Nippon Telegraph and Telephone Corporation

Tsutomu Tatsuta

Hayato Fukuzono

Keita Kuriyama

Masafumi Yoshioka

Tomohiro Tokuyasu

Hiroyuki Furuya

Yu Ono

Tomohiro Nakayama

Hiroyuki Nakamura

Toshio Ito

Shuta Ueno

In a wireless communication system for performing single-carrier MIMO transmission, a transmitting station apparatus includes a training signal generation unit and a transmit beamforming unit that performs transmit beamforming processing using transmit weights and a receiving station apparatus includes a communication path estimation unit, an interference amount determination unit that determines whether or not a residual inter-stream interference exceeds a predetermined threshold value, a receive weight calculation unit that calculates a receive weight used for receive beamforming processing when the residual inter-stream interference exceeds the threshold value, and a receive beamforming unit that performs receive beamforming processing for suppressing residual inter-stream interferences using the receive weight.

Wireless communication system, wireless communication method and receiving station device

A transmission station device includes a training signal generation unit, a CP addition unit, and a transmission beamforming unit that performs transmission beamforming processing in a time domain using a transmission weight for removing inter-antenna interference. A reception station device includes a CP removal unit, a channel estimation unit, and an equalization unit that performs equalization processing for removing inter-symbol interference in a frequency domain using a reception weight. Either of the transmission station device or the reception station device is provided with a weight calculation unit that calculates the transmission weight and the reception weight based on the channel response, an effective CIR length calculation unit that calculates an effective CIR length between antennas, and a CP length setting unit that sets, to the CP length, a maximum CIR length among the CIR lengths of respective items of the reception weight.

Wireless communication system, wireless communication method, transmitting station device and receiving station device

A wireless communication system includes a plurality of sets of base station devices and terminal station devices configured to perform communications in an equal frame length using a time division duplex scheme, the communications of the plurality of sets being simultaneously operated in adjacent areas, in which each of the base station devices includes a control unit configured to control a transmission timing of a downlink signal transmitted from the base station device itself based on a communication distance between the base station device and the terminal station device of each of the sets or a reception timing of a downlink signal in the terminal station device such that reception timings of downlink signals transmitted from the base station device itself and other base station devices in the terminal station devices of the sets fall within a predetermined range determined in advance.

Wireless communication system, wireless communication method, management station device, base station device, and terminal station device

In a signal transmission system for transmitting an analog signal, in which a billing signal is superposed on an audio signal, from a transmitting device to a receiving device, the transmitting device includes a separation unit configured to separate the audio signal from the analog signal, an AD conversion unit configured to perform AD conversion on the audio signal separated by the separation unit, a detection unit configured to detect the billing signal from the analog signal, a coding unit configured to encode the billing signal detected by the detection unit, and a transmission unit configured to transmit the audio signal subjected to the AD conversion by the AD conversion unit and the billing signal encoded by the coding unit to the receiving device, and the receiving device includes a reception unit configured to receive the audio signal and the billing signal transmitted by the transmission unit, a DA conversion unit configured to perform DA conversion on the audio signal received by the reception unit, a decoding unit configured to decode the billing signal received by the reception unit, a conversion unit configured to convert the billing signal decoded by the decoding unit into an analog wave, and a combination unit configured to combine the audio signal subjected to the DA conversion by the DA conversion unit and the analog wave.

Signal transmission system and signal transmission method

According to the present invention, in a wireless communication system that performs single carrier MIMO transmission between a transmitting station device and a receiving station device, the transmitting station device includes a time-domain linear equalization unit, a propagation path characteristics estimation unit configured to receive a training signal and estimate a transfer function matrix of propagation path characteristics, a filter tap calculation unit configured to calculate filter tap coefficients for the time-domain linear equalization unit based on the transfer function matrix by a predefined approach, and a transmission mode determination unit configured to make the filter tap calculation unit calculate the filter tap coefficients when the transfer function matrix meets a predefined condition, and to change a transmission mode and determine the transmission mode that meets the predefined condition when the transfer function matrix does not meet the predefined condition. The receiving station device includes a training signal generation unit configured to generate the training signal for use in estimation of propagation path characteristics and transmit the training signal to the transmitting station device.

According to the present invention, in a wireless communication system that performs single carrier MIMO transmission between a transmitting station device and a receiving station device, the transmitting station device including: a time-domain linear equalization unit configured to remove inter-symbol interference and inter-stream interference from a data signal to be transmitted to the receiving station device; a propagation path characteristics estimation unit configured to receive a training signal which is transmitted by the receiving station device and estimate a transfer function matrix of propagation path characteristics; and a filter tap calculation unit configured to calculate filter tap coefficients for the time-domain linear equalization unit by representing the estimated transfer function matrix as a matrix polynomial, taking an inverse response of the matrix polynomial as a transmit weight matrix, and approximating the transmit weight matrix with Neumann series, and the receiving station device including a training signal generation unit configured to generate the training signal for use in estimation of propagation path characteristics and transmit it to the transmitting station device.

