Data transmitting method and data transmitting apparatus

A data transmitting apparatus used for a data transmitting method including the steps of:

• inputting a transmission symbol data at a transmission symbol rate which is one-Nth (N is an integer of 2 or more) of a base-point symbol rate to create a transmission symbol waveform at the base-point symbol rate by a precoder;
• transmitting the transmission symbol waveform through a roll-off filter having a band corresponding to the base-point symbol rate;
• inputting a reception signal to a fractionally-spaced equalizer that operates at the base-point symbol rate and is forcibly equalized at the transmission symbol rate by using a reference signal;
• determining a level of a signal output from the fractionally-spaced equalizer at the transmission symbol rate;
• and
• obtaining a sawtooth function output of a level-determined symbol data, thereby outputting a reception symbol data;
• wherein the precoder has a sawtooth-function output unit;
• wherein once in N times of a base-point symbol timing corresponding to the base-point symbol rate, another transmission symbol data is input to the sawtooth-function output unit, the another transmission symbol data is obtained by subtracting from the input transmission symbol data an output of the sawtooth-function output unit that is passed through a filter with a transmission function F2(D)−1;
• an output of the sawtooth-function output unit is taken as an output symbol data of the precoder, wherein, in a base-point symbol timing that does not input the transmission symbol data, zero symbol data is output to the filter with the transmission function F2(D)−1 and zero symbol data is taken as the output symbol data of the precoder;
• thereby creating the transmission symbol waveform, and
• the transmission function F2(D) is set so that a signal-to-noise ratio is improved by controlling a band selection characteristic of the fractionally-spaced equalizer.

A data transmitting apparatus used for a data transmitting method including the steps of:

• inputting a transmission symbol data at a transmission symbol rate which is one-Nth (N is an integer of 2 or more) of a base-point symbol rate to create a transmission symbol waveform at the base-point symbol rate by a precoder and a correlator;
• transmitting the transmission symbol waveform through a roll-off filter having a band corresponding to the base-point symbol rate;
• inputting a reception signal to a fractionally-spaced equalizer that operates at the base-point symbol rate and is forcibly equalized at the transmission symbol rate by using a reference signal;
• determining a level of a signal output from the fractionally-spaced equalizer at the transmission symbol rate;
• and
• obtaining a sawtooth function output of a level-determined symbol data, thereby outputting a reception symbol data,
• wherein the precoder has a sawtooth-function output unit;
• wherein once in N times of a base-point symbol timing corresponding to the base-point symbol rate, another transmission symbol data is input to the sawtooth-function output unit, the another transmission symbol data is obtained by subtracting from the input transmission symbol data an output of the sawtooth-function output unit that is passed through a filter with a transmission function F1(D)F2(D)−1;
• an output of the sawtooth-function output unit is taken as an output symbol data of the precoder, wherein, in a base-point symbol timing that does not input the transmission symbol data, zero symbol data is output to the filter with the transmission function F1(D)F2(D)−1 and zero symbol data is taken as the output symbol data of the precoder,
• the correlator adds the output symbol data of the precoder and one obtained by passing the output symbol data though a filter with the transmission function F1(D)−1 to take the addition result as an output symbol data of the correlator,
• thereby creating the transmission symbol waveform,
• the transmission function F1(D) is set so that a channel passage rate of a spectrum energy of a transmission signal is increased, and the transmission function F2(D) is set so that a signal-to-noise ratio is improved by controlling a band selection characteristic of the fractionally-spaced equalizer.

A data transmitting apparatus used for a data transmitting method including the steps of:

• inputting a transmission symbol data at a transmission symbol rate which is one-Nth (N is an integer of 2 or more) of a base-point symbol rate to create a transmission symbol waveform at the base-point symbol rate by a precoder and a correlator;
• transmitting the transmission symbol waveform through a roll-off filter having a band corresponding to the base-point symbol rate;
• inputting a reception signal to a fractionally-spaced equalizer that operates at the base-point symbol rate and is forcibly equalized at the transmission symbol rate by using a reference signal;
• determining a level of a signal output from the fractionally-spaced equalizer at the transmission symbol rate;
• and
• obtaining a sawtooth function output of a level-determined symbol data, thereby outputting a reception symbol data,
• wherein the precoder has a sawtooth-function output unit;
• wherein once in N times of a base-point symbol timing corresponding to the base-point symbol rate, another transmission symbol data is input to the sawtooth-function output unit, the another transmission symbol data is obtained by subtracting from the input transmission symbol data an output of the sawtooth-function output unit that is passed through a filter with a transmission function N(D)F2(D)−1;
• an output of the sawtooth-function output unit is taken as an output symbol data of the precoder, wherein, in a base-point symbol timing that does not input the transmission symbol data, zero symbol data is output to the filter with the transmission function N(D)F2(D)−1 and zero symbol data is taken as the output symbol data of the precoder,
• the correlator adds the output symbol data of the precoder and one obtained by passing the output symbol data though a filter with the transmission function N(D)−1 to take the addition result as an output symbol data of the correlator,
• thereby creating the transmission symbol waveform,
• the N(D) is a transmission function of a notch filter for providing a notch characteristic to a spectrum energy of a transmission signal, and the transmission function F2(D) is set so that the fractionally-spaced equalizer serves as a phase equalizer.

A data transmitting apparatus used for a data transmitting method including the steps of:

• inputting a transmission symbol data at a transmission symbol rate which is one-Nth (N is an integer of 2 or more) of a base-point symbol rate to create a transmission symbol waveform at the base-point symbol rate by a precoder and a correlator;
• transmitting the transmission symbol waveform through a roll-off filter having a band corresponding to the base-point symbol rate;
• inputting a reception signal to a fractionally-spaced equalizer that operates at the base-point symbol rate and is forcibly equalized at the transmission symbol rate by using a reference signal;
• determining a level of a signal output from the fractionally-spaced equalizer at the transmission symbol rate;
• and
• obtaining a sawtooth function output of a level-determined symbol data, thereby outputting a reception symbol data,
• wherein the precoder has a sawtooth-function output unit;
• wherein once in N times of a base-point symbol timing corresponding to the base-point symbol rate, another transmission symbol data is input to the sawtooth-function output unit, the another transmission symbol data is obtained by subtracting from the input transmission symbol data an output of the sawtooth-function output unit that is passed through a filter with a transmission function N(D)F1(D)F2(D)−1;
• an output of the sawtooth-function output unit is taken as an output symbol data of the precoder, wherein, in a base-point symbol timing that does not input the transmission symbol data, zero symbol data is output to the filter with the transmission function N(D)F1(D)F2(D)−1 and zero symbol data is taken as the output symbol data of the precoder,
• the correlator adds the output symbol data of the precoder and one obtained by passing the output symbol data though a filter with the transmission function N(D)F1(D)−1 to take the addition result as an output symbol data of the correlator,
• thereby creating the transmission symbol waveform,
• the N(D) is a transmission function of a notch filter for providing a notch characteristic to a spectrum energy of a transmission signal, and an amplitude characteristic of the transmission function F1(D) is set to be close to a peak restriction characteristic of a power spectrum of the transmission signal, and the transmission function F2(D) is set so that the fractionally-spaced equalizer serves as a phase equalizer.