Transmission reception device and distortion compensation method

1. A reception device comprising:

a receiver configured to receive a frame signal including synchronization data, main signal data, and an error correction code;

a compensator configured to compensate for distortion of the frame signal based on a compensation coefficient;

a detector configured to detect synchronization timing of the frame signal from the synchronization data;

a corrector configured to correct an error of the frame signal according to the synchronization timing after the distortion is compensated, based on the error correction code;

a generator configured to generate a replica signal from the frame signal after the error is corrected by the corrector, based on the synchronization timing, the replica signal corresponding to the frame signal before the distortion is compensated; and

an update processor configured to update the compensation coefficient based on the replica signal and the frame signal before the distortion is compensated.

2. The reception device as claimed in claim 1 , wherein the update processor updates the compensation coefficient based on the compensation coefficient before the update, the replica signal, and the frame signal before the distortion is compensated.

3. The reception device as claimed in claim 1 , wherein

the frame signal includes data of an I component and a Q component, the compensator has a first filter circuit and a second filter circuit to which compensation coefficients are set by the update processor, respectively,

the first filter circuit compensates for distortion of the data of the I component by filtering the data of the I component and the Q component, and

the second filter circuit compensates for distortion of the data of the Q component by filtering the data of the I component and the Q component.

4. The reception device as claimed in claim 1 , wherein

the frame signal includes data of a first polarized wave component and a second polarized wave component included in an optical signal,

the compensator has a first filter circuit and a second filter circuit to which compensation coefficients are set by the update processor, respectively,

the first filter circuit compensates for distortion of the data of the first polarized wave component by filtering the data of the first polarized wave component and the second polarized wave component, and

the second filter circuit compensates for distortion of the data of the second polarized wave component by filtering the data of the first polarized wave component and the second polarized wave component.

5. The reception device as claimed in claim 1 , further comprising:

a first storage configured to store the frame signal before the distortion is compensated;

a second storage configured to store the frame signal after the error is corrected by the corrector; and

a storage processor configured to store the frame signal in the first storage at first timing whose reference is the synchronization timing, and store the frame signal in the second storage at second timing whose reference is the synchronization timing;

wherein the generator reads the frame signal which is a generation source of the replica signal from the second storage, and

the update processor reads the frame signal corresponding to the replica signal from the first storage.

6. The reception device as claimed in claim 1 , wherein the generator generates the replica signal by omitting at least one of the synchronization data and the error correction code among the synchronization data, the main signal data and the error correction code according to selection.

7. A distortion compensation method executed by a reception device, the method comprising:

receiving a frame signal including synchronization data, main signal data, and an error correction code;

compensating for distortion of the frame signal based on a compensation coefficient;

detecting synchronization timing of the frame signal from the synchronization data;

correcting an error of the frame signal according to the synchronization timing after the distortion is compensated, based on the error correction code;

generating a replica signal from the frame signal after the error is corrected, based on the synchronization timing, the replica signal corresponding to the frame signal before the distortion is compensated; and

updating the compensation coefficient based on the replica signal and the frame signal before the distortion is compensated.

8. The distortion compensation method as claimed in claim 7 , wherein the updating updates the compensation coefficient based on the compensation coefficient before the update, the replica signal, and the frame signal before the distortion is compensated.

9. The distortion compensation method as claimed in claim 7 , wherein

the frame signal includes data of I component and Q component,

the compensating for the distortion comprising:

compensating for distortion of the data of the I component by filtering the data of the I component and the Q component; and

compensating for distortion of the data of the Q component by filtering the data of the I component and the Q component.

10. The distortion compensation method as claimed in claim 7 , wherein

the frame signal includes data of a first polarized wave component and a second polarized wave component included in an optical signal,

the compensating for the distortion comprising:

compensating for distortion of the data of the first polarized wave component by filtering the data of the first polarized wave component and the second polarized wave component; and

compensating for distortion of the data of the second polarized wave component by filtering the data of the first polarized wave component and the second polarized wave component.

11. The distortion compensation method as claimed in claim 7 , the method further comprising:

storing the frame signal before the distortion is compensated in a first storage at first timing whose reference is the synchronization timing;

storing the frame signal after the error is corrected in a second storage at second timing whose reference is the synchronization timing;

reading the frame signal which is a generation source of the replica signal from the second storage; and

reading the frame signal corresponding to the replica signal from the first storage.

12. The distortion compensation method as claimed in claim 7 , wherein the generating generates the replica signal by omitting at least one of the synchronization data and the error correction code among the synchronization data, the main signal data and the error correction code according to selection.