Provided is a wireless communication system configured to accommodate a plurality of circuits to transmit a signal from a transmitter to a receiver, the system including a number-of-circuits observation unit configured to observe the number of circuits among the plurality of circuits through which communication is being performed; a quality observation unit configured to observe a quality of each of a plurality of communications; a determination unit configured to determine a modulation scheme for transmitting a signal based on the number of circuits observed by the number-of-circuits observation unit, the quality of each of the plurality of communications observed by the quality observation unit, and a required throughput of each of the plurality of circuits; and a modulation unit configured to modulate the signal using the modulation scheme determined by the determination unit.

Wireless communication system, wireless communication method, and wireless communication device

A transmitting station device at least comprises a training signal generation unit, and a receiving station device at least comprises a communication path estimation unit which estimates a communication path response from the known signal, and a beam forming unit which performs a beam forming process using a weight to suppress inter-stream interference, a channel fluctuation amount calculation unit which calculates as a channel fluctuation amount a difference between the communication path responses estimated in a manner of one following another in time, and a weight calculation unit which calculates a new weight using an updated value of the weight calculated based on the channel fluctuation amount are included in one of the transmitting station device and the receiving station device. This can significantly reduce the amount of calculation related to update of a weight.

A wireless communication device includes an estimation observation unit that observes a channel condition by estimating a tendency of a long delay wave and a channel fluctuation from a received signal in which a training signal is added to a data frame, a first equalizer that compensates for the received signal, a second equalizer that compensates for the received signal with a property of having a higher long delay wave tolerance and a lower channel fluctuation tolerance than the first equalizer, and a control unit that performs control which switches such that the first equalizer or the second equalizer performs compensation for the received signal, on the basis of the channel condition observed by the estimation observation unit.

Wireless communication device, wireless communication system, and wireless communication method

A transmitting station apparatus includes a training signal generation unit, a transmission end linear equalization unit configured to equalize data signals by a transmission end transfer function, and a transmitting station communication unit configured to transmit a training signal or a plurality of data signals and receive information of the transmission end transfer function from a receiving station apparatus. The receiving station apparatus includes a communication path estimation unit configured to estimate a communication path response from the training signal, a reception end coefficient calculation unit configured to calculate the transmission end transfer function with an adjugate matrix of a transfer function matrix H of the communication path response as a transfer function and a reception end transfer function with an inverse of a determinant of the transfer function matrix H as a transfer function, and a reception end linear equalization unit configured to equalize reception signals by using the reception end transfer function. The reception end linear equalization unit determines whether the determinant of the transfer function matrix H is a minimum phase, performs a forward direction equalization in a case of the minimum phase, and performs an inverse direction equalization in a case of a non-minimum phase.

In the present invention, a transmitting station apparatus includes a training signal generation unit, a transmission end linear equalization unit configured to output a plurality of second data signals obtained by equalizing IAI of a plurality of first data signals by using a transmission end transfer function for equalizing IAI, and a transmitting station communication unit configured to transmit a training signal or the plurality of second data signals to a receiving station apparatus and receive information on the transmission end transfer function from the receiving station apparatus, and the receiving station apparatus includes a communication path estimation unit configured to estimate a communication path response from the training signal received by the receiving station communication unit, a reception end coefficient calculation unit configured to calculate the transmission end transfer function and a reception end transfer function for equalizing ISI, based on the communication path response, and a reception end linear equalization unit configured to output a plurality of third data signals obtained by equalizing ISI from the plurality of second data signals received by the receiving station communication unit by using the reception end transfer function.

According to the present invention, a transmitting station apparatus includes: a plurality of modulation units that modulates a plurality of streams into which transmission data is divided to generate a plurality of first data signals; a training signal generation unit that generates a known training signal; a linear equalization unit that linearly equalizes the plurality of first data signals using a tap coefficient for removing inter-antenna interference and inter-symbol interference and outputs second data signals on which transmission beam forming and equalization are simultaneously performed; and a plurality of transmitting station communication units that transmit the training signal or the second data signals to a receiving station apparatus and receive the tap coefficient from the receiving station apparatus, and a receiving station apparatus includes: a coefficient estimation unit that estimates a channel impulse response from the training signal and calculates the tap coefficient based on the channel impulse response; and a receiving station communication unit that receives the second data signals or the training signal and transmits the tap coefficient calculated by the coefficient estimation unit to the transmitting station apparatus.

A radio communication system includes a transmitting station, and at least one receiving apparatus. The transmitting station includes a plurality of modulation units configured to modulate a plurality of input data to generate first data signals in units of blocks having a predetermined data length, a subtraction unit configured to calculate, by using information acquired in advance and indicating a communication path response between the transmitting station and the receiving apparatus, information indicating directivity upon transmission of the first data signals of each of the plurality of modulation units, and predetermined information included in an additional signal to be added to a data signal, a delay wave component of the additional signal and subtract the delay wave component calculated, from each of the first data signals of the plurality of modulation units, to generate a plurality of second data signals, a beam forming unit configured to adjust, by using the information indicating directivity, power and a phase upon transmission of each of the plurality of second data signals to generate a plurality of third data signals, a plurality of adding units configured to add the additional signal to each of the plurality of third data signals to generate a plurality of fourth data signals, and a plurality of communication units configured to transmit the plurality of fourth data signals to the receiving apparatus.

Growing community of inventors

Musashino, Japan

Tsutomu Tatsuta