3.2.4.4.1. Polar Encoder parameters¶
3.2.4.4.1.1. --enc-type
¶
Type: text Allowed values: POLAR
AZCW
COSET
USER
Default: POLAR
Examples: --enc-type AZCW
Type of the encoder to use in the simulation.
Description of the allowed values:
Value | Description |
---|---|
POLAR |
Select the standard Polar encoder. |
AZCW |
See the common --enc-type parameter. |
COSET |
See the common --enc-type parameter. |
USER |
See the common --enc-type parameter. |
3.2.4.4.1.2. --enc-no-sys
¶
Enable non-systematic encoding. By default the encoding process is systematic.
3.2.4.4.1.3. --enc-fb-gen-method
¶
Type: text Allowed values: FILE
GA
TV
Examples: --enc-fb-gen-method FILE
Select the frozen bits generation method.
Description of the allowed values:
Value | Description |
---|---|
GA |
Select the GA method from [Tri12]. |
TV |
Select the TV method which is based on Density Evolution (DE) approach from [TV13], to use with the --enc-fb-awgn-path parameter. |
FILE |
Read the best channels from an external file, to use with the --enc-fb-awgn-path parameter. |
Note
By default, when using the GA or the TV method, the frozen bits are optimized for each SNR point. To override this behavior you can use the --enc-fb-sigma parameter.
Note
When using the FILE
method, the frozen bits are always the same
regardless of the SNR value.
3.2.4.4.1.4. --enc-fb-awgn-path
¶
Type: path Rights: read only Examples: --enc-fb-awgn-path example/path/to/the/right/place/
Set the path to a file or a directory containing the best channels to select the frozen bits.
An ASCII file is expected, for instance, the following file describes the most reliable channels optimized for a codeword of size \(N = 8\) and for an AWGN channel where the noise variance is \(\sigma = 0.435999\):
8
awgn
0.435999
7 6 5 3 4 2 1 0
Given the previous file, if we suppose a Polar code of size \(N = 8\) with
\(K = 4\) information bits, the frozen bits are at the 0, 1, 2, 4
positions in the codeword. The strategy is to freeze the less reliable channels.
Warning
The FILE
frozen bits generator expects a file and not a
directory.
Warning
The TV
frozen bits generator expects a directory and not a
file. AFF3CT comes with input configuration files, a part of those
configuration files are a set of best channels pre-generated with the TV
method (see conf/cde/awgn_polar_codes/TV/
).
3.2.4.4.1.5. --enc-fb-sigma
¶
Type: real number Examples: --enc-fb-sigma 1.0
Selects the noise variance \(\sigma\) for which the frozen bits will be optimized. All the noise points in the simulation will use the same frozen bits configuration.
3.2.4.4.1.6. References¶
[TV13] | I. Tal and A. Vardy. How to construct polar codes. IEEE Transactions on Information Theory (TIT), 59(10):6562–6582, October 2013. doi:10.1109/TIT.2013.2272694. |
[Tri12] | P. Trifonov. Efficient design and decoding of polar codes. IEEE Transactions on Communications (TCOM), 60(11):3221–3227, November 2012. doi:10.1109/TCOMM.2012.081512.110872. |