Hitachi, Ltd.

Hitachi-kokusai Electric Inc.

Hitachi Communication Technologies, Ltd.

Fipa Frohwitter Intellectual Property Ag

Hironari Masui

Takashi Yano

Nobukazu Doi

Yasuo Ohgoshi

Takehiko Kobayashi

Masayuki Ariyoshi

Ikuo Matsuba

A radio communication system having a base station and a plurality of radio terminals, wherein each radio terminal having a transmission request transmits a reservation packet at arbitrary timing through a reservation channel in accordance with a CDMA scheme, and the base station assigns a traffic channel and a time slot to be used to each radio terminal requesting a reservation through a reply packet outputted onto a reply channel. On the reservation channel, a short spreading code corresponding to a matched filter is applied.

CDMA mobile communication system and communication 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

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

CDMA mobile communications system and communication method

A frequency band for communication between a base station and mobile stations is divided into a reverse-link and a forward-link bands. In each of these bands, carrier frequencies are defined in correspondence with sub frequency bands each having one of several bandwidths. To each of these bands of each mobile station, a sub frequency band with a bandwidth matching a data traffic rate is assigned in advance. Each mobile station spectrum-spreads a reservation packet and transmits the resultant packet by a prescribed carrier frequency corresponding to the reverse-link sub frequency band. The base station spectrum-spreads a response packet and transmits the resultant packet by a prescribed carrier frequency corresponding to the forward-link sub frequency band. Each mobile station spectrum-spreads a data packet by a spreading code for data traffic channel specified in the response packet and transmits the resultant packet by the reverse-link carrier frequency.

CDMA communication method and spread spectrum communication system

A neural network system includes an input unit, an operation control unit, a parameter setting unit, a neural network group unit, and a display unit. The network group unit includes first and second neural networks. The first neural network operates according to the mean field approximation method to which the annealing is added, whereas the second neural network operates in accordance with the simulated annealing. Each of the first an second neural networks includes a plurality of neurons each connected via synapses to neurons so as to weighting outputs from the neurons based on synapse weights, thereby computing an output related to a total of weighted outputs from the neurons according to an output function. The parameter setting unit is responsive to a setting instruction to generate neuron parameters including synapse weights, threshold values, and output functions, which are set to the first neural network and which are selective set to the second neural network. The operation control unit responsive to an input of a problem analyzes the problem and then generates a setting instruction based on a result of the analysis to output the result to the parameter setting unit. After the neuron parameters are set thereto, in order for the first and second neural network to selectively or to iteratively operate, the operation control unit controls operations of computations in the network group unit in accordance with the analysis result and then presents results of the computations in the network group unit on the display unit.

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Yokohama, Japan

Hironari Masui