Ntt Docomo, Inc.

Nec Corporation

Noriyuki Maeda

Satoshi Nagata

Hideaki Takahashi

Mamoru Sawahashi

Hiroyuki Atarashi

Kenichi Higuchi

Junichiro Kawamoto

Sadayuki Abeta

Hiroyuki Kawai

Shousei Yoshida

Yoshikazu Kakura

Shunji Miura

Hiromitsu Asakura

Hiromasa Fujii

Mariko Matsumoto

Masayuki Kimata

The radio communication apparatus includes

Radio communication apparatus and a radio communication method

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.

Radio communication system, transmitter, receiver and radio communicating method

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.

Signal reception device and method of signal reception timing detection

A transmission apparatus including: a layer multiplexing unit configured to assign, to a radio resource which is divided based on a time, a frequency and a layer, a bit sequence which constitutes at least one information source to be transmitted, in accordance with a communication state and a priority level of the information source; and a layer coding unit configured to perform a layer coding processing for the bit sequence assigned to the radio resource. The layer multiplexing unit performs the assignment so that a length of each bit sequence assigned to each radio resource becomes equivalent.

Transmission apparatus and transmission method

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.

Noise power estimation apparatus, noise power estimation method and signal detection apparatus

A corrected channel estimating apparatus is disclosed, which is capable of removing side-lobe components mutually leaking into transmission paths from channel estimates to increase the accuracy. A channel estimation unit calculates channel estimates for a plurality of transmission paths due to a signal that arrives through multipath. A channel estimate correction unit removes side-lobe components mutually leaking into the transmission paths from the channel estimates calculated by the channel estimation unit to correct the channel estimates. In this way, the corrected channel estimating apparatus estimates transmission paths of a multipath.

Channel estimating apparatus, CDMA receiving apparatus, and channel estimating method

A receiving apparatus, a receiving method, and a radio communications system are disclosed. The receiving apparatus is for receiving CDMA signals transmitted by M antennas and received by N antennas, where M and N are positive integers. The receiving apparatus includes a multipath receiving signal demodulating unit for primary demodulation of the CDMA signals received by the receiving antennas to obtain estimated transmission signals, and for obtaining signals in a multipath environment of each path of the receiving antennas based on the estimated results. Further, the receiving apparatus includes a multipath interference canceling unit for deducting signals of the paths other than a target path from the signals received by the receiving antennas to obtain multipath interference cancelled signals. Further, the receiving apparatus includes a demodulator for secondary demodulation of the multipath interference cancelled signals.

Receiver apparatus, receiving method, and wireless communication system

The object of the present invention is to achieve reduction of interference between cells and improvement of maximum throughput so as to improve spectrum efficiency. A wireless base station which transmits a radio signal between itself and a plurality of mobile stations by means of OFDMA includes: a multiplexing part for generating user data; a channel assignment control part for selecting a plurality sets of sub-carriers among a plurality of sub-carriers so as to constitute a radio frame containing sub-channels assigned to each of the plurality sets of sub-carriers and for setting in the radio frame the user data and control data by means of orthogonal frequency division multiplexing; and a transmission part for transmitting a radio signal containing the radio frame; where, the channel assignment control part is constituted so that the radio frame is divided into 2 zones for the control and user data and all the sub-channels in the zone for control data are divided into groups for each of sectors; the control data is allocated on the corresponding divided groups; and the user data is allocated on all the sub-channels in the zone for user data.

Wireless base station, mobile station, radio communication system, and radio communication method

A disclosed receiver in a MIMO multiplexing communication system, in which plural signals are simultaneously transmitted from plural transmitting antenna branches using the same frequency, and the transmitted signals are retrieved by receiving signals at plural receiving antennas, separating the received signals and searching for proper symbol metrics for each branch, comprises a QR decomposer for QR decomposing the received signals to orthogonalize the transmitted signals; a symbol replica candidate ranking unit for subtracting surviving symbol replica candidates from the QR decomposed received signals to get remaining received signals and rank the remaining signals in the increasing order of expected branch metrics of the remaining received signals; a symbol replica candidate selector for selecting symbol replica candidates in the ranked order; a branch metric calculator for calculating the branch metrics of the selected symbol replica candidates; and a threshold comparator for comparing the calculated branch metrics with a predetermined threshold; wherein if a calculated branch metric is larger than the predetermined threshold, the branch metric and successive branch metrics are deleted without further searching.

MIMO multiplexing communication system and a signal separation method

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. The present invention relates to the transmitter for multi-carrier transmission configured to transmit a plurality of sub-carriers having at least one pilot symbol duration. The transmitter according to the present invention comprises a pilot symbol allocater configured to allocate a plurality of pilot symbol patterns which are orthogonal to each other, to the at least one pilot symbol durations in at least two sub-carriers.

Transmitter for multi-carrier transmission and multi-carrier transmitting method

A signal detection apparatus improving signal detection accuracy in a receiver for communications system complying with the MIMO scheme. The signal detection apparatus detects transmission signals sent from transmission antennas based on received signals received by receiving antennas. The apparatus includes: a first determination mechanism for determining symbol candidates of the transmission signals in sequence based on the QRM-MLD method using the received signals arranged in first order; a second determination mechanism for determining symbol candidates of the transmission signals in sequence based on the QRM-MLD method using the received signals arranged in second order that is different from the first order; and an output mechanism for outputting symbol candidates and likelihood of the transmission signals based on determination results of at least the first and the second determination mechanisms.

Signal separating device and signal separating method

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&#xd7;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.

Radio transmitter-receiving apparatus and radio transmitting-receiving method for estimating noise and interference power in radio transmission using code spread

A MIMO multiple transmission device, comprising a packet data block generator () for generating a packet data block as a resent unit for hybrid ARQ; a CRC adder () for adding an error detection code; a channel encoder () 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 () for converting output of the channel encoder to serial form; an interleaver between transmission streams () for performing interleaving between transmission streams on outputs from the parallel-to-serial converter; a serial-to-parallel converter () for converting outputs from the interleaver between transmission streams to parallel form; a coding rate changer () for changing a coding rate; and a data modulator () 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.

MIMO multiple transmission device and method

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.

Signal separation device and signal separation method

The object of the present invention is to prevent continued reception of unreliable information symbols at the receiver apparatusin the OFDM radio communication system, so that it is possible to improve transmission quality. The radio communication system according to the present invention comprises a transmitter apparatusconfigured 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 apparatusconfigured 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.

Growing community of inventors

Yokohama, Japan

Noriyuki Maeda