Hitachi-kokusai Electric Inc.

Nikko Chemical Institute Inc.

Toyoko Giken Co., Ltd.

Mitsubishi Gas Chemical Company, Inc.

Tokyo Denki University

Takehiko Kobayashi

Takashi Yano

Hiroyuki Akutagawa

Masashi Naito

Hironari Masui

Takashi Horiguchi

Satoru Ejima

Nobuyuki Sakamoto

Keisuke Yamamoto

Manabu Nakamura

Naoki Hongo

Yoshihiko Akaiwa

Keat Beng Toh

Takashi Kajiyama

Takehiko Nishide

Takashi Seike

Hironobu Yamamoto

The present invention relates to a radio communication system that provides a transmission technique capable of suppressing degradation of communication quality even in an area other than an interference area of two base station radio waves. Further, the transmission technique and the communication system include implementation of a Differential Space-Time Block Coding (DSTBC) method relating to transmission diversity in radio communication utilizing, for example, base stations with transmission antennas that transmit respective sequence signals of the DSTBC.

Wireless communication system and transmitter

Provided is a transmitter for transmitting signals by means of the STBC method or the DSTBC method, wherein communication is carried out effectively. The transmitter for transmitting signals by means of the STBC method or the DSTBC method has the following configuration. A frame in which synchronization words are arranged at specified positions is used. An encoding means in the transmitter encodes the entire frame to be transmitted including the synchronization words, by means of the STBC method or the DSTBC method. It is also possible to implement a communication system and a communication method for communicating signals by means of the STBC method or the DSTBC method.

Transmitter, receiver, communication system, and communication method

The present invention is directed to reduction of operation amount of likelihood calculation (LLR calculation) in a communication apparatus for performing communications using an extended mapping in which a plurality of bit sequences are assigned to a single symbol point. A receiving unit receives a signal which is transmitted from a transmitting unit by using the extended mapping. A repetition process unit decodes the received signal from the receiving unit by calculating an LLR of the received signal and performing a repetition process. In this case, the LLR is calculated for every bit using a MAX-LOG approximation and a thus-derived approximation formula is multiplied by weighting factors corresponding to proportions of '0' and '1' in each bit assigned to a symbol point closest to the received signal.

Communication apparatus

In a transmitter which transmits a signal by a DSTBC scheme, communication is efficiently performed by the DSTBC scheme. In the transmitter which transmits the signal by the DSTBC scheme, a frame in which a sync word is disposed in a predetermined position subsequent to the head is used. Initial value controller (to) sets initial values of differential encoding (differential encoding unit) when a DSTBC encoder which processes a transmission target processes the frame on the basis of values from the head of the frame to a position before the sync word so that a signal point corresponding to the position immediately before the sync word in the DSTBC encoder which processes the transmission target becomes a specific point.

Transmitter and transmission method

A wireless communications device and method carries out a process including estimating channel information based on a received signal; generating pseudo-transmission signal point candidates based on the channel information and/or transmission signal point candidates; and generating a replica of the received signal based on the pseudo-transmission signal point candidates and the estimated channel information. The process further includes performing matrix operations on the basis of the received signal and the replica thereof; selecting pseudo-transmission signal point candidates which have a greater effect on likelihood calculations; reverting the selected pseudo-transmission signal point candidates to original transmission signal point candidates and calculating final likelihoods; and restoring the received signal on the basis of the calculated likelihoods.

Wireless communications device and method

Provided is a maximum likelihood decoding method that includes the steps of; firstly arranging channel impulse responses corresponding to the received signals in a plurality of different orders; secondly specifying the same number of parts as the plurality of different orders in which the channel impulse responses are arranged, so that the received signals are placed in each of the parts; thirdly generating channel matrices each having the channel impulse responses as matrix elements, by using the channel impulse responses arranged in the plurality of different orders, obtaining triangular matrices by applying QR decomposition to the generated channel matrices, and determining at least one combination candidate for each of the parts of the plurality of transmission signals by using the obtained triangular matrices; and fourthly selecting the combination candidates so that a Euclidean distance between the combination candidates determined in the third step is shortest.

Maximum likelihood decoding method and receiver

In a transmitter, communication is efficiently performed by a DSTBC scheme. In a transmitter which transmits a signal using the DSTBC scheme, the content of a transmission process is set so that a state where a symbol is not present is realized at the origin of signal arrangement in a DSTBC encoder. As an example, the setting is performed so that an input to the DSTBC encoder is calculated using a predetermined operation in which a state where a symbol is not present is realized at the origin of signal arrangement in the DSTBC encoder. As another example, the setting is performed so that initial values in which a state where a symbol is not present is realized at the origin of signal arrangement in the DSTBC encoder are used in differential encoding of the DSTBC encoder.

Transmitter

Provided is a maximum likelihood decoding method of separating and estimating multiple transmitted signals transmitted by multiple transmitter antennas from multiple received signals received by multiple receiver antennas, comprising: a first step of generating a channel matrix based on channel impulse responses corresponding to the received signals; a second step of dividing the generated channel matrix into multiple sub-matrices, of identifying parts of the received signals corresponding to the sub-matrices obtained through the division, and of transforming the sub-matrices obtained through the division, by using inverse matrices of the sub-matrices obtained through the division; a third step of applying QR decomposition to the transformed sub-matrices to obtain triangular matrices, and of transforming the received signals of the parts by using the obtained triangular matrices; and a fourth step of determining one combination candidate for the parts of the transmitted signals corresponding to the transformed received signals.

Maximum likelihood decoding method, equipment, and receiver

Disclosed herewith is a radio communication apparatus capable of selecting proper one of plural communication modes such as a MIMO communication system so as to obtain a higher communication rate within a range in which chain retransmission occurrence is prevented. The MIMO system deciding section of the transmitter unit decides a proper MIMO system with reference to the CQI value demultiplexed by a demultiplexer and the AMC table controlling section changes the MCS value step by step according to the transmission count and the result (success/failure) of the communication. Furthermore, the AMC table controlling section updates the mean rate in the measured rate table when the subject data is received successfully or when the transmission count reaches the maximum value.

Coding and modulation selecting method and wireless communication equipment

In a radio communication apparatus, a MIMO system deciding section of a transmitter unit decides an object MIMO communication system with reference to a CQI value and a measured rate table while an AMC table controlling section selects an object MCS value according to the decided MIMO communication system and CQI value. The AMC table controlling section changes the MCS value step by step according to a transmission count and a result (success/failure) of the communication. If the communication (receiving) is successful or if the transmission count reaches the maximum value, the controlling section updates the mean value of the measured rate table. At this time, based on a value estimated from the combination of the MIMO communication system, the encoding system, and the modulating system that are used currently, the controlling section changes the reference for selecting another combination that are not used currently.

MIMO transmission mode selecting method and wireless communication equipment

The invention provides a game ball, useful for children's safety, which can be detected far enough away a distance by a vehicle-onboard radar. The invention provides a game ball wherein a reflector memberis disposed within a spherical shell, the diagonal distance of the reflector member coincides with the inner diameter of the spherical shell, the reflector member has a shape constructed by combining three regular polygon platesA,B,C, the center angle of one side thereof being an integral submultiple of 90&#xb0;, in such a manner that the centers of the three regular polygon plates are coincident and that the three regular polygon plates are perpendicular to each other, and a surface of said reflector memberis imparted with electromagnetic wave reflectivity.

Game ball

The invention aims to converge predistortion coefficients efficiently in a predistorter adapted to compensate for distortion generated in an amplifier. Level detection means detects the level of a signal input to an amplifier. Signal acquisition means acquire a signal output from the amplifier as a feedback signal. Correspondence acquisition means updates a predistortion coefficient expressed using a set of orthogonal polynomials so that a distortion component contained in the acquired feedback signal is reduced and acquires a correspondence between the level of the signal input to the amplifier and a control coefficient for predistortion (contents of a distortion compensation table). Predistortion executing means applies distortion for predistortion with respect to the signal input to the amplifier in accordance with the control coefficient for predistortion that corresponds to the detected level based on the acquired correspondence.

Predistorter

A demodulator of a differential detection system for a &#x3c0;/4 shifted QPSK or DQPSK modulation wave in digital communication. The demodulator includes a differential detector connected to receive orthogonal components of the modulation wave, a corrector connected to receive an output of the differential detector for correcting a deviated distribution of signal points on a constellation, and a slicer/decoder connected to receive an output of the corrector. The slicer/decoder decodes a received bit from the signal points after the deviated distribution is corrected. The corrector has average calculators connected to receive respective outputs of the differential detector, and subtractors connected to receive the associated outputs of the differential detector and also to receive associated outputs of the average calculators for subtracting an average value of the outputs of the differential detector from the outputs of the differential detector.

Demodulation method and apparatus based on differential detection system for &#x3c0;/4 shifted QPSK modulated wave

A concrete coloring material and a process for coloring concrete by means of such a concrete coloring material capable of permitting concrete to exhibit natural color or aesthetic properties while preventing concrete from being substantially discolored. Polyethylene oxide is used as a water-soluble adhesive or gIue. The oxide is mixed with a composition such as dye, pigment, a mixture thereof or the like, to thereby permit the composition to penetrate into the concrete.

Process for coloring concrete

A concrete coloring material and a process for coloring concrete by means of such a concrete coloring material capable of permitting concrete to exhibit natural color or aesthetic properties while preventing concrete from being substantially discolored. Polyethylene oxide is used as a water-soluble adhesive or glue. The oxide is mixed with a composition such as dye, pigment, a mixture thereof or the like, to thereby permit the composition to penetrate into the concrete.

Growing community of inventors

Tokyo, Japan

Takehiko Kobayashi