Method and device for decoding low-density parity check code and optical information reproducing apparatus using the same

• US 7,707,482 B2
• Filed: 07/13/2006
• Issued: 04/27/2010
• Est. Priority Date: 06/07/2006
• Status: Expired

• Current Assignee: Wi-LAN Inc.
• Original Assignee: Dongbu Daewoo Electronics Corporation
• Inventors: Chung, Bi-Woong
• Primary Examiner(s): Baker, Stephen M
• Application Number:
  US11/486,449
• Publication Number:
  US 20070288825A1
• Time in Patent Office: 1,384 Days
• Field of Search: 714/780
• US Class Current: 714/780
• CPC Class Codes: G11B 20/10 Digital recording or reproducing
• CPC Class Codes: H03M 13/1102 Codes on graphs and decoding on graphs, e.g. low-density parity check [LDPC] codes
• CPC Class Codes: H03M 13/1105 Decoding
• CPC Class Codes: H03M 13/1111 Soft-decision decoding, e.g. by means of message passing or belief propagation algorithms
• CPC Class Codes: H03M 13/1151 Algebraically constructed LDPC codes, e.g. LDPC codes derived from Euclidean geometries [EG-LDPC codes] H03M13/116, H03M13/1174 take precedence
• CPC Class Codes: H03M 13/1154 Low-density parity-check convolutional codes [LDPC-CC]
• CPC Class Codes: H03M 13/1162 Array based LDPC codes, e.g. array codes
• CPC Class Codes: H03M 13/1177 Regular LDPC codes with parity-check matrices wherein all rows and columns have the same row weight and column weight, respectively
• CPC Class Codes: H03M 13/3723 using means or methods for the initialisation of the decoder

Abstract

A method of decoding a received signal encoded with an LDPC code is provided. The method comprises initializing bits with an initial value of the received signal, obtaining posterior values of the bits by iteratively decoding the bits in a row direction and a column direction, determining on the basis of the posterior values whether an iterative decoding operation should be performed and comparing the posterior values with predetermined values and updating the initial value of the bits, when it is determined that the iterative decoding operation is be performed.

Claims

1. A method of decoding a received signal encoded with an LDPC code, the method comprising:

initializing bits with an initial value of the received signal;

obtaining posterior values of the bits by iteratively decoding the bits in a row direction and a column direction;

determining on the basis of the posterior values whether an iterative decoding operation should be performed; and

comparing the posterior values with predetermined values and updating the initial value of the bits, when it is determined that the iterative decoding operation is performed.

2. The method according to claim 1, wherein the updating of the initial values comprises updating the initial value of the bits when the absolute values of the posterior values are greater than the absolute value of the predetermined value.

3. A device for decoding a received signal encoded with an LDPC code, the device comprising:

an initialization unit initializing bits with an initial value of the received signal;

an iterative decoding unit obtaining posterior values of the bits by iteratively decoding the bits in a row direction and a column direction;

an iteration determining unit determining on the basis of the posterior values whether an iterative decoding operation should be performed; and

a partial compensation unit comparing the posterior values with a predetermined value and updating the initial value of the bits, when it is determined that the iterative decoding operation is performed.

4. The device according to claim 3, wherein the partial compensation unit updates the initial value of the bits when the absolute values of the posterior values are greater than the absolute value of the predetermined value.

5. An optical information reproducing apparatus for reproducing optical information from a reproducing beam generated by irradiating a reference beam to a recording medium, the apparatus comprising:

an optical information detector detecting the reproducing beam and detecting an image of a data page from the reproducing beam;

an equalizer equalizing the image of a data page; and

a data decoder receiving an output of the equalizer as a received signal and decoding an LDPC code,

wherein the data decoder comprises;

an initialization unit initializing bits with an initial value of the received signal;

an iterative decoding unit obtaining posterior values of the bits by iteratively decoding the bits in a row direction and a column direction;

an iteration determining unit determining on the basis of the posterior values whether an iterative decoding operation should be performed; and

a partial compensation unit comparing the posterior values with a predetermined value and updating the initial value of the bits, when it is determined that the iterative decoding operation is performed.

6. The optical information reproducing apparatus according to claim 5, wherein the partial compensation unit varies the degree of increase of the initial value on the basis of values of neighboring data pixels resulting from misalignment between the optical information detector and the recording medium.

7. The optical information reproducing apparatus according to claim 5, wherein the equalizer is MMSE equalizer.

8. The optical information reproducing apparatus according to claim 5, wherein the partial compensation unit updates the initial value of the bits when the absolute values of the posterior values are greater than the absolute value of the predetermined value.