Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital data error correction
Reexamination Certificate
2002-02-19
2004-12-07
Decady, Albert (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital data error correction
C714S701000
Reexamination Certificate
active
06829742
ABSTRACT:
TITLE OF THE INVENTION
Coding method and coding apparatus for coding a serial data stream.
1. Field of the Invention
The invention relates to a coding method and a coding apparatus for coding a serial data stream using “turbo codes”.
2. Background
The coding matches the data stream from an information data source to a transmission system in order to increase the security of information transmission against interference. In the mobile radio sector, the transmission channel is subject to particularly severe interference. A new class o- coders have therefore been developed, “turbo coders”, which are particularly suitable for coding data to be transmitted in the mobile radio sector. Turbo coders are binary interlinked coding apparatuses comprising a plurality of interlinked coders. In this context, a distinction is drawn between serial-interlinked turbo coders and parallel-interlinked turbo coders.
FIG. 1
shows the design of a serial-interlinked turbo coding apparatus based on the prior art. A serial data stream d originating from an information data source is supplied to a data read-in device for reading in the data d, which reads in the data and codes them to form data frames of predetermined length. The data frames or data blocks are passed to a first coder A, which codes each data item within the data frame on the basis of a coding specification and outputs the coded data as a code data block C
1
to an interleaving circuit. The interleaving circuit scrambles the coded data block C
1
on the basis of an interleaving association specification stored in the interleaving circuit. The interleaving association specification or permutation matrix assigns to each data position within the code data block C
1
a particular other data position. If the code data block comprises five bits, the interleaving circuit assigns the data item at the first position in the coded data block C
1
, for example, to the first position in the interleaved code data block C
1
′, while, by way of example, the data bit situated at the second position in the code data block C
1
is set to the third position of the interleaved code output data block C
1
′.
Table 1 shows an example of an interleaving association or interleaving specification in which an output data sequence is produced from an input data sequence on the basis of the interleaving association specification.
TABLE 1
Input data sequence
x
1
x
2
x
3
x
4
x
5
Output data sequence
x
1
x
3
x
4
x
5
x
2
As can be seen from Table 1, by way of example, the data bit read in at the second position is not output until at the fifth position in the output data block which is output.
The interleaved coded data block C
1
′ is supplied to a downstream-connected coder B which carries out new coding to form a coded data block C
2
. The coded data block C
2
is likewise interleaved by an interleaving circuit and is output via a modulation device to an antenna for data transmission. The coder A is also called the external coder, while the coder B is called the internal coder. The coder A, the interleaving circuit I
1
and the coder B form the actual data channel coder.
The serial-interlinked turbo coding apparatus, as shown in
FIG. 1
, does not perform systematic coding, since the data contained in the original data stream are not themselves transmitted, but instead only coded data are transmitted.
The second group of turbo coders, namely the parallel-interlinked coders, also performs systematic coding.
FIG. 2
shows the design of a parallel-interlinked turbo coder based on the prior art. A serial data stream originating from an information data source and having serial data d is read in by a data read-in device and is combined in groups to form data blocks X. Each data block X comprises a plurality of data bits x
1
. The output of the data read-in device is connected to a first input of a multiplexer by means of a line L
1
. In addition, the output of the data read-in device is connected to the input of a first coder A by means of a line L
2
, said first coder coding the data block X on the basis of a coding specification to form a coded data block C
1
, and outputting it to a puncturing device. In addition, the data block X output at the output of the data read-in device via a line L
3
is interleaved or re-sorted by an interleaving circuit I on the basis of a prescribed permutation matrix. The interleaved data block I(X) is supplied to a second coder (B), which codes the interleaved data block I(X) on the basis of a coding specification to form a code data block C
2
. The coded data block C
2
is likewise supplied to the puncturing device P.
The puncturing device P logically combines the coded data block C
1
and the coded data block C
2
with a respective associated puncturing data field. The puncturing by the puncturing device P is carried out in order to increase the data transmission rate. The punctured coded data block P (C
1
) and the punctured data block P (C
2
) are applied to inputs of the multiplexer, which subjects the data block X which is read in and the two punctured data blocks P(C
1
) and P(C
2
) to time-division multiplexing to form a transmission data block S.
The text below describes the exact manner of operation of the parallel-interlinked turbo coder based on the prior art, as shown in
FIG. 2
, using an example to illustrate the problem on which the invention is based. In this example, the length of the data frame is 5 bits.
From a data source, a serial data stream is read in by the data read-in device and is coded to form a data block X comprising 5 bits:
x=(x
1
,x
2
,x
3
,x
4
,x
5
)
The coder A codes the read-in data block X on the basis of a coding specification to form a code data block C
1
:
C
1
=(c
11
,c
12
,c
13
,c
14
,c
15
)
The interleaving circuit I interleaves the read-in data block X on the basis of the following interleaving association, for example:
TABLE 2
Input X
Output I(x)
x
1
x
1
x
2
x
3
x
3
x
4
x
4
x
5
x
5
x
2
The interleaved data block I(x) is supplied to the coder B, which codes the interleaved data block on the basis of a coding specification to form a coded data block C
2
:
C
2
=(c
21
,c
22
,c
23
,c
24
,c
25
)
To increase the data transmission rate, the puncturing device P punctures the data block C
1
coded by the coder A and the data block C
2
coded by the coder B using a respective associated puncturing data field.
The puncturing data field for puncturing the first coded data block C
1
is as follows:
P
1
=(10101)
The puncturing data field for puncturing the second coded data block C
2
is as follows:
P
2
=(01010)
By logically combining the first coded data block C
1
with the puncturing data field P
1
, a punctured coded data block P(C
1
) having the following form is produced:
P(C
1
)=(c
11
,0,c
23
,0,c
25
)
By puncturing the second coded data block C
2
, a punctured coded data block P(C
2
) is produced:
P(C
2
)=(0,c
22
,0,c
24
,0)
The multiplexer Mux multiplexes the read-in data block X and also the two punctured and coded data blocks P(C
1
), P(C
2
) output by the puncturing device P to form a transmission data block S.
TABLE 3
X = (x
1
, x
2
, x
3
, x
4
, x
5
)
P(C
1
) = (c
11
, 0, c
13
, 0, c
15
),
P(C
2
) = (0, c
22
, 0, c
24
, 0)
S = (x
1
, c
11
, x
2
, c
22
, x
3
, c
13
, x
4
, c
24
, x
5
, c
15
)
The transmission data block S, contains, firstly, a systematic coding information content, because the original read-in data x
1
, x
2
, x
3
, x
4
, x
5
are contained In the transmission data block S, and, secondly, the transmission data block S contains a nonsystematic information content, on account of the coded data c.
However, the parallel-interlinked turbo coding apparatus based on the prior art, as shown in
FIG. 2
, has the drawback that an associated, nonsystematic coded data bit c is not transmitted as nonsystematic information content for each original data bit of the read-in data block X, as becomes evident from the following table:
TABLE 4
X
=
x
1
x
2
x
3
x
4
x
5
C
1
=
c
11
c
12
c
13
c
14
c
15
I
(
x
Jung Peter
Plechinger Joerg
De'cady Albert
Fish & Richardson P.C.
Infineon - Technologies AG
Torres Joseph D.
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