# US 2017/0288708 A1 · Distortion compensation device and distortion compensation method

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- Number: US 2017/0288708 A1
- Document ID: US20170288708A1
- Status: Published application
- Kind: A1
- Application number: 15/426,655
- Filed: 2017-02-07
- Published: 2017-10-05
- Earliest claimed: 2016-03-30
- Assignees: Fujitsu Limited
- Applicants: Fujitsu Limited
- Inventors: Tomoya OTA
- Web page: https://patentgrep.com/patent/US20170288708A1

## CPC

- H04B 1/0475: {with means for limiting noise, interference or distortion (H04B1/0483 takes precedence)}
- H04B 2001/0425: {with linearisation using predistortion}
- H04B: TRANSMISSION

## Abstract

A distortion compensation device includes: an odd-order distortion compensation unit that compensates an odd-order distortion occurring at first frequencies used for transmitting an amplified signal, the first frequencies including a plurality of frequencies; and an even-order distortion compensation unit that compensates an even-order distortion occurring at second frequencies different from the first frequencies due to the amplification of the signal, the second frequencies including one or more frequencies.

## Claims

### Claim 1

A distortion compensation device comprising:
an odd-order distortion compensation unit that compensates an odd-order distortion occurring at first frequencies used for transmitting an amplified signal, the first frequencies including a plurality of frequencies; and
an even-order distortion compensation unit that compensates an even-order distortion occurring at second frequencies different from the first frequencies due to the amplification of the signal, the second frequencies including one or more frequencies.

### Claim 2 (depends on 1)

The distortion compensation device according to claim 1, wherein
the odd-order distortion compensation unit generates a signal resulting from an odd-order distortion compensation process by using, for the first frequencies, a transmission signal at a corresponding frequency and an odd-order distortion compensation coefficient for the corresponding frequency, and
the even-order distortion compensation unit generates a signal resulting from an even-order distortion compensation process by using, for the second frequencies, a transmission signal at one of the first frequencies and an even-order distortion compensation coefficient for the second frequencies.

### Claim 3 (depends on 2)

The distortion compensation device according to claim 2, wherein
when the one of the second frequencies is twice as high as the one of the first frequencies, the even-order distortion compensation unit generates the signal resulting from the even-order distortion compensation process by using a value obtained by squaring the transmission signal at the one of the first frequencies and the even-order distortion compensation coefficient for the one of the second frequencies, and
when the one of the second frequencies is equal to a difference between the plurality of frequencies included in the first frequencies, the even-order distortion compensation unit generates the signal resulting from the even-order distortion compensation process by using a complex conjugate of the transmission signal at the one of the first frequencies, the transmission signal at the one of the first frequencies, and the even-order distortion compensation coefficient for the second frequencies.

### Claim 4 (depends on 2)

The distortion compensation device according to claim 2, further including:
an odd-order updating unit that updates the odd-order distortion compensation coefficient by using, for the first frequencies, an error signal indicating a difference between a transmission signal at a corresponding frequency and a feedback signal and a complex conjugate of a transmission signal at the corresponding frequency; and
an even-order updating unit that updates the even-order distortion compensation coefficient by using, for the second frequencies, an error signal indicating a difference between a zero signal and a feedback signal and a complex conjugate of a signal being a source of an even-order distortion at a corresponding frequency.

### Claim 5

A distortion compensation method comprising:
first compensating an odd-order distortion occurring at first frequencies used for transmitting an amplified signal, the first frequencies including a plurality of frequencies; and
second compensating an even-order distortion occurring at second frequencies different from the first frequencies due to the amplification of the signal, the second frequencies including one or more frequencies.