Other

Toyo Communication Equipment Co., Ltd.

University of Tsukuba

Tama-tlo Corporation

Yokohama Tlo Company, Ltd.

Daiei Electronics Co., Ltd.

Noriyoshi Kuroyanagi

Naoki Suehiro

Mitsuhiro Tomita

Kohei Otake

Satoru Ozawa

Masakazu Takahashi

Shinya Matsufuji

Pingzhi Fan

Toshikatsu Naitoh

Toshikatsu Naito

A transmitting device and a receiving device wherein, on the transmitting side, a signal creation unit creates, as its output, a signal generated adding up the signals assuming that different data has passed through multiple virtual channels and, on the receiving side, oversampling is performed, the sampled data is distributed, and signals are detected assuming that the distributed data is the output of multiple virtual reception antennas.

Transmission method, transmission device, receiving method, and receiving device

A parallel sampling device includes a memory that stores the values of the sampling function (Sin &#x3c0;t/&#x3c0;t), a low pass filter, a sampler that samples a signal, which has passed through low pass filter, at a sampling period of Ts, and a parallel sampler provided in a stage following the sampler. The parallel sampler generates parallel sampled values at an interval of the sampling period Ts/N (N is a natural number equal to or larger than 2) based on sampled values obtained by the sampler and the values of the sampling function stored in the memory. This configuration allows parallel sampling to be performed easily even if the frequency is high or the sampling period of parallel sampling is narrow.

Parallel sampling device, parallel sampling method, receiving device, and receiving method

A de-correlating discriminating system of code division multiple access signals including a system structure composed of a plurality of cells, each of the plurality of cells including a base-station and a plurality of user-stations, each of the user-stations including a user-transmitter and a user-receiver, communicating through a multi-access channel with the base station which includes a base-station receiver and a base-station transmitter, and the user-transmitter is capable of transmitting a data symbol to convey a data with a spreading sequence and a pilot symbol that is the spreading sequence to identify a channel from the user transmitter to the base-station receiver and the base-station receiver includes a minimum means square error detector to analyze an input vector that is a received signal containing both multiple users specific data responses.

Decorrelating discrimination system of code division multiple access signals

In a communication method for transmitting a multipath characteristic measurement signal and a plurality of data transmission signals, the multipath characteristic measurement signal and data transmission signals are a signal array formed by a plurality of coefficient matrices that are orthogonal to one another within the matrices and which comprise at least one coefficient array that is common in the column direction or row direction. The multipath characteristic measurement signal formed by the coefficient matrices is the same signal array formed by the one common coefficient array. As a result, the transmission wait time and the signal reception time required for transmission of a multiplicity of data transmission signals are shortened in the simultaneous transmission of the multipath characteristic measurement signal and the plurality of data transmission signals by the spread modulation of transmission data by means of a spread spectrum, whereby the scale of the reception processing device is miniaturized.

Communication method, transmission signal forming method, and data structure of transmission signal

This invention provides techniques for a CDMA system having high spectrum efficiency with low transmit power. Each transmitter comprises means of selecting some core-sequences out of multiple sequences to make them convey plural data, means of producing an enveloped selected sequence with such a method as to arrange as guard sequences to a repeated sequence made by repeating each of the selected core-sequences, means of modulating a user specific orthogonal carrier frequency by the enveloped selected sequence to produce a transmit-symbol, and means of transmitting the transmit-symbols. And a receiver comprises means of demodulating a receive-symbol with one of the user specific carrier frequencies to produce a base-band receive-symbol, means of separating respective components corresponding to the sequences selected by the user, by analyzing the base-band receive-symbol with a matrix composed of a channel response vector from the user to the receiver to detect plural data on the components.

CDMA communications system using multiple spreading sequences

A direct sequence spread spectrum system consisting of modulator and demodulator wherein the spreading sequence with zero correlation zone properties, and the despreading consists of multiplying the received signal with the same spreading sequence, followed by a low pass filter, decoder and deinterleaver. The bit rate of the spreading sequence for each user is normally much higher than the input encoded data bit rate, and therefore it spreads the system spectrum.

Adaptive interference-free spread-spectrum system employing binary code sequence sets with zero correlation zone properties

In comb-form spectrum communication systems using repeated complementary sequence modulation, a transmitting signal is constituted by assigning one set of N auto-complementary sequences to each user, where N is an integer equal to or higher than 2, and by transforming the N sequences to N repeated signals which have comb-form spectra without overlapping in frequency with one another with a method of repeating each sequence of the set of auto-complementary sequences a plurality of times, and by assigning the N complementary sequences with auto-complementary sequence characteristics to the N comb-form spectra. Thus, the near-far problem is solved by making the cross-correlation between a signal input to a user's station but addressed to another station and the user's reference code sequence, zero.

Comb-form spectrum communication systems using repeated complementary sequence modulation

When communications are performed between a transmitter and a receiver via a transmission path , the transmitter prepares a basic sequence consisting of two-phase or four-phase tips, and transmits an expanded transmission frame which is constructed by repeatedly arranging one or a plurality of the basic sequence so as to obtain a finite length periodic sequence with a comb-form spectrum and by adding the replica of one or a plurality of tips of a back portion and front portion of the finite length periodic sequence to the outside of the front portion and the outside of the back portion of the finite length periodic sequence; and the receiver demodulates the expanded transmission frame using a matched filter which is matched with the finite length periodic sequence which is the central part of the expanded transmission frame, that is not including the added tips. In other words, the present invention can simplify the construction of communication equipment by using two-phase signals or four-phase signals.

Growing community of inventors

Tsukuba, Japan

Naoki Suehiro