading code sequence of a designated spreading factor.

Abstract: Received signals of the respective sub-carriers are multiplied by a weighting controlled for each sub-carrier, using a weighting control part 2-8 and multipliers 2-9, so that the mean square error between the signals following despreading and the signals that are actually transmitted is minimized. Afterward, MMSE combining is performed.

Abstract: A regenerative brake device increases its regenerative brake power during high-speed driving, without impairing driveability. A regenerative brake device includes a driving wheel linked with a rotary shaft of an electric motor through a power transmission system and a battery charging circuit provided between the electric motor and a set of batteries. The battery charging circuit is switched OFF and ON to execute the regenerative braking in response to the duty factor of control pulse signals inputted to the battery charging circuit. The duty factor of control pulse signals inputted to the battery charging circuit decreases as the rotational speed of the rotary shaft of the electric motor increases, thereby increasing the braking power within a range that does not exceed a predetermined braking power.

Abstract: A regenerative brake device increases its regenerative brake power during high-speed driving, without impairing driveability. A regenerative brake device includes a driving wheel linked with a rotary shaft of an electric motor through a power transmission system and a battery charging circuit provided between the electric motor and a set of batteries. The battery charging circuit is switched OFF and ON to execute the regenerative braking in response to the duty factor of control pulse signals inputted to the battery charging circuit. The duty factor of control pulse signals inputted to the battery charging circuit decreases as the rotational speed of the rotary shaft of the electric motor increases, thereby increasing the braking power within a range that does not exceed a predetermined braking power.