Fujitsu Corporation

Kyoko Hirao

Takashi Kaku

Hideo Miyazawa

Hiroyasu Murata

Noboru Kawada

Yuri Nigaki

Hiroki Kishimoto

A polling communication system includes a main station and a plurality of sub stations connected to the main station. The main station includes an address control part and a polling control part. The address control part divides a predetermined polling cycle into a plurality of kinds of polling intervals each having a different number of times of polling, and holds addresses of polling target sub stations corresponding to the respective polling intervals. The polling control part switches the polling intervals and changes the addresses in the address control part according to states of the sub stations. Each of the sub stations includes another polling control part that sends a response when the sub station is polled by the main station.

Polling communication system and polling control method

A data transmission method that includes the steps of: a) performing two-dimensional interleaving along a time axis and along a frequency axis; b) transmitting the thus-obtained data by a multi-carrier transmission form; and c) producing, by channel copy operation, data which is short for the number of channels required for fast inverse Fourier transform performed antecedent and subsequent to step a).

Data transmission method and data transmission apparatus

A data transmission method includes the steps of: a) performing two-dimensional interleaving along a time axis and along a frequency axis; b) transmitting thus-obtained data by a multi-carrier transmission form; and c) producing, by channel copy operation, data which is short with respect to the required number of channels for fast inverse Fourier transform performed antecedent and subsequent to the step a).

A peak suppression method detects a peak value exceeding a threshold value of a transmitting signal, forms a peak value prediction signal which is limited to a noise cancelling frequency band of a receiving end, based on the detected peak value of the transmitting signal, and subtracts the peak value prediction signal from the transmitting signal.

Peak suppression method and data transmission apparatus

A transfer process in which, an original vector signal is precoded to an intermediately-precoded vector signal, and the extended modulo operation is performed when the intermediately-precoded vector signal is located outside a predetermined extended-modulo limit area, and the precoded vector signal is transferred through a system having a predetermined filtering characteristic. From the transferred vector signal, the original vector signal is detected, based on a relationship between the vector components of the original vector signal and the transferred vector signal.

Process and system for transferring vector signal with precoding for

The invention relates to an eye pattern which is generated upon transmission and also to a modulation and demodulation method which employs the eye pattern. The eye pattern and the modulation and demodulation method are improved in that, by devising the arrangement of signal points, the timing jitter amount is minimized and a frequency offset can be followed up accurately. The eye pattern to be generated upon transmission is constructed such that the arrangement of signal points thereof is not symmetrical with respect to the origin on a signal point arrangement plane on which the signal points are arranged.

Special eye pattern and modulation and demodulation method using the same

An automatic equalizer which converges by a received signal and a data mode convergence method. A variance extracting unit extracts the variance of an output signal of a transversal automatic equalizing section and changes a predecision input signal to a proper level according to the extracted variance. A decision unit makes a decision for the predecision input signal which has been changed by the variance extracting unit and allocates the predecision input signal to a signal point. An amplitude error extracting unit extracts an amplitude error from a predecision input signal and a postdecision output signal of the decision unit and corrects the tap coefficients of the transversal automatic equalizing section according to the extracted amplitude error.

Automatic equalizer and data mode convergence method

In a timing generation device coupled to a transmission line having a main channel and a secondary channel, the main channel having a transmission speed higher than that of the secondary channel, a first unit extracts a timing signal component transmitted via the secondary channel. A second unit generates an internal timing signal in synchronism with the timing signal component, the internal timing signal being used to reproduce data transmitted via the main channel.

Timing generation device and data transmission device having the timing

A modulation and demodulation system suitable for use with a modem (modulator and demodulator apparatus) of a first polling type. The system allows reproduction of a signal necessary for initialization of a reception section of a modulator and demodulator apparatus with certainty in a short training time. The modulation and demodulation system is constructed such that, upon transmission of data, training data of a particular pattern are modulated and transmitted prior to transmission of the data, and such training data are demodulated by demodulation means and initialization of a reception section of the modulation and demodulation system is performed using the demodulation training data. The pattern of the training data to be transmitted includes an arrangement of signals wherein signals having phases different by 180.degree. from each other are arranged alternately, and a signal having the same phase as the last signal is arranged intermediately.

Initialization equalization for modulation and demodulation using

The invention provides a frequency offset dealing modulator and demodulator apparatus which modulates and demodulates transmission/reception data and is improved in that it can reproduce an accurate impulse when data are transmitted. The modulator and demodulator apparatus includes a modulator for modulating data, and a demodulator for demodulating a receive signal to reproduce such data. The demodulator includes a demodulation processing unit, a roll-off filter, a receive level adjustment unit, an equalizer, a carrier frequency offset removing correction signal generation unit, a normalizer, a multiplier and a sum calculation unit.

Growing community of inventors

Kawasaki, Japan

Kyoko Hirao