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US 2021/0288746 A1Published application
Error Correction for LDPC Decoders
AssigneeTesat-Spacecom GmbH & Co. KG
InventorFranz Josef Hagmanns
Life of this patent
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Abstract
A reception unit for use in a data link and a method for error correction on a reception word in a data link are specified. A low-density parity-check code, LDPC code, is used to iteratively adapt the reception word by virtue of bit node messages and check node messages being exchanged. The check node messages that are transmitted to the bit nodes are quantized in three levels and adopt the values −1, 0 or +1. The method may thus be implemented with low computational expenditure.
Claims8
A reception unit for use in a data link, comprising:
- a preprocessing unit configured to quantize an analogue value, received from a transmission channel, into a three-level signal Q, wherein the three-level signal may adopt a first value, a second value or a third value, wherein the first value corresponds to a first logic state, the third value corresponds to a second logic state and the second value corresponds to an indeterminate logic state;
- and
- a decoder having a multiplicity of bit nodes and a multiplicity of check nodes, wherein a number of bit nodes is linked in each case to one check node;
- wherein the decoder is configured to iteratively update bit node messages in accordance with the rule:
- B
- (
- n
- )
-
- (
- k
- )
- =
- r
-
- (
- k
- )
- +
- ∑
- l
- ∈
- γ
-
- (
- k
- )
-
- C
- k
- (
- n
- -
- 1
- )
-
- (
- l
- )
- ,
- wherein:
- B(n)(k) is the nth iteration of a message from the bit node n to the check node linked to the bit node n;
- Ck(n) is the nth iteration of a message from the check node n to the bit node k;
- and
- γ(k) is a set of indices of the check nodes linked to the bit node k;
- wherein the decoder (120) is configured to iteratively update check node messages to the bit nodes in accordance with the rule:
- C
- l
- (
- n
- )
-
- (
- k
- )
- =
- ∏
- λ
- ∈
- β
-
- (
- k
- )
- ,
- λ
- ≠
- 1
-
- Q
-
- (
- B
- (
- n
- )
-
- (
- λ
- )
- -
- C
- λ
- (
- n
- -
- 1
- )
-
- (
- k
- )
- )
- ,
- wherein β(k) is a set of indices of the bit nodes linked to the check node k;
- and
- wherein the decoder is configured to determine the three-level signal Q(x) as follows:
- Q
-
- (
- x
- )
- =
- {
- +
- 1
- ,
-
- x
- >
- 0
- ,
- 0
- ,
-
- x
- =
- 0
- ,
- -
- 1
- ,
-
- x
- <
- 0
- .
124 more elements
A method for error correction on a response word on a data link, comprising:
- quantizing an analogue value into a three-level signal Q, wherein the three-level signal may adopt a first value, a second value or a third value, wherein the first value corresponds to a first logic state, the third value corresponds to a second logic state and the second value corresponds to an indeterminate logic state;
- assigning a multiplicity of quantized analogue values to a multiplicity of bit nodes;
- determining check values in a multiplicity of check nodes, wherein each check node is linked to a predefined group of bit nodes;
- iteratively updating bit node messages to the check nodes in accordance with the rule:
- B
- (
- n
- )
-
- (
- k
- )
- =
- r
-
- (
- k
- )
- +
- ∑
- l
- ∈
- γ
-
- (
- k
- )
-
- C
- k
- (
- n
- -
- 1
- )
-
- (
- l
- )
- ,
- wherein:
- B(n)(k) is the nth iteration of a message from the bit node n to the check node linked to the bit node n;
- Ck(n) is the nth iteration of a message from the check node n to the bit node k;
- and
- γ(k) is a set of indices of the check nodes linked to the bit node k;
- iteratively updating check node messages to the bit nodes in accordance with the rule:
- C
- l
- (
- n
- )
-
- (
- k
- )
- =
- ∏
- λ
- ∈
- β
-
- (
- k
- )
- ,
- λ
- ≠
- 1
-
- Q
-
- (
- B
- (
- n
- )
-
- (
- λ
- )
- -
- C
- λ
- (
- n
- -
- 1
- )
-
- (
- k
- )
- )
- ,
- wherein β(k) is a set of indices of the bit nodes linked to the check node k;
- and
- wherein the three-level signal Q(x) is determined as follows:
- Q
-
- (
- x
- )
- =
- {
- +
- 1
- ,
-
- x
- >
- 0
- ,
- 0
- ,
-
- x
- =
- 0
- ,
- -
- 1
- ,
-
- x
- <
- 0
- .
124 more elements
Dependencies are inferred from the claim text.