Communication device and communication method

• US 8,976,879 B2
• Filed: 06/06/2013
• Issued: 03/10/2015
• Est. Priority Date: 06/25/2012
• Status: Active Grant

• Current Assignee: ICOM Incorporated
• Original Assignee: ICOM Incorporated
• Inventors: Nishikawa, Nobuyoshi
• Primary Examiner(s): Bocure, Tesfaldet
• Application Number:
  US13/911,945
• Publication Number:
  US 20130343371A1
• Time in Patent Office: 642 Days
• Field of Search: 375/260, 375295-297, 375/316, 370/203, 370/210
• US Class Current: 375/260
• CPC Class Codes: H04L 27/2621 Reduction thereof using phase offsets between subcarriers
• CPC Class Codes: H04L 27/2663 Coarse synchronisation, e.g. by correlation
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT

Abstract

A modulator performs a predetermined operation for making an absolute value of an operation result of at least one element of an input signal greater than 0 on the individual elements of the input signal. The modulator generates post-operation data by associating individual elements of the input signal with individual elements of a data series which is a set of pieces of data which are equal in number to the elements of the input signal and whose absolute values are equal to one another, and multiplying the individual elements of the input signal which are subjected to the predetermined operation by the elements of the data series. An IFFT calculator performs inverse fast Fourier transformation on the post-operation data, and a synthesizer synthesizes operation results from the IFFT calculator to generate a baseband signal. A transmitter generates a transmission signal from the baseband signal and transmits the transmission signal.

Claims

1. A communication device for communicating with another device in orthogonal frequency-division multiplexing wireless communication, the communication device comprising:

a modulator that generates post-operation data which is a parallel signal by associating individual elements of an input signal with individual elements of a data series which is a set of pieces of data which are equal in number to the elements of the input signal and whose absolute values are equal to one another, performing a predetermined operation on the individual elements of the input signal, and multiplying the individual elements of the input signal which are subjected to the predetermined operation by the elements of the data series which are associated with the elements of the input signal, the predetermined operation making an absolute value of an operation result of at least one element of the input signal greater than 0;

an IFFT calculator that performs inverse fast Fourier transformation on the post-operation data;

a synthesizer that synthesizes operation results from the IFFT calculator to generate a baseband signal; and

a transmitter that generates a transmission signal from the baseband signal and transmits the transmission signal.

2. The communication device according to claim 1, wherein the modulator uses, as the data series, an arbitrary data series having an auto-correlation characteristic such that an auto-correlation value between the data series and same data series whose data has not been shifted is higher than an auto-correlation value between the data series and a data series whose data has been subjected to an arbitrary shift.

3. The communication device according to claim 1, further comprising:

a receiver that receives the transmission signal and generates the baseband signal;

an FFT calculator that performs serial-parallel conversion on the baseband signal and performs fast Fourier transformation on a conversion result to generate a parallel signal; and

a demodulator that replaces elements whose absolute values are equal to or greater than a threshold value with 1 and replaces elements other than the elements with 0 in elements of the parallel signal.

4. The communication device according to claim 3, further comprising a synchronizer that uses a predetermined reception-side data series which is a set of pieces of data which are equal in number to the elements of the parallel signal and whose absolute values are equal to one another, the predetermined reception-side data series having an auto-correlation characteristic such that an auto-correlation value between the reception-side data series and same data series whose data has not been shifted is higher than an auto-correlation value between the reception-side data series and a data series whose data has been subjected to an arbitrary shift, and detects a synchronization position of the baseband signal based on a correlation between the reception-side data series and the parallel signal or between data synthesized by performing inverse fast Fourier transformation on the reception-side data series and the baseband signal, wherein the receiver receives the transmission signal, and generates the baseband signal based on the synchronization position detected by the synchronizer.

5. A communication method that is executed by a communication device which communicates with another device in orthogonal frequency-division multiplexing wireless communication, the communication method comprising:

a modulation step of generating post-operation data which is a parallel signal by associating individual elements of an input signal with individual elements of a data series which is a set of pieces of data which are equal in number to the elements of the input signal and whose absolute values are equal to one another, performing a predetermined operation on the individual elements of the input signal, and multiplying the individual elements of the input signal which are subjected to the predetermined operation by the elements of the data series which are associated with the elements of the input signal, the predetermined operation making an absolute value of an operation result of at least one element of the input signal greater than 0;

an IFFT calculation step of performing inverse fast Fourier transformation on the post-operation data;

a synthesis step of synthesizing operation results obtained in the IFFT calculation step to generate a baseband signal; and

a transmission step of generating a transmission signal from the baseband signal and transmitting the transmission signal.

6. The communication method according to claim 5, wherein in the modulation step, an arbitrary data series having an auto-correlation characteristic such that an auto-correlation value between the data series and same data series whose data has not been shifted is higher than an auto-correlation value between the data series and a data series whose data has been subjected to an arbitrary shift is used as the data series.

7. The communication method according to claim 5, further comprising:

a reception step of receiving the transmission signal and generates the baseband signal;

an FFT calculation step of performing serial-parallel conversion on the baseband signal and performs inverse fast Fourier transformation on a conversion result to generate a parallel signal; and

a demodulation step of replacing elements whose absolute values are equal to or greater than a threshold value with 1 and replacing elements other than the elements with 0 in elements of the parallel signal.

8. The communication method according to claim 7, further comprising a synchronization step of using a predetermined reception-side data series which is a set of pieces of data which are equal in number to the elements of the parallel signal and whose absolute values are equal to one another, the predetermined reception-side data series having an auto-correlation characteristic such that an auto-correlation value between the reception-side data series and same data series whose data has not been shifted is higher than an auto-correlation value between the reception-side data series and a data series whose data has been subjected to an arbitrary shift, and detecting a synchronization position of the baseband signal based on a correlation between the reception-side data series and the parallel signal or between data synthesized by performing inverse fast Fourier transformation on the reception-side data series and the baseband signal, wherein in the reception step, the transmission signal is received, and the baseband signal is generated based on the synchronization position detected in the synchronization step.