Concatenated convolutional encoder and decoder of mobile...

Details Concatenated convolutional encoder and decoder of mobile... Concatenated convolutional encoder and decoder of mobile...

2000-12-07

2004-12-07

Chin, Stephen (Department: 2634)

Pulse or digital communications

Pulse code modulation

C714S751000

Reexamination Certificate

active

06829305

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
Pursuant to 35 U.S.C. §119(a), this application claims the benefit of earlier filing date and right of priority to Korean Application Nos. 55783/1999, filed on Dec. 8, 1999 and 10166/2000, filed on Feb. 29, 2000, the contents of which are hereby incorporated by reference herein in their entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a encoder and a decoder considered for the next generation mobile communication system requiring high channel coding performance, in particular to a concatenated convolutional encoder and a decoder of a mobile communication system which is capable of providing a dual mode encoder and a decoder for supporting both a parallel concatenated convolutional code and a serially concatenated convolutional code and improving the performance of the system by using punctured and thrown away sequence in a convolutional encoder.
2. Description of the Prior Art
In a mobile communication system according to the conventional technology, a turbo encoder showing high performance is used for low SNR (Signal to Noise Ratio).
The turbo encoder comprises a parallel concatenated convolutional encoder and a serially concatenated convolutional encoder.
Between them, the serially concatenated convolutional encoder showing continual performance improvement stood in the spotlight because the parallel concatenated convolutional encoder shows a performance saturation phenomenon in high SNR.
The serially concatenated convolutional encoder will now be described with reference to accompanying FIG.
1
.
FIG. 1
is a construction profile illustrating the conventional serially concatenated convolutional encoder of the mobile communication system.
As depicted in
FIG. 1
, the conventional serially
3
of the mobile communication system comprises a first RSC (Recursive Systematic Convolutional) encoder
11
for coding an inputted data sequence DO with ½ code rate, a puncturer
12
for puncturing a code outputted from the first RSC encoder
11
with a puncturing pattern
1110
and outputting it, an interleaver
13
for lowering correlation between adjacent data by relocating position of the code outputted from the puncturer
12
after being punctured, and a second RSC encoder
14
for decoding the code relocated by the interleaver
13
with the ½ decode rate and outputting the final code CO.
The operation will now be described in detail.
First, when the data sequence DO is inputted to the first RSC encoder
11
the first RSC encoder
11
codes the inputted data sequence DO with ½ code rate, generates two new sequences and outputs them. Herein, the two sequences outputted from the first RSC encoder
11
are combined as one sequence by a switch (not shown), and is provided to the puncturer
12
.
After that, the puncturer
12
punctures the sequence outputted from the first RSC encoder
11
with the puncturing pattern
1110
, and outputs it to the interleaver
13
.
Herein, in the puncturing pattern
1110
, “1” means the data outputted from the first RSC encoder
11
is outputted to the interleaver
13
as it is, and “0” means the data outputted from the first RSC encoder
11
is punctured, in other words, it is thrown away.
After all, when 4 bits data is outputted from the first RSC encoder
11
, the fourth data is thrown away (punctured), and the rest 3 bits are passed.
In addition, the interleaver
13
randomly relocates the data punctured on the multiple proportion bit of 4, reads it to a column direction, and outputs it. Accordingly the interleaver can lower the correlation between the adjacent codes and outputs it to the second RSC encoder
14
.
The second RSC encoder
14
codes the code outputted from the interleaver
13
with ½ code rate, generates new two sequences, and outputs them. Herein, the outputted two sequences are added by a switch (not shown) as one sequence, and is outputted as a final coded code CO.
Herein, in the conventional serially concatenated convolutional encoder, a encoder of which constraint length is 3 and ½ code rate is used, the first RSC encoder
11
and second RSC encoder
14
use the encoder having same construction.
Meanwhile, the conventional parallel concatenated convolutional encoder comprises two RSC encoders and an interleaver. In other words, in the conventional coding technology, after the input sequence of the first convolutional encoder is relocated through the interleaver, the sequence is used as an input sequence of the second convolutional encoder.
Accordingly, because only data part of the output of the first convolutional encoder can be provided to the input of the second convolutional encoder, the system performance lowering problem occurs in the SNR increasing region, accordingly the credibility of the system lowers due to that.
As described above in detail, in the conventional technology, the input sequence of the first convolutional encoder and second convolutional encoder have same weight values, in partucular when the weight value is 2, a code having low weight value about a certain sequence pattern is generated according to the characteristic of the RSC encoder.
In addition, in the conventional technology, because only data part of the output of the first convolutional encoder can be provided to the input of the second convolutional encoder, accordingly the sudden performance lowering problem occurs in the high SNR region.
In addition, in the conventional technology, because the sudden performance lowering problem occurs in the SNR increasing region, accordingly there is a credibility lowering problem due to that.
In addition, in the conventional technology, in the parallel concatenated convolutional encoder, extrinsic information transmitted/received between the each module in iterative decoding only deals with information about the input sequence to the exclusion of information about parity sequence.
In addition, in the conventional technology, the performance of the system lowers due to the sequence punctured by the serially concatenated convolutional encoder.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide a concatenated convolutional encoder and a decoder of a mobile communication system which is capable of improving performance of the system by using sequence punctured inside of a encoder.
The other object of the present invention is to provide a concatenated convolutional encoder and a decoder of a mobile communication system which is capable of providing a serially convolutional encoder structure having same construction with a parallel concatenated convolutional encoder used in the next generation communication system.
The another object of the present invention is to provide a concatenated convolutional encoder and a decoder of a mobile communication system which is capable of providing single form structure usable as a serially concatenated convolutional encoder and a parallel concatenated convolutional encoder as occasion demands.
The another object of the present invention is to provide a concatenated convolutional encoder and a decoder of a mobile communication system which is capable of multiplexing the output data and parity bit of the first convolutional encoder with an appropriate rate and providing it as an input of the next terminal convolutional encoder.
The another object of the present invention is to provide a concatenated convolutional encoder and a decoder of a mobile communication system which is capable of showing stable performance regardless of SNR fluctuation by setting weight value of the input sequence of the parallel convolutional encoder different from the weight value of the first convolutional encoder in the parallel concatenated convolutional encoder.
In order to achieve the above-mentioned objects, in the concatenated convolutional encoder of the mobile communication system according to the present invention, a serially concatenated convolutional encoder of a mobile communication system for coding an inputted code by puncturing compri

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