RECEIVING METHOD, SYNCHRONIZATION DEVICE AND RECEIVING APPARATUS
The synchronization device includes detecting units, a calculation unit, correcting units, a Doppler estimation unit, and offsetting units. The detecting units detect a position of the first sequence and a position of the second sequence in the received signal of each of the plurality of channels received by the plurality of reception units. The calculation unit calculates a time period required to receive a predetermined part of the received signal of each channel on the basis of the detected positions. The correcting unit performs a correcting process of correcting one or both of an outlier included in the position of the first sequence of each channel and an outlier included in the time period calculated for each channel. The Doppler estimation unit estimates Doppler shift by using the time period after the correcting process for each channel. The offsetting unit offsets the received signal by using the Doppler shift for each channel and outputs the received signal divided on the basis of the position of the first sequence after the correcting process to an equalizer.
1 . A receiving method comprising:
detecting a position of a first sequence and a position of a second sequence in a received signal of each of a plurality of channels received by a plurality of receivers;
calculating, for each of the plurality of channels, a time period which has been required to receive a predetermined part of the received signal, based on the detected position of the first sequence and the detected position of the second sequence;
performing a correcting process of correcting one or both of an outlier included in the position of the first sequence having been detected for each of the plurality of channels and an outlier included in the time period having been calculated for each of the plurality of channels;
estimating Doppler shift by using the time period after the correcting process for each of the plurality of channels; and
offsetting the received signal by using the Doppler shift having been estimated for each of the plurality of channels and outputting the received signal divided based on the position of the first sequence after the correcting process to an equalizer.
2 . The receiving method according to claim 1 , wherein
the received signal includes a payload sandwiched between a preamble and a postamble,
the first sequence is a preamble data included in the preamble,
the second sequence is a postamble data included in the postamble, and
the predetermined part of the received signal is from a predetermined position of the preamble to a predetermined position of the postamble.
3 . The receiving method according to claim 1 , wherein
one or both of the outlier included in the position of the first sequence and the outlier included in the time period are is corrected using a robust regression method.
4 . The receiving method according to claim 3 , wherein
the robust regression method is one or more of an iterative weighted least square method, a least median method, a random sample consensus method, convex relaxation, a greedy method for a purpose of lp norm minimization, a proximity gradient method for a purpose of Ip norm minimization, logistic regression, ridge regression, and LASSO regression.
5 . The receiving method according to claim 1 , wherein
each of the plurality of receivers receives a sound wave propagating in water.
6 . A synchronization device comprising:
a detector that detects a position of a first sequence and a position of a second sequence in a received signal of each of a plurality of channels received by a plurality of receivers;
a calculator that calculates, for each of the plurality of channels, a time period which has been required to receive a predetermined part of the received signal, based on the detected position of the first sequence and the detected position of the second sequence;
a correcting circuitry that performs a correcting process of correcting one or both of an outlier included in the position of the first sequence having been detected for each of the plurality of channels and an outlier included in the time period having been calculated for each of the plurality of channels;
a Doppler estimation circuitry that estimates Doppler shift by using the time period after the correcting process for each of the plurality of channels; and
an offsetting circuitry that offsets the received signal by using the Doppler shift having been estimated for each of the plurality of channels and outputs the received signal divided based on the position of the first sequence after the correcting process to an equalizer.
7 . A receiving apparatus comprising:
a plurality of receivers that receive signals of different individual channels;
a detector that detects a position of a first sequence and a position of a second sequence in a received signal of each of a plurality of the channels, the received signals is each of the signals having been received by the plurality of receivers;
a calculator that calculates, for each of the plurality of channels, a time period which has been required to receive a predetermined part of the received signal, based on the detected position of the first sequence and the detected position of the second sequence;
a correcting circuitry that performs a correcting process of correcting one or both of an outlier included in the position of the first sequence having been detected for each of the plurality of channels and an outlier included in the time period having been calculated for each of the plurality of channels;
a Doppler estimation circuitry that estimates Doppler shift by using the time period after the correcting process for each of the plurality of channels;
an offsetting circuitry that offsets the received signal by using the Doppler shift having been estimated for each of the plurality of channels and outputs the received signal divided based on the position of the first sequence after the correcting process; and
an equalizer that performs an equalizing process by using the received signal of each of the plurality of channels output from the offsetting circuitry